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A pheromone-mediated mass-trapping program for three species of ambrosia beetle in a commercial sawmill Shore, Terence Leckie 1982

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A PHEROMONE-MEDIATED MASS-TRAPPING PROGRAM FOR THREE SPECIES OF AMBROSIA BEETLE IN A COMMERCIAL SAWMILL by Terence L e c k i e Shore B.Sc. (Honours), U n i v e r s i t y of B r i t i s h Columbia A t h e s i s submitted i n p a r t i a l f u l f i l l m e n t of the requirements f o r the degree of Doctor of Philosophy i n the Department of F o r e s t r y We accept t h i s t h e s i s as conforming to the r e q u i r e d standard The U n i v e r s i t y of B r i t i s h Columbia September, 1982 ©Terence L e c k i e Shore In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available f o r reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of T^O/^ST^-Y  The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 D a t e SePT 7, i i ABSTRACT A commercial sawmill i n B r i t i s h Columbia, Canada, was surveyed i n 1979 f o r the presence of the ambrosia b e e t l e s Trypodendron lineatum ( O l i v i e r ) and Gna t h o t r i c h u s retusus (LeConte) using pheromone-baited t r a p s . The temporal and s p a t i a l d i s t r i b u t i o n and r e l a t i v e abundance of these s p e c i e s were determined. T h i s i n f o r m a t i o n was used d u r i n g 1980 and 1981 to develop a mass-trapping program f o r these s p e c i e s while m a i n t a i n i n g the i n t e g r i t y of an e x i s t i n g t r a p p i n g program f o r a t h i r d ambrosia b e e t l e s p e c i e s , (3^ s u l c a t u s (LeConte). A f o u r t h ambrosia b e e t l e s p e c i e s , Platypus w i l s o n i (Swaine) responded i n s i g n i f i c a n t l y l a r g e r numbers to t r a p s b a i t e d with the pheromone s u l c a t o l p l u s ethanol and o-pinene than to those b a i t e d with the pheromone l i n e a t i n or unbaited. S e v e r a l experiments were conducted i n order to improve or assess the t r a p p i n g system. I t was found that both G_j_ retusus and T\_ lineatum response to t h e i r r e s p e c t i v e pheromones was i n c r e a s e d by the i n c l u s i o n of ethanol and c-pinene on the t r a p s . T. lineatum response to l i n e a t i n was s i g n i f i c a n t l y reduced when s u l c a t o l was i n c l u d e d i n the b a i t . An experiment conducted to determine optimum t r a p height showed that l a r g e s t numbers of T. lineatum were caught on the lowest t r a p s that c l e a r e d surrounding understory v e g e t a t i o n . A mark-recapture technique was t e s t e d as a p o t e n t i a l means of a s s e s s i n g t r a p p i n g e f f i c i e n c y . Recommendations were made that c o u l d r e s u l t i n t h i s technique becoming a u s e f u l means of o p t i m i z i n g and e v a l u a t i n g ambrosia b e e t l e mass-trapping programs. T h i s concurrent mass-trapping program f o r three s p e c i e s of ambrosia b e e t l e s demonstrated that l a r g e numbers of b e e t l e s can be captured using pheromone-baited t r a p s . The r e l a t i v e l y low c o s t of t h i s pest management t a c t i c compared with the high v a l u e s at r i s k has a l r e a d y r e s u l t e d i n much of the technology developed i n t h i s t h e s i s being i n c o r p o r a t e d i n ambrosia b e e t l e management programs by f o r e s t i n d u s t r i e s i n B r i t i s h Columbia. i v DEDICATION T h i s t h e s i s i s d e d i c a t e d to my wife, Jane, who p r o v i d e d constant encouragement and support throughout i t ' s development. V ACKNOWLEDGEMENTS I express my deepest g r a t i t u d e to the f o l l o w i n g persons and o r g a n i z a t i o n s who c o n t r i b u t e d s i g n i f i c a n t l y to t h i s t h e s i s . Dr. J.A. McLean, my s u p e r v i s o r , who int r o d u c e d me to t h i s t o p i c and taught me a great d e a l about r e s e a r c h ; my committee members, Mr. L. V a l g and Drs. R.H. E l l i o t t , D.D. Munro and J . Damaerschalk f o r t h e i r h e l p f u l suggestions and ad v i c e ; J . Bebyck and J . Holman f o r e x c e l l e n t f i e l d and l a b o r a t o r y t e c h n i c a l support; S. Chiyenda f o r s t a t i s t i c a l a d v i c e and Dr. N. A n g e r i l l i f o r advice on the manuscript. A l s o , to personnel from M a c M i l l a n - B l o e d e l L t d . f o r encouraging and a s s i s t i n g me i n t h i s work, e s p e c i a l l y J . R ustulka, G. Grouhel, K. Purchase and the l a t e H. Hagg from the Chemainus sawmill. I would a l s o l i k e to acknowledge the D.S. McPhee F e l l o w s h i p Fund and the N a t u r a l Sciences and Eng i n e e r i n g Research C o u n c i l of Canada f o r f i n a n c i a l support d u r i n g t h i s r e s e a r c h . v i TABLE OF CONTENTS ABSTRACT i i DEDICATION i v ACKNOWLEDGEMENTS v TABLE OF CONTENTS v i LIST OF TABLES v i i i LIST OF FIGURES x i 1.0 INTRODUCTION 1 2.0 BROOD PRODUCTION AND SURVIVAL OF THE AMBROSIA BEETLE Trypodendron lineatum ON YEAR-OLD SPRING-FELLED DOUGLAS-FIR AND WESTERN HEMLOCK LOGS 17 3.0 ESTABLISHMENT OF A PHEROMONE-MEDIATED MASS-TRAPPING PROGRAM AT THE CHEMAINUS SAWMILL FOR THREE SPECIES OF AMBROSIA BEETLE 35 3.1 Survey of the S p a t i a l and Temporal D i s t r i b u t i o n of T. lineatum and G_j_ retusus i n the Chemainus Sawmill, 1979 39 3.2 Expansion of the Mass-trapping Program i n the Chemainus Sawmill to i n c l u d e G^ s u l c a t u s , G. retusus and T_j_ lineatum, 1980 61 3.3 O p e r a t i o n a l Phase of the Mass-trapping Program f o r Three Species of Ambrosia B e e t l e at the Chemainus Sawmill, 1981 75 3.4 A t t r a c t i o n of Platypus w i l s o n i (Swaine) to Traps B a i t e d With S u l c a t o l p l u s Ethanol p l u s o-piriene 86 4.0 FIELD INVESTIGATIONS FOR IMPROVING AND ASSESSING THE AMBROSIA BEETLE MASS-TRAPPING PROGRAM 92 4.1 The E f f e c t of Trap Height on Catches of T. lineatum 92 4.2. D i s t r i b u t i o n of T_y_ lineatum on Suppression t r a p s R e l a t i v e to Pheromone Placement Height 100 4.3 I n v e s t i g a t i o n of the Movement of T\ lineatum and G_j_ s u l c a t u s between the Chemainus Sawmill and I Neighbouring Sawmill 105 v i i 4.4 A F u r t h e r E v a l u a t i o n of the I n t e r a c t i o n s between the Pheromones and Two Host Kairomones of the Ambrosia B e e t l e s , T\ lineatum and G_j_ s u l c a t u s 111 4.5 I n v e s t i g a t i o n of Mark-Recapture as a Technique f o r E v a l u a t i n g the E f f i c i e n c y of an Ambrosia B e e t l e Mass-Trapping Program 120 5.0 CONCLUDING DISCUSSION 146 REFERENCES ...154 v i i i LIST OF TABLES Page Table I Table II Table I I I Table IV Table V Table VI Table VII Table VIII Table IX Table X Dates of f i r s t c o l o n i z a t i o n by S c o l y t i d b e e t l e s on D o u g l a s - f i r and western hemlock f e l l e d May 8, 1978 at the U.B.C. Research F o r e s t , Maple Ridge, B.C 22 Numbers of a t t a c k s by Trypodendron 1ineatum d u r i n g 1979 on D o u g l a s - f i r and western hemlock lo g s f e l l e d on May 8, 1978 a t the U.B.C. Research F o r e s t , Maple Ridge, B.C. .. Brood p r o d u c t i v i t y of Trypodendron lineatum i n D o u g l a s - f i r and western hemlock lo g s at the U.B.C. Research F o r e s t , Maple Ridge, B.C., 1979 Comparison of the mean l e n g t h (± S.E.) of Trypodendron lineatum g a l l e r i e s which produced brood with t h a t of u n s u c c e s s f u l g a l l e r i e s i n D o u g l a s - f i r and western hemlock , R e s u l t s of the a n a l y s i s of v a r i a n c e of Trypodendron lineatum caught on survey t r a p s i n 11 l o c a t i o n s over 29 weeks at the Chemainus sawmill, 1979 23 28 30 T o t a l numbers of Trypodendron 1ineatum caught on t r a p s i n 11 l o c a t i o n s at the Chemainus sawmill, 1979 45 49 R e s u l t s of the a n a l y s i s of v a r i a n c e of Gnathotrichus retusus caught on survey t r a p s i n 11 l o c a t i o n s over 29 weeks at the Chemainus sawmill, 1979 T o t a l numbers of Gnathotrichus retusus caught on t r a p s i n 11 l o c a t i o n s at the Chemainus sawmill, 1979 56 57 The e f f e c t of ethanol p l u s c-pinene on response of Gna t h o t r i c h u s retusus to ( + ) - s u l c a t o l on t r a p s around the Chemainus sawmill, 1979 L o c a t i o n , semiochemical b a i t and t a r g e t s p e c i e s of suppression t r a p s used i n the Chemainus sawmill, 1980 59 64 ix Table XI Numbers of ambrosia b e e t l e s trapped i n the Chemainus sawmill from A p r i l to October, 1980 69 Table XII A comparison of catches of TV lineatum and G_j_ s u l c a t u s between t r a p s b a i t e d with t h e i r r e s p e c t i v e pheromones alone or i n tandem 74 Table XIII Location,semiochemical b a i t and t a r g e t s p e c i e s of suppression t r a p s used i n the Chemainus sawmill, 1981 78 Table XIV Numbers of ambrosia b e e t l e s trapped i n the Chemainus sawmill from A p r i l to October, 1981 81 Table XV R e s u l t s of the two way ANOVA with unequal but p r o p o r t i o n a l s u b c l a s s numbers f o r Platypus w i l s o n i caught over f i v e time p e r i o d s on semiochemical-baited s t i c k y t r a p s i n the Chemainus sawmill, 1980 89 Table XVI Mean number per t r a p of Platypus w i l s o n i caught over f i v e time p e r i o d s on semio-c h e m i c a l - b a i t e d s t i c k y t r a p s i n the Chemainus sawmill, 1980 90 Table XVII R e s u l t s of the a n a l y s i s of v a r i a n c e of T. lineatum caught on pheromone-baited t r a p s suspended at f i v e h e i g h t s i n four l o c a t i o n s f o r three time p e r i o d s 96 Table XVIII Mean number of T_;_ lineatum caught on pheromone-baited t r a p s suspended at f i v e h e i g h t s i n four l o c a t i o n s f o r three time p e r i o d s 97 Table XIX D i s t r i b u t i o n of TV 1 ineatum on a l i n e a t i n -b a i t e d suppression t r a p i n the Chemainus sawmill, 1981 102 Table XX D i s t r i b u t i o n of TV lineatum and G_;_ s u l c a t u s on t r a p s at f i v e l o c a t i o n s between the Chemainus sawmill and a neighbouring sawmill o p e r a t i o n 109 Table XXI Release d e v i c e s and l a b o r a t o r y r e l e a s e r a t e s of semiochemicals used i n Scandin-a v i a n d r a i n p i p e t r a p s set up on the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands, 1981 113 X Table XXII Percentage of t o t a l sums of squares a s s i g n e d to each source of v a r i a t i o n f o r data on response of T\ lineatum and s u l c a t u s to pheromones and two host kairomones 1 15 Table XXIII Table XXIV Table XXV Table XXVI Response by two s p e c i e s of ambrosia b e e t l e to Scandinavian d r a i n p i p e t r a p s b a i t e d with racemic s u l c a t o l , l i n e a t i n or ethanol p l u s o-pinene, alone or i n combination or unbaited c o n t r o l at the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands, 1981 116 Numbers of Trypodendron lineatum marked, r e l e a s e d and recaptured i n the Chemainus sawmill, May 28, 1981 129 Numbers of G n a t h o t r i c h u s s u l c a t u s marked, r e l e a s e d and recaptured i n the Chemainus sawmill, September 8-9, 1981 130 Estimated c o s t s of o p e r a t i n g the mass-tr a p p i n g program f o r G^ s u l c a t u s , G. retusus and T. lineatum at the Chemainus sa w m i l l . . . 1 52 x i LIST OF FIGURES Pages F i g u r e 1 Ambrosia b e e t l e damage on dimension lumber. Holes and dark fungal s t a i n r e s u l t i n degrade 8-9 F i g u r e 2 P e t r i d i s h p l a c e d over T\ lineatum entrance h o l e on a D o u g l a s - f i r l o g i n the U.B.C. Research F o r e s t , Maple Ridge B.C., d u r i n g May 1979 19-20 F i g u r e 3 A c t i v i t y of T\ lineatum recorded d u r i n g 1979 at Maple Ridge, B.C.: (a) Temporal d i s t r i b u t i o n of percent of t o t a l a t t a c k . (b) Mean maximum temperature between sampling i n t e r v a l s . (c) Mean weekly f r a s s p r o d u c t i o n per s u c c e s s f u l g a l l e r y , covered 8 May 1979, of T\ lineatum i n D o u g l a s - f i r and western hemlock l o g s . (d) Temporal d i s t r i b u t i o n of percent of t o t a l emergence 24-25 F i g u r e 4 Developmental p r o f i l e of T_;_ lineatum i n two host s p e c i e s at the U.B.C. Research F o r e s t , 1979 32-33 F i g u r e 5 Wire-mesh survey t r a p as used in the Chemainus sawmill d u r i n g 1979 40-41 F i g u r e 6. Temporal d i s t r i b u t i o n of two s p e c i e s of ambrosia b e e t l e at the Chemainus sawmill, 1979. a. T_^  lineatum, showing maximum d a i l y temperatures and the c r i t i c a l f l i g h t temperature (Tf) (Chapman and Kinghorn 1958). b. G_^  retusus 46-47 F i g u r e 7 S p a t i a l d i s t r i b u t i o n of two s p e c i e s of ambrosia b e e t l e at the Chemainus sawmill, 1979. a. T\ lineatum b. G_^  retusus 50-51 F i g u r e 8 Sex r a t i o and number of T\ lineatum caught on survey t r a p s i n the Chemainus sawmill, . 1979 53-54 x i i F i g u r e 9 F i g u r e 10 F i g u r e 11 F i g u r e 12 F i g u r e 13 F i g u r e 14 F i g u r e 15 F i g u r e 16 F i g u r e 17 F i g u r e 18 F i g u r e 19 Suppression t r a p c o n s i s t i n g of two vanes o r i e n t e d at 90 degrees from a support post, as used i n the Chemainus sawmill i n 1980, 1981 62-63 Temporal d i s t r i b u t i o n of p r o p o r t i o n of t o t a l of three s p e c i e s of ambrosia b e e t l e captured on suppression t r a p s i n the Chemainus sawmill, 1980. a. T_j_ lineatum b. G_j_ s u l c a t u s c. G_j_ retusus 67-68 D i s t r i b u t i o n of t o t a l catches of three s p e c i e s of ambrosia b e e t l e s caught on suppression t r a p s at the Chemainus sawmill, 1980 70-71 Aluminum pheromone-holder and r a i n -p r o t e c t o r d evice a t t a c h e d to suppression t r a p s i n the Chemainus sawmill, 1981 76-77 D i s t r i b u t i o n of t o t a l catches of three s p e c i e s of ambrosia b e e t l e s caught on suppression t r a p s at the Chemainus sawmill, 1981 82-83 F i v e survey t r a p s suspended i n s e r i e s such that the bottoms of the t r a p s were at 0.0, 1„0, 2.0, 3.0 and 4.0 metres above ground. ... 94-95 Scandinavian d r a i n p i p e t r a p (Borregaard A.S., Sarpsborg, Norway) 107-108 T. lineatum marked with f l u o r e s c e n t p a i n t powder and photographed i n u l t r a - v i o l e t l i g h t 1 26-1 27 D i s t r i b u t i o n of percentage of t o t a l marked T. lineatum recaptured on t r a p s around the Chemainus sawmill, 28 May 1981. a. Orange b. Purple 135-136 D i s t r i b u t i o n of percentage of t o t a l marked T. lineatum recaptured on t r a p s around the Chemainus sawmill, 28 May 1981. a. Red b. Green 137-138 D i s t r i b u t i o n of percentage of t o t a l Blue marked T_j_ lineatum r e c a p t u r e d on t r a p s around the Chemainus sawmill, 28 May 1981. ...140-141 x i i i F i g u r e 20 D i s t r i b u t i o n of numbers of four c o l o u r s of marked s u l c a t u s recaptured on t r a p s around the Chemainus sawmill, 8-9 September, 1981 143-144 1 1.0 INTRODUCTION Ambrosia b e e t l e s or "pinworms" as they are o f t e n termed i n the f o r e s t i n d u s t r y , are a group of b e e t l e s composed of a l l of the f a m i l y P l a t y p o d i d a e and many of the S c o l y t i d a e , t o t a l l i n g over 1000 s p e c i e s . They range i n l e n g t h from 1 to 10 mm and are d i s t r i b u t e d worldwide (Anonymous 1972). In B r i t i s h Columbia there are at l e a s t f i v e ambrosia b e e t l e s p e c i e s , Trypodendron lineatum ( O l i v i e r ) , G n a thotrichus s u l c a t u s (LeConte), G_L retusus (LeConte), Platypus w i l s o n i Swaine, and Xyleborus saxeseni (Ratz.) which bore i n t o commercial c o n i f e r s (Prebble and Graham 1957). Of these f i v e s p e c i e s i t i s g e n e r a l l y acknowledged that lineatum i s the most abundant and r e s p o n s i b l e f o r the m a j o r i t y of the ambrosia b e e t l e damage i n B r i t i s h Columbia, f o l l o w e d by G_^  s u l c a t u s (McBride and Kinghorn 1960; McMullan 1956). G^ retusus i s s i m i l a r i n s i z e and appearance to G_^  s u l c a t u s . I t s s i g n i f i c a n c e i n B r i t i s h Columbia as a pest i s not w e l l documented. G^ retusus damage may have been confused with and i n c l u d e d as s u l c a t u s damage i n some of the e a r l i e r l i t e r a t u r e . X_^  saxeseni i s a small h o l a r c t i c s p e c i e s that due to i t s s i z e and h a b i t of only b o r i n g i n wood to a shallow depth i s of minor importance to the B r i t i s h Columbia f o r e s t i n d u s t r y . P_j_ w i l s o n i i s an extremely damaging sp e c i e s but i t s long development p e r i o d r e s u l t s i n i t s being of l e s s economic importance than T\ lineatum, G. s u l c a t u s and retusus (Prebble and Graham 1957). 2 The B i o l o g i e s of TV lineatum, G. s u l c a t u s and G_j_ retusus Trypodendron lineatum The most economically important ambrosia b e e t l e s p e c i e s i n B r i t i s h Columbia, TV^  lineatum, has been e x t e n s i v e l y s t u d i e d with l i t e r a t u r e d a t i n g from 1873 r e c e n t l y reviewed by N i j h o l t (1979). T h i s i n s e c t i s from 2.7 to 3.5 mm long and 1.7 mm wide ( B r i g h t 1976). I t s range extends from Alaska and Newfoundland to Mexico and North C a r o l i n a as w e l l as Europe and Northern A s i a . Most c o n i f e r o u s and some hardwood s p e c i e s w i t h i n i t s range are a t t a c k e d (Wood 1982). In B r i t i s h Columbia a l l native'commercial s p e c i e s are s u b j e c t to a t t a c k by TV lineatum (McMullan 1956). Adu l t b e e t l e s overwinter i n the f o r e s t duff and the bark of t r e e s and o l d stumps (Hadorn 1933; Dyer and N i j h o l t 1965). In the s p r i n g the b e e t l e s emerge from the duff and f l y when the temperature exceeds 15.5° C (Chapman and Kinghorn 1958). Most a t t a c k f l i g h t occurs w i t h i n a few weeks of t h i s occurrence (Chapman and N i j h o l t 1980). Peak d i u r n a l f l i g h t i s around mid-afternoon (Daterman et a l . 1965). T h i s f l i g h t i s at f i r s t s t r o n g l y p h o t o p o s i t i v e but the p h o t i c response i s soon r e p l a c e d by a chemotropic response p o s s i b l y r e l e a s e d by a i r - s w a l l o w i n g d u r i n g f l i g h t (Graham 1959, 1961). TV lineatum p r e f e r s logs f e l l e d at l e a s t two to four months p r i o r to i t s s p r i n g f l i g h t (Mathers 1935; Prebble and Graham 1957; Dyer and Chapman 1965) and l o c a t e s s u i t a b l e m a t e r i a l through d e t e c t i o n of c e r t a i n host v o l a t i l e s termed "primary a t t r a c t a n t s " (Chapman 1962). E t h a n o l , l a t e r found to be one of 3 these a t t r a c t a n t s (Moeck 1970, 1971) i s produced i n the dead or dying t r e e by anaerobic r e s p i r a t i o n of host t i s s u e (Graham 1968). V a r i o u s terpenes, e s p e c i a l l y c-pinene have a l s o been c o n s i d e r e d to have a r o l e i n primary a t t r a c t i o n (Chararas 1961; Bauer and V i t e 1975; N i j h o l t and SchSnherr 1976). However, there are some r e p o r t s of T i lineatum being r e p e l l e d by or i n d i f f e r e n t to terpenes (Werner and Graham 1957; Rudinsky 1966; Moeck 1970; N i j h o l t 1973a). The host t r e e i s i n i t i a l l y a t t a c k e d by a very few b e e t l e s of the " f i r s t - a t t a c k i n g sex" c a l l e d " pioneer" b e e t l e s . As i n most monogamous s c o l y t i d s p e c i e s (Borden 1974) t h i s i s the female i n T\ lineatum. 1974). A f t e r l o c a t i n g a s u i t a b l e host, b o r i n g i s i n i t i a t e d by the female b e e t l e and subsequently a "secondary" a t t r a c t a n t , produced in the hindgut r e g i o n of the b e e t l e i s r e l e a s e d (Rudinsky and Daterman 1964; Chapman 1966; Borden and S l a t e r 1969; Schneider and Rudinsky 1969). T h i s secondary a t t r a c t a n t i s an "aggregation pheromone" which causes both sexes of a s p e c i e s to aggregate i n a p a r t i c u l a r area as opposed to a "sex pheromone" which a c t s as a chemical messenger between sexes of a s p e c i e s (Shorey 1973). The pheromone of T\ lineatum was i s o l a t e d and i d e n t i f i e d as one of two t r i c y c l i c k e t a l s and given the t r i v i a l name " l i n e a t i n " (MacConnell et a l . 1977). These compounds were l a t e r s y n t h e s i z e d and f i e l d t e s t e d thus c o n f i r m i n g the i d e n t i t y of the pheromone as 3 , 3 , 7 - t r i m e t h y l - 2 , 9 - d i o x a t r i c y c l o -[3.3.1.0°» 7] nonane (Borden et a l . 1979, 1980a). Once both sexes are present, mating occurs on the l o g s u r f a c e (Hadorn 1933; Chapman 1955a, 1962) f o l l o w e d by continued 4 e x c a v a t i o n of the g a l l e r y . The female does the b o r i n g and the male c l e a r s the tunnel of f r a s s , although male presence i s not necessary f o r g a l l e r y completion or brood p r o d u c t i o n f o l l o w i n g mating (Chapman 1959). I t has been suggested that the male r e l e a s e s a "pheromone mask" which r e s u l t s i n eventual r e d u c t i o n in l o g a t t r a c t i v e n e s s as i t becomes w e l l c o l o n i z e d ( N i j h o l t 1970, 1973b; Borden 1973). Klimetzek et a l . (1981) found that t r a p catches were reduced when wood m a t e r i a l c o l o n i z e d by male and female b e e t l e s was added and that pheromone p r o d u c t i o n i n the female was reduced i n the presence of male b e e t l e s . The b e e t l e s do not feed on the wood (Chapman 1955a) but on an e c t o s y m b i o t i c fungus which the females c a r r y i n s p e c i a l i z e d ectodermal r e p o s i t o r i e s c a l l e d "mycangia" or "mycetangia". The fungus i s i n t r o d u c e d i n t o the g a l l e r y d u r i n g the i n i t i a l a t t a c k (Francke-Grosman 1956, 1963; F a r r i s and Chapman 1957; Schneider and Rudinsky 1969). The s p e c i e s of "ambrosia" fungus a s s o c i a t e d with TV 1ineatum has been i d e n t i f i e d as M o n i l i a f e r r u g i n e a Mathiesen-Kaarik (Mathiesen-KaSrik 1953; Funk 1965). Once intr o d u c e d to the g a l l e r y the fungus begins to grow. The hyphae penetrate the surrounding cut c e l l s and the fungus begins to s p o r u l a t e i n t o the g a l l e r y . The ambrosia b e e t l e s feed on these " c o n i d i o p h o r e s " which, when cropped, continue to r e p l a c e themselves. T h i s fungal growth r e s u l t s i n a dark s t a i n w i t h i n a few weeks of b e e t l e a t t a c k ( F i s h e r et a l . 1953, 1954). O v i p o s i t i o n commences w i t h i n the f i r s t two weeks of g a l l e r y c o n s t r u c t i o n with the eggs l a i d i n d i v i d u a l l y i n niches along the g a l l e r y . The eggs hatch i n about 10 days and the l a r v a e extend 5 these niches i n t o l a r v a l " c r a d l e s " i n which they pupate about 3 weeks a f t e r h a t c h i n g . F o l l o w i n g an approximate 10 day pupation the young a d u l t s emerge and 2-3 weeks l a t e r leave the g a l l e r i e s and f l y to nearby duff to overwinter (Hadorn 1933; Prebble and Graham 1957). An average of approximately 10 brood per s u c c e s s f u l g a l l e r y or 6 brood per g a l l e r y has been found i n s t u d i e s on western hemlock Tsuga h e t e r o p h y l l a (Raf.) Sarg. and D o u g l a s - f i r Pseudotsuqa m e n z i e s i i (Mirb.) Franco (Dyer 1963; Chapman and Dyer 1969). Parent b e e t l e s have been found to emerge, overwinter and a t t a c k l o g s again the f o l l o w i n g year (Chapman 1955b, 1956; Chapman and N i j h o l t 1965). G n a t h o t r i c h u s spp. The b i o l o g i e s of G^ retusus and GV s u l c a t u s are s i m i l a r (Doane et a l . 