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Biology of Gnathotrichus retusus and behavioural responses of G. retusus and G. sulcatus to semiochemicals Liu, Youngbiao 1986

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BIOLOGY OF GNATHOTRICHUS RETUSUS AND BEHAVIOURAL RESPONSES OF G. RETUSUS AND G. SULCATUS TO SEMIOCHEMICALS by YONGBIAO LIU B. A g r i . , B e i j i n g F o r e s t r y U n i v e r s i t y , 1 9 8 2 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in FACULTY OF GRADUATE STUDIES (Faculty of Forestry) 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 UNIVERSITY OF BRITISH COLUMBIA December, 1986 © Yongbiao L i u , 1986 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the The U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t permission f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s or her r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook Pl a c e Vancouver, Canada V6T 1W5 Date: December, 1986 A b s t r a c t Gnat hotrichus retusus i s p r i m a r i l y u n i v o l t i n e with a minor f r a c t i o n of the p o p u l a t i o n t a k i n g more than one year to complete the l i f e c y c l e . From the s p r i n g to the summer, the development of brood from egg to a d u l t took about 40 days or more in D o u g l a s - f i r l o g s . Brood p r o d u c t i o n was s i g n i f i c a n t l y r e l a t e d to the g a l l e r y l e n g t h . Boring a c t i v i t i e s were not c o n s i s t e n t l y r e l a t e d with temperature, s h i f t i n g from shallow sapwood to deep sapwood over time. Fungal s t a i n i n g was u s u a l l y l i m i t e d to the wood near the g a l l e r y entrance, and became darker i n c o l o u r over time • beginning i n June. Abandonment of some g a l l e r i e s mainly occ u r r e d i n June and J u l y by females, and was probably induced by high temperatures. G. retusus p r e f e r r e d D o u g l a s - f i r stumps to western hemlock stumps, but both host t r e e s p e c i e s were e q u a l l y s u i t a b l e f o r G. retusus brood development. S i g n i f i c a n t d i f f e r e n c e s were found among i n d i v i d u a l D o u g l a s - f i r and western hemlock stumps in a t t a c k d e n s i t y and brood p r o d u c t i o n . Within a stump, a t t a c k d e n s i t y and brood p r o d u c t i o n f o r D o u g l a s - f i r , and a t t a c k d e n s i t y f o r western hemlock i n c r e a s e d from the stump top to the bottom. G. retusus emergence from D o u g l a s - f i r and western hemlock stumps and G. retusus and G. sulcat us f l i g h t s began i n l a t e A p r i l when the d a i l y maximum temperature reached 13.5°C, and peaked i n l a t e May. Brood emergence of G. retusus ceased, with rare e x c e p t i o n , i n l a t e June. G. i retusus had only one b i g peak f l i g h t while G. sulcatus had a small second peak f l i g h t i n l a t e J u l y . Seasonal f l i g h t s ceased i n October when weekly mean maximum temperatures dropped below 15°C. Brood emergence, seasonal f l i g h t s , and the sex r a t i o s of brood ready to emerge and captured f l y i n g b e e t l e s were p o s i t i v e l y c o r r e l a t e d with maximum temperature. G. retusus had a bimodal d i u r n a l f l i g h t rhythm: a very small morning f l i g h t and a much l a r g e r dusk f l i g h t . L i g h t i n t e n s i t y seemed to be a major stimulus i n i n i t i a t i n g the f l i g h t . However, d i u r n a l f l i g h t might a l s o be i n f l u e n c e d by both temperature and r e l a t i v e humidity. Both G. retusus and G. sulcatus of both sexes responded s i g n i f i c a n t l y to ethanol or t h e i r own aggregation pheromones, ( + ) - s u l c a t o l and ( t ) - s u l c a t o l r e s p e c t i v e l y , and ethanol was a s y n e r g i s t of ( + ) - s u l c a t o l f o r G. retusus of both sexes. Alpha-pinene was n e i t h e r a primary host a t t r a c t a n t nor a s y n e r g i s t of aggregation pheromones. The sex r a t i o s (female/male) of both s p e c i e s i n c r e a s e d s