1936; Prebble and Graham 1957) and so s h a l l be c o n s i d e r e d t o g e t h e r . These b e e t l e s are from 3.4 to 4.0 mm long and approximately 1.3 mm wide ( B r i g h t 1976). U n l i k e T\_ 1ineatum  G n a t h o t r i c h u s spp. overwinter w i t h i n the host wood m a t e r i a l . The g e n e r a t i o n s of Gnathotrichus spp. are not d i s t i n c t as eggs, l a r v a e , pupae and a d u l t s can o f t e n be found at any given time (Doane et a l . 1936; Zanuncio 1981). B e e t l e s begin to emerge and f l y i n the s p r i n g when temperatures exceed 16° C but are l e s s than 26° C (Rudinsky and Schneider 1969). Mature b e e t l e s w i l l c o n tinue to emerge, f l y and a t t a c k host m a t e r i a l throughout the summer (Daterman et a l . 1965; Richmond 1968). U n l i k e T. lineatum both G n a t h o t r i c h u s s p e c i e s are c r e p u s c u l a r , p r e f e r r i n g f l i g h t when l i g h t i n t e n s i t i e s are l e s s than 2000 6 f o o t c a n d l e s but not dark (Rudinsky and Schneider 1969). Gna t h o t r i c h u s spp. do not appear to have the same "aging" requirement f o r t h e i r hosts as T\ 1ineatum. G. s u l c a t u s were found a t t a c k i n g western hemlock logs as soon as one week and as long as 15 months a f t e r f e l l i n g (Mathers 1935). Gnathotrichus spp. may p r e f e r stumps over logs but w i l l c o l o n i z e both (McLean and Borden 1977a; Zanuncio 1981). U n l i k e T\ lineatum and as an exception i n monogamous s c o l y t i d s p e c i e s , male Gnathotrichus spp. are the f i r s t - a t t a c k i n g sex (Borden 1974), i n i t i a t e b o r i n g (Prebble and Graham 1957) and produce the pheromone (Borden and Stokkink 1973; Borden and McLean 1979). The aggregation pheromones of G^ s u l c a t u s and G^ retusus have been i s o l a t e d and i d e n t i f i e d as d i f f e r e n t enantiomeric r a t i o s of the same compound, 6-methyl-5-hepten-2-ol, given the t r i v i a l name " s u l c a t o l " (Byrne et a l . 1974; Borden et a l . 1976, 1980b; Borden and McLean 1979). G_^  s u l c a t u s responds to the racemic and other mixtures while G^ retusus responds to S - ( + ) - s u l c a t o l ( h e r e a f t e r r e f e r r e d to as ( + ) - s u l c a t o l ) . Response of G^ retusus i s i n h i b i t e d when a high p r o p o r t i o n of the R-(-) enantiomer i s present (Borden et a l . 1980c). Ethanol has been i d e n t i f i e d as a primary a t t r a c t a n t f o r G. s u l c a t u s (Cade et a l . 1970; Moeck 1971; McLean 1976) and c-pinene was a l s o found to be a t t r a c t i v e to G n a t h o t r i c h u s spp. (Rudinsky 1966). Ethanol and c-pinene were found to act s y n e r g i s t i c a l l y with the pheromones of both s p e c i e s i n a t t r a c t i n g b e e t l e s to t r a p s (Borden et a l . 1980). Once on the host the male Gnathotrichus spp. i n i t i a t e s the 7 b o r i n g of the g a l l e r y but the female takes over t h i s r o l e s h o r t l y a f t e r j o i n i n g the male (Prebble and Graham 1957). Male Gn a t h o t r i c h u s spp. c a r r y the ambrosia fungi ( F a r r i s 1963; Schneider and Rudinsky 1969) which have been i d e n t i f i e d as A m b r o s i e l l a s u l c a t i Funk, Raphaella s u l c a t i Funk and Graphiurn spp. f o r G_j_ s u l c a t u s (Funk 1970). As with T\ lineatum, G n a t h o t r i c h u s spp. bore a branched g a l l e r y i n a s i n g l e plane at r i g h t angles to the long a x i s of the l o g (Prebble and Graham 1957). U n l i k e T\ lineatum however, Gn a t h o t r i c h u s spp. overwinter i n the host m a t e r i a l and may continue to extend g a l l e r i e s as long as the wood r e t a i n s s u f f i c i e n t moisture f o r the growth of the a s s o c i a t e d fungi (Doane et a_l. 1936). An average of 2.3 and 10.7 brood per g a l l e r y were produced by G n a t h o t r i c h u s spp. i n D o u g l a s T f i r and western hemlock trunks r e s p e c t i v e l y (Zanuncio 1981). Economic Importance S e v e r a l aspects of the b i o l o g i e s of T_^  lineatum, G. s u l c a t u s and G^ retusus b r i n g these i n s e c t s i n t o c o n f l i c t with the f o r e s t i n d u s t r y . T h e i r preference f o r commercial c o n i f e r s p e c i e s s i n g l e s them out as p e s t s . The h o l e s from t h e i r g a l l e r i e s and the d a r k - s t a i n i n g of the wood caused by the a s s o c i a t e d f u n g i occur i n the most v a l u a b l e , c l e a r p o r t i o n of the l o g s ( F i g . 1). Attack d e n s i t i e s of over 250 holes per square foot (.093 m2) have been r e p o r t e d (Prebble and Graham 1957). T h i s damage, although more a t e c h n i c a l than s t r u c t u r a l d e f e c t r e s u l t s i n degrade of the lumber or plywood veneer 8 F i g u r e 1. Ambrosia b e e t l e damage on dimension lumber. Holes and dark fungal s t a i n r e s u l t i n degrade. 9 10 product g r e a t l y reducing v a l u e . For example, i n J u l y 1979 c l e a r D o u g l a s - f i r 2 X 8 inch (5 X 20 cm) dimension lumber was worth $989.00 1 per Mfbm. I f t h i s lumber was densely a t t a c k e d by ambrosia b e e t l e s i t c o u l d be degraded to No. 3 Common grade worth $160.00 per Mfbm, an 84% r e d u c t i o n i n v a l u e . T h e i r h a b i t of a t t a c k i n g and d e v e l o p i n g i n green lumber ( F i s h e r et a_l. 1953, 1954; McLean and Borden 1975a) has r e s u l t e d i n export and quarantine problems i n s e n s i t i v e markets such as New Zealand and A u s t r a l i a (Graham and Boyes 1950; M i l l i g a n 1970; Bain 1974). For t h i s reason a d d i t i o n a l care has to be taken to keep damaged or i n f e s t e d m a t e r i a l out of export shipments. T h i s p r e c a u t i o n means a d d i t i o n a l c o s t s due to i n c r e a s e d h a n d l i n g , repackaging and remanufacturing (Richmond 1968). Other l o s s e s occur because of higher c u l l f a c t o r s i n s c a l i n g (McBride 1950), reduced lumber recovery caused by e x t r a s l a b b i n g i n order to e s t a b l i s h a c l e a r f a c e , p r o d u c t i o n of more boards and dimension lumber and l e s s volume of the more v a l u a b l e timbers (McMullan 1956) and i n c r e a s e d manufacturing time (Graham and Boyes 1950). Although T_j_ 1 ineatum appears to cause most of the ambrosia b e e t l e damage i n B r i t i s h Columbia due to i t s l a r g e and c o n c e n t r a t e d s p r i n g a t t a c k - f l i g h t , G n a t h o t r i c h u s spp. may be i n d i v i d u a l l y more damaging (McMullan 1956). Gnathotrichus spp. bores to a depth of about 6.5 cm i n D o u g l a s - f i r and 7.5 to 9 cm i n western hemlock and a m a b i l i s f i r Abies a m a b i l i s (Dougl.) Forbes, while T\ lineatum a t t a c k s are g e n e r a l l y l i m i t e d to the 1 Lumber p r i c e s p r o v i d e d by M a c M i l l a n - B l o e d e l L t d . 11 outer 4 cm i n D o u g l a s - f i r and 5 to 6 cm i n western hemlock and a m a b i l i s f i r (Graham et a l . 1950; McBride 1950; Prebble and Graham 1957). Gnathotrichus b e e t l e s a l s o seem to more f r e q u e n t l y a t t a c k green lumber, are l e s s p a r t i c u l a r with respect to seasoning of the host m a t e r i a l and have a more continuous f l i g h t p e r i o d than J_;_ lineatum (McMullan 1956). Attempts to e v a l u a t e l o s s e s due to ambrosia b e e t l e s have been l a r g e l y u n s u c c e s s f u l because of the many f a c t o r s i n v o l v e d . Damage v a r i e s with ambrosia b e e t l e s p e c i e s , d e n s i t y of a t t a c k , t r e e s p e c i e s and t r e e diameter (Graham et a l . 1950). A l s o , the eventual grade of a wood product depends on many f a c t o r s and i t i s d i f f i c u l t to i s o l a t e ambrosia b e e t l e damage from other d e f e c t s . To a c e r t a i n extent grading i s r e l a t e d to the eventual market f o r the wood product and s p e c i a l grades are sometimes e s t a b l i s h e d f o r s p e c i a l o r d e r s . Another c o m p l i c a t i n g f a c t o r i n e v a l u a t i n g degrade l o s s e s i s that lumber showing b e e t l e damage i s sometimes remanufactured; f o r example an otherwise c l e a r p i e c e of 2 X 12 inch (5 X 30 cm) dimension lumber may be degraded due to b e e t l e damage along one edge or i t may be remanufactured i n t o one c l e a r 2 X 6 (5 X 15 cm) p i e c e and one degraded 2 X 6 p i e c e . The l o s s i n value i s not equal i n the two cases and complicates e v a l u a t i o n procedures (Richmond 1968). Some e f f o r t s have been made to e v a l u a t e grade l o s s e s i n a t t a c k e d l o g s however (Graham et a l . 1950; McBride 1950; McBride and Kinghorn 1960). The study by McBride and Kinghorn ( i 9 6 0 ) , updated i n 1978 by Dobie, showed l o s s e s i n l i g h t to moderately a t t a c k e d f i r grade 2 logs of $33.87 per Mfbm and i n f i r grade 3 1 2 logs of $20.38 per Mfbm using "R L i s t " grading rules'. N i j h o l t (1978a) s t a t e d that 1975-6 l o s s e s due to the ambrosia b e e t l e i n B r i t i s h Columbia were estimated at $7 m i l l i o n by the Western F o r e s t Products L a b o r a t o r y . 1 T h i s f i g u r e i s b e l i e v e d to be low by people f a m i l i a r with the problem i n c l u d i n g the author ( N i j h o l t p e r s . comm.)2 and no i n f o r m a t i o n was pro v i d e d on how i t was d e r i v e d . C e r t a i n trends i n f o r e s t r y p r a c t i c e s i n B r i t i s h Columbia are i n c r e a s i n g the p o t e n t i a l impact of ambrosia b e e t l e s on the f o r e s t i n d u s t r y . R e s t r i c t i o n s on water t r a n s p o r t and storage of logs have r e s u l t e d i n many op e r a t i o n s changing over to d r y l a n d s o r t i n g and storage yards. T h i s i n c r e a s e s the s u r f a c e area exposed to ambrosia b e e t l e a t t a c k ( N i j h o l t 1978a) and c u r t a i l s immersion-induced m o r t a l i t y of b e e t l e s i n i n f e s t e d logs i n water (McLean and Borden 1977b). A l s o , with c o n t i n u i n g i n c r e a s e s i n energy c o s t s there i s a tr e n d away from k i l n - d r y i n g and towards s h i p p i n g green lumber (L. Va l g , p e r s . comm.).3 T h i s i n c r e a s e s the r i s k of l i v e b e e t l e s being t r a n s p o r t e d to export markets. For example l i v e Gnathotrichus spp. l a r v a e were i n t e r c e p t e d i n New Zealand i n green D o u g l a s - f i r lumber shipped from North America (Bain 1974). I n t e r c e p t i o n s such as t h i s r e s u l t i n quarantine and fumigation of the cargo, the c o s t s of which are borne by the exporter (Graham and Boyes 1950). K i l n - d r y i n g has 1 Now F o r i n t e k Canada Corp., Western La b o r a t o r y . 2 Formerly Research T e c h n i c i a n , Canadian F o r e s t r y S e r v i c e , P a c i f i c F o r e s t Research Centre; p r e s e n t l y Research S c i e n t i s t , Safer Agro-Chem L t d . , V i c t o r i a B r i t i s h Columbia. 3 A s s i s t a n t P r o f e s s o r , F a c u l t y of F o r e s t r y , U n i v e r s i t y of B r i t i s h Columbia. 13 been found to be e f f e c t i v e i n k i l l i n g a l l ambrosia b e e t l e s i n t r e a t e d lumber (Hopping and Jenkins 1933). Another t r e n d i n the f o r e s t i n d u s t r y that i s i n c r e a s i n g the economic impact of ambrosia b e e t l e s i s the trend towards the u t i l i z a t i o n of s m a l l e r t r e e s as the i n d u s t r y begins to r e l y on "second-growth" f o r e s t s . The sapwood area, which i s i n h a b i t e d and thus degraded by ambrosia b e e t l e s , r e p r e s e n t s a g r e a t e r p r o p o r t i o n of t o t a l volume i n small t r e e s than i n l a r g e ones. F i n a l l y , the use of chemical p e s t i c i d e s i n f o r e s t r y has been l a r g e l y c u r t a i l e d due to environmental concerns. Some i n s e c t i c i d e s had been found to be e f f e c t i v e i n p r o t e c t i n g logs from ambrosia b e e t l e a t t a c k (Richmond 1968). Reduction of l o s s e s due to ambrosia b e e t l e s There i s , at present, no s u c c e s s f u l method of e l i m i n a t i n g damage caused by ambrosia b e e t l e s but i t i s p o s s i b l e to minimize l o s s e s . The most e f f e c t i v e method of reducing ambrosia b e e t l e damage i s through c a r e f u l i n v e n t o r y management. By minimizing the time between f e l l i n g and p r o c e s s i n g , the r i s k of damage i s reduced. Logs f e l l e d before February are "high r i s k " f o r T. lineatum i n the f o l l o w i n g s p r i n g and so should be given p r i o r i t y f o r removal and u t i l i z a t i o n ( N i j h o l t 1978a). I n v e n t o r i e s should be kept low du r i n g the a c t i v e f l i g h t p e r i o d s of the b e e t l e although t h i s i s not u s u a l l y f e a s i b l e as t h i s p e r i o d c o i n c i d e s with the p e r i o d of optimum l o g g i n g weather (Richmond 1968). Some chemical c o n t r o l of ambrosia b e e t l e s has been 1 4 attempted but t h i s has been l a r g e l y u n s a t i s f a c t o r y both from a c o n t r o l and environmental p o i n t of view. Benzene h e x a c h l o r i d e (BHC), and i n p a r t i c u l a r i t s gamma isomer " l i n d a n e " , became the most widely used chemical i n s e c t i c i d e f o r s u r f a c e p r o t e c t i o n of l o g s as i t gave the most c o n s i s t e n t and l a s t i n g p r o t e c t i o n . Many other compounds have been t e s t e d and determined to be u n s a t i s f a c t o r y (Kinghorn 1956). The main problem was access to a l l s u r f a c e s of logs i n the f i e l d . Reasonable p r o t e c t i o n c o u l d be given u s i n g BHC on p i l e d l o g s but chemical spray was only economically advantageous when exposed s u r f a c e s of l o g booms were sprayed with BHC by h e l i c o p t e r (Richmond 1961). T h i s usage, however, was c u r t a i l e d when BHC and l i n d a n e were determined to accumulate i n a q u a t i c organisms. Attempts to f i n d replacement chemical i n s e c t i c i d e s have been u n s u c c e s s f u l (Hedlin and Woods 1970). Reducing damage i n d r y l a n d s o r t i n g areas by "water-misting" has proven s u c c e s s f u l (Richmond and N i j h o l t 1972). T h i s i n v o l v e s p i l i n g logs i n the range of a s p r i n k l e r system and g i v e s good p r o t e c t i o n i n a l i m i t e d s i t u a t i o n . A n a l y s i s has shown that t h i s o p e r a t i o n i s economically e f f i c i e n t with a c o s t / b e n e f i t of 1:4 to 1:6 ( N i j h o l t 1978b). However, t h i s method does nothing f o r l o g s a t t a c k e d before they reach the s o r t or lumber a t t a c k e d i n the sawmill. A l s o , a s u b s t a n t i a l water r e s e r v o i r and good drainage are necessary ( N i j h o l t 1980) and the c o n t i n u a l wetness makes working c o n d i t i o n s unpleasant. N i j h o l t (1980) has found that " p i n e - o i l " , a d i s t i l l a t e d e r i v e d as a by-product of sulphate woodpulping, and o l e i c a c i d 15 a p p l i e d to l o g s e c t i o n s s i g n i f i c a n t l y delayed and reduced a t t a c k by ambrosia b e e t l e s . F u r t h e r work needs to be done to e v a l u a t e the mode of a c t i o n and p o t e n t i a l of these compounds i n ambrosia b e e t l e c o n t r o l . The development of systems f o r i n t e r c e p t i n g ambrosia b e e t l e s before they can a t t a c k v a l u a b l e wood m a t e r i a l shows c o n s i d e r a b l e promise. Trap logs or lumber p i l e s i . e . wood l e f t d e l i b e r a t e l y to absorb f l y i n g b e e t l e s and processed before the b e e t l e s complete brood p r o d u c t i o n , have been suggested as a means f o r p o p u l a t i o n r e d u c t i o n (McLean 1976; N i j h o l t 1978a). V a r i a t i o n s i n t h i s technique i n c l u d e b a i t i n g the wood m a t e r i a l with pheromones to i n c r e a s e a t t r a c t i v e n e s s , and s p r a y i n g the m a t e r i a l with i n s e c t i c i d e to both k i l l and prevent or delay i t s s a t u r a t i o n by b e e t l e s . Disadvantages to t h i s method are that the t i m i n g i s c r i t i c a l , that i s , i f the logs are not processed i n time t h i s method may simply p r o v i d e a breeding s i t e f o r the b e e t l e s , and the value of the t r a p m a t e r i a l i s reduced. The use of t r a p s b a i t e d with pheromones as a means of suppressing b e e t l e p o p u l a t i o n s i n timber p r o c e s s i n g areas i s a way of overcoming these disadvantages. McLean and Borden (1975b, 1977b, 1979) achieved a high l e v e l of suppression of G. s u l c a t u s using pheromone-baited " s t i c k y " t r a p s i n the Chemainus 1 sawmill. The apparent success of the pheromone-mediated "mass-trapping" technique f o r G^ s u l c a t u s and 1 M a c M i l l a n - B l o e d e l L t d . Chemainus D i v i s i o n Sawmill, Chemainus B r i t i s h Columbia. 16 the subsequent i d e n t i f i c a t i o n and s y n t h e s i s of the pheromones fo r the two other major ambrosia b e e t l e s p e c i e s presented the o p p o r t u n i t y to extend the mass-trapping program to i n c l u d e the three major s p e c i e s of ambrosia b e e t l e s w i t h i n the Chemainus sawmi11. My o b j e c t i v e s were t o : 1. F u r t h e r the knowledge of the b i o l o g y of T\ lineatum. 2. Survey the Chemainus sawmill f o r the presence and temporal and s p a t i a l d i s t r i b u t i o n s of 1ineatum and G_^  retusus using pheromone-baited t r a p s . 3. E s t a b l i s h a mass-trapping program f o r T\_ 1 ineatum and G. retusus while , m a i n t a i n i n g the i n t e g r i t y of the e s t a b l i s h e d G_^  s u l c a t u s t r a p p i n g program. 4. I n v e s t i g a t e aspects of ambrosia b e e t l e b i o l o g y and ecology that r e l a t e to t r a p performance and u t i l i z e these f i n d i n g s in order to i n c r e a s e t r a p e f f i c i e n c y . 5. Develop techniques f o r e v a l u a t i n g the e f f i c i e n c y of the mass-trapping program. 1 7 2.0 BROOD PRODUCTION AND SURVIVAL OF THE AMBROSIA BEETLE TRYPODENDRON LINEATUM ON YEAR-OLD SPRING-FELLED DOUGLAS-FIR AND WESTERN HEMLOCK LOGS I n t r o d u c t i o n Two of the major hosts of T_j_ lineatum i n B r i t i s h Columbia are D o u g l a s - f i r , Pseudotsuqa menz i e s i i (Mirb.) Franco, and western hemlock, Tsuqa h e t e r o p h y l l a (Raf.) Sarg.. Both are p r i n c i p a l commercial s p e c i e s of the c o a s t a l f o r e s t i n d u s t r y . I t has been found that logs f e l l e d l a t e r than January are r e l a t i v e l y immune to a t t a c k s by T\ 1ineatum i n the same year. Mathers (1935) noted that s p r i n g - f e l l e d western hemlock logs were not a t t a c k e d by T_j_ lineatum i n the f i r s t year but were a t t a c k e d the f o l l o w i n g s p r i n g . No- q u a n t i t a t i v e data were p u b l i s h e d however. Prebble and Graham (1957) found that a few a t t a c k s by T\ lineatum o c c u r r e d on s p r i n g - f e l l e d D o u g l a s - f i r but not on western hemlock i n the year of f e l l i n g , but both s p e c i e s s u s t a i n e d some a t t a c k the f o l l o w i n g year. S i m i l a r f i n d i n g s f o r T. lineatum on D o u g l a s - f i r were q u a n t i f i e d by Dyer and Chapman (1965). A l s o i t has been found that v i r t u a l l y no s u c c e s s f u l g a l l e r i e s were e s t a b l i s h e d when p a i r s of T^ lineatum were f o r c e d onto s p r i n g - f e l l e d l o g s i n the year of f e l l i n g , whereas h i g h r a t e s of success o c c u r r e d on l o g s f e l l e d the p r e v i o u s f a l l and winter (Chapman 1959; Dyer and Chapman 1965). I t i s not unusual i n c o a s t a l B r i t i s h Columbia f o r logs to take a year or more to be manufactured a f t e r f e l l i n g as a r e s u l t of weather, market or 18 labour c o n d i t i o n s . In 1978 an experiment was s e t u p to monitor a c t i v i t y of the ambrosia b e e t l e Gnathotrichus s u l c a t u s (LeConte) on western hemlock and D o u g l a s - f i r l o g s f e l l e d i n two s e l e c t i v e l y logged stands at the U n i v e r s i t y of B r i t i s h Columbia Research F o r e s t at Maple Ridge, B.C. (Zanuncio 1981). T h i s f o r e s t i s i n the c o a s t a l western hemlock b i o g e o c l i m a t i c zone ( K l i n k a 1975). In 1979, T\ lineatum a t t a c k e d these l o g s and the o p p o r t u n i t y was taken to monitor a t t a c k , f r a s s p r o d u c t i o n , and emergence p a t t e r n s of t h i s ambrosia b e e t l e on y e a r - o l d D o u g l a s - f i r and western hemlock logs and to compare s u r v i v o r s h i p of v a r i o u s l i f e stages i n each host s p e c i e s by monitoring i n d i v i d u a l g a l l e r i e s . M a t e r i a l s and Methods In the i n i t i a l experiment, four p a i r s of t r e e s were f e l l e d on 8 May 1978 at each of two s i t e s approximately one ki l o m e t r e a p a r t . Each p a i r c o n s i s t e d of a D o u g l a s - f i r and a western hemlock t r e e . The t r e e s had a mean age (range) of 71.6 years (59-85), a mean base diameter diameter (range) of 40.4 cm (30-58) and a mean len g t h (range) of 29.3 m (17.2-44.5). On 24 A p r i l 1979 a t t a c k s by the ambrosia b e e t l e T\ lineatum were f i r s t recorded and g a l l e r i e s were subsequently monitored beginning 8 May 1979 by c o v e r i n g the entrance with p l a s t i c p e t r i d i s h e s (Hosking 1972). The base of the 5.5 cm diameter p e t r i d i s h had a c e n t r a l hole which was a l i g n e d with the g a l l e r y entrance ( F i g . 2). To i n s t a l l the d i s h , bark was f i r s t smoothed with a c h i s e l and a small q u a n t i t y of p l a s t i c i n e used 19 F i g u r e 2. P e t r i d i s h p l a c e d over D o u g l a s - f i r l o g i n the Ridge B.C., d u r i n g May T. lineatum entrance hole on a U.B.C. Research F o r e s t , Maple 1979. 21 to ensure a s e a l between the d i s h and the l o g . Dishes were n a i l e d to the bark and covered a f t e r one week. The delay was to allow f o r p a i r formation. The cover of the p e t r i d i s h was secured by an e l a s t i c band s t r e t c h e d over the l i d between two n a i l s p l a c e d c l o s e to the edge of the p e t r i d i s h . In a l l , 69 g a l l e r i e s were covered, 37 on western hemlock and 32 on D o u g l a s - f i r . These g a l l e r i e s were monitored on a weekly b a s i s and f r a s s and emerging b e e t l e s c o l l e c t e d . The f r a s s was d r i e d and weighed, the b e e t l e s counted and t h e i r sex determined. In the s p r i n g of 1980, s e c t i o n s of ' l o g s i n c l u d i n g 60 of the monitored g a l l e r i e s were removed and d i s s e c t e d . The l e n g t h and depth as w e l l as the number of egg and l a r v a l - p u p a l niches i n each g a l l e r y were recorded. R e s u l t s and D i s c u s s i o n S e v e r a l members of the f a m i l y S c o l y t i d a e had a t t a c k e d these t r e e s i n 1978 p r i o r to the T\ lineatum a t t a c k i n A p r i l 1979 (Table I ) . F i v e of the e i g h t D o u g l a s - f i r t r e e s were s u b s t a n t i a l l y a t t a c k e d , a l a r g e r percentage than the 25% ( t r e e base) or 45% ( t r e e tops) found by Dyer and Chapman (1965) f o r second growth D o u g l a s - f i r l o g s f e l l e d the p r e v i o u s May. Only three of the e i g h t western hemlock l o g s r e c e i v e d more than a few T. lineatum a t t a c k s . O v e r a l l D o u g l a s - f i r s u s t a i n e d about t h r e e - q u a r t e r s of. the t o t a l a t t a c k (Table I I ) . The temporal d i s t r i b u t i o n s of T_j_ lineatum a t t a c k f l i g h t , f r a s s p r o d u c t i o n and emergence are shown i n F i g u r e 3. The m a j o r i t y of b e e t l e s a t t a c k e d w i t h i n a two week p e r i o d ( F i g . 22 Table I. Dates of f i r s t c o l o n i z a t i o n by S c o l y t i d b e e t l e s on D o u g l a s - f i r and western hemlock f e l l e d May 8,1978 at the U.B.C. Research F o r e s t , Maple Ridge, B.C. Date of Tree Species Insect f i r s t a t t a c k D o u g l a s - f i r Dendroctonus pseudotsuqae Hopk. May 26,1978 Gnat h o t r i c h u s s u l c a t u s (LeConte) May 26,1978 S c o l y t u s u n i s p i n o s u s LeConte June 9,1978 Trypodendron lineatum ( O l i v i e r ) A p r i l 24,1979 western hemlock Gnathotrichus s u l c a t u s (LeConte) May 26,1978 Pseudohylesinus tsugae Swaine June 9,1978 S c o l y t u s tsugae (Swaine) June 9,1978 Trypodendron lineatum ( O l i v i e r ) A p r i l 24,1979 23 Table I I . Numbers of a t t a c k s by Trypodendron lineatum d u r i n g 1979 on D o u g l a s - f i r and western hemlock logs f e l l e d on May 8,1978 at the U.B.C. Research F o r e s t , Maple Ridge, B.C. Host S i t e Log p a i r number number western hemlock D o u g l a s - f i r T o t a l 1 1 2 160 2 93 2 3 2 0 4 5 171 S u b - t o t a l 102 333 435 5 0" 936 6 170 190 7 291 293 8 6 0 S u b - t o t a l 467 1419 1886 T o t a l s 569 1752 2321 24 F i g u r e 3. A c t i v i t y of T_;_ lineatum recorded d u r i n g 1979 at Maple Ridge, B.C.: (a) Temporal d i s t r i b u t i o n of percent of t o t a l a t t a c k . (b) Mean maximum temperature between sampling i n t e r v a l s ; l i n e at 15.5° C i n d i c a t e s c r i t i c a l temperature f o r f l i g h t (Chapman and Kinghorn 1958). (c) Mean weekly f r a s s p r o d u c t i o n per s u c c e s s f u l T. lineatum g a l l e r y , covered 8 May, 1979. (d) Temporal d i s t r i b u t i o n of percent of t o t a l emergence. 25 f u - j 2 a* u a co CO < E Z O u B O PINNED ATTACKS (n-2321) b: MEAN MAXIMUM TEMPERATURE -I C: FRASS PRODUCTION OF SUCCESSFUL GALLERIES 151 O WESTERN HEMLOCK (n-81 'n-3) • DOUGLAS-FIR (n-17. Ni-14) J i t . * EMERGENCE (n-492) 26 3a). T h i s a t t a c k corresponded to the p e r i o d when the mean maximum temperature ( F i g . 3b) between sampling p e r i o d s exceeded 15.5° C, the t h r e s h o l d f l i g h t temperature f o r T\ 1ineatum (Chapman and Kinghorn 1958). F r a s s p r o d u c t i o n r e f l e c t e d a c t i v i t y w i t h i n the g a l l e r y ( F i g . 3 c ) . The i n i t i a l peak c l e a r l y marked the beginning of the major p e r i o d of g a l l e r y c o n s t r u c t i o n (Prebble and Graham 1957) while the subsequent peak i n f r a s s p r o d u c t i o n i n D o u g l a s - f i r g a l l e r i e s i n l a t e May and e a r l y June probably was a r e s u l t of the l a r v a e extending t h e i r egg niches to pupal n i c h e s . The d i f f e r e n c e i n the amount of f r a s s produced between hosts i n t h i s p e r i o d probably r e f l e c t e d the higher number of l a r v a e i n D o u g l a s - f i r . Temperature a l s o a f f e c t e d f r a s s p r o d u c t i o n . For example i n the middle of June a sharp drop i n temperature r e s u l t e d i n a sharp drop i n f r a s s p r o d u c t i o n ( F i g . 3b,c). The emerging b e e t l e s i n May and June ( F i g . 3d) represented a d u l t s abandoning u n s u c c e s s f u l 1 g a l l e r i e s . The a t t a c k d u r i n g t h i s p e r i o d probably represented the second attempt of some a d u l t s to e s t a b l i s h a s u c c e s s f u l g a l l e r y . No evidence was found that b e e t l e s which had e s t a b l i s h e d a s u c c e s s f u l b r o o d 2 would r e - a t t a c k and s t a r t a second brood. No b e e t l e s l e f t the 1 A g a l l e r y was termed " s u c c e s s f u l " i f 3 or more b e e t l e s emerged from i t . 2 The t o t a l number of b e e t l e s from a g a l l e r y minus two parents were termed "brood" based on the f a c t that two parents normally occupy a g a l l e r y d u r i n g brood development (Chapman 1955a). 27 s u c c e s s f u l g a l l e r i e s d u r i n g the a t t a c k p e r i o d . In s u c c e s s f u l g a l l e r i e s there was no apparent p a t t e r n of parents emerging before o f f s p r i n g , or e i t h e r sex emerging f i r s t . The o f f s p r i n g began to emerge at the beginning of J u l y which i n d i c a t e d a development p e r i o d of nine to ten weeks from time of a t t a c k to emergence of the brood. T h i s i s w i t h i n the range of Hadorn's (1933) f i n d i n g s f o r T\ lineatum i n Europe which showed a development p e r i o d of 7 to 12 weeks. T. lineatum produced o f f s p r i n g i n about h a l f of the 69 g a l l e r i e s monitored (Table I I I ) . The g a l l e r i e s i n D o u g l a s - f i r showed a higher r a t e of success than those i n western hemlock, the o p p o s i t e r e s u l t of that r e p o r t e d by Dyer (1963) f o r f a l l and w i n t e r - f e l l e d t r e e s . That author reported 38.6 percent u n s u c c e s s f u l g a l l e r i e s compared to the 49.3 percent found in t h i s experiment. T h i s d i f f e r e n c e was p o s s i b l y r e l a t e d to changes i n host s u i t a b i l i t y caused by the extended aging of the wood p r i o r to a t t a c k i n the y e a r - o l d s p r i n g - f e l l e d l o g s . The mean number of o f f s p r i n g produced was s i g n i f i c a n t l y g r e a t e r i n D o u g l a s - f i r than i n western hemlock lo g s even i f two e x c e p t i o n a l g a l l e r i e s from which over 50 o f f s p r i n g emerged were not c o n s i d e r e d . T h i s r e s u l t c o n t r a s t e d with those on f a l l and w i n t e r - f e l l e d logs where no s i g n i f i c a n t d i f f e r e n c e i n brood s i z e between the two t r e e s p e c i e s was found (Dyer 1963), and suggested that western hemlock may have d e t e r i o r a t e d as a s u i t a b l e host more r a p i d l y than D o u g l a s - f i r . The o v e r a l l mean number of o f f s p r i n g per g a l l e r y of 5.4 was T a b l e I I I . Brood p r o d u c t i v i t y of Trypodendron l i n e a t u m i n D o u g l a s - f i r and western hemlock l o g s a t the U.B.C. Research F o r e s t , Maple Ridge B.C. 1979. Host western hemlock D o u g l a s - f i r T o t a l Number of s u c c e s s f u l g a l l e r i e s 1 15/37 19/32 34/69 T o t a l number of b r o o d 2 74 299 373 Brood sex r a t i o (male:female) 1 .00:1.00 1. 21:1.00 1.17:1 .00 Mean number of brood f o r s u c c e s s f u l g a l l e r i e s ± S.E.3 4 .9 ± 1.2b 15. 7 ± 3.5a 10.9 ± 2.2 Range 1 - 19 1 - 56 1 - 56 Mean number of brood f o r t o t a l g a l l e r i e s ± S.E.3 2 .0 ± 0.06b 9. 3 ± 2.5a 5.4 ± 1.3 Shown as a p r o p o r t i o n of t o t a l g a l l e r i e s m o n i t o r e d . Taken as t o t a l b e e t l e s emerged per g a l l e r y minus two ( p a r e n t s ) f o r s u c c e s s f u l g a l l e r i e s . 3 Means w i t h i n rows f o l l o w e d by the same l e t t e r a r e not s i g n i f i c a n t l y d i f f e r e n t , T - t e s t , P < 0.05. 29 s i m i l a r to the 6.5 1 found by Dyer (1963) and i n d i c a t e d an approximate t h r e e - f o l d p o p u l a t i o n i n c r e a s e from t h i s group of l o g s . The 10.9 o f f s p r i n g per s u c c e s s f u l g a l l e r y was i n c l o s e agreement to the 11.3 (Dyer 1963) and 10.0 (Chapman and Dyer 1969) 1 found i n pre v i o u s experiments. T h i s r e s u l t i n d i c a t e s that where g a l l e r i e s were s u c c e s s f u l the y e a r - o l d s p r i n g f e l l e d hosts were as s u i t a b l e f o r brood p r o d u c t i o n as were logs f e l l e d the p r e v i o u s f a l l and w i n t e r . In an e a r l i e r study, Chapman (1959) found that when T_j_ 1 ineatum was f o r c e d to at t a c k s p r i n g - f e l l e d logs i n the year of f e l l i n g no s u c c e s s f u l g a l l e r i e s were e s t a b l i s h e d . In t h i s study no a t t a c k s o c c u r r e d on the log s i n 1978 but approximately h a l f the a t t a c k s were s u c c e s s f u l the year f o l l o w i n g f e l l i n g which suggested that these logs had e i t h e r i n c r e a s e d i n a t t r a c t i v e n e s s and s u i t a b i l i t y or l o s t r e p e l l e n c y during the p e r i o d of aging. The sex r a t i o of emerging T^ 1ineatum was not s i g n i f i c a n t l y d i f f e r e n t from 1:1 (Table I I I ) . G a l l e r i e s i n which a brood was produced were s i g n i f i c a n t l y longer than u n s u c c e s s f u l g a l l e r i e s on the same host s p e c i e s (Table I V ) . Even so, i t appeared that i n many cases c o n s i d e r a b l e excavation was done before the b e e t l e s that f a i l e d to produce o f f s p r i n g abandoned t h e i r g a l l e r i e s . T h i s suggests that a t e s t i n g phase, i n which the b e e t l e bores f o r approximately 50 mm, may e x i s t . In s e v e r a l cases s u c c e s s f u l and 1 These f i g u r e s were d e r i v e d by t a k i n g the mean number of b e e t l e s per hole and s u b t r a c t i n g two b e e t l e s as parents so the data c o u l d be compared with ours. 30 Table IV. Comparison of the mean l e n g t h (± S.E.) of Trypodendron 1ineatum g a l l e r i e s which produced brood with that of u n s u c c e s s f u l g a l l e r i e s i n D o u g l a s - f i r and western hemlock Host t r e e G a l l e r y l e n g t h (mm)1 D o u g l a s - f i r n western hemlock n With Brood Without Brood 115.50 ± 14.74a 16 44.86 ± 8.35b 7 109.93 ± 20.22a 15 54.22 ± 6.16b 18 1 Means w i t h i n columns f o l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , S c h e f f e ' s Test (P<.05). 31 u n s u c c e s s f u l g a l l e r i e s o c c u r r e d on the same l o g . Twenty of the 35 u n s u c c e s s f u l g a l l e r i e s c o n t a i n e d both a male and a female b e e t l e which suggested that m i c r o s i t e d i f f e r e n c e s i n the l o g or inadequate q u a n t i t y or q u a l i t y of fungi r a t h e r than f a i l u r e to mate may have been a s i g n i f i c a n t f a c t o r i n g a l l e r y f a i l u r e . The l e n g t h s of each category of g a l l e r y are s i m i l a r i n the two host s p e c i e s (Table I V ) . A developmental p r o f i l e of T_j_ 1 ineatum was c o n s t r u c t e d from data on the number of egg n i c h e s , l a r v a l - p u p a l niches and numbers of emerging o f f s p r i n g ( F i g . 4). There are a few p o i n t s to c o n s i d e r i n i n t e r p r e t i n g t h i s i n f o r m a t i o n ; f i r s t i t i s not known i f an egg was a c t u a l l y l a i d i n each n i c h e , and second, the f a c t that each g a l l e r y was covered by a p e t r i d i s h may have a r t i f i c i a l l y p r o t e c t e d the i n s e c t s a g a i n s t n a t u r a l enemies. However, a comparison of egg and l a r v a l - p u p a l m o r t a l i t y between covered and uncovered g a l l e r i e s of the ambrosia b e e t l e G. s u l c a t u s showed no s i g n i f i c a n t d i f f e r e n c e s (Zanuncio 1981). The d i f f e r e n c e between the number of l a r v a l - p u p a l niches and the number of emerging brood does, at l e a s t , give a good measure of m o r t a l i t y due to other causes such as inadequate n u t r i t i o n , d i s e a s e , g e n e t i c d e f e c t and c a n n i b a l i s m . T h i s d i f f e r e n c e was found to be 19.5% i n D o u g l a s - f i r and 35.5% i n western hemlock ( F i g . 4 ) . These r e s u l t s suggest that i n d u s t r y should ensure that s p r i n g - f e l l e d logs are u t i l i z e d w i t h i n twelve months of f e l l i n g or they w i l l be r e a d i l y and s u c c e s s f u l l y a t t a c k e d by T. lineatum. 32 F i g u r e 4. Developmental p r o f i l e of T_;_ 1 ineatum in two host s p e c i e s at the U.B.C. Research F o r e s t , 1979. Percentages i n d i c a t e r e d u c t i o n in mean numbers between l i f e s t a g e s. 33 DOUGLAS FIR BASED ON 17 GALLERIES WESTERN HEMLOCK BASED ON 14 GALLERIES 34 The p o t e n t i a l f o r r a p i d p o p u l a t i o n b u i l d u p given s u i t a b l e hosts i s evidenced by the two g a l l e r i e s which produced over 50 brood b e e t l e s . The tr e n d towards u t i l i z i n g d r y l a n d s o r t i n g areas c o u l d r e s u l t i n a s i g n i f i c a n t i n c r e a s e i n ambrosia b e e t l e damage. The l a r g e number of log s i n these areas c r e a t e s i d e a l circumstances f o r s e l e c t i o n of optimum host m a t e r i a l by the ambrosia b e e t l e . Resident p o p u l a t i o n s w i l l b u i l d up as i n f e s t e d l o g s are imported to the s o r t i n g a r e a s . Emerging brood w i l l overwinter i n the surrounding f o r e s t margins and have host m a t e r i a l r e a d i l y a v a i l a b l e , i n s t e a d of having to search f o r i t . I t i s l i k e l y t h a t the e f f o r t i n v o l v e d in s e a r c h i n g , and the f a i l u r e to f i n d s u i t a b l e host m a t e r i a l , are major l i m i t i n g f a c t o r s i n T\_ lineatum p o p u l a t i o n dynamics. The r e d u c t i o n of these m o r t a l i t y f a c t o r s by man's l o g g i n g a c t i v i t i e s w i l l need to be o f f s e t by the conscious use of management s t r a t e g i e s aimed at p r e v e n t i n g the e s c a l a t i o n of ambrosia b e e t l e damage i n timber p r o c e s s i n g a r e a s . 35 3.0 ESTABLISHMENT OF A PHEROMONE-MEDIATED MASS-TRAPPING PROGRAM AT THE CHEMAINUS SAWMILL FOR THREE SPECIES OF AMBROSIA BEETLE I n t r o d u c t i o n In 1959 the f i r s t a c t i v e chemical cpmpound from a female moth was c h e m i c a l l y i d e n t i f i e d and the term "pheromone" given f o r i n t r a s p e c i f i c chemical s i g n a l s (Karlson and Liischer 1959; S i l v e r s t e i n 1981). Since then pheromones have been i d e n t i f i e d f o r many i n s e c t s . The use of chemical i n s e c t i c i d e s i n pest management has been l a r g e l y c u r t a i l e d i n recent years due to environmental concerns and entomologists have been seeking a l t e r n a t e s o l u t i o n s to pest problems. Pheromones have become one of the new " t o o l s " of i n s e c t pest management and can be used t o : 1. Trap i n s e c t s f o r monitoring and survey so that p o p u l a t i o n s can be estimated and new areas of i n f e s t a t i o n d e t e c t e d at an e a r l y stage. T h i s allows treatment to be a p p l i e d only when and where necessary. 2. Lure i n s e c t s i n t o areas t r e a t e d with i n s e c t i c i d e s or pathogens. 3. Mass-trap i n s e c t s f o r p o p u l a t i o n s u p p r e s s i o n . 4. Permeate the a i r i n order to d i s r u p t m a t e - f i n d i n g or aggregation ( S i l v e r s t e i n 1981). 36 The use of pheromones f o r survey and d e t e c t i o n has been very s u c c e s s f u l and t h i s procedure i s now a r e g u l a r p a r t of many pest management programs ( M i t c h e l l 1981). McLean and Borden (1979) ach i e v e d a h i g h l e v e l of suppression of the ambrosia b e e t l e G n a t h o t r i c h u s s u l c a t u s with a mass-trapping program in the Chemainus s a w m i l l . 1 The purpose of t h i s r e s e a r c h was to expand t h i s mass-trapping program to i n c l u d e the three major ambrosia b e e t l e s p e c i e s i n B r i t i s h Columbia, s u l c a t u s , G. retusus and T. lineatum. I t should be noted t h a t the o b j e c t i v e of a mass-trapping program i s not p o p u l a t i o n e r a d i c a t i o n but p o p u l a t i o n s u p p r e s s i o n . Mass-trapping i s but one component of an i n t e g r a t e d pest management s t r a t e g y . In the case of ambrosia b e e t l e s , c a r e f u l i n v e n t o r y management i s an e s s e n t i a l p a r t of the program. Mass-trapping of ambrosia b e e t l e s can never be t o t a l l y e f f e c t i v e i n removing b e e t l e s because of the nature of the timber p r o c e s s i n g o p e r a t i o n s . I n f e s t e d m a t e r i a l i s o f t e n brought i n t o the heart of a d r y l a n d s o r t or sawmill and n a t u r a l pheromone emanating from t h i s m a t e r i a l competes with s y n t h e t i c pheromone from the t r a p s . A l s o , b e e t l e s may emerge from t h i s m a t e r i a l and a t t a c k adjacent host m a t e r i a l without ever encountering the s y n t h e t i c pheromone source (Borden and McLean 1981). T h i s r e s e a r c h was undertaken at the sawmill end of the timber p r o c e s s i n g o p e r a t i o n with the knowledge t h a t much of the ambrosia b e e t l e damage w i l l have occ u r r e d by the time the logs 1 M a c M i l l a n - B l o e d e l L t d . Chemainus Sawmill D i v i s i o n , Chemainus B r i t i s h Columbia. 37 reach the m i l l . However, the known presence of G_^  r e t u s u s , G. s u l c a t u s and lineatum (McLean and Borden 1977b), the h i s t o r y of G_^  s u l c a t u s pheromone-based t r a p p i n g (McLean and Borden 1975b, 1977b, 1979) and the a c c e s s i b i l i t y of t r a p s i t e s makes i t a s u i t a b l e l o c a t i o n f o r r e s e a r c h of the mass-trapping technique. The Chemainus sawmill i s a l a r g e sawmill on Vancouver I s l a n d , B r i t i s h Columbia, producing approximately 190,000 Mfbm of timber a n n u a l l y . P r e s e n t l y t h i s timber i s approximately 50% western hemlock, 15% A m a b i l i s f i r and 35% D o u g l a s - f i r . Logs are e i t h e r towed i n t o Horseshoe Bay i n booms, or brought to the Chemainus Woodlands D i v i s i o n booming grounds, l o c a t e d i n the e a s t e r n h a l f or the bay, by t r u c k . From the booming grounds logs are e i t h e r shunted a c r o s s to the m i l l or towed to other m i l l s . The i n i t i a l phase i n the establishment of a mass-trapping program i s a survey undertaken to d e t e c t the presence and temporal and s p a t i a l d i s t r i b u t i o n of the s p e c i e s i n v o l v e d . T h i s i n f o r m a t i o n i s then u t i l i z e d i n the d e t e r m i n a t i o n of t r a p s i t e s , t r a p numbers and set-up dates i n the subsequent mass-trapping o p e r a t i o n . The o b j e c t i v e s of the mass-trapping program i n the Chemainus sawmill were t o : 1. I n t e r c e p t T\ lineatum emerging from t h e i r o v e r w i n t e r i n g s i t e s around the m i l l before they c o u l d a t t a c k l o g s and green lumber. 38 I n t e r c e p t G n a t h o t r i c h u s spp. emerging from wood m a t e r i a l before they c o u l d a t t a c k logs or green lumber. A t t r a c t ambrosia b e e t l e s to t r a p s away from high value export m a t e r i a l . 39 3.1 SURVEY OF THE SPATIAL AND TEMPORAL DISTRIBUTION OF T\ LINEATUM AND RETUSUS IN THE CHEMAINUS SAWMILL, 1979 M a t e r i a l s and Methods Survey t r a p s , c o n s i s t i n g of a c y l i n d e r of .64 cm wire mesh 20 cm i n diameter and 46 cm i n l e n g t h a t t a c h e d to a plywood d i s k and supported by a 130 cm pole ( F i g . 5) were coated with Stikem Special® ( M i c h e l - P e l t o n L t d . , E m e r y v i l l e , C a l i f . ) . The m i l l was d i v i d e d i n t o 11 t r a p p i n g l o c a t i o n s and, on 4 A p r i l 1979, f i v e t r a p s were pl a c e d in each l o c a t i o n . Each group of f i v e c o n s i s t e d of two traps b a i t e d with l i n e a t i n , the pheromone of T. lineatum, two t r a p s b a i t e d with ( + ) - s u l c a t o l , the pheromone of retusus and an unbaited c o n t r o l t r a p . L i n e a t i n was r e l e a s e d from four Conrel® (Albany I n t e r n a t i o n a l Co., Needham, Mass.) f i b r e s of 0.2 mm i n s i d e diameter g i v i n g a combined r e l e a s e r a t e of approximately 40 ug/24 hours at 22.5° C in the l a b o r a t o r y (H.D. P i e r c e J r . , 1 unpub. d a t a ) . F i e l d r e l e a s e r a t e s f o r l i n e a t i n were measured on four f i b r e s on a t r a p i n the Chemainus sawmill f o r 10 weeks. S u l c a t o l was r e l e a s e d from a 4 mL g l a s s v i a l with an 8 mm diameter ap e r t u r e y i e l d i n g r e l e a s e r a t e s of approximately 5 mg/day in the l a b o r a t o r y at 22° C and 70% r e l a t i v e humidity (McLean 1976). The t r a p s were checked at weekly i n t e r v a l s except f o r two 1 Department of Chemistry, Simon F r a s e r U n i v e r s i t y , Burnaby, B r i t i s h Columbia. gure 5. Wire-mesh survey t r a p as used i n the Chemainus sawmill during 1979. 41 42 p e r i o d s , one of nine days and one of s i x days. B e e t l e s were pi c k e d from the t r a p s except when too numerous, i n which case the t r a p s were r e p l a c e d . The d i r t y t r a p s were washed by immersing them i n warm s o l v e n t . The b e e t l e s were then s t r a i n e d from the s o l v e n t . A l l c o l l e c t e d ambrosia b e e t l e s were counted and separated by s p e c i e s and sex. A r e g r e s s i o n f o r number of b e e t l e s per u n i t volume of b e e t l e s was developed f o r T\_ lineatum to f a c i l i t a t e the counting of b e e t l e s . Traps were r e p l a c e d when d i r t y and pheromones r e p l e n i s h e d when necessary. On 24 May 1979, 95% ethanol and racemic c-pinene were added to one of two randomly s e l e c t e d ( + ) - s u l c a t o l - b a i t e d t r a p s i n each zone. T h i s a d d i t i o n was made in order to v e r i f y p r e l i m i n a r y r e p o r t s that these compounds acted s y n e r g i s t i c a l l y with the pheromone (Borden et a l . 1980c). Ethanol was r e l e a s e d from a neoprene b o t t l e having an 8 mm hole i n the l i d which gave r e l e a s e r a t e s of approximately 1 gram/day i n the l a b o r a t o r y , o-pinene was r e l e a s e d from open 4 mL g l a s s v i a l s r e l e a s i n g approximately 50 mg/day under l a b o r a t o r y c o n d i t i o n s . The e f f e c t i v e n e s s of the pheromones i n a t t r a c t i n g the t a r g e t s p e c i e s was examined using Student t - t e s t comparisons between T\ lineatum caught on l i n e a t i n - b a i t e d t r a p s and those caught on c o n t r o l t r a p s and retusus caught on ( + ) - s u l c a t o l - b a i t e d t r a p s and those caught on c o n t r o l t r a p s . A two way a n a l y s i s of v a r i a n c e was used f o r each ambrosia b e e t l e s p e c i e s to i n d i c a t e i f s i g n i f i c a n t d i f f e r e n c e s e x i s t e d i n the number of b e e t l e s caught between t r a p p i n g l o c a t i o n s and time p e r i o d s and to i d e n t i f y any i n t e r a c t i o n between the two. The 43 Newman Keul's t e s t was used to i d e n t i f y any d i f f e r e n c e s between means w i t h i n s i g n i f i c a n t f a c t o r s . A p a i r e d t - t e s t was used to determine i f the a d d i t i o n of e t h a n o l and c-pinene to ( + ) - s u l c a t o l - b a i t e d t r a p s i n c r e a s e d the c a t c h of r e t u s u s . R e s u l t s and D i s c u s s i o n Regression of Number on Volume of T_j_ 1 ineatum The r e g r e s s i o n of number on volume of T\ 1ineatum was h i g h l y s i g n i f i c a n t (r=0.997; p < 0.001) and y i e l d e d the e q u a t i o n : Number of b e e t l e s = 116.59 mL of b e e t l e s - 33.351 The i n t e r c e p t value was s i g n i f i c a n t at the 5% p r o b a b i l i t y l e v e l , probably because no v a l u e s were i n c l u d e d at very low volumes. In p r a c t i c e , volumes l e s s than 2 mL were counted by hand. At the 10% p r o b a b i l i t y l e v e l the r e g r e s s i o n c o u l d pass through the o r i g i n y i e l d i n g the equation: Number of b e e t l e s = 111.70 mL of b e e t l e s F i e l d Release Rates of L i n e a t i n The r e l e a s e r a t e (R) of l i n e a t i n i n the f i e l d was measured on four f i b r e s a t t a c h e d to a survey t r a p i n the Chemainus 44 sawmill f o r 10 weeks beginning 10 May 1979. The d e n s i t y of the pheromone i s 1.08 g/mL and the volume of pheromone c o n t a i n e d i n the f i b r e i s 0.0324 uL/mm (H.D. P i e r c e J r . Unpub. d a t a ) . The mean change (± s.e.) i n d i s t a n c e of the miniscus from the top of the f i b r e was found to be 0.211 (± 0.020) mm. The r e l e a s e r a t e per f i b r e i s t h e r e f o r e estimated as: R = 0.211mm X 0.0324 uL/mm X 1.08 g/mL = 7.38 (± 0.69) ug/day or 29.52 (± 2.79) ug/day f o r the group of four f i b r e s on each t r a p . D i s t r i b u t i o n of T_j_ lineatum T. 1ineatum demonstrated a stro n g response to l i n e a t i n . There were 108,115 b e e t l e s caught on the 22 l i n e a t i n - b a i t e d t r a p s and only 136 b e e t l e s on the 11 unbaited c o n t r o l t r a p s i n 1979. The a n a l y s i s of v a r i a n c e showed s i g n i f i c a n t time and l o c a t i o n e f f e c t s but no s i g n i f i c a n t time by l o c a t i o n i n t e r a c t i o n (Table V ) . A very l a r g e f l i g h t o c c u r r e d i n the p e r i o d between 18 A p r i l and 3 May which corresponded to the f i r s t s u s t a i n e d p e r i o d where maximum d a i l y temperatures exceeded the f l i g h t t h r e s h o l d temperature of 15.5° C ( F i g . 