i g n i f i c a n t l y from l e s s than one f o r host chemicals alone to above one f o r treatments i n c l u d i n g aggregation pheromones. The sex r a t i o of G. sulcatus i n c r e a s e d with i n c r e a s e s i n r e l e a s e r a t e s of (±)-sulcatol. i i Acknowledgements I wish to express my deepest g r a t i t u t 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 with whose c o n t r i b u t i o n t h i s t h e s i s becomes r e a l i t y . Dr. J.A. McLean, my s u p e r v i s o r , f o r great enthusiasm to i n t r o d u c e me to t h i s t o p i c , f i r m guidance, v a l u a b l e suggestions and a d v i c e , and tremendous he l p ; my committee members, Drs. M.B. Isman, T.L. Shore, B.J. van der Kamp f o r t h e i r care and h e l p f u l suggestions and a d v i c e ; J . Northrop, M. Putland, N. Ryant f o r t h e i r h e l p i n the f i e l d and l a b o r a t o r y work; and the Government of the People's Republic of China fo r f i n a n c i a l support. I a l s o wish to thank Mr. E. Burke, Ms. L. F r i s k i e , Mr. D. MacCarthy, and Mr. J . Sweeney f o r t e c h n i c a l h e l p and conveniencing the l a b o r a t o r y work; Phero Tech Inc. i n Vancouver f o r p r o v i d i n g me with semiochemical b a i t s ; and personnel of the UBC Research F o r e s t f o r s h a r i n g weather data and l o g g i n g i n f o r m a t i o n with me and a s s i s t a n c e . Table of Contents A b s t r a c t i Acknowledgements i i i L i s t of F i g u r e s v i L i s t of Tables i x L i s t of Appendices x 1. INTRODUCTION 1 2. MATERIALS AND METHODS 12 2.1 Experimental S i t e s at the UBC Research F o r e s t ...12 2.2 G a l l e r y and Brood Development 14 2.3 F r a s s Production and G a l l e r y Abandonment 16 2.4 Brood Emergence from D o u g l a s - F i r and Western Hemlock Stumps and G. retusus Attack and Brood Prod u c t i o n 18 2.4.1 Brood emergence from D o u g l a s - f i r and western hemlock stumps 18 2.4.2 Brood p r o d u c t i o n and att a c k d e n s i t y 20 2.5 G a l l e r y D i s t r i b u t i o n and S t r u c t u r e 21 2.5.1 D i s t r i b u t i o n i n a D o u g l a s - f i r l o g 21 2.5.2 D i s t r i b u t i o n s i n D o u g l a s - f i r and western hemlock stumps 22 2.5.3 G a l l e r y s t r u c t u r e 22 2.6 D i u r n a l F l i g h t of G. retusus and Seasonal F l i g h t of G. retusus and G. sulcatus .23 2.7 E f f e c t s of Semiochemicals on the Behaviour of G. retusus and G. sulcatus 26 2.7.1 E v a l u a t i o n of e f f e c t s of semiochemical b a i t combinations 26 2.7.2 E v a l u a t i o n of e f f e c t s of (±)-sulcatol r e l e a s e r a t e s 27 3. RESULTS AND DISCUSSION 29 3.1 G a l l e r y and Brood Development 29 i v 3.2 Fr a s s Production and G a l l e r y Abandonment ...34 3.3 Brood Emergence from D o u g l a s - F i r and Western Hemlock Stumps and G. retusus Attack and Brood Prod u c t i o n 40 3.3.1 Brood emergence from D o u g l a s - f i r and western hemlock stumps 40 3.3.2 Brood p r o d u c t i o n and att a c k d e n s i t y 44 3.4 G a l l e r y D i s t r i b u t i o n and S t r u c t u r e 54 3.4.1 G a l l e r y d i s t r i b u t i o n s i n a D o u g l a s - f i r l o g , D o u g l a s - f i r stumps, and western hemlock stumps 54 3.4.2 G a l l e r y s t r u c t u r e 58 3.5 D i u r n a l F l i g h t of G. retusus and Seasonal F l i g h t of G. retusus and G. sulcatus 65 3.5.1 D i u r n a l f l i g h t of G. retusus 65 3.5.2 Seasonal f l i g h t of G. retusus and G. s ul cat us 73 3.6 E f f e c t s of Semiochemicals on the Behaviour of G. retusus and G. sulcatus 76 3.6.1 E f f e c t s of semiochemical b a i t combinations 76 3.6.2 E f f e c t s of (±)-sulcatol r e l e a s e r a t e s 82 3.6.3 A l l e l o c h e m i c a c t i v i t y of aggregation pheromones between G. retusus and G. sulcatus 85 4. SUMMARY 88 REFERENCES 92 APPENDICES 98 v L i s t of F i g u r e s F i g u r e 1. Map of the experimental s i t e at the UBC Research F o r e s t . Maple Ridge, B.C. 1986. .