6a). Cooler temperatures from 3 t o 10 May r e s u l t e d i n a drop i n b e e t l e response but subsequent warmer temperatures caused f l i g h t to resume, although not of the e a r l i e r magnitude. By 7 June, 92% of the t o t a l T_j_ lineatum f l i g h t had occurred ( F i g . 6a). The low catches i n J u l y and August when brood should have emerged ( s e c t i o n 2.0, F i g . 3d) suggested t h a t brood b e e t l e s do not respond to pheromone i n the year of emergence. T h i s theory was supported by the f i n d i n g that b e e t l e s removed from t r a p s d u r i n g 45 Table V. R e s u l t s of the a n a l y s i s of v a r i a n c e of Trypodendron  lineatum caught on survey t r a p s i n 11 l o c a t i o n s over 29 weeks at the Chemainus sawmill, 1979. Source of Mean 1 V a r i a t i o n D.F. Square F value Locat ion 10 4.872 47.924 ** 2 Week 28 1 3.805 135.797 ** L o c a t i o n X Week 280 0.097 0.952 E r r o r 319 0. 102 T o t a l 637 1 Data transformed to x'= I o g 1 0 ( x + 1 ) . 2 S i g n i f i c a n c e l e v e l i n d i c a t e d : ** = P < 0.01. 46 Fi g u r e 6. Temporal d i s t r i b u t i o n of two s p e c i e s of ambrosia b e e t l e at the Chemainus sawmill, 1979. a. T_j_ lineatum, showing maximum d a i l y temperatures and the c r i t i c a l f l i g h t temperature (TF) (Chapman and Kinghorn 1958). b. G. retusus 47 60,000 50.000 40,000 30,000 20.00CT a. Trypodendron lineatum 11.000' 10.000 9000 8000 7000 6000 5000 4000 w 3000 < 2000I H 10001 £ 0 z o < o (0 U I _ J »-LU UJ 00 CC UJ 00 2 Z 400 300 200 100 18 APRIL Z>. Gnathotrichus retusus 17 31 7 21 MAY JUNE 5 19 JULY 1979 2 16 30 6 20 4 18 AUGUST SEPTEMBER OCTOBER 48 t h i s p e r i o d were s e x u a l l y mature ( N i j h o l t pers. comm.). The number and d i s t r i b u t i o n of T\ lineatum trapped are shown i n Table VI and F i g u r e 7a. The l a r g e s t c a t c h was on the e a s t e r n boundary of the Planer M i l l Yard. T h i s i s approximately the same area where the l a r g e s t catches of G_^  s u l c a t u s o c c u r r e d and where the l a r g e s t number of T\_ lineatum were i n t e r c e p t e d on (±)-sulcatol-baited t r a p s i n e a r l i e r s t u d i e s (McLean and Borden 1975b, 1977b). A l s o , i n these e a r l i e r s t u d i e s , l a r g e numbers of T. 1ineatum were i n t e r c e p t e d at l o c a t i o n 3, north of the Planer M i l l . High catches of T^ lineatum were a l s o found at t h i s l o c a t i o n (Table V I ) . The second l a r g e s t c a t c h o c c u r r e d on Bare P o i n t , which was somewhat s u r p r i s i n g as there was no wood s t o r e d t h e r e . However, the f o r e s t e d t i p of the p o i n t and other patches of brush may serve as o v e r w i n t e r i n g s i t e s . T h i s r e s u l t suggested that brood emerging from i n f e s t e d l o g s i n Horseshoe Bay f l y t o the p o i n t t o overwinter. These b e e t l e s would then emerge from the duff the f o l l o w i n g s p r i n g and a t t a c k wood m a t e r i a l i n the bay and m i l l a r ea. The two l o c a t i o n s where most of the b e e t l e s were caught were s i m i l a r i n that they both were at higher e l e v a t i o n s near the edge of embankments, and c l o s e t o p o t e n t i a l o v e r w i n t e r i n g s i t e s . T h i s was a l s o the case f o r l o c a t i o n 7 where h i g h numbers of J_j_ lineatum were a l s o caught ( F i g . 7a). Traps i n l o c a t i o n 7 would presumably i n t e r c e p t b e e t l e s f l y i n g i n t o the m i l l from f o r e s t e d areas t o the south or emerging from o v e r w i n t e r i n g s i t e s i n the embankment below. The t r a p s on the southern shore of Horseshoe Bay caught the l e a s t number of b e e t l e s which suggests that b e e t l e s are e i t h e r not Table VI. T o t a l numbers of Trypodendron lineatum caught on t r a p s i n 11 l o c a t i o n s at the Chemainus sawmill, 1979. T o t a l Number Zone L o c a t i o n of B e e t l e s % of Caught 1 T o t a l 1 Assembly Yard, Western Boundary 5, 142 e 4. 76 2 Home Yard, Eastern Boundary 9,201 c ,d 8. 51 3 Planer M i l l Yard, Northern Boundary 11,550 c 10. 68 4 Loading Shed, North End 5,119 f 4. 73 5 Planer M i l l Yard, E a s t e r n Boundary 18,423 a 17. 04 6 P i t Lumber Yard, Western Boundary 10,990 d 10. 1 7 7 H e l i c o p t e r Yard, Northern Boundary 12,886 d 1 1 . 92 8 P i t Lumber Yard, Seaward Boundary 8,712 c ,d 8. 06 9 Bark S e t t l i n g Pond, Seaward Boundary 10,208 c, d 9. 44 1 0 Horseshoe Bay, Southern Shore 2,446 f 2. 26 1 1 Bare P o i n t , Western Boundary 13,438 b 12. 43 T o t a l 108,115 100. 00 1 T o t a l s f o l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , Newman Keul's t e s t on data transformed to x'= log,o(x+1), p<0.05. 50 F i g u r e 7. S p a t i a l d i s t r i b u t i o n of two s p e c i e s of ambrosia b e e t l e at the Chemainus sawmill, 1979. a. T. 1ineatum b. G. retusus 51 52 o v e r w i n t e r i n g there or are f l y i n g over the t r a p s on r e e n t e r i n g the m i l l a r e a . Other low catches o c c u r r e d at the western boundary of the assembly yard and between the l o a d i n g shed and the p l a n e r m i l l (Table VI and F i g . 7a). The sex r a t i o of T\ lineatum brood has been found to be 1:1 (Table I I I ) . However, the mean (± s.e.) male:female sex r a t i o of trapped T\ lineatum i n the 11 l o c a t i o n s was 1.598 (± 0.035). T h i s i n d i c a t e s a stronger response to the pheromone by the male than the female, as would be expected i n t h i s s p e c i e s where the female i s the f i r s t - a t t a c k i n g sex and the male the responding sex. Over time, however, the sex r a t i o changed ( F i g . 8). In the e a r l y part of the season the male response was higher than the female response, but t h i s r a t i o d e c l i n e d such that by J u l y , female response exceeded that of the males. T h i s may r e f l e c t a st r o n g mating response by the males e a r l y i n the season with l a t e r catches c o n s i s t i n g l a r g e l y of already-mated females from u n s u c c e s s f u l g a l l e r i e s seeking new host m a t e r i a l . Another p o s s i b l e e x p l a n a t i o n f o r the high e a r l y season sex r a t i o i s that the female b e e t l e s , being the f i r s t - a t t a c k i n g sex, r e q u i r e the a d d i t i o n a l s timulus of host odours f o r maximum response (see s e c t i o n 4.4). D i s t r i b u t i o n of G_j_ retusus The t o t a l c a t c h of 2,360 retusus was r e l a t i v e l y small when compared to the numbers of T\ lineatum caught i n t h i s survey and s u l c a t u s trapped i n an e a r l i e r survey (McLean and Borden 1975b). However, the pheromone was d e f i n i t e l y a t t r a c t i v e as evidenced by only 10 retusus caught on c o n t r o l t r a p s . As with T_j_ lineatum there were s i g n i f i c a n t time and l o c a t i o n 53 F i g u r e 8. Sex r a t i o and number of T\ lineatum caught on survey t r a p s i n the Chemainus sawmill, 1979. 54 I 1 1 1 1 1 1 1 1 1 1 — ' " " 11 27 10 24 7 21 5 19 2 16 30 6 20 4 APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER 1979 55 e f f e c t s f o r G_^  retusus c a t c h but the i n t e r a c t i o n was not s i g n i f i c a n t (Table V I I ) . The temporal d i s t r i b u t i o n of f l i g h t f o l l o w s a s i m i l a r p a t t e r n to that of T\ 1ineatum, although i t peaks f i v e weeks l a t e r ( F i g . 6b). There was no second peak at the end of the summer as with s u l c a t u s (McLean and Borden 1975b, 1977b, 1979). Table VIII and F i g u r e 7b show the number and s p a t i a l d i s t r i b u t i o n of r e t u s u s around the sawmill. I t i s i n t e r e s t i n g to note that the most b e e t l e s were caught in l o c a t i o n 4, between the Loading Shed and the Planer M i l l , which was among the l o c a t i o n s of lowest I\ 1ineatum c a t c h . The other major area f o r retusus was l o c a t i o n 2, the Home Yard. T h i s area experienced one of the lowest catches of G^ s u l c a t u s in an e a r l i e r survey (McLean and Borden 1975b). T h i s f i n d i n g suggests that G_^  r etusus was s p a t i a l l y s e p a r a t i n g i t s e l f from the other two s p e c i e s . P o s s i b l e mechanisms f o r t h i s are response to d i f f e r e n t host kairomones or i n h i b i t i o n of response by the pheromones of the sympatric ambrosia b e e t l e s p e c i e s . Neither of these l o c a t i o n s appear to be unique i n e i t h e r p h y s i c a l c h a r a c t e r i s t i c s or type of m a t e r i a l s t o r e d . However, response of G_^  r etusus to ( + ) - s u l c a t o l i s i n h i b i t e d by ( - ) - s u l c a t o l (Borden e_t a l . 1980b). Traps f o r G_^  s u l c a t u s , b a i t e d with racemic s u l c a t o l , were l o c a t e d i n l o c a t i o n s 3 and 5. Thus the r e l a t i v e l y high G_j_ retusus catches i n l o c a t i o n s 2 and 4 may have r e f l e c t e d i n h i b i t e d response due to the presence of the (-) enantiomer i n l o c a t i o n s 3 and 5. G^ retusus has demonstrated s l i g h t c r o s s - a t t r a c t i o n to l i n e a t i n , and T\ lineatum was found to be t o l e r a n t of ( + ) - s u l c a t o l (Borden et a l . 1981). Th e r e f o r e , 56 Table V I I . R e s u l t s of the a n a l y s i s of v a r i a n c e of Gnathotrichus  retusus caught on survey t r a p s i n 11 l o c a t i o n s over 29 weeks at the Chemainus sawmill, 1979. Source of Mean 1 V a r i a t i o n D.F. Square F value L o c a t i o n 10 2.825 23.410 ** 2 Week 28 1 . 176 9.743 ** L o c a t i o n X Week 280 0. 122 1 .015 E r r o r 319 0.121 T o t a l 637 1 Data transformed to x'= I o g 1 0 ( x + 1 ) . 2 S i g n i f i c a n c e l e v e l i n d i c a t e d : ** = P < 0.01. Table V I I I . T o t a l numbers of Gnat h o t r i c h u s retusus caught on t r a p s i n 11 l o c a t i o n s at the Chemainus sawmill, 1979. T o t a l Number Zone L o c a t i o n of B e e t l e s % of Caught 1 T o t a l 1 Assembly Yard, Western Boundary 344 b 14. 58 2 Home Yard, Eastern Boundary 502 a 21 . 27 3 Planer M i l l Yard, Northern Boundary 216 b 9. 15 4 Loading Shed, North End 707 a 29. 96 5 Planer M i l l Yard, E a s t e r n Boundary 238 b 10. 08 6 P i t Lumber Yard, Western Boundary 204 b 8. 64 7 H e l i c o p t e r Yard, Northern Boundary 55 c 2. 33 8 P i t Lumber Yard, Seaward Boundary 20 c 0. 85 9 Bark S e t t l i n g Pond, Seaward Boundary 58 c 2. 46 10 Horseshoe Bay, Southern Shore 7 c 0. 30 1 1 Bare P o i n t , Western Boundary 9 c 0. 38 T o t a l 2,360 100. 00 1 T o t a l s f o l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , Newman Keul's t e s t on data transformed to x'= l o g 1 0 ( x + 1 ) , p<0.05. 58 the low T\ lineatum c a t c h at l o c a t i o n 4 was probably not a r e s u l t of pheromone i n h i b i t i o n , but of some other b e h a v i o u r a l response. Low numbers of G_^  retusus were caught i n the southern p a r t of the m i l l , Horseshoe Bay and on Bare P o i n t (Table VIII and F i g . 7b). The female:male sex r a t i o (± s.e.) of trapped retusus f o r 1979, based on catches at l o c a t i o n s 1 to 9 ( l o c a t i o n s 10 and 11 excluded due to low numbers) was 3.55 (± 0.32). T h i s r a t i o shows a much stronger response by the females, which are the responding sex i n t h i s s p e c i e s . The f a c t that t h i s sex r a t i o i s so high suggested that a semiochemical (Law and Regnier 1971) component or some other stimulus was mi s s i n g from the t r a p s . A d d i t i o n of ethanol and a-pinene to ( + ) - s u l c a t o l - b a i t e d t r a p s S i g n i f i c a n t l y more of both sexes of retusus were caught on t r a p s b a i t e d with ( + ) - s u l c a t o l p l u s ethanol p l u s o-pinene than on t r a p s b a i t e d with ( + ) - s u l c a t o l alone (Table I X ) . These r e s u l t s concur with those of Borden et a l . (1980c). The sex r a t i o was reduced with the t e r n a r y mixture, r e f l e c t i n g an i n c r e a s e i n the p r o p o r t i o n of males captured (Table I X ) . T h i s would be expected i f ethanol and a-pinene were i n f a c t host kairomones u t i l i z e d by the f i r s t - a t t a c k i n g sex (Borden et a l . 1980c). 59 Table IX. The e f f e c t of Ethanol (E) p l u s c-Pinene (a-P) on response of Gn a t h o t r i c h u s retusus to ( + ) - S u l c a t o l (S) on t r a p s around the Chemainus sawmill, 1979. Number of B e e t l e s Trapped Female:Male Treatment n Male Female T o t a l Sex R a t i o S 11 43a 1 231a 274a 5.37 S + E + a-P 11 272b 930b 1202b 3.42 1 Numbers w i t h i n a column f o l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , p a i r e d t - t e s t , P<0.01. Data transformed to x'= l o g 1 0 ( x + 1 ) f o r a n a l y s i s . 60 Summary of the Survey R e s u l t s T. lineatum appears to be the most p r e v a l e n t of the three major ambrosia b e e t l e s p e c i e s i n the Chemainus sawmill based on the number of b e e t l e s trapped i n t h i s and a p r e v i o u s survey (McLean and Borden 1975b). The comparatively low number of G. retusus trapped suggests that t h i s s p e c i e s i s not a major problem i n t h i s m i l l . However the f a c t that G_^  r e tusus appeared to be co n c e n t r a t e d i n r e l a t i v e l y few areas suggests that a few w e l l - p l a c e d t r a p s might r e s u l t i n a high l e v e l of c o n t r o l of t h i s s p e c i e s f o r minimal c o s t and e f f o r t . S i g n i f i c a n t l y more G. retusus were caught on t r a p s when ethanol and c-pinene were added to the pheromone. These compounds should be i n c l u d e d i n f u t u r e G_^  retusus t r a p p i n g programs. The l a r g e s t catches of T^ lineatum were on t r a p s at the top of embankments near p o t e n t i a l o v e r w i n t e r i n g s i t e s . I t i s recommended that t r a p p i n g e f f o r t s be co n c e n t r a t e d i n these l o c a t i o n s i n hopes of i n t e r c e p t i n g b e e t l e s emerging from the duff before they reach the wood m a t e r i a l i n the sawmill. Traps should be kept out of the higher value timber and export storage areas such as the Assembly Yard and P i t Yard i n order to a v o i d a t t r a c t i n g b e e t l e s to t h i s m a t e r i a l . 61 3.2 EXPANSION OF THE MASS-TRAPPING PROGRAM IN THE CHEMAINUS SAWMILL TO INCLUDE G^ SULCATUS, G_^  RETUSUS AND T\ LINEATUM, 1980 M a t e r i a l s and Methods Survey t r a p s were r e p l a c e d with suppression t r a p s ( F i g . 9) f o r the mass-trapping program. Each t r a p c o n s i s t e d of two Stikem Special®-coated, 75 X 120 cm f i b e r g l a s s screen vanes of mesh s i z e 1.7 X 1.4 mm, supported top and bottom by d o w e l l i n g i n s e r t e d i n t o a 10 X 10 cm support post 1.6 m h i g h . T h i s t r a p design was e s s e n t i a l l y the same as that d e s c r i b e d by McLean and Borden (1979) except f o r being s l i g h t l y l a r g e r . The e f f e c t i v e t r a p p i n g s u r f a c e area was 3.6 m2. On 27 March 1980, 15 s u p p r e s s i o n t r a p s were d i s t r i b u t e d throughout the m i l l area and b a i t e d as d e s c r i b e d i n Table X. Trap l o c a t i o n s and b a i t s were determined as a r e s u l t of i n f o r m a t i o n obtained i n the 1979 survey f o r G^ retusus and T. 1ineatum and the 1974 survey (McLean and Borden 1975b) f o r G. s u l c a t u s . L i n e a t i n was r e l e a s e d from four Conrel® f i b r e s as in the 1979 survey. S u l c a t o l * was r e l e a s e d from an open 2 mL g l a s s v i a l having a 4.5 mm a p e r t u r e . T h i s y i e l d e d a mean (± s.e.) 24 hour l a b o r a t o r y r e l e a s e r a t e of 1.95 (± 0.21) mg. Ethanol and o-pinene were r e l e a s e d from b o t t l e s which had 8 mm holes i n the l i d s . Approximate 24 hour l a b o r a t o r y r e l e a s e r a t e s of these compounds were one gram ethanol and 50 mg a-pinene. Release d e v i c e s were fastened to the support pole at a l e v e l 62 F i g u r e 9. Suppression t r a p c o n s i s t i n g of two vanes o r i e n t e d at 90 degrees from a support post, as used i n the Chemainus sawmill i n 1980, 1981. 63 64 Table X. L o c a t i o n , semiochemical b a i t and t a r g e t s p e c i e s of suppression t r a p s used i n the Chemainus sawmill, 1980. Trap Semiochemical 1 Code Trap L o c a t i o n B a i t Target S p e c i e s 2 T1 N. Planer M i l l L 3 1ineatum T2 S.E. Planer M i l l L 3 T\ 1ineatum T3 H e l i c o p t e r Yard L 3 1ineatum T4 H e l i c o p t e r Yard L 3 T\ lineatum T5 S. Bare P o i n t L l i 1ineatum T6 Mid Bare Point L T\ 1ineatum T7 N. Bare P o i n t L 1ineatum SI E. Planer M i l l (±)-S + EP <L. s u l c a t u s S2 S.E. Planer M i l l (±)-S + EP s u l c a t u s TS1 N. Planer M i l l L + (±)-S + EP T . l . and G.s. TS2 S.E. Planer M i l l L + (±)-S + EP T . l . and G.s. R1 Home Yard (+)-S + EP G. retusus R2 N. Loading Shed (+)-S + EP retusus CI E. Planer M i l l u nbaited C o n t r o l C2 N. Bare P o i n t unbaited C o n t r o l 1 L = l i n e a t i n , (±)-S=(±)-sulcatol, (+)-S=(+)-sulcatol, EP=ethanol p l u s a-pinene. 2 T.1.= T. lineatum, G.s.= G. s u l c a t u s . 3 (±)-S added to t r a p on 21 August 1980, t h e r e f o r e t a r g e t s p e c i e s became T . l . and G.s. from t h a t time to the end of the season. 65 approximately 30 cm from the top of the vane. Inverted wax-coated paper cups were fastened above these d e v i c e s f o r r a i n p r o t e c t i o n . Traps were monitored weekly from 3 A p r i l to 28 October 1980. Ambrosia b e e t l e s were e i t h e r p i c k e d o f f vanes or, when too numerous, vanes were r e p l a c e d , cleaned i n hot solvent and the b e e t l e s separated from the m a t e r i a l s t r a i n e d from the s o l v e n t . A l l ambrosia b e e t l e s were counted and separated by s p e c i e s and sex. A r e g r e s s i o n of number on volume was developed f o r s u l c a t u s . G. retusus were never trapped i n s u f f i c i e n t numbers to warrant use of v o l u m e t r i c e s t i m a t i o n . Two t r a p s were b a i t e d with both (±)-sulcatol and l i n e a t i n in order to examine the e f f e c t on catches of both t a r g e t s p e c i e s . The catches of these t r a p s were compared with those on the nearest s i n g l e pheromone-baited t r a p s f o r each s p e c i e s . R e s u l t s and D i s c u s s i o n Regression of Number on Volume f o r G_^  s u l c a t u s The r e g r e s s i o n of number on volume f o r s u l c a t u s y i e l d e d the e q u a t i o n : Number of b e e t l e s = 177.48 mL of b e e t l e s - 58.329 (r = 0.995; p < 0.001) As with the T^ lineatum r e g r e s s i o n , the i n t e r c e p t was s i g n i f i c a n t probably because of l a c k of values at very low volumes. In p r a c t i c e , volumes l e s s than 2 mL were counted manually. 66 Mass Trapping of T\ lineatum There were 364,924 T\ lineatum trapped i n the Chemainus sawmill i n 1980 using nine l i n e a t i n - b a i t e d s uppression t r a p s . T h i s represented more than a t h r e e - f o l d i n c r e a s e over the 108,115 b e e t l e s caught on 22 l i n e a t i n - b a i t e d survey t r a p s i n 1979. F i g u r e 10 shows the temporal d i s t r i b u t i o n of T\ lineatum c a t c h which was s i m i l a r to that found the p r e v i o u s year. The d i p i n the peak f l i g h t can be a t t r i b u t e d to a p e r i o d of c o o l , wet weather. Trap placement appeared to be s a t i s f a c t o r y as l a r g e numbers of b e e t l e s were caught i n a l l l o c a t i o n s (Table XI and F i g . 11). As i n 1979, the l a r g e s t catches were in the southeast Planer M i l l Yard and on Bare P o i n t . A r e l a t i v e l y l a r g e c a t c h of T^ lineatum on the c o n t r o l t r a p C1 suggested that t h i s p o s i t i o n , between S1 and TS2, may be a "hot spot" f o r t h i s s p e c i e s (Table X I ) . Mass Trapping of G^ s u l c a t u s Two major f l i g h t p e r i o d s were noted f o r s u l c a t u s , a sm a l l e r one i n May and a l a r g e r one i n September ( F i g . 10). T h i s agrees with f i n d i n g s by McLean and Borden (1975b, 1979). The t o t a l of 38,027 G_j_ s u l c a t u s caught on t r a p s i s s i m i l a r to the 42,907 caught i n the 1976 suppression program (McLean and Borden 1979). T h i s r e s u l t suggests that the expansion of the suppression program to i n c l u d e the other two major ambrosia b e e t l e s p e c i e s d i d not s i g n i f i c a n t l y i n t e r f e r e with the G. s u l c a t u s mass-trapping program. The l a r g e s t G^ s u l c a t u s 67 F i g u r e 10. Temporal d i s t r i b u t i o n of three s p e c i e s of ambrosia b e e t l e s captured on suppression t r a p s i n the Chemainus sawmill, 1980. a. T. 1ineatum b. G. s u l c a t u s c. G. retusus 68 O LU a. < o z g i -cc O 0_ O QC O. 0.25 0.20 0.15 0.10 0.05 0 0.20 0.15 0.10 0.05 0 0.25 0.20 0.15 0.10 0.05 0 a. Trypodendron lineatum (n = 364,924) < t T-t—t-TT ] I T* t "7 < t •» • « » » b. Gnathotrichus sulcatus (n= 38,027) * 7 T t < " I T~-T ) — i — i — i T I. T I 1 l ~ r i <—I—1—i—t—i—i—I—•—•—i—^-c. Gnathotrichus retusus (n = 7,527) APRIL MAY JUNE JULY AUG. SEPT. OCT. 1980 Table XI. Numbers of ambrosia b e e t l e s trapped i n the Chemainus sawmill from A p r i l to October, 1980. Trap Species Trapped Code T. lineatum G. s u l c a t u s G. retusus T1 36,673 2,497 1 8 T2 55,163 3,1 1 1 1 13 T3 40,842 485 1 21 T4 45,417 1 ,448' 37 T5 51,359 8 2 T6 34,415 5 1 T 7 2 27,006 4 2 SI 3,043 12,302 422 S2 1 ,066 7,922 340 TS1 25,661 6,570 284 TS2 40,572 3, 1 05 95 R1 62 125 1 ,544 R2 205 284 4,704 C1 3,399 161 52 C2 2 41 0 2 T o t a l s 364,924 38,027 7,527 1 (±)-s added to t r a p s on 21 August, 1980. 2 Trap set up two weeks l a t e r than o t h e r s . 70 F i g u r e 11. D i s t r i b u t i o n of t o t a l catches of three s p e c i e s of ambrosia b e e t l e s caught on suppression t r a p s at the Chemainus sawmill, 1980. 71 72 ca t c h was on t r a p SI, j u s t east of the Planer M i l l ( F i g . . 10 and Table X I ) . T h i s f i n d i n g agrees with the r e s u l t s of the survey f o r t h i s s p e c i e s (McLean and Borden 1975b). Adding (±)-sulcatol to t r a p s T1 to T4 i n l a t e August appeared to be a u s e f u l idea as these t r a p s made a s i g n i f i c a n t c o n t r i b u t i o n to the s u l c a t u s c a t c h (Table X I ) . Mass Trapping of retusus G. retusus were trapped i n r e l a t i v e l y low numbers when compared to T\_ lineatum and G_^  s u l c a t u s (Table X I ) . However, the 7,527 b e e t l e s caught on two pheromone-baited suppression t r a p s represented more than a t h r e e - f o l d i n c r e a s e over the 2,360 b e e t l e s caught on 22 b a i t e d survey t r a p s i n 1979. T h i s r e s u l t supports the hypothesis that a few w e l l - p l a c e d t r a p s c o u l d c a t c h l a r g e numbers of t h i s s p e c i e s with minimal expense and e f f o r t . The l a r g e s t G_^  retusus c a t c h was on the t r a p between the Loading Shed and Planer M i l l ( F i g . 11), as was the case i n the 1979 survey. The temporal d i s t r i b u t i o n was s i m i l a r to that found i n 1979, with no l a t e summer f l i g h t as i n G_;_ s u l c a t u s ( F i g . 10). Comparison of S i n g l e - and Double-Pheromone-baited Traps A comparison of the catches of T^ lineatum and G_^  s u l c a t u s on s i n g l e and double-pheromone-baited t r a p s using p a i r e d t - t e s t s gave mixed r e s u l t s . More b e e t l e s of both s p e c i e s were caught on s i n g l e - b a i t e d than d o u b l e - b a i t e d t r a p s but these d i f f e r e n c e s were s i g n i f i c a n t i n only one of two cases f o r both T_^  lineatum 73 and s u l c a t u s (Table X I I ) . The e f f e c t of ethanol and a-pinene on T^ 1ineatum c o u l d not be assessed from t h i s experiment but, i f a nything, t h e i r i n c l u s i o n might have r e s u l t e d i n i n c r e a s e d response (Moeck 1970, 1971; Bauer and V i t e 1975; N i j h o l t and Sch6nherr 1976). Borden et a l . (1981) found that these two s p e c i e s were t o l e r a n t of each ot h e r ' s pheromones. T h i s f i n d i n g c o u l d n e i t h e r be confirmed nor denied by these r e s u l t s , probably because of high v a r i a n c e r e l a t e d to t r a p p o s i t i o n and low number of r e p l i c a t e s . However, the l a r g e r catches on the s i n g l e pheromone-baited t r a p s suggested that the semiochemical i n t e r a c t i o n between these two s p e c i e s should be f u r t h e r i n v e s t i g a t e d . T h i s was done i n 1981 ( s e c t i o n 4.4). 74 Table X I I . A comparison of cat c h e s of T_^  1 ineatum and G. s u l c a t u s between t r a p s b a i t e d with t h e i r r e s p e c t i v e pheromones alone or i n tandem. 1 Target Species S i n g l e - B a i t e d Double-Baited Trap Code 2 T o t a l C a t c h 3 Trap Code T o t a l Catch T. lineatum T1 T2 36,673a 55,163a TS1 TS2 25,661a 40,572b G. s u l c a t u s S1 S2 12,302a 7,922a TS1 TS2 6,570b 3,105a 1 S u l c a t o l accompanied by ethanol and c-pinene on a l l t r a p s . 2 L o c a t i o n as shown i n F i g . 11. 3 T o t a l s w i t h i n rows fo l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , p a i r e d t - t e s t , p < 0.05, 75 3.3 OPERATIONAL PHASE OF THE MASS-TRAPPING PROGRAM FOR THREE SPECIES OF AMBROSIA BEETLE AT THE CHEMAINUS SAWMILL, 1981 Methods and M a t e r i a l s Suppression t r a p s and pheromone r e l e a s e d e v i c e s used i n the 1981 program were the same as used i n 1980. However, the Conrel® f i b r e s were p l a c e d i n a small v i a l so that the open ends extended through the a p e r t u r e . E t h a n o l was r e l e a s e d from a 20 mL p o l y e t h y l e n e s c i n t i l l a t i o n v i a l and c-pinene from a 4 mL g l a s s v i a l , both with 1.5 mm holes i n the l i d s . These gave 24 hour l a b o r a t o r y r e l e a s e r a t e s of approximately 150 mg and 17 mg, r e s p e c t i v e l y . The assign e d semiochemicals were p l a c e d i n a combination pheromone-holder and r a i n - p r o t e c t o r device attached to each t r a p ( F i g . 12). Trap p o s i t i o n s were approximately the same as i n 1980 except f o r some minor adjustments. The semiochemical b a i t s a s s i g n e d to the tr a p s d i f f e r e d from 1980, however, with a l l traps being double-pheromone-baited except T1 to T4 on Bare Point (Table XIII) where Gnathotrichus spp. catches were very low i n pr e v i o u s y e a r s . The d e c i s i o n to d o u b l e - b a i t the tr a p s was based l a r g e l y on the f i n d i n g s of Borden e_t a_l. (1981) which showed no s i g n i f i c a n t adverse e f f e c t s on T_j_ 1 ineatum and G^ s u l c a t u s or T\ lineatum and G_^  retusus catches when t r a p s were d o u b l e - b a i t e d with t h e i r r e s p e c t i v e pheromones. The advantages of reduced c a p i t a l c o s t s (Borden e_t a l . 1981) i f each t r a p c o u l d be u t i l i z e d f o r two s p e c i e s was an a d d i t i o n a l f a c t o r i n the d e c i s i o n t o d o u b l e - b a i t the t r a p s . 76 F i g u r e 12. Aluminum pheromone-holder and rain-protVctor device attached to suppression t r a p s i n the Chemainus sawmill, 1981. 77 78 Table X I I I . L o c a t i o n , semiochemical b a i t and t a r g e t s p e c i e s of suppression t r a p s used i n the Chemainus sawmill, 1981. Trap Semiochemical 1 Code Trap L o c a t i o n B a i t Target S p e c i e s 2 TS1 N. Planer M i l l L + (± ] -s + EP T. 1. and G.s. TS2 E. Planer M i l l L + (± -s + EP I i 1. and G.s. TS3 E. Planer M i l l L + (± -s + EP T. 1. and G.s. TS4 S.E. Planer M i l l L + (+ -s + EP T. 1. and G.s. TS5 S.E. Planer M i l l L + (± -s + EP T. 1. and G.s. TS6 H e l i c o p t e r Yard L + (± -s + EP T. 1. and G.s. TS7 H e l i c o p t e r Yard L + (± -s + EP T. 1. and G.s. TS8 V a r i e d P o s i t i o n s L + (± -s + EP T. 1. and G.s. TR1 N.E. Planer M i l l L + (+ \ -s + EP T. 1. and G.r. TR2 N. Loading Shed L + (+ ] -s + EP T. 1. and G.r. T1 S. Bare Point L + EP I i 1ineatum T2 S. Bare Point L + EP I i lineatum T3 Mid Bare Point L + EP I i lineatum T4 N. Bare Point L + EP T. lineatum 1 L = l i n e a t i n , (±)-S=(±)-sulcatol, (+)-S=(+)-sulcatol, EP=ethanol p l u s a-pinene. 2 T.1.= T. lineatum, G.s.= G. s u l c a t u s and G.r.= G. r e t u s u s . 79 Trap TS8 was used as a " f l o a t i n g " t r a p to examine catches i n d i f f e r e n t p a r t s of the m i l l . There were no c o n t r o l t r a p s i n 1981. Vanes were changed on the t r a p s only when accumulated b e e t l e s or d e b r i s threatened t h e i r e f f i c i e n c y . On these o c c a s i o n s d i r t y vanes were c l e a n e d and the trapped ambrosia b e e t l e s counted as i n 1980. R e s u l t s and D i s c u s s i o n P r o d u c t i o n i n the sawmill was i n t e r r u p t e d by a labour d i s p u t e from 26 June to 8 September, 1981. During the s t r i k e a l l movement of l o g s and lumber ceased. Most of the trapped T. 1ineatum had been caught by e a r l y June as in p r e v i o u s years, but the t o t a l c a t c h of 21,985 s u l c a t u s was d e f i n i t e l y lower than i n p r e v i o u s years, due to a minimal l a t e summer f l i g h t . A s i m i l a r reduced l a t e summer f l i g h t o c c u r r e d d u r i n g a m i l l c l o s u r e i n 1975 (McLean and Borden 1977b). The r e d u c t i o n of G. s u l c a t u s but not T\ lineatum c a t c h r e f l e c t s the d i f f e r e n t b i o l o g i e s of the two s p e c i e s . T\ lineatum trapped i n 1981 would have emerged i n 1980 from m a t e r i a l brought i n t o the sawmill i n that summer, while G^ s u l c a t u s caught i n 1981 would have emerged from c u r r e n t i n v e n t o r i e s . When log s are not being imported to the m i l l , numbers of G_^  s u l c a t u s are reduced. T h e o r e t i c a l l y , lower numbers of T_j_ 1ineatum would be expected i n the Chemainus sawmill i n 1982 because of reduced volumes of l o g s p a s s i n g through the m i l l i n the brood emergence p e r i o d i n 1981. The t o t a l c a t c h of 353,559 T^ lineatum was very s i m i l a r to the 364,924 b e e t l e s caught i n 1980. However, i n 1980 only nine 80 t r a p s were b a i t e d with l i n e a t i n , while i n 1981 a l l 14 t r a p s i n c l u d e d l i n e a t i n i n the b a i t . The s i m i l a r i t y of the catches i n these two years c o u l d be e n t i r e l y c o i n c i d e n t a l or i t c o u l d be a f u n c t i o n of s i m i l a r l o g flow p a t t e r n s i n the two years r e s u l t i n g i n a f a i r l y constant T_j_ 1 ineatum p o p u l a t i o n . I f the l a t t e r was the case then the s i m i l a r catches might suggest that the upper l i m i t of t r a p p i n g c a p a b i l i t y with t h i s system had been reached. Fewer t r a p s c o u l d then be u t i l i z e d s i n c e a d d i t i o n a l t r a p s would onl y serve to r e d i s t r i b u t e the same number of b e e t l e s . The q u e s t i o n of optimum number of t r a p s i s complex but c o u l d p o s s i b l y be answered using the mark-recapture method ( s e c t i o n 4.5). B a i t i n g a d d i t i o n a l t r a p s f o r both s u l c a t u s and T. 1ineatum r e s u l t e d i n changes from 1980 i n the d i s t r i b u t i o n of catches between l o c a t i o n s , (Table XIV and F i g . 13). For example, t r a p TS5 was at the optimum l o c a t i o n f o r T_j_ 1 ineatum c a t c h i n 1979 and 1980. In 1981, however, i t was one of the l e a s t p r o d u c t i v e l o c a t i o n s (Table XIV). T h i s low p r o d u c t i o n was probably due to the a d d i t i o n of t r a p s TS2 and TS3 ( F i g . 13), n e i t h e r of which were b a i t e d f o r T\ lineatum the p r e v i o u s year. Trap TS3 was at the l o c a t i o n of the unbaited c o n t r o l which i n t e r c e p t e d over 3,000 T\ 1ineatum i n 1980. The capture of 34,033 b e e t l e s i n 1981 confirmed t h i s l o c a t i o n as a "hot spot" f o r T\ lineatum. Traps TS6 and TS7 i n the H e l i c o p t e r Yard were in e x a c t l y the same l o c a t i o n s as i n 1980, but caught l e s s than h a l f the number of b e e t l e s i n 1981. A p o s s i b l e e x p l a n a t i o n f o r t h i s reduced p r o d u c t i v i t y was the heavy growth of a l d e r , Alnus  rubra Bong, around the t r a p s which may have a f f e c t e d the 81 Table XIV. Numbers of ambrosia b e e t l e s trapped in the Chemainus sawmill from A p r i l to October, 1981. Species Trapped Trap Code T. lineatum G. s u l c a t u s G. retusus TS1 40,978 4,539 0 TS2 21,791 3,644 3 TS3 34,033 2,769 28 TS4 22,074 3,259 8 TS5 15,226 2,845 2 TS6 16,910 635 18 TS7 19,869 737 38 TS8 9,986 91 62 TR1 26,418 583 3, 167 TR2 18,612 715 942 T1 42,021 10 1 T2 42,863 15 1 T3 31,915 48 0 T4 30,859 15 0 T o t a l s 353,559 21,985 4,270 F i g u r e 13. D i s t r i b u t i o n of t o t a l catches of three s p e c i e s ambrosia b e e t l e s caught on suppression t r a p s at the Chemainus sawmill, 1981. 84 pheromone plume and i n h i b i t e d b e e t l e f l i g h t . I t i s recommended that t r a p s be placed i n c o r r i d o r s cut through the a l d e r i n the f u t u r e . Trap T1 on Bare P o i n t ( F i g . 13) was added i n 1981 to supplement the other three l i n e a t i n - b a i t e d t r a p s , which remained i n the same p o s i t i o n s as i n 1980. T h i s t r a p was p l a c e d j u s t south of the most s u c c e s s f u l Bare Point t r a p l o c a t i o n of pr e v i o u s years (T2). In 1981 these were the two optimum l o c a t i o n s accounting f o r 24% of the t o t a l T\ lineatum c a t c h (Table XIV). Lower catches on t r a p s w i t h i n the sawmill probably were at l e a s t p a r t i a l l y due to the removal of a l a r g e r p r o p o r t i o n of the T_^  lineatum p o p u l a t i o n by the Bare Point t r a p s . Trap TS1, north of the pla n e r m i l l ( F i g . 13), was perhaps i n the most p r o d u c t i v e o v e r a l l l o c a t i o n , having amongst the h i g h e s t T\ 1 ineatum c a t c h and the highest G_^  s u l c a t u s c a t c h . The p r e v i o u s year there were two l i n e a t i n - b a i t e d t r a p s i n t h i s l o c a t i o n and the l a r g e c a t c h i n 1981 suggests that at l e a s t two t r a p s should be used.in the f u t u r e . Trap TS8 was t r i e d at three l o c a t i o n s , the southeast H e l i c o p t e r Yard, the e a s t e r n P i t Yard and the northwest corner of the Planer M i l l which r e s u l t e d i n catches of 6,759, 2,273 and 1,107 ambrosia b e e t l e s , r e s p e c t i v e l y . G. s u l c a t u s were d i s t r i b u t e d f a i r l y u n i f o r m l y among t r a p s TS1 to TS5 around the Planer M i l l (Table XIV and F i g . 13). The lower but s u b s t a n t i a l number of G_^  s u l c a t u s caught on the ( + ) - s u l c a t o l - b a i t e d t r a p s , TR1 and TR2, supports the f i n d i n g that there i s s l i g h t c r o s s - a t t r a c t i o n by t h i s s p e c i e s to the G. retusus pheromone (Borden et a l . 1981). Trap TR1 was moved, 85 i n 1981, s l i g h t l y south of i t s 1980 p o s i t i o n i n the Home Yard to the northeast corner of the Planer M i l l ( F i g . 13). T h i s appeared to be an improvement over i t s p r e v i o u s l o c a t i o n as t h i s t r a p g r e a t l y i n c r e a s e d i t s c o n t r i b u t i o n to the t o t a l retusus c a t c h (Table XIV). Trap TR2 was i n the same l o c a t i o n i n 1981 as R2 i n 1980 and yet the number of retusus caught on t h i s t r a p was much lower than i n the pr e v i o u s year as was the t o t a l G. retusus c a t c h . Most of the G^ retusus were trapped i n May and June, as i n pr e v i o u s years, so i t i s u n l i k e l y that the m i l l shutdown a f f e c t e d the p o p u l a t i o n . A p o s s i b l e e x p l a n a t i o n f o r the lower numbers and reduced e f f i c i e n c y of TR2 i s that the new l o c a t i o n f o r TR1 may have been i n the usual pheromone plume path of TR2 and was outcompeting that t r a p f o r the same b e e t l e s r a t h e r than producing i t s own d i s t i n c t plume as i n i t s 1980 l o c a t i o n . T h i s hypothesis c o u l d be t e s t e d by adding a t h i r d ( + ) - s u l c a t o l - b a i t e d t r a p at the former p o s i t i o n i n the Home Yard and comparing catches with those of 1980, t r e a t i n g TR1 and TR2 as a s i n g l e t r a p . Changing vanes only when they were d i r t y r e s u l t e d in a c o n s i d e r a b l e saving i n the labour i n v o l v e d i n the program. A f t e r t h e i r i n i t i a l i n s t a l l a t i o n on 19 March 1981, vanes were changed only four times, 23 A p r i l , 20 May, 11 June and 10 August before being c o l l e c t e d f o r the season on 15 October. 86 3.4 ATTRACTION OF PLATYPUS WILSONI (SWAINE) TO TRAPS BAITED WITH SULCATOL PLUS ETHANOL PLUS c-PINENE I n t r o d u c t i o n P. w i l s o n i i s one of f i v e ambrosia b e e t l e s p e c i e s commonly found i n commercial t r e e s p e c i e s i n B r i t i s h Columbia, and the only member of the f a m i l y Platypodidae i n Canada (Prebble and Graham 1957). I t i s g e n e r a l l y c o n s i d e r e d to be a l e s s important pest of the f o r e s t i n d u s t r y than T\ lineatum, G. s u l c a t u s or G. r e t u s u s , probably because i t takes a "year or more" to develop w i t h i n the host (Prebble and Graham 1957). Most logs would be processed w i t h i n t h i s p e r i o d so P\ w i l s o n i p o p u l a t i o n s would not b u i l d up in timber p r o c e s s i n g areas as do T\_ 1ineatum and G n a t h o t r i c h u s spp. which have s h o r t e r development p e r i o d s . N e v e r t h e l e s s , i t does cause s e r i o u s damage to D o u g l a s - f i r , western hemlock and a m a b i l i s f i r logs as i t bores to depths of 20 cm or more. Primary or secondary a t t r a c t a n t s f o r t h i s s p e c i e s have not yet been i d e n t i f i e d i f the e x i s t , as i n other ambrosia b e e t l e s p e c i e s . P_j_ f l a v i c o r n i s ( F . ) , common in the southeastern U n i t e d S t a t e s , produces an aggregation pheromone (Madrid et a_l. 1972) of which s u l c a t o l , the pheromone of G. s u l c a t u s and G^ retusus i s a component (Renwick et a l . 1977). Pl a t y p o d i d a e have a l s o been found to be a t t r a c t e d to ethanol (Samaniego et a l . 1970). Response of P^ f l a v i c o r n i s to s u l c a t o l was i n c r e a s e d with the a d d i t i o n of ethanol but reduced with the a d d i t i o n of c-pinene (Renwick et a l . 1977). 87 During the 1980 mass-trapping program f o r G_^  s u l c a t u s , G. r e t u s u s and T\ lineatum i t was n o t i c e d t h a t s u b s t a n t i a l numbers of E\ w i l s o n i were caught on some t r a p s . Presence of t h i s s p e c i e s i n the Chemainus sawmill was f i r s t noted by McLean and Borden (1979). The o p p o r t u n i t y was taken to examine any d i f f e r e n c e s i n numbers of trapped P^ w i l s o n i between treatments in order to determine whether there were p o s i t i v e responses to any of the chemicals employed i n the program. M a t e r i a l s and Methods Each of the 15 t r a p s used i n the suppression program was b a i t e d with one of f i v e treatments, l i n e a t i n , (±)-sulcatol plus ethanol p l u s c-pinene (ethanol p l u s c-pinene h e r e a f t e r a b b r e v i a t e d as EP), (±)-sulcatol p l u s l i n e a t i n p l u s EP, ( + ) - s u l c a t o l p l u s EP or unbaited c o n t r o l . P^ w i l s o n i were removed from t r a p s at the end of each of f i v e time p e r i o d s , 21 to 28 August, 29 August to 4 September, 5 to 12 September, 13 to 25 September and 26 September to 28 October. As t h i s was not a designed experiment the number of t r a p s per treatment was unbalanced and t h e r e f o r e r e q u i r e d a somewhat complex s t a t i s t i c a l a n a l y s i s . The data were f i r s t transformed to x'=log, 0(x+1) to normalize the d i s t r i b u t i o n and then s t a n d a r d i z e d to make the v a r i a n c e s uniform. A two way ANOVA f o r unequal but p r o p o r t i o n a l s u b c l a s s numbers (Sokal and Rohlf 1969) was then conducted on the a d j u s t e d data. The sex r a t i o was determined from a sample of 434 b e e t l e s . 88 R e s u l t s and D i s c u s s i o n The a n a l y s i s of v a r i a n c e showed t h a t both time and treatment e f f e c t s were s i g n i f i c a n t (Table XV). The J*\ w i l s o n i f l i g h t p e r i o d i n the Chemainus sawmill began 14 August, peaked between 5 and 25 September but continued i n t o October. T h i s was s l i g h t l y l a t e r than the J u l y to mid-September f l i g h t p e r i o d d e s c r i b e d by Prebble and Graham (1957) and c o i n c i d e d with peak G. s u l c a t u s f l i g h t . P. w i l s o n i showed a s i g n i f i c a n t l y g r e a t e r response to t r a p s b a i t e d with s u l c a t o l p l u s EP than to those b a i t e d with l i n e a t i n or unbaited (Table XVI). U n f o r t u n a t e l y , no t r a p s were b a i t e d with s u l c a t o l , e thanol or e-pinene alone, so i t i s not p o s s i b l e to e v a l u a t e t h e i r i n d i v i d u a l i n f l u e n c e on b e e t l e response. However, the c a t c h was much l a r g e r on the (±)-sulcatol p l u s EP treatment than the ( + ) - s u l c a t o l p l u s EP treatment. T h i s suggests that the pheromones may have c o n t r i b u t e d more than EP to P_j_ w i l s o n i response. A l s o , the femalermale sex r a t i o of trapped b e e t l e s was 2.1:1.0. As the male i s the f i r s t - a t t a c k i n g sex i n t h i s s p e c i e s (Prebble and Graham 1957) and thus p o t e n t i a l l y the pheromone-producing sex as i n Gnathotrichus spp., the g r e a t e r response by female b e e t l e s would be expected i f s u l c a t o l was indeed a pheromone component. T h i s p o s s i b i l i t y seems even more l i k e l y given the f i n d i n g s f o r P_^  f l a v i c o r n i s . T h i s suggests that there are s t i l l unknown mechanisms m a i n t a i n i n g the b i o l o g i c a l and e c o l o g i c a l i n t e g r i t y of three s p e c i e s of ambrosia b e e t l e s , w i t h i n two genera, that c o e x i s t g e o g r a p h i c a l l y and yet o v e r l a p i n t h e i r chemical communication 89 Table XV. R e s u l t s of the two way ANOVA with unequal but p r o p o r t i o n a l s u b c l a s s numbers f o r Platypus  w i l s o n i caught over f i v e time p e r i o d s on ambrosia b e e t l e semiochemical-baited s t i c k y t r a p s i n the Chemainus sawmill, 1980. Source D.F. Mean Square 1 F - v a l u e 2 Subgroup 24 1 .40673 Treatment 4 3.77380 3.22 * Time 4 3.18882 2.72 * Treatment X Time 16 0.36944 0.32 E r r o r 50 1 .17723 T o t a l 74 1 Data transformed to x' =log, 0(x+1) and s t a n d a r d i z e d f o r ANOVA. 2 S i g n i f i c a n c e l e v e l i n d i c a t e d : * = p < 0.05. Table XVI. Mean number per t r a p of Platypus w i l s o n i caught over f i v e time p e r i o d s on semiochemical-baited s t i c k y t r a p s i n the Chemainus sawmill, 1980. Number Treatment of Traps Mean (±)-S + ethanol + (±)-S + l i n e a t i n + (+)-S + et h a n o l + l i n e a t i n u nbaited a-pinene ethanol + a-pinene a-pinene 2 45.8 a 1 6 14.8 a 2 4.5 a 3 0.2 b 2 0.2 b 1 Means f o l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , S c h e f f e ' s t e s t , p < 0.05. 91 systems. In 1981, four d r a i n p i p e t r a p s were set up i n the Chemainus sawmill. Each t r a p was b a i t e d with one of four treatments, (±)-sulcatol, (±)-sulcatol p l u s ethanol p l u s o-pinene, ethanol p l u s c-pinene or unbaited. I t was hoped that i n a d d i t i o n to t e s t i n g response to treatments, l i v e b e e t l e s c o u l d be obtained f o r l a b o r a t o r y bioassay purposes. However, no w i l s o n i were caught i n these t r a p s although many were caught on neighbouring suppression t r a p s . If s u l c a t o l can be confirmed as a pheromone f o r P_j_ w i l s o n i in f u t u r e f i e l d and l a b o r a t o r y t e s t s i t would mean that t h i s mass-trapping program i n c l u d e d four of the f i v e major ambrosia b e e t l e s p e c i e s of B r i t i s h Columbia. 92 4.0 FIELD INVESTIGATIONS FOR IMPROVING AND ASSESSING THE AMBROSIA BEETLE MASS-TRAPPING PROGRAM 4.1 THE EFFECT OF TRAP HEIGHT ON CATCHES OF T^ LINEATUM I n t r o d u c t i o n C o n s i d e r a b l e v a r i a t i o n i n T^ lineatum catches can occur between pheromone-baited s t i c k y t r a p s even when they are only 20-30 m apart ( F i g s . 7a, 11 and 13). In t r a p p i n g experiments with t h i s s p e c i e s i n the Chemainus sawmill the l a r g e s t catches were on t r a p s at higher e l e v a t i o n s near the edges of embankments ( F i g s . 7a, 11 and 13). T h i s f i n d i n g c o u l d i n d i c a t e that the b e e t l e s conduct t h e i r s e a r c h i n g f l i g h t s at r e l a t i v e l y high a l t i t u d e s or that these higher t r a p p o s i t i o n s present a l e s s o b s t r u c t e d pheromone plume than t r a p s i n more s h e l t e r e d p o s i t i o n s . An experiment was e s t a b l i s h e d i n the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands to determine the best t r a p height f o r c a t c h i n g T\ lineatum. M a t e r i a l s and Methods Twenty survey t r a p s were threaded i n s e r i e s onto four nylon ropes, f i v e to a rope. Two Conrel® f i b r e s c o n t a i n i n g l i n e a t i n were a t t a c h e d to the rope i n a c e n t r a l p o s i t i o n f o r each t r a p . 10 ug per day under l a b o r a t o r y c o n d i t i o n s . Each group of f i v e 93 t r a p s was then suspended from a t r e e branch at one of four l o c a t i o n s i n the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands on 21 May 1980. Traps were p o s i t i o n e d at f i v e h e i g h t s on each rope so that the bottoms of the t r a p s were at 0.0, 1.0, 2.0, 3.0 and 4.0 m above the ground ( F i g . 14). At the end of each of three t r a p p i n g p e r i o d s , 21 May to 3 June, 4 June to 16 June and 17- June to 5 August, a l l T_j_ lineatum b e e t l e s were removed from the t r a p s and the height c l a s s , l o c a t i o n , time p e r i o d and sex were recorded. R e s u l t s and D i s c u s s i o n Data a n a l y s i s r e v e a l e d no major d i f f e r e n c e s between male and female catches; t h e r e f o r e t o t a l c a t c h w i l l be d i s c u s s e d . The a n a l y s i s of v a r i a n c e showed two s i g n i f i c a n t i n t e r a c t i o n s , l o c a t i o n by time and height c l a s s by l o c a t i o n (Table X V I I ) . Examination of the l o c a t i o n by time i n t e r a c t i o n showed that the l a r g e s t numbers of T^ lineatum were caught between 4 June and 16 June at a l l l o c a t i o n s except l o c a t i o n 2 where the l a r g e s t numbers of b e e t l e s were caught from 17 June to 5 • August. The s i g n i f i c a n t height by l o c a t i o n i n t e r a c t i o n i s a r e s u l t of d i f f e r e n c e s i n optimum t r a p height at l o c a t i o n 4 (Table X V I I I ) . The t r a p at 3.0 - 3.5 m above ground p o s i t i o n caught the most b e e t l e s at t h i s l o c a t i o n while at the other three p o s i t i o n s the 1.0 - 1.5 m p o s i t i o n was optimal (Table X V I I I ) . An examination of the understory v e g e t a t i o n surrounding the t r a p s at the four l o c a t i o n s r e v e a l e d that l o c a t i o n s 1 through 3 were r e l a t i v e l y open s i t e s with average v e g e t a t i o n h e i g h t s of 1.2, 1.2 and 1.5 m 94 F i g u r e 14. F i v e survey t r a p s suspended i n s e r i e s such that the bottoms of the t r a p s were at 0.0, 1.0, 2.0, 3.0 and 4.0 metres above ground. 95 96 Table XVII. R e s u l t s of the a n a l y s i s of v a r i a n c e of T\ lineatum caught on pheromone-baited t r a p s suspended at f i v e h e i g h t s i n four l o c a t i o n s f o r three time p e r i o d s . Source of V a r i a t i o n D.F. Mean 1 Square F - v a l u e 2 Trap Height 4 0.296 11.306** L o c a t i o n 3 0.624 23.867** Trap Height X L o c a t i o n 12 0.189 7.226** Time P e r i o d 2 5.285 202.016** Trap Height X Time P e r i o d 8 0.023 0.875 L o c a t i o n X Time P e r i o d 6 0. 129 4.915** E r r o r 24 0.026 T o t a l 59 1 Data transformed to x'= l o g 1 0 2 S i g n i f i c a n c e l e v e l i n d i c a t e d : (x+1). **=p<0. 01 . 97 Table XVIII. Mean number of T\ lineatum caught on pheromone-b a i t e d b a i t e d t r a p s suspended at f i v e h e i g h t s i n four l o c a t i o n s f o r three time p e r i o d s . Trap Height L o c a t i o n Mean 1 Above Ground (m) 1 2 3 4 4.0 - 4.5 50.3 43.7 19. 0 219.7 83.2c 3.0 - 3.5 76.3 49.7 36. 7 257.7 105.1b 2.0 - 2.5 149.7 84.0 77. 7 184.7 1 24.0b 1 .0 - 1 . 5 232.3 140.0 198. 7 1 04.3 168.8a 0.0 - 0.5 136.3 32.0 1 33. 7 121.3 105.8b Mean 1 129.0a 69.9b 93. 1b 177.5a 1 Means w i t h i n rows or columns f o l l o w e d by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , Newman Keul's t e s t on data transformed to x'= l o g , 0 ( x + 1 ) , p<0.05. 98 r e s p e c t i v e l y . L o c a t i o n 4, however, was surrounded by l a r g e ocean spray H o l o d i s c u s d i s c o l o r (Pursh) Maxim, bushes with an average height of 3.5 m. Thus, i t appears r e s u l t s that T. lineatum searches, and w i l l respond o p t i m a l l y to pheromone-baited t r a p s , at as low a height as necessary to c l e a r the surrounding v e g e t a t i o n . Pheromone plumes o r i g i n a t i n g from sources below the height of the surrounding v e g e t a t i o n would not l i k e l y d i s p e r s e as f a r or o f f e r as d i r e c t a "beacon" as plumes from sources p l a c e d c l e a r of o b s t r u c t i o n s . However, T\ lineatum appears to show maximum response to the lowest c l e a r pheromone source. Apparently a s h i f t i n the f l y i n g behaviour occurs from an i n i t i a l p e r i o d of p h o t o p o s i t i v e f l i g h t (Graham 1959; personal obs.) to one of low l e v e l s e a r c h i n g . In s t u d i e s of optimal t r a p height i n another s c o l y t i d s p e c i e s , S c o l y t u s m u l t i s t r i a t u s (Marsham), the lower t r a p s were a l s o p r e f e r r e d (Cuthbert and Peacock 1975; L a n i e r et a l . 1976; B i r c h et a l . 1981). These r e s u l t s suggest that the success of t r a p l o c a t i o n s at the edge of embankments at the Chemainus sawmill i s not a r e s u l t of t h e i r e l e v a t i o n s c o i n c i d i n g with f l y i n g height of searching b e e t l e s . I t i s , more l i k e l y , a r e s u l t of pheromone plumes emanating from these p o s i t i o n s being l e s s o b s t r u c t e d by surrounding v e g e t a t i o n or o b s t a c l e s , and perhaps being more fa v o u r a b l y p o s i t i o n e d with respect to wind p a t t e r n s . These f i n d i n g s have i m p l i c a t i o n s f o r mass-trapping programs d i r e c t e d at t h i s ambrosia b e e t l e s p e c i e s . Traps should be p o s i t i o n e d i n l o c a t i o n s or at h e i g h t s such that there i s no i n t e r f e r e n c e from surrounding v e g e t a t i o n or o b s t a c l e s . Brush should be c l e a r e d from around t r a p s f o r maximum e f f i c i e n c y of the system. 100 4.2 DISTRIBUTION OF T\ LINEATUM ON SUPPRESSION TRAPS RELATIVE TO PHEROMONE PLACEMENT HEIGHT I n t r o d u c t i o n In order to optimize the p o s i t i o n i n g of the pheromone b a i t on the suppression t r a p s f o r maximum T\ 1ineatum c a t c h , an experiment was e s t a b l i s h e d at the Chemainus sawmill. T h i s study i n v o l v e d an examination of the d i s t r i b u t i o n of T_;_ 1 ineatum on the vanes, a subsequent adjustment of the pheromone p o s i t i o n and a reexamination. A s i m i l a r study was p r e v i o u s l y c a r r i e d out f o r G. s u l c a t u s i n which i t was found that the g r e a t e s t p r o p o r t i o n of t h i s s p e c i e s was caught at the height where the pheromone was deployed (McLean and Borden 1979). M a t e r i a l s and Methods The .vanes of a suppression t r a p , TS5 ( F i g . 13), were each d i v i d e d i n t o four rows and three columns, thus forming 12 c e l l s of 25 X 30 cm on each s i d e of a vane. The pheromone d i s p e n s e r was p o s i t i o n e d on the s u p p o r t i n g post approximately 30 cm below the top of the vane (upper p o s i t i o n ) at the j u n c t i o n of the top and upper middle rows. T h i s was the same p o s i t i o n used on a l l suppression t r a p s i n the Chemainus sawmill i n 1980 and 1981. On 27 May, 4 June and 2 J u l y 1981, a l l T^ lineatum were p i c k e d from the vanes n o t i n g aspect, row, column and sex of b e e t l e . On 2 J u l y the pheromone di s p e n s e r was lowered to a p o s i t i o n 60 cm 101 below the top of the vane ( c e n t r a l p o s i t i o n ) at the j u n c t i o n of the upper middle and lower middle rows. In order to determine i f aspect e f f e c t s were r e l a t e d to t r a p o r i e n t a t i o n or t r a p design a second t r a p , T2 ( F i g . 13), with the vanes o r i e n t e d i n o p p o s i t e d i r e c t i o n s to the i n i t i a l t r a p , but with the pheromone dis p e n s e r a l s o at the c e n t r a l p o s i t i o n , was examined. T. lineatum were c o l l e c t e d from the t r a p s on 16 J u l y and 10 August. Data f o r t r a p TS5 were analyzed f o r each pheromone p o s i t i o n u sing a four way a n a l y s i s of v a r i a n c e with aspect, row, column and time as main e f f e c t s . Data for t r a p T2 were analyzed f o r aspect e f f e c t s o n l y . R e s u l t s and D i s c u s s i o n A l l main e f f e c t s were s i g n i f i c a n t i n the a n a l y s i s of v a r i a n c e . There were no s i g n i f i c a n t i n t e r a c t i o n s at the 99% p r o b a b i l i t y l e v e l but a f e w , s i g n i f i c a n t i n t e r a c t i o n s f o r male and female but not t o t a l T\ lineatum c a t c h at the 95% p r o b a b i l i t y l e v e l . These were examined and c o n s i d e r e d to be minor. S i g n i f i c a n t l y fewer b e e t l e s were caught d u r i n g each s u c c e s s i v e t r a p p i n g p e r i o d , as would be expected with T. lineatum d u r i n g t h i s time of year ( F i g s . 6a, 10a).' With the pheromone i n both the upper and c e n t r a l p o s i t i o n s the north and west as p e c t s of the vanes caught s i g n i f i c a n t l y more b e e t l e s than the south and east aspects f o r t r a p TS5 (Table XIX). Due to the 90° arrangement of the vanes, two aspects are exposed to a much wider angle of approach by the b e e t l e s than the other two. On 102 Table XIX. D i s t r i b u t i o n of T\ l ineatum on a l i n e a t i n - b a i t e d suppress ion t r ap an the Chemainus sawmi l l , 1981. Mean Number of Bee t le s Caught '•* 27 May to 2 J u l y Pheromone at In ter -sec t i on of Top and Upper Middle Rows 2 J u l y to 10 August Pheromone at I n te r -s e c t i o n of Upper and Lower Middle Rows Female Male T o t a l Female Male T o t a l Height: Top 19.2 a 21.5 a 40.7 a 3.3 a 3.7 a 7.0 a Upper Middle 11 .4 b 11.4 b 22.6 b 3.7 a 4.0 a 7.7 ab Lower Middle 6.2 c 6.6 c 12.8 c 2.2 b 2.8 a 5.0 b Bottom 1.9 d 1.6 d 3.5 d 1 .6 b 1.3 b 2.9 c Column: Inner 15.4 a 16.2 a 31.6 a 4.6 a 5.3 a 9.9 a Middle 7.8 b 8.0 b 15.8 b 1.9 b 2.3 b 4.2 b Outer 5.7 c 6.7 b 12.4 c 1.7 b 1 .1 c 2.6 c Aspect : North 14.1 a 12.3 b 26.4 a 4.7 a 4.0 a 8.7 a South 4.2 b 5.6 c 9.8 b 1.2 b 1.5 b 2.7 b East 5.0 b 4.9 c 9.9 b 0.8 b 1.2 b 2.0 b Nest 15.4 a IB.3 a 33.7 a 4.1 a 4.9 a 9.0 a 1 Data transformed to x' • l o g 1 0 ( « + D for a n a l y s i s . * Means w i th in sex groups and ca tego r i e s fo l lowed by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , p < 0.05. 103 t r a p TS5 most b e e t l e s were caught on the north and west a s p e c t s . However, on t r a p T2 the south and east aspects were exposed to the wider approach angle but the most b e e t l e s were caught on the north and south a s p e c t s . Thus the angle of exposure of a vane s u r f a c e does not appear to be the s o l e f a c t o r r e s p o n s i b l e f o r tr a p p i n g success of a p a r t i c u l a r a s p e c t . Wind d i r e c t i o n and o r i g i n of b e e t l e s are probably c o n t r i b u t i n g f a c t o r s . At both the upper and c e n t r a l pheromone p o s i t i o n s s i g n i f i c a n t l y more b e e t l e s of both sexes were caught on the column c l o s e s t to the support post than on the middle or outer columns (Table XIX). T h i s r e s u l t c o u l d i n d i c a t e a strong response to the s p e c i f i c source*of the pheromone, r a t h e r than random movement around the v i c i n i t y of the source of a t t r a c t i o n . With the pheromone i n the upper p o s i t i o n , s i g n i f i c a n t l y more b e e t l e s of both sexes were caught on the top row than on the second row, on the second row than on the t h i r d row and on the t h i r d row than on the bottom row (Table XIX). When the pheromone was lowered to the c e n t r a l p o s i t i o n , more female T. lineatum were caught on the top two rows than on the bottom two rows. More male b e e t l e s were caught on each of the top three rows than on the bottom row (Table XIX). These r e s u l t s are s i m i l a r to those f o r G_j_ s u l c a t u s (McLean and Borden 1 979) i n that the v e r t i c a l d i s t r i b u t i o n of the b e e t l e s was d i r e c t l y r e l a t e d to the v e r t i c a l p o s i t i o n i n g of the pheromone. With the pheromone i n the upper p o s i t i o n the hig h c a t c h i n the top row co u l d suggest that b e e t l e s were f l y i n g over the top of the vanes. When the pheromone was lowered, the v e r t i c a l 1 04 d i s t r i b u t i o n of b e e t l e s on the vane appeared to be more uniform. However, the s i g n i f i c a n t l y lower c a t c h e s on the bottom row of the vanes i n t h i s experiment, as w e l l as the f i n d i n g that catches of T\ 1ineatum were reduced at the lowest h e i g h t s , probably as a r e s u l t of i n t e r f e r e n c e from surrounding v e g e t a t i o n ( s e c t i o n 4.1), suggests that a moderate change i n t r a p design may improve t r a p performance. I t i s t h e r e f o r e recommended that the s u p p o r t i n g post be extended by 30 cm and the vanes be e l e v a t e d by t h i s same amount. Pheromone placement should be at a c e n t r a l p o s i t i o n to the vanes i n order to d i s t r i b u t e b e e t l e s more evenly and thus use the a v a i l a b l e t r a p p i n g s u r f a c e area more e f f i c i e n t l y . 105 4.3 INVESTIGATION OF THE MOVEMENT OF LINEATUM AND G^ SULCATUS BETWEEN THE CHEMAINUS SAWMILL AND A NEIGHBOURING SAWMILL I n t r o d u c t i o n In order to e s t a b l i s h a s u c c e s s f u l pest management program i t i s necessary to understand the source and range of the p e s t . The management program f o r ambrosia b e e t l e s i n the Chemainus sawmill would have a c o n s i d e r a b l y higher chance of success i f the b e e t l e p o p u l a t i o n s were o r i g i n a t i n g from m a t e r i a l moving through that m i l l than i f they were a l s o coming from sources not p a r t i c i p a t i n g i n the program. Usual f l y i n g d i s t a n c e s f o r T. 1ineatum a f t e r emerging from the duff i n the s p r i n g are not known. However t h i s s p e c i e s r e q u i r e s a p e r i o d of f l i g h t e x e r c i s e before the chemotropic response i s r e l e a s e d (Graham 1959; Bennett and Borden 1971). A l s o , a marked T\ lineatum was found approximately four k i l o m e t r e s from where i t was r e l e a s e d the p r e v i o u s year (Dyer 1961). An experiment was e s t a b l i s h e d i n 1981 to determine i f there was movement of T_^  1 ineatum between the Chemainus sawmill and a neighbouring m i l l . M a t e r i a l s and Methods D r a i n p i p e t r a p s , c o n s i s t i n g of a 1.2 m s e c t i o n of 10 cm diameter p e r f o r a t e d , c o r r u g a t e d p l a s t i c pipe strapped onto a 1.2 m pole and f i t t e d with a cap at the top and a funnel and 1 06 c o l l e c t i n g b o t t l e at the bottom, were made to simulate the Scandinavian d r a i n p i p e t r a p design (Bakke and Saether 1978)(Fig. 15). Each t r a p was b a i t e d with two Conrel® f i b r e s c o n t a i n i n g l i n e a t i n , suspended approximately halfway down the t r a p . On 19 March 1981, f i v e of these t r a p s were p o s i t i o n e d at approximately equal i n t e r v a l s on a l i n e from the Chemainus sawmill and a s m a l l e r d r y l a n d o p e r a t i o n about 1.5 k i l o m e t r e s away. A second t r a p was added to each of the f i v e l o c a t i o n s on 20 May. On 26 June ( i ) - s u l c a t o l was added to the t r a p s i n order to monitor G. s u l c a t u s movement. Traps were emptied p e r i o d i c a l l y u n t i l the end of J u l y and numbers of captured T_^  1 ineatum and G_^  s u l c a t u s recorded. R e s u l t s and D i s c u s s i o n T o t a l c a t c h e s of 1ineatum i n the s e r i e s of d r a i n p i p e t r a p s between the neighbouring sawmill o p e r a t i o n and the Chemainus sawmill are shown i n Table XX. While the p a t t e r n of catches at the f i v e l o c a t i o n s d i d not r u l e out movement of T. lineatum between the two o p e r a t i o n s , the s w e l l i n g of numbers in the c e n t r a l t r a p suggests there was a separate p o p u l a t i o n around each m i l l with an o v e r l a p i n t e r r i t o r y approximately halfway between the two sawmills (Table XX). The data f o r G^ s u l c a t u s were minimal as t r a p p i n g was not continued through the l a t e summer peak f l i g h t p e r i o d . However, the low c a t c h at l o c a t i o n 4 suggests that there are separate, non-overlapping p o p u l a t i o n s around each sawmill (Table XX). The h i g h number of b e e t l e s caught at the l o c a t i o n c l o s e s t to the F i g u r e 15. Scandinavian d r a i n p i p e t r a p (Borregaard A.S. Sarpsborg, Norway). T a b l e XX. D i s t r i b u t i o n of T\ l i n e a t u m and s u l c a t u s on t r a p s at f i v e l o c a t i o n s between the Chemainus s a w m i l l and a n e i g h b o u r i n g s a w m i l l o p e r a t i o n . Approximate T o t a l T o t a l L o c a t i o n C l o s e s t D i s t a n c e From T\ l i n e a t u m G. s u l c a t u s Number S a w m i l l C l o s e s t S a w m i l l C a p t u r e d C a p t u r e d 1 Chemainus .25 k i l o m e t r e s 2184 77 2 Chemainus .50 k i l o m e t r e s 952 74 3 Both .75 k i l o m e t r e s 1907 86 4 N e i g h b o u r i n g .50 k i l o m e t r e s 1 147 2 5 N e i g h b o u r i n g .25 k i l o m e t r e s 2449 668 1 10 neighbouring sawmill i n d i c a t e s that t h i s o p e r a t i o n may have an ambrosia b e e t l e problem. The Chemainus sawmill i s a much l a r g e r o p e r a t i o n than the neighbouring m i l l . However, r e l a t i v e l y few G. s u l c a t u s and a s i m i l a r number of T_j_ lineatum were caught at the l o c a t i o n c l o s e s t to the Chemainus sawmill compared to that c l o s e s t to the neighbouring m i l l . T h i s f i n d i n g p o s s i b l y r e f l e c t s a r e d u c t i o n i n these p o p u l a t i o n s as a r e s u l t of the mass-trapping program at the former o p e r a t i o n . F u r t h e r i n f o r m a t i o n on the movement of ambrosia b e e t l e s between the two o p e r a t i o n s c o u l d probably be obtained using a mark-recapture technique. 111 4.4 A FURTHER EVALUATION OF THE INTERACTIONS BETWEEN THE PHEROMONES AND TWO HOST KAIROMONES OF THE AMBROSIA BEETLES, T_L LINEATUM AND SULCATUS I n t r o d u c t i o n The ambrosia b e e t l e s T\ lineatum, G. s u l c a t u s and G. retusus were found to be t o l e r a n t of each o t h e r ' s pheromones (Borden et a l . 1981). However, two of f i f t e e n s t i c k y vane suppression t r a p s , d o u b l e - b a i t e d with the pheromones (±)-sulcatol and l i n e a t i n together with EP, i n the Chemainus sawmill i n 1980 had lower catches than nearby s i n g l e - b a i t e d t r a p s (Table X I I ) . The primary a t t r a c t a n t s EP have been r e p o r t e d to act s y n e r g i s t i c a l l y with the pheromones for female (Borden et a l . 1980c) and male (Borden et a l . 1982) G^ s u l c a t u s . In Europe, the response of both sexes of T\ lineatum was s y n e r g i s e d by the a d d i t i o n of EP to l i n e a t i n - b a i t e d d r a i n p i p e t r a p s ( V i t e and Bakke 1979; Klimetzek et a l . 1980; Borden et a l . 1982). However, t h i s synergism was not found f o r North American T. lineatum (Borden et a l . 1982). In order to e v a l u a t e whether these apparent i n c o n s i s t e n c i e s were a r e s u l t of s i t e d i f f e r e n c e s or i n t e r a c t i o n s between the semiochemicals, i t was decided to i n v e s t i g a t e f u r t h e r the i n t e r a c t i o n of the primary and secondary a t t r a c t a n t s of G_^  s u l c a t u s and T_;_ lineatum by t e s t i n g the pheromones and EP i n a f i e l d experiment. 1 1 2 M a t e r i a l s and Methods An 8 X 8 L a t i n square design, with t r a p p o s i t i o n and t r a p p i n g o c c a s i o n as the rows and columns, was used to t e s t the e i g h t treatments c o n s i s t i n g of an unbaited c o n t r o l , l i n e a t i n , (±)-sulcatol, EP and a l l combinations of the l a t t e r t hree. E i g h t Scandinavian d r a i n p i p e t r a p s ( F i g . 15) were set out at approximate 20 m i n t e r v a l s on 21 A p r i l , 1981 i n a wooded foreshore area of the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands adjacent to l o g boom storage areas on the F r a s e r R i v e r . Release r a t e s and d e v i c e s used f o r each semiochemical are shown in Table XXI. Ethanol and a-pinene r e l e a s e r a t e s conformed to the "low" r e l e a s e r a t e s d e s c r i b e d by Borden et a l . (1982). On 28 A p r i l , 8,22 May, 15 June, 3,14 and 23 J u l y , treatments were assigned to new p o s i t i o n s . The experiment was terminated on 11 August. Ambrosia b e e t l e s were c o l l e c t e d from t r a p s at the end of each t r a p p i n g i n t e r v a l . The major sources of v a r i a t i o n i n t r a p p i n g ambrosia b e e t l e s have been time and t r a p p o s i t i o n e f f e c t s (Tables V, V I I ) . The L a t i n square design ensured that every treatment was t e s t e d once at each t r a p p o s i t i o n and on each o c c a s i o n and that v a r i a n c e s due to p o s i t i o n and time c o u l d be p a r t i t i o n e d i n the a n a l y s i s of v a r i a n c e (Perry et a l . 1980). 1 13 Table XXI. Release d e v i c e s and l a b o r a t o r y r e l e a s e r a t e s of semiochemicals used i n Scandinavian d r a i n p i p e t r a p s 1 set up on the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands, 1981. Semiochemical Release Device Approximate 24-hour Release Rate S u l c a t o l L i n e a t i n 95% Ethanol c-pinene open 2 ml g l a s s v i a l 4.5 mm a p e r t u r e 4 Conrel® f i b r e s with 0.2 mm i n s i d e diameter 20 ml p o l y e t h y l e n e s c i n t i l l a t i o n v i a l with 1.5 mm hole i n l i d 4 ml g l a s s v i a l with 1.5 mm hole i n l i d 2 mg 40 ug 1 50 mg 1 7 mg 1 Borregaard A.S., Sarpsborg, Norway. 1 14 R e s u l t s and D i s c u s s i o n The L a t i n square design proved to very e f f e c t i v e , r e a d i l y a l l o w i n g d i f f e r e n c e s between treatments to be i d e n t i f i e d by s e p a r a t i n g the v a r i a b i l i t y due to p o s i t i o n and o c c a s i o n . T h i s design a l l o w s the a d d i t i o n a l advantage of p r o v i d i n g i n f o r m a t i o n on the v a r i a b i l i t y between t r a p p o s i t i o n s (Table X X I I ) . The presence of (±)-sulcatol on both the l i n e a t i n and the l i n e a t i n + EP treatments r e s u l t e d i n a s i g n i f i c a n t decrease in response by both male and female T\ lineatum (Table X X I I I ) . T h i s r e s u l t i s i n c o n t r a s t with the r e p o r t e d t o l e r a n c e of T. lineatum to (±)-sulcatol (Borden et a l . 1981) and i n d i c a t e s that the i n s i g n i f i c a n t lower responses found by them were probably r e a l . The number of G_^  s u l c a t u s that responded to treatments was comparatively low (Table X X I I I ) . Response was s u f f i c i e n t , however, to c o n f i r m the s y n e r g i s t i c r o l e of EP f o r female (Borden e_t a l . 1980c) and male (Borden et a l . 1982) G. s u l c a t u s response to ( t ) - s u l c a t o l . G_;_ s u l c a t u s was found to be t o l e r a n t of l i n e a t i n (Table XXIII) as r e p o r t e d by Borden e_t a l . (1981). EP c l e a r l y enhanced the response of T\ lineatum t o l i n e a t i n - b a i t e d d r a i n p i p e t r a p s (Table X X I I I ) . These r e s u l t s are i n agreement with those of V i t e and Bakke (1979), Klimetzek et a l . (1980) and Borden et a l . (1982) i n Europe, but are i n disagreement with those of Borden et a l . (1982) in North America. Our r e s u l t s suggest that i n general EP a c t s s y n e r g i s t i c a l l y with l i n e a t i n i n d r a i n p i p e t r a p s . The a d d i t i o n of EP to the l i n e a t i n + (±)-sulcatol treatment a l s o i n c r e a s e d T a b l e X X I I . Percentage of t o t a l v a r i a n c e a s s i g n e d t o each s o u r c e of v a r i a t i o n f o r d a t a on response of Trypodendron  l i n e a t u m and G n a t h o t r i c u s s u l c a t u s t o pheromones and two host kairomones. P e r c e n t a g e of V a r i a n c e A s s i g n e d Source of T\ l i n e a t u m G. s u l c a t u s V a r i a t i o n D.F. Male Female T o t a l Male Female T o t a l O c c a s i o n 7 6. ,41** 4. .89** 5. ,53** 14 .86** 16. .97** 17, .12** S i t e 7 1 . .29 0, .80 1 . .01 12 .35* 10, .01* 1 1 . .37** Treatment 7 85. .40** 87, .06** 88. .00** 44 .38** 49, .94** 52, .62** E r r o r 42 6, .90 7, .25 5. .46 28 .41 23, .08 18, .89 1 S i g n i f i c a n t s o u r c e s of v a r i a n c e i n d i c a t e d a s : ** = p < 0.01, * = p < 0.05. 116 Tab le XXII I . Response by two spec ies of ambrosia bee t l e to Scand-inav ian d ra inp ipe t raps ba i t ed with racemic s u l c a t o l (S), l i n e a t i n (L) or ethano l p lus o-pinene (EP) a lone or in combinat ion or unbaited c o n t r o l at the U n i v e r s i t y of B r i t i s h Columbia Endowment Lands, 19B1, T o t a l Response 1 Responding Sex 2 Spec ies Treatment Female Male T o t a l Rat io T . l ineatum L + EP 934 L 191 L + S + EP 219 L * S 75 S • EP 3 EP 4 S 1 Con t ro l 0 G. s u l c a tu s S + EP 120 S • L + EP 92 S • L 55 S 41 L-+ EP IB EP 4 L 1 Con t ro l 0 a ' 1668 a 2622 a 1.61 b 611 b B02 b 3.20 b 392 be 61 1 b 1 .79 c 1B0 c 255 c 2.40 d 6 d 9 d d 3 d 7 d d 1 d 2 d d 0 d 0 d a 100 a 220 a 1 .20 ab 41 ab 133 ab 2.24 ab 22 be 77 b 2.50 b 12 c 53 b 3.42 c 3 c 21 c c 3 c 7 c c 0 c 1 c c 0 c 0 c 1 Data transformed to x'« l o g , o ( x + l ) fo r a n a l y s i s . * Male:Female for "J\ l ineatum; Female:Male for s u l c a t u s . Sex r a t i o not c a l c u l a t e d for treatments with low numbers. ' Numbers w i th in a column fo l lowed by the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t , Newman K e u l ' s t e s t P < 0.05. 1 17 response by T\ l i n e a t u m t o the l i n e a t i n + (±)-sulcatol t r e a t m e n t , a l t h o u g h o n l y the female and t o t a l i n c r e a s e s were s i g n i f i c a n t . T h i s r e s u l t s u p p o r t e d the f i n d i n g f o r the l i n e a t i n , A s i g n i f i c a n t i n c r e a s e i n response t o the t e r n a r y m i x t u r e over the pheromone a l o n e was a l s o found f o r b o t h sexes of the s y m p a t r i c s p e c i e s G_^  r e t u s u s (Borden e t a_l. 1980c). Thus, i n g e n e r a l , the s y m p a t r i c a mbrosia b e e t l e s p e c i e s T\ l i n e a t u m , G. s u l c a t u s and G^ r e t u s u s demonstrate a s i g n i f i c a n t l y g r e a t e r r esponse t o t h e i r r e s p e c t i v e pheromones p l u s EP than t o t h e i r pheromones a l o n e . E t h a n o l and o-pinene were used o n l y i n c o m b i n a t i o n ; t h e r e f o r e , no i n f e r e n c e can be made on t h e i r i n d i v i d u a l r o l e s i n T. l i n e a t u m r e s p o n s e . However, EP a l o n e i n d r a i n p i p e t r a p s was not a t t r a c t i v e t o t h i s b e e t l e , i n agreement w i t h f i n d i n g s i n N o r t h America (Borden e t a l . 1982). The sex r a t i o of b o t h s p e c i e s d e c l i n e d w i t h the a d d i t i o n of EP t o the r e s p e c t i v e pheromones. T h i s d e c l i n e i s a r e s u l t of an i n c r e a s e i n the p r o p o r t i o n of t h e f i r s t a t t a c k i n g sex, female T. 1ineatum and male G^ s u l c a t u s . T h i s conforms t o r e s u l t s r e p o r t e d f o r G^ s u l c a t u s (Borden e t a l . 1980c, 1982) and f o r T. l i n e a t u m i n Europe and N o r t h America (Borden e t a l . 1982). The g r e a t e r i n c r e a s e i n response by the f i r s t a t t a c k i n g sex would be e x p e c t e d i f EP were i n f a c t s i m u l a t i n g a t t r a c t i v e host odours (Borden e t a l . 1980c, 1982). In l i g h t of the s e r e s u l t s the model f o r a l l e l o c h e m i c i n t e r a c t i o n s between the t h r e e s y m p a t r i c ambrosia b e e t l e s p e c i e s T. l i n e a t u m , G. s u l c a t u s and G. r e t u s u s (Borden e t a l . 1981) 118 should be m o d i f i e d to show p a r t i a l r a ther than complete i n t e r s p e c i f i c t o l e r a n c e of pheromones between G^ s u l c a t u s and T. lineatum. The s i g n i f i c a n t response by T\ lineatum to l i n e a t i n treatments c o n t a i n i n g (±)-sulcatol suggests that the s p e c i e s i s not r e p e l l e d by t h i s pheromone. I t seems l i k e l y that the 20 m i n t e r v a l between t r a p s p l a c e d treatments c l o s e enough to o f f e r the b e e t l e s a c h o i c e , r a t h e r than t e s t i n g response to i n d i v i d u a l treatments. T h i s h y p o t h e s i s i s supported by r e s u l t s showing a s t r o n g response by T^ lineatum to EP i n experiments not c o n t a i n i n g pheromone (Bauer and V i t e 1975; N i j h o l t and Schonherr 1976). Response to the most a t t r a c t i v e treatment has been demonstrated f o r the bark b e e t l e genus Ips where three non-sympatric s p e c i e s demonstrated s l i g h t c r o s s - a t t r a c t i o n to each o t h e r ' s pheromones i f o f f e r e d no c h o i c e , but when given a c h o i c e p r e f e r r e d t h e i r own pheromone (Wood 1970). The p a r t i a l t o l e r a n c e of T^ 1ineatum to the pheromone (±)-sulcatol probably r e f l e c t s the f a c t that the two s p e c i e s f r e q u e n t l y c o l o n i z e the same host m a t e r i a l . However, when o f f e r e d a c h o i c e of l i n e a t i n alone or l i n e a t i n + (±)-sulcatol, T^ lineatum showed a p r e f e r e n c e f o r the former. G_^  s u l c a t u s , on the other hand, d i d not demonstrate any p r e f e r e n c e f o r (±)-sulcatol alone or (±)-sulcatol + l i n e a t i n (Table X X I I I ) . A p o s s i b l e e x p l a n a t i o n f o r t h i s d i f f e r e n c e i s that T\ lineatum has s t r i c t e r host requirements and f l i e s e a r l i e r i n the s p r i n g than s u l c a t u s . The p r e f e r r e d wood m a t e r i a l of T\_ lineatum, that which was f e l l e d the p r e v i o u s September to January, would not u s u a l l y be c o l o n i z e d by G_^  s u l c a t u s when T\ lineatum makes i t s s p r i n g 119 f l i g h t . T h e r e f o r e , i t seems l i k e l y that T\_ lineatum would show a p r e f e r e n c e f o r host m a t e r i a l from which l i n e a t i n alone was emanating. I f t h i s c h o i c e were not a v a i l a b l e the next best c h o i c e would be o l d e r host m a t e r i a l c o l o n i z e d by G_^  s u l c a t u s the pr e v i o u s year. Both pheromones would l i k e l y be emitted i n the o v e r l a p p i n g p e r i o d between c o l o n i z a t i o n by T\ 1ineatum and G. s u l c a t u s emergence and r e - a t t a c k . G_^  s u l c a t u s , on the other hand, would f i n d most s u i t a b l e host m a t e r i a l a l r e a d y a t t a c k e d by T. lineatum by the time of i t s s p r i n g f l i g h t and thus would develop t o l e r a n c e to the pheromone of that s p e c i e s . The s i t u a t i o n where a choice between semiochemicals i s presented t o the b e e t l e r e f l e c t s the n a t u r a l s i t u a t i o n and should be co n s i d e r e d in experimental design and i n t e r p r e t a t i o n . I t a l s o should be co n s i d e r e d i n mass t r a p p i n g programs where only the most a t t r a c t i v e semiochemical combination w i l l be able to e f f e c t i v e l y compete with n a t u r a l odours. For maximum response by T^ lineatum and G^ s u l c a t u s , ethanol and a-pinene should be added to both l i n e a t i n and (±)-sulcatol. D r a i n p i p e , and probably other t r a p s as w e l l , should be s i n g l e pheromone-baited f o r maximum catches of T\ lineatum. 1 20 4.5 INVESTIGATION OF MARK-RECAPTURE AS A TECHNIQUE FOR EVALUATING THE EFFICIENCY OF AN AMBROSIA BEETLE MASS-TRAPPING PROGRAM I n t r o d u c t i o n E v a l u a t i o n of mass-trapping programs where the host i s s t a t i o n a r y i s d i f f i c u l t , i n v o l v i n g " s o p h i s t i c a t e d understanding of i n s e c t - h o s t p o p u l a t i o n dynamics, a method f o r e v a l u a t i n g simultaneous i n t e r a c t i o n s of m u l t i p l e v a r i a b l e s , e s t i m a t i o n procedures with d e f i n e d p r e c i s i o n and accuracy and a procedure fo r measuring cost e f f e c t i v e n e s s " (Coulson e_t a_l. 1 979). However, the hosts f o r ambrosia b e e t l e s are log s and green lumber, both of which are mobile i n a m i l l s i t e . In a d d i t i o n to the d i f f i c u l t i e s i n sampling b e e t l e damage on a moving p o p u l a t i o n , i t i s never c e r t a i n whether the damage occurred before or a f t e r the host m a t e r i a l entered the t r a p p i n g zone. T h i s problem i s e s p e c i a l l y d i f f i c u l t at the sawmill end of the o p e r a t i o n where both logs and lumber are present and, as i n the Chemainus sawmill, logs are s o r t e d i n the water. The major problem i n e v a l u a t i n g the b e n e f i t s of the suppression program, apart from the d i f f i c u l t i e s i n sampling ambrosia b e e t l e damage, i s the esta b l i s h m e n t of treatment and c o n t r o l groups. Ambrosia b e e t l e p o p u l a t i o n l e v e l s and damage vary with l o c a t i o n , management p r a c t i c e s , s p e c i e s and s i z e of l o g and lumber i n v e n t o r i e s . T h i s v a r i a t i o n between d i f f e r e n t o p e r a t i o n s would confound the suppression program versus no suppression program 121 treatment r e s u l t s . P o p u l a t i o n l e v e l s of ambrosia b e e t l e s a l s o vary with time ( F i g s . 6a,b). T h i s , and the f a c t that suppression programs have a lower chance of success i f t a r g e t i n s e c t s are allowed to set up competing sources of a t t r a c t i o n , prevents program-on versus program-off comparisons w i t h i n a s i n g l e o p e r a t i o n , both w i t h i n a year or between ye a r s . As a r e s u l t of the problems i n e v a l u a t i n g suppression programs in terms of reduced damage, methods based on e s t i m a t i n g ambrosia b e e t l e p o p u l a t i o n r e d u c t i o n have been examined. These assume a d i r e c t r e l a t i o n s h i p between ambrosia b e e t l e p o p u l a t i o n l e v e l s and damage. McLean and Borden (1979) used a "suppression r a t i o " to i n v e s t i g a t e the e f f i c i e n c y of the s u l c a t u s mass-trapping program in the Chemainus sawmill. T h i s r a t i o was the number of b e e t l e s caught on t r a p s and t r a p l o a d s of lumber d i v i d e d by the estimated number of a t t a c k i n g b e e t l e s p l u s number of b e e t l e s caught on t r a p s and t r a p l o a d s . . While t h i s r a t i o g i v e s an i n d i c a t i o n of the p r o t e c t i o n o f f e r e d the lumber by the program, i t does not i n c l u d e damage o c c u r r i n g on l o g s . T\ lineatum does not seem to a t t a c k green lumber as f r e q u e n t l y as s u l c a t u s (McMullen 1956). T h e r e f o r e , f o r the expanded ambrosia b e e t l e suppression program an a l t e r n a t i v e method of a s s e s s i n g t r a p p i n g e f f i c i e n c y was sought. The mark-recapture technique was s e l e c t e d f o r study. T h i s technique has been used to evaluate a mass-trapping program f o r m u l t i s t r i a t u s i n C a l i f o r n i a ( B i r c h et a l . 1981). Mark-recapture or c a p t u r e - r e c a p t u r e r e f e r s to a technique i n v o l v i n g i n i t i a l capture of i n d i v i d u a l s i n a p o p u l a t i o n of 122 i n t e r e s t , marking them in some manner and r e l e a s i n g them back i n t o the p o p u l a t i o n . Inferences on the p o p u l a t i o n are made based on the number of marked i n s e c t s recaptured i n subsequent samples. The main purpose of t h i s i s p o p u l a t i o n e s t i m a t i o n but the method i s o f t e n used to g a i n i n f o r m a t i o n on p o p u l a t i o n movement, s u r v i v a l and l o n g e v i t y . For p o p u l a t i o n e s t i m a t i o n the u n d e r l y i n g idea i s b a s i c a l l y simple. If a known number of marked i n d i v i d u a l s i s r e l e a s e d and they mix randomly with the p o p u l a t i o n , the p r o p o r t i o n of marked i n d i v i d u a l s i n a subsequent p o p u l a t i o n sample should equal the p r o p o r t i o n of t o t a l marked i n s e c t s to t o t a l p o p u l a t i o n , or: m = M p P T h e r e f o r e , the p o p u l a t i o n estimate i s : Pe = pM m where: P = P o p u l a t i o n t o t a l Pe = P o p u l a t i o n t o t a l estimate p = number of i n d i v i d u a l s captured i n sample M = T o t a l number of marked i n d i v i d u a l s r e l e a s e d m = number of marked i n d i v i d u a l s recaptured i n sample T h i s formula i s r e f e r r e d to as the simple L i n c o l n Index ( L i n c o l n 1930). Although the idea i s b a s i a l l y simple there are s e v e r a l assumptions that must be met i n order to use t h i s technique 123 p r o p e r l y . These a r e : 1 1. The marked animals are not a f f e c t e d by being marked and the marks w i l l not be l o s t . 2. The marked animals are completely mixed i n the p o p u l a t i o n . 3. The p o p u l a t i o n i s sampled randomly with respect to i t s mark s t a t u s . 4. Sampling must be at d i s c r e t e time i n t e r v a l s and the a c t u a l time i n v o l v e d i n t a k i n g the samples must be small i n r e l a t i o n to t o t a l time. 5. The p o p u l a t i o n i s a c l o s e d one or, i f not, immigration and e m i g r a t i o n can be measured or estimated. 6. There are no b i r t h s and deaths i n the p e r i o d between sampling, or i f there are allowance can be made f o r them. For sampling without replacement, the Chapman estim a t o r i s l e s s b i a s e d than the simple L i n c o l n Index (Wensel 1977). T h i s i s : Pc = (M + 1)(p + 1) - 1 m + 1 with v a r i a n c e c a l c u l a t e d as: S 2 c = (M + 1)(p + 1)(M - m)(p-m) (m + 1 ) 2 (m + 2) 1 Taken from Southwood (1968). 124 The p r o p o r t i o n a l b i a s i s given a s : 1 -(M + 1)(p + 1 )/P b = e Confidence l i m i t s on the p o p u l a t i o n estimate can be set as: Pc ± 2Sc If the d i s t r i b u t i o n of the p o p u l a t i o n i s normal t h i s formula would p r o v i d e the 95% confidence i n t e r v a l and i f the d i s t r i b u t i o n i s unknown, the 75% confidence i n t e r v a l (Wensel 1977). In the Chemainus sawmill the mark-recapture method was c o n s i d e r e d as a p o t e n t i a l means of measuring t r a p p i n g e f f i c i e n c y and e s t i m a t i n g ambrosia b e e t l e p o p u l a t i o n s . However, there were d i f f i c u l t i e s i n meeting the r e q u i r e d assumptions. T_^  lineatum and G n a t h o t r i c h u s spp. emerge from the duff or wood m a t e r i a l r e s p e c t i v e l y , over a p e r i o d of time. Thus the whole p o p u l a t i o n i s not a v a i l a b l e f o r sampling or f o r marked b e e t l e s to mix with at a given time. If b e e t l e s were marked, r e l e a s e d and a sample taken w i t h i n twenty-four hours, the d e r i v e d estimate would only be of the p o p u l a t i o n a v a i l a b l e d u r i n g that p e r i o d . It was t h e r e f o r e decided to use a s l i g h t v a r i a t i o n on the standard mark-recapture technique by u t i l i z i n g the t o t a l season's c a t c h 1 -(m+1)(p+1)/P Given i n Wensel (1977) as 1-e which I b e l i e v e to be an e r r o r . 125 of s u l c a t u s and T\ 1ineatum.on the suppression t r a p s as the p o p u l a t i o n sample. As t h i s was a d e s t r u c t i v e sampling technique the Chapman estimator was used f o r p o p u l a t i o n e s t i m a t i o n . The t r a p p i n g e f f i c i e n c y was determined by p r o p o r t i o n e s t i m a t i o n using the p r o p o r t i o n s of t o t a l marked b e e t l e s recaptured and not re c a p t u r e d . M a t e r i a l s and Methods L i v e T\_ 1ineatum and G_^  s u l c a t u s were c o l l e c t e d using pheromone-baited Scandinavian d r a i n p i p e t r a p s ( F i g . 15). B e e t l e s were marked with a f l u o r e s c e n t p a i n t powder 1 ( F i g . 16). The powder was put i n a 250 cc p o l y e t h y l e n e wash b o t t l e and "p u f f e d " over the b e e t l e s u n t i l they were s u f f i c i e n t l y coated. T h i s method was s u p e r i o r to other powder a p p l i c a t i o n techniques attempted (eg. T a f t and Agee 1962) i n that i t allowed the amount of powder to be r e g u l a t e d and d i s t r i b u t e d u n i f o r m l y . Attempts at marking the b e e t l e s with p a i n t and f l u o r e s c e n t ink (P o r t e r and Jorgensen 1980) r e s u l t e d i n the e l y t r a being bound to g e t h e r . Examination of marked b e e t l e s under the microscope showed that the powder c o u l d be a p p l i e d i n a dosage such that i t was v i s i b l e to the human eye, e s p e c i a l l y under u l t r a v i o l e t l i g h t ( T a f t and Agee 1962), but d i d not p h y s i c a l l y i n t e r f e r e with the i n s e c t ' s v i s u a l or o l f a c t o r y organs. Marked b e e t l e s were able to s u r v i v e f o r s e v e r a l days i n the l a b o r a t o r y without n o t i c e a b l e l o s s of powder mark. The marking was s t i l l v i s i b l e a f t e r 1 F e r r o I n d u s t r i a l Products L t d . , Surrey, B r i t i s h Columbia. 126 F i g u r e 16. lineatum marked with f l u o r e s c e n t p a i n t powder and photographed i n u l t r a - v i o l e t l i g h t . 127 1 28 soaking the b e e t l e s i n water. On 28 May 1 981, 6,000 l i v e lineatum b e e t l e s were pl a c e d i n 12 r e l e a s e boxes, 500 to a box. The malerfemale r a t i o of these b e e t l e s was 1.62:1.0. Release boxes c o n s i s t e d of a wooden 25 X 30 cm r e c t a n g l e , 9 cm deep. The bottom was covered with 1.7 X 1.4 mm f i b r e g l a s s mesh c l o t h and the top with a removable p l e x i g l a s s cover. Boxes were a l l o c a t e d to f i v e general l o c a t i o n s i n the m i l l to simulate p o i n t s of o r i g i n of the b e e t l e s . The number of boxes a l l o c a t e d to a p a r t i c u l a r area r e f l e c t e d the h i s t o r i c c o n t r i b u t i o n of t r a p s i n that area to t o t a l T\ 1ineatum c a t c h . B e e t l e s at each l o c a t i o n were marked with a d i f f e r e n t c o l o u r of f l o u r e s c e n t powder and the l i d to the r e l e a s e box was removed. C o l o u r s , numbers and r e l e a s e l o c a t i o n s of marked b e e t l e s are shown i n Table XXIV. A f t e r dark on 28 May, t r a p s were examined with an u l t r a v i o l e t l i g h t run from a v o l t a g e c o n v e r t e r connected to the b a t t e r y of a t r u c k . A l l marked b e e t l e s were pi c k e d from the t r a p s ; t r a p number and c o l o u r of b e e t l e were noted. B e e t l e s remaining i n r e l e a s e boxes were counted. The procedure for the s u l c a t u s mark-recapture experiment was approximately the same as that f o r T_j_ lineatum. However, because only 800 l i v e b e e t l e s were obtained, only four l o c a t i o n s were s e l e c t e d , with a s i n g l e r e l e a s e box c o n t a i n i n g 200 b e e t l e s at each l o c a t i o n . Colour and r e l e a s e l o c a t i o n s are shown in Table XXV. The r e l e a s e boxes were s l i g h t l y a l t e r e d from the T. lineatum experiment. A f i n e r mesh was used to prevent the b e e t l e s from c r a w l i n g through the bottom, the depth of the boxes T a b l e XXIV. Numbers of Trypodendron l i n e a t u m marked, r e l e a s e d and r e c a p t u r e d i n the Chemainus s a w m i l l , May 28,1981. C o l o u r R e l e a s e P o i n t Number Number Number P e r c e n t a g e Marked Rel e a s e d R e c a p t u r e d R e c a p t u r e d Orange E. P l a n e r 2000 M i l l Yard P u r p l e N.W. P l a n e r 500 M i l l Yard Green Bare P o i n t 1500 Red P i t Yard 1000 B l u e H e l i c o p t e r 1000 Yard 1240 250 854 609 447 119 23 37 14 9.6 9.2 4.3 2.3 2.0 T o t a l s 6000 3400 202 5.9 T a b l e XXV. Numbers of G n a t h o t r i c h u s s u l c a t u s marked, r e l e a s e d and r e c a p t u r e d i n the Chemainus s a w m i l l , September 8-9,1981. C o l o u r Release P o i n t Number Marked Number R e l e a s e d Number R e c a p t u r e d P e r c e n t a g e R e c a p t u r e d Green P i t Yard 200 79 5.1 Orange N. P l a n e r 200 M i l l Yard Red Bark S e t t l i n g 200 Pond P u r p l e S. P l a n e r 200 M i l l Yard 89 64 23 7 0 7.9 0.0 13.0 T o t a l s 800 255 14 5.5 131 was i n c r e a s e d to 14 cm to make i t more d i f f i c u l t f o r weak or damaged b e e t l e s to crawl out and the box was p l a c e d on a Stikem Special®-coated vane to c a t c h c r a w l i n g b e e t l e s . B e e t l e s were r e l e a s e d on 8 September and t r a p s were checked on both the n i g h t s of 8 and 9 September. R e s u l t s and D i s c u s s i o n The marking and recovery techniques worked very w e l l . Marked b e e t l e s on t r a p s were very v i s i b l e i n u l t r a v i o l e t l i g h t . For lineatum 3,400 of the 6,000 marked b e e t l e s l e f t the box. Of these 3,400 b e e t l e s 202 were recaptured (Table XXIV). The sex r a t i o of recaptured b e e t l e s was not s i g n i f i c a n t l y d i f f e r e n t from that of r e l e a s e d b e e t l e s . Trapping e f f i c i e n c y (95% c . l . ) was estimated as 5.94 ± 0.84 p e r c e n t . Using the t o t a l T_;_ lineatum c a t c h f o r 1981 of 353,559 as the sample p, the m i l l p o p u l a t i o n (75% c . l . ) of t h i s s p e c i e s can be estimated at 5,923,435 ± 804,081 . For s u l c a t u s only 255 of the 800 marked b e e t l e s flew from the boxes. Of these, 14 were recovered (Table XXV) g i v i n g an estimated t r a p p i n g e f f i c i e n c y (95% c . l . ) of 5.49 ± 1.62 p e r c e n t . Using the t o t a l c a t c h of 21,985 G_^  s u l c a t u s i n 1981 as the sample p, a m i l l p o p u l a t i o n of 375,227 ± 181,972 b e e t l e s (75% c . l . ) i s estimated. These f i g u r e s can be c o n s i d e r e d as p r e l i m i n a r y estimates, c a l c u l a t e d i n order to i n v e s t i g a t e the p o t e n t i a l of the mark-recapture technique f o r e v a l u a t i o n of the ambrosia b e e t l e mass-trapping program. Furt h e r work w i l l be needed to improve 1 32 the accuracy of the e s t i m a t e s . The f a c t that the mark-recapture was done on only one o c c a s i o n f o r each s p e c i e s does not allow f o r seasonal v a r i a t i o n i n t r a p p i n g e f f i c i e n c y . The process should be repeated s e v e r a l times f o r each s p e c i e s throughout the season. A l s o , these estimates of t r a p p i n g e f f i c i e n c y represent the most p e s s i m i s t i c v a l u e s . Given the number of d r a i n p i p e t r a p s and manpower a v a i l a b l e , at l e a s t one week was r e q u i r e d to c o l l e c t s u f f i c i e n t l i v e b e e t l e s f o r the mark-recapture experiments. The extended p e r i o d the b e e t l e s spent in these t r a p s was a p p a r e n t l y d e l e t e r i o u s to t h e i r vigour as witnessed by the high r a t e of m o r t a l i t y i n the r e l e a s e boxes. A l l weakened, marked b e e t l e s that crawled from the r e l e a s e boxes or flew only a short d i s t a n c e before c o l l a p s i n g , r e s u l t e d i n reduced estimates of t r a p p i n g e f f i c i e n c y and overestimates of the p o p u l a t i o n s . The r e l e a s e box used f o r s u l c a t u s was an improvement over that used f o r T^ lineatum i n that i t prevented the c r a w l i n g b e e t l e s from being i n c l u d e d in the r e l e a s e d number. Fur t h e r improvements to the r e l e a s e boxes c o u l d be made to prevent l o s s e s of marked b e e t l e s due to b i r d s or gusts of wind and to allow only the more vigorous b e e t l e s to escape. The assumption that f l i g h t of a l l marked T\ lineatum would be terminated w i t h i n one day may have been i n e r r o r as demonstrated by the G^ s u l c a t u s mark-release experiment. Three of the 14 marked G^ s u l c a t u s were recovered at the end of the second day f o l l o w i n g r e l e a s e . T h i s f i n d i n g suggests that t r a p s should be checked on s u c c e s s i v e n i g h t s u n t i l no more marked b e e t l e s are recovered. 1 33 While there appear to be many problems i n the use of the mark-recapture technique f o r e s t i m a t i n g the e f f i c i e n c y of the ambrosia b e e t l e suppression progam, none of these i s insurmountable. Through the use of more d r a i n p i p e t r a p s , or other more e f f i c i e n t t r a p designs, s u f f i c i e n t numbers of l i v e b e e t l e s c o u l d be trapped i n a s h o r t e r time thus improving t h e i r v i g o u r . Another p o s s i b i l i t y f o r T_j_ lineatum, and one that would improve the mixing of the marked b e e t l e s with the unmarked p o p u l a t i o n , would be to mark brood b e e t l e s emerging from host m a t e r i a l . These b e e t l e s would then f l y to o v e r w i n t e r i n g s i t e s and r e - e n t e r the m i l l the f o l l o w i n g s p r i n g with the r e s t of the p o p u l a t i o n . O v e r w i n t e r i n g m o r t a l i t y of T\_ lineatum has been estimated at only about 5% (Chapman 1960) and c o u l d be allowed f o r i n the c a l c u l a t i o n s . The f l u o r e s c e n t powder marking technique would have to be examined i n order to determine i f the marking remained v i s i b l e f o l l o w i n g t h i s o v e r w i n t e r i n g p e r i o d . F u r t h e r work i s needed in order to determine i f the behaviour of captured, marked and r e l e a s e d T_;_ 1 ineatum and G_j_ s u l c a t u s i s the same as that of the n a t u r a l p o p u l a t i o n . T h i s c o u l d p o s s i b l y be determined i n a wind-tunnel. I f the recommended s t u d i e s and improvements are c a r r i e d out t h i s technique should p r o v i d e a means of e v a l u a t i n g the mass-trapping program in terms of p o p u l a t i o n r e d u c t i o n . 134 D i s p e r s a l Within the M i l l S i t e In a d d i t i o n to the i n f o r m a t i o n gained on t r a p p i n g e f f i c i e n c y , the use of d i f f e r e n t c o l o u r s of marked b e e t l e s p r o v i d e s i n f o r m a t i o n on p o p u l a t i o n movement. Orange-coloured T. lineatum were r e l e a s e d around the Planer M i l l to simulate b e e t l e s emerging from o v e r w i n t e r i n g s i t e s below the Planer M i l l and those emerging from d r y i n g lumber. While the m a j o r i t y of orange b e e t l e s were recaptured on t r a p s near the r e l e a s e p o i n t s , at l e a s t one b e e t l e was caught on every t r a p i n the m i l l ( F i g . 17a). There was a s i n g l e r e l e a s e p o i n t f o r the purple b e e t l e s i n the northwest corner of the Planer M i l l , s e l e c t e d to simulate b e e t l e s e n t e r i n g t h i s p a r t of the m i l l from a f o r e s t e d area a few b l o c k s away. As with the orange b e e t l e s , the purple b e e t l e s d i s p e r s e d widely around the m i l l ( F i g . 17b). The red b e e t l e s were r e l e a s e d i n the low e l e v a t i o n P i t Yard, a lumber storage area where r e l a t i v e l y low catches of T\_ 1ineatum occurred i n the 1979 survey f o r t h i s s p e c i e s . The recaptured red b e e t l e s were mainly a t t r a c t e d to higher e l e v a t i o n t r a p s near the edges of embankments ( F i g . 18a). There i s a p o s s i b l e e x p l a n a t i o n f o r t h i s behaviour. The b e e t l e s were observed t o f l y v e r t i c a l l y upon r e l e a s e , p o s s i b l y r e p e a t i n g the i n i t i a l p h o t o t r o p i c response phase of t h e i r e a r l y season f l i g h t behaviour. T h i s f l i g h t would, t h e o r e t i c a l l y , l e a d to a subsequent r e l e a s e of the chemotropic response (Graham 1959). The b e e t l e s would probably be above the height of the P i t Yard t r a p by the time the chemotropic response was t r i g g e r e d and would respond to the nearest u n i n t e r r u p t e d source of a t t r a c t i o n , as d i s c u s s e d i n 135 F i g u r e 17. D i s t r i b u t i o n of percentage of t o t a l marked T. lineatum recaptured on t r a p s around the Chemainus sawmill, 28 May 1981. a. Orange b. Purple 136 1 37 F i g u r e 1 8 . D i s t r i b u t i o n of percentage of t o t a l marked T. lineatum recaptured on t r a p s around the Chemainus sawmill, 28 May 1981. a. Red b. Green 138 139 s e c t i o n 4.1. Traps such as the one i n the P i t Yard may have been l e s s s u c c e s s f u l than those at the edges of embankments not because they are more d i s t a n t from sources of b e e t l e s , but because the pheromone plumes emanating from them are s u b j e c t to eddies around lumber p i l e s and b u i l d i n g s . Bare P o i n t was suspected as a major o v e r w i n t e r i n g l o c a t i o n f o r T\ lineatum. Large numbers of b e e t l e s caught on Bare Point t r a p s i n 1979 through 1981 r e i n f o r c e d these s u s p i c i o n s . The green b e e t l e s r e l e a s e d on Bare Point demonstrated that T. 1ineatum c l e a r l y can f l y from the p o i n t a c r o s s to the m i l l s i t e ( F i g . 18b). A l s o , the r e l a t i v e l y l a r g e catches of green b e e t l e s on Bare Point t r a p s suggests that these t r a p s do, i n f a c t , i n t e r c e p t b e e t l e s o r i g i n a t i n g from the p o i n t . However, T. lineatum moved in both d i r e c t i o n s a c r o s s the bay. Purple, orange and red b e e t l e s r e l e a s e d i n the m i l l area were found on Bare P o i n t t r a p s and green b e e t l e s r e l e a s e d on Bare Point were found on m i l l t r a p s ( F i g s . 17a,b and 18a,b). T h i s f i n d i n g i n d i c a t e s t hat some b e e t l e s flew at l e a s t one k i l o m e t r e from the r e l e a s e p o i n t to the t r a p . The lowest p r o p o r t i o n of b e e t l e s recaptured were i n the blue c o l o u r group (Table XXIV and F i g . 19). For an unknown reason t h i s group s u f f e r e d the highest m o r t a l i t y . P o s s i b l y the low t r a p p i n g e f f i c i e n c y was a r e s u l t of lack of v i g o u r of these b e e t l e s . Another p o s s i b l e reason f o r the low recovery i s that of the f i v e c o l o u r s , blue was the l e a s t v i s i b l e on the t r a p s . I t i s p o s s i b l e t h a t a few blue-marked b e e t l e s c o u l d have been missed. The f a c t that marked T\ lineatum d i s p e r s e d i n many 140 F i g u r e 19. D i s t r i b u t i o n of percentage of t o t a l Blue marked T. lineatum recaptured on t r a p s around the Chemainus sawmill, 28 May 1981. 141 142 d i f f e r e n t d i r e c t i o n s and f o r c o n s i d e r a b l e d i s t a n c e s from the r e l e a s e p o i n t s i n d i c a t e s that t h i s s p e c i e s i s very mobile. Many non-recaptured b e e t l e s f l y i n g a c r o s s Horseshoe Bay may have responded to n a t u r a l pheromone sources emanating from l o g booms. The f e a s i b i l i t y of suspending t r a p s above the l o g booms in Horseshoe Bay should be i n v e s t i g a t e d . G. s u l c a t u s marked with four c o l o u r s were r e l e a s e d . However, none of the red b e e t l e s were recovered (Table XXV), p o s s i b l y because the r e l e a s e p o i n t was very c l o s e to l o g booms s t o r e d i n Horseshoe Bay. N a t u r a l pheromone sources from a t t a c k e d l o g s may have outcompeted the more d i s t a n t pheromone-baited t r a p s . No marked G^ s u l c a t u s were recovered on t r a p s i n the H e l i c o p t e r Yard ( F i g . 20). The hi g h e s t p r o p o r t i o n s of recovered b e e t l e s were from the orange and pu r p l e groups r e l e a s e d around the planer m i l l (Table XXV). A l l recaptured b e e t l e s from these two groups were on t r a p s c l o s e to the p o i n t s of r e l e a s e ( F i g . 20). Low numbers of r e l e a s e d and recaptured b e e t l e s reduced the i n t e r p r e t a t i v e value of these r e s u l t s . In a d d i t i o n to monitoring t r a p p i n g e f f i c i e n c y of the mass-trapping program and movement of ambrosia b e e t l e s p e c i e s , the mark-recapture technique c o u l d be u t i l i z e d to optimize t r a p placement and t r a p numbers. T h i s c o u l d be accomplished by s u c c e s s i v e r e l e a s e s of e q u i v a l e n t numbers of b e e t l e s from f i x e d r e l e a s e p o i n t s under d i f f e r e n t t r a p p i n g regimes. D i f f e r e n t c o l o u r s c o u l d be used f o r each r e l e a s e to a v o i d c o n f u s i o n . Through comparisons of t r a p p i n g e f f i c i e n c y estimates a s s o c i a t e d 143 F i g u r e 20. D i s t r i b u t i o n of s u l c a t u s of four c o l o u r s recaptured on t r a p s around the Chemainus sawmill, 8-9 September, 1981. ) 144 145 with each t r a p p i n g regime, trends c o u l d be i d e n t i f i e d and numbers and p o s i t i o n s of t r a p s o p t i m i z e d . 1 46 5.0 CONCLUDING DISCUSSION Damage to c o a s t a l l o g and lumber i n v e n t o r i e s by ambrosia b e e t l e s i s l i k e l y to become an i n c r e a s i n g problem to the B r i t i s h Columbia f o r e s t i n d u s t r y with the trends toward d r y l a n d s o r t i n g and use of smaller logs from second growth f o r e s t s . A l s o , the decommisioning of k i l n s i n many c o a s t a l sawmills i n e f f o r t s to reduce p r o d u c t i o n c o s t s w i l l r e s u l t i n i n c r e a s e d volumes of green lumber, v u l n e r a b l e t o ambrosia b e e t l e a t t a c k , being s t o r e d i n m i l l y ards. Ambrosia b e e t l e s can r a p i d l y i n c r e a s e i n numbers when p r o v i d e d with an abundance of host m a t e r i a l (Dyer 1963; Chapman and Dyer 1969; Zanuncio 1981), even on y e a r - o l d logs ( s e c t i o n 2.0). Aggregation pheromones show c o n s i d e r a b l e promise f o r use in pest management plans f o r S c o l y t i d b e e t l e s because they a t t r a c t both sexes of the t a r g e t i n s e c t and because aggregation i s e s s e n t i a l f o r re p r o d u c t i o n (Bedard and Wood 1981). A l s o , they are not envir o n m e n t a l l y hazardous as are many chemical i n s e c t i c i d e s (Wood 1980; Peacock et a l . 1981). At present there are no p e s t i c i d e s r e g i s t e r e d f o r use a g a i n s t ambrosia b e e t l e s i n Canada. T h e r e f o r e , the only " t o o l s " a v a i l a b l e f o r ambrosia b e e t l e management are c a r e f u l inventory management, water m i s t i n g (where p o s s i b l e ) , and pheromone-mediated mass-trapping. Pheromone-mediated mass-trapping i s a r e l a t i v e l y new pest management technique and r e s e a r c h i s s t i l l i n i t s e a r l y stages. The progress i n i d e n t i f y i n g and s y n t h e s i z i n g semiochemicals has 147 exceeded that of i n t e g r a t i n g them i n t o pest management systems which, i n t u r n , has exceeded that of e v a l u a t i n g these systems (Wood 1979, 1980). There are two s i t u a t i o n s , not always d i s t i n g u i s h a b l e , to which mass-trapping i s a p p l i e d . Each s i t u a t i o n i n v o l v e s a d i f f e r e n t pest management t a c t i c . The f i r s t s i t u a t i o n i s where there i s an unattacked crop with c l e a r l y d i s t i n g u i s h a b l e boundaries. The mass-trapping t a c t i c i n t h i s case i n v o l v e s s e t t i n g up a b a r r i e r of t r a p s to p r o t e c t the crop from i n v a s i o n by an i n s e c t p e s t . T h i s i s the t a c t i c used a g a i n s t T^ lineatum in the Chemainus sawmill where b e e t l e s overwinter i n the duff i n surrounding f o r e s t e d a r e a s . A b e t t e r example would be T. 1ineatum in a d r y l a n d s o r t i n g area where the boundary between o v e r w i n t e r i n g area and l o g storage area i s w e l l defined, and thus more d e f e n s i b l e . The second s i t u a t i o n e x i s t s where the i n s e c t i s a l r e a d y spread throughout the crop. In t h i s case the o b j e c t i v e i s to suppress the numbers in order to prevent or r e t a r d the expansion of the i n f e s t a t i o n i n t o the unattacked crop. T h i s o b j e c t i v e i s g e n e r a l l y approached by e s t a b l i s h i n g a network or g r i d of t r a p s i n the i n f e s t e d area or throughout the range of the crop (Peacock et a l . 1981). S e v e r a l examples of mass-trapping Coleopteran f o r e s t p e s t s using t h i s t a c t i c e x i s t , i n c l u d i n g the spruce bark b e e t l e Ips typographus (L.) ( L i e and Bakke 1981; Bakke and Strand 1981), the elm bark b e e t l e S. m u l t i s t r i a t u s ( L a n i er 1981; Peacock e_t a l . 1981; B i r c h et a l . 1981) and the western pine b e e t l e Dendroctonus brevicomis LeConte (Bedard and Wood 1981). T h i s i s a l s o the major t a c t i c 1 48 used a g a i n s t Gnathotrichus spp. i n the Chemainus sawmill where the major source of b e e t l e s may be r e c e n t l y sawn lumber. As the lumber begins to dry, b e e t l e s emerge and seek more s u i t a b l e h a b i t a t s . During t h i s r e d i s t r i b u t i o n process the pheromone-baited t r a p s i n t e r c e p t b e e t l e s (Borden and McLean 1981). There i s a f i n e d i f f e r e n c e between s i t u a t i o n 1 and s i t u a t i o n 2. I f the i n s e c t s penetrate the b a r r i e r , which i s more l i k e l y to occur when d e a l i n g with l a r g e p o p u l a t i o n s , s i t u a t i o n 1 becomes s i t u a t i o n 2, and the b a r r i e r - e f f e c t i s reduced. In t h i s case the t r a p s are f o r c e d i n t o d i r e c t c o m p e t i t i o n with n a t u r a l sources of a t t r a c t i o n as the i n s e c t s a t t a c k the h o s t s . The chances of success using pheromone-mediated mass t r a p p i n g would seem to be g r e a t e r in s i t u a t i o n 1 than i n s i t u a t i o n 2 not only because there are fewer competing n a t u r a l sources of a t t r a c t i o n but because the o b j e c t i v e i s more r e a l i s t i c . The o b j e c t i v e of a resource p r o t e c t i o n entomological program i s p r o t e c t i o n of the resource from an i n s e c t pest, not e r a d i c a t i o n of that p e s t . The b i o l o g i e s of some i n s e c t s p e c i e s lend themselves b e t t e r to a b a r r i e r t a c t i c than o t h e r s . For example, the d i s t i n c t o v e r w i n t e r i n g phase of T\ lineatum o u t s i d e the host a l l o w s f o r the establishment of a b a r r i e r of t r a p s between o v e r w i n t e r i n g areas and unattacked h o s t s . G n a t h o t r i c h u s spp., on the other hand, overwinter w i t h i n t h e i r h o s t s . Thus in a l o g or lumber storage area there i s l i k e l y to be a t t a c k e d and unattacked m a t e r i a l . B e e t l e s of these s p e c i e s can emerge from logs or 149 severed g a l l e r i e s i n green lumber and a t t a c k adjacent host m a t e r i a l without encountering pheromone-baited t r a p s . However, more than the b i o l o g y of the i n s e c t s p e c i e s , the s i t u a t i o n d i c t a t e s the t r a p p i n g t a c t i c . For example, unattacked m a t e r i a l c o u l d be p r o t e c t e d from Gn a t h o t r i c h u s spp. a t t a c k using the b a r r i e r t a c t i c . I f a pest s p e c i e s i s spread u b i q u i t o u s l y through the range of i t s host and i s present i n very l a r g e numbers, mass-trapping i s not l i k e l y to reduce the numbers s u f f i c i e n t l y to o f f s e t the g e n e r a l l y high r e p r o d u c t i v e p o t e n t i a l of that i n s e c t (Daterman 1979). For example, i n Norway, approximately 2.9 b i l l i o n I_j_ typoqraphus were caught i n 600,000 pheromone-baited t r a p s i n 1979 ( L i e and Bakke 1981). In 1980, t h i s i n c r e a s e d to 4.5 b i l l i o n b e e t l e s . However, t o t a l damage to the f o r e s t s , i n c u b i c metres, was about the same i n 1980 as i n 1979 (Bakke and Strand 1981). In mass-trapping experiments f o r S. m u l t i s t r i a t u s Peacock et §_1. (1981) achieved a higher r a t e of success p r o t e c t i n g small groups of unattacked elm t r e e s using the b a r r i e r t a c t i c than they d i d reducing a t t a c k s using a c i t y - w i d e g r i d of t r a p s . Pheromone-mediated mass-trapping has the p o t e n t i a l to become an important component of an i n t e g r a t e d ambrosia b e e t l e management program. C a r e f u l i n v e n t o r y management w i l l continue to be the most e f f e c t i v e method of reducing b e e t l e damage and p o p u l a t i o n l e v e l s . The f a c t t h a t l i v i n g hosts are not i n v o l v e d allows f o r much gr e a t e r f l e x i b i l i t y i n t h i s management. I f through these e f f o r t s lower p r o p o r t i o n s of a t t a c k e d m a t e r i a l enter the storage areas and p o p u l a t i o n s of ambrosia b e e t l e s are 1 50 reduced, the amount of p r o t e c t i o n o f f e r e d unattacked host m a t e r i a l by mass-trapping should i n c r e a s e . I t i s not s u f f i c i e n t to base success or f a i l u r e of a mass-trapping program on the number of i n s e c t s caught w i t h i n or between y e a r s . E v a l u a t i o n of a program has to be taken to the b e n e f i t / c o s t l e v e l where b e n e f i t i s based on the r e d u c t i o n of damage to the resource. The i n i t i a l steps i n the development of a mass-trapping program can be c a r r i e d out by b i o l o g i s t s and chemists. However, the e v a l u a t i o n process r e q u i r e s a d d i t i o n a l e x p e r t i s e from economists, modellers and people f a m i l i a r with the p r o d u c t i o n end of the business (Bedard and Wood 1981). In order to evaluate mass-trapping programs i t i s necessary to understand "the r e l a t i o n s h i p between the number of a p a r t i c u l a r l i f e stage of the pest and the damage caused by the pest; and the r e l a t i o n s h i p between changes i n the number of t h i s l i f e stage caused by a behaviour-modifying chemical treatment and subsequent damage" (Wood 1980). If these v i t a l r e l a t i o n s h i p s can be q u a n t i f i e d , then techniques such as mark-recapture can be used not only to e v a l u a t e system e f f i c i e n c y and estimate the t a r g e t p o p u l a t i o n , but to r e l a t e these numbers to damage l e v e l s . In t h i s manner a true b e n e f i t / c o s t a n a l y s i s of pheromone-mediated mass t r a p p i n g can be developed. In the meantime, however, both the value at r i s k and p r e s s u r e from the i n t e r n a t i o n a l market d i c t a t e that something must be done. Ma c M i l l a n - B l o e d e l L t d . has r e c e n t l y developed a model to estimate l o s s e s due to degrade of lumber caused by ambrosia b e e t l e s . P r e l i m i n a r y estimates at the Chemainus sawmill suggest 151 that t h i s l o s s c o u l d approach two m i l l i o n d o l l a r s per year (K. Purchase, p e r s . comm.).1 The l e v e l s of damage at t h i s o p e r a t i o n are probably t y p i c a l or, i f anything, lower than at other o p e r a t i o n s ; e s p e c i a l l y those on dry land where the e n t i r e s u r f a c e area of logs i s exposed to ambrosia b e e t l e a t t a c k . With l o s s e s of t h i s magnitude, and much more at r i s k , the c o s t s i n v o l v e d i n mass-trapping are r e l a t i v e l y s m a l l . For example, at the Chemainus sawmill, an estimate of the c o s t of o p e r a t i n g the t r a p p i n g program f o r one season i s $1,072.50 (Table XXVI). In summary, t h i s r e s e a r c h has demonstrated that the pheromones (±)-sulcatol, ( + ) - s u l c a t o l and l i n e a t i n can be used to a t t r a c t l a r g e numbers of s u l c a t u s , G. retusus and T. lineatum, r e s p e c t i v e l y , i n t o t r a p s . T h i s technique was demonstrated to be u s e f u l f o r s u r v e y i n g the s p a t i a l and temporal d i s t r i b u t i o n of these s p e c i e s . In a d d i t i o n , l a r g e numbers of T. lineatum, G. s u l c a t u s and G_^  r etusus were removed from the p o p u l a t i o n s by suppression t r a p s . A f o u r t h ambrosia b e e t l e , P. w i l s o n i , was a t t r a c t e d i n t o s t i c k y t r a p s by s u l c a t o l p l u s ethanol p l u s c-pinene. S t u d i e s on t r a p performance and semiochemical i n t e r a c t i o n have r e s u l t e d i n s e v e r a l changes being suggested, that i f implemented should improve the performance of the mass-trapping program. A technique f o r e v a l u a t i n g t r a p p i n g e f f i c i e n c y and e s t i m a t i n g ambrosia b e e t l e p o p u l a t i o n s was developed. Fur t h e r work r e l a t i n g r e d u c t i o n of b e e t l e p o p u l a t i o n s through mass-trapping to end product damage 1 P r o d u c t i o n Manager, M a c M i l l a n - B l o e d e l L t d . , Chemainus Sawmill D i v i s i o n . 152 Table XXVI. Estimated c o s t s of o p e r a t i n g the mass-trapping program f o r G^ s u l c a t u s , G. retusus and T. lineatum at the Chemainus s a w m i l l . 1 Item Number Required Approximate Cost Per Item Cost Traps ( r e - u s a b l e ) 15 17.00 255.00 Stikem Special® 2 2 cans 110.00 220.00 Pheromones 3 — 282.50 282.50 Trap Maintenance 24 hours 10.00 240.00 M i s c e l l a n e o u s — 75.00 75.00 T o t a l E stimated Cost $1 ,072.50 1 Based on c l e a n i n g 2 M i c h e l - P e l t o n L t d . and r e p l a c i n g , E m e r y v i l l e , the vanes three C a l i f o r n i a . times. 3 Based on approximate pheromone p r i c e s as suggested by S. Burke, S t r a t f o r d Chemical Developments L t d . , Vancouver, B r i t i s h Columbia. 153 r e d u c t i o n i s necessary i n order to produce r e l i a b l e b e n e f i t / c o s t i n f o r m a t i o n . C a r e f u l inventory management remains as the most e f f e c t i v e means of reducing ambrosia b e e t l e p o p u l a t i o n s . The i n t e g r a t i o n of pheromone-mediated mass-trapping at a l l l o g and lumber storage areas i n t o an ambrosia b e e t l e management program should act to minimize damage caused by these i n s e c t s . The c o n t r i b u t i o n of mass-trapping c o u l d be f u r t h e r i n c r e a s e d by implementing improvements to t r a p design, placement and semiochemical b a i t s as they become a v a i l a b l e . At the time of w r i t i n g , mass-trapping of ambrosia b e e t l e s has been i n c o r p o r a t e d i n t o the 1982 management plans of at l e a s t two major f o r e s t companies i n B r i t i s h Columbia. The program at the Chemainus sawmill w i l l be continued through the c o o p e r a t i v e e f f o r t s of company personnel and a c o n s u l t i n g company. 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