- 13 Fi g u r e 2. D-f l o g set up and i n s t a l l a t i o n of p e t r i d i s h e s to monitor G. retusus f r a s s p r o d u c t i o n . UBC, Vancouver, B.C. Spr i n g 1985 17 Fi g u r e 3. M u l t i p l e funnel t r a p set up to monitor ambrosia b e e t l e f l i g h t . UBC Research F o r e s t , Maple Ridge, B.C. Spring 1986 24 Fig u r e 4. R e l a t i o n s h i p between G. retusus brood p r o d u c t i o n and g a l l e r y l e n g t h i n D-f l o g s . UBC Research F o r e s t , Maple Ridge, B.C. 1985 31 Fi g u r e 5. G. retusus g a l l e r y l e n g t h d i s t r i b u t i o n over depth of sapwood i n a D-f l o g at d i f f e r e n t time. UBC Research F o r e s t , Maple Ridge, B.C. 1985. .. 32 F i g u r e 6-7 6: G. retusus f r a s s p r o d u c t i o n p a t t e r n and i t s r e l a t i o n s h i p with maximum temperatures. UBC Vancouver, B.C. 1985. 7: G. retusus g a l l e r y extension p a t t e r n and i t s r e l a t i o n s h i p with maximum temperatures. UBC Research F o r e s t , Maple Ridge, B.C. 1985 35 Fi g u r e 8. G a l l e r y abandonment by G. retusus a d u l t s i n a D-f l o g . UBC, Vancouver, B.C. 1985 37 Fi g u r e 9. G. retusus f r a s s c o l o u r changes over time i n a D-f l o g . UBC, Vancouver, B.C. 1 985 38 F i g u r e 10. G. retusus brood emergence p a t t e r n from D-f and WH stumps (middle), and i t s r e l a t i o n s h i p with temperature (top) and the seasonal f l i g h t p a t t e r n (bottom). UBC Research F o r e s t , Maple Ridge, B.C. 1986. 41 Fi g u r e 11. R e l a t i o n s h i p between the sex r a t i o of G. retusus brood ready to emerge and temperature. UBC Research F o r e s t , Maple Ridge, B.C. 1986 43 Fi g u r e 12. G. retusus brood d i s t r i b u t i o n s f o r D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986 46 F i g u r e 13. G. retusus g a l l e r y d e n s i t y d i s t r i b u t i o n s on D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986 49 F i g u r e 14. R e l a t i o n s h i p between G. retusus a t t a c k d e n s i t y , v i brood p r o d u c t i o n and p o s i t i o n s on D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1 986 51 Fig u r e 15. G. retusus g a l l e r y d i s t r i b u t i o n s over depth of sapwood. top: UBC, Vancouver, B.C. 1985, middle and bottom: UBC Research F o r e s t , Maple Ridge, B.C. 1986 55 Fig u r e 16. G. retusus g a l l e r y d i s t r i b u t i o n s over percentage depth of sapwood i n a D-f l o g and D-f stumps. top: UBC, Vancouver, B.C. 1986. bottom: UBC Research F o r e s t , Maple Ridge, B.C. 1986 56 Fi g u r e 17. A model of a G. retusus g a l l e r y i n D-f l o g s . 59 F i g u r e 18. D i s t r i b u t i o n s of G. retusus g a l l e r y l e n g t h , l a r v a l n i che, and pupal niche over sapwood depth and d i s t r i b u t i o n s of l a r v a l niche and pupal niche d e n s i t y per u n i t g a l l e r y l e n g t h over sapwood depth i n D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986 60 Fi g u r e 19. G. retusus g a l l e r y s t r u c t u r e i n D-f stumps: e l o n g a t i o n of pupal niches i n t o maturation feeding tunnels and i n t e r - g a l l e r y c r o s s i n g s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. ... 61 F i g u r e 20. G. retusus g a l l e r y s t r u c t u r e i n D-f stumps: e l o n g a t i o n of pupal niches i n t o maturation feeding t u n n e l s and i n t e r - g a l l e r y c r o s s i n g s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. ... 62 F i g u r e 21. G. retusus g a l l e r y s t r u c t u r e i n WH stumps: s l i g h t e l o n g a t i o n of pupal n i c h e s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. 64 F i g u r e 22. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 27, 1986. UBC Research F o r e s t , Maple Ridge, B.C 67 Fig u r e 23. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 28, 1986. UBC Research F o r e s t , Maple Ridge, B.C. 68 F i g u r e 24. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 29, 1986. UBC Research F o r e s t , Maple Ridge, B.C 69 F i g u r e 25. Record of temperature, r e l a t i v e humidity, l i g h t v i i i n t e n s i t y , and G. retusus f l i g h t on May 30, 1986. UBC Research F o r e s t , Maple Ridge, B.C. 70 Fi g u r e 26. Temperature re c o r d {top), seasonal f l i g h t p a t t e r n s of G. retusus and G. sulcatus (middle), and seasonal sex r a t i o f l u c t u a t i o n s (bottom). UBC Research F o r e s t , Maple Ridge, B.C. 1986 74 Fi g u r e 27. R e l a t i o n s h i p between ( t ) - s u l c a t o l r e l e a s e r a t e and G. sulcatus t r a p c a t c h . UBC Research F o r e s t , Maple Ridge, B.C. 1986 83 Fi g u r e 28. Comparison between G. retusus catches i n (±)-sulcatol and etha n o l b a i t e d t r a p s (top) and G. retusus catches i n ( + ) - s u l c a t o l and ethanol b a i t e d t r a p s (bottom). UBC Research F o r e s t , Maple Ridge, B.C. 1986 87 v i i i L i s t of Tables Table 1. Summary of e f f e c t s of a-pinene and eth a n o l as host kairomones or s y n e r g i s t s of aggregation pheromones f o r Gnat hotri chus spp 8 Table 2. D i s t r i b u t i o n s of g a l l e r i e s and g a l l e r y d e n s i t y sampling u n i t s on D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. Spring 1986 19 Table 3. G. retusus g a l l e r y success and brood p r o d u c t i o n i n D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. June 1986 47 Table 4. G. retusus a t t a c k d e n s i t y and brood p r o d u c t i o n i n D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. June 1986. 48 Table 5. ANOVA of G. retusus 8X8 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. 1986. ...77 Table 6. A n a l y s i s of f a c t o r i a l e f f e c t s i n G. retusus 8X8 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. 1986 78 Table 7. ANOVA of G. sulcatus 8X8 L a t i n Square experiment. UBC Endowment Lands, Vancouver, B.C. 1985 79 Table 8. A n a l y s i s of f a c t o r i a l e f f e c t s i n G. sulcatus 8X8 L a t i n Square experiment. UBC Endowment Lands, Vancouver, B.C. 1985 80 Table 9. Mean catches of G. sulcatus i n r e l a t i o n to ( i ) - s u l c a t o l r e l e a s e r a t e s . UBC Research F o r e s t , Maple Ridge, B.C. 1985. 84 ix L i s t " of Appendices Appendix 1. ANOVA of G. retusus a t t a c k d e n s i t y on D-f stumps and t h e i r a s p e c t s . UBC Research F o r e s t , Maple Ridge, B.C. 1986 98 Appendix 2. ANOVA of G. retusus a t t a c k d e n s i t y on WH stumps and t h e i r a s p e c t s . UBC Research F o r e s t , Maple Ridge, B.C. 1986 99 Appendix 3. Layout and data of G. retusus 8X8 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. 1 986 100 Appendix 4. Layout and data of G. sulcatus 8X8 L a t i n Square experiment. UBC Endowment Lands, Vancouver, B.C. 1985. 101 Appendix 5. Layout and data of (±)-sulcatol r e l e a s e r a t e 5X5 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. August 1985 102 x 1 . INTRODUCTION Ambrosia b e e t l e s c o n s i s t of many members of the fa m i l y S c o l y t i d a e and a l l members of the fa m i l y P l a t y p o d i d a e . The t o t a l number of s p e c i e s i s w e l l above 1000, with n e a r l y 400 sp e c i e s i d e n t i f i e d on the America c o n t i n e n t (Wood 1982). Ambrosia b e e t l e s are so named as both a d u l t s and l a r v a e feed on ambrosia fungi (Chamberlin 1939). In c o a s t a l B r i t i s h Columbia (B.C.), f i v e ambrosia b e e t l e s p e c i e s are known: Trypodendron Ii neat urn O l i v e r , Gnat hotrichus sulcatus LeConte, G. retusus LeConte, Xyleborus saxeseni Ratz, and PI at ypus wilsoni Swaine (Johnson 1958; McMullan 1956; Prebble and Graham 1957). Ambrosia b e e t l e damage i n c l u d e s the black s t a i n around g a l l e r i e s , which i s probably caused by symbiotic ambrosia fung i ( F i s h e r et al. 1953), and the p i n h o l e s themselves. The damage i s mainly a e s t h e t i c r e s u l t i n g from the black fungal s t a i n i n g r a t h e r than any r e d u c t i o n i n the p h y s i c a l s t r e n g t h of the wood. The problem caused by ambrosia b e e t l e s to the B.C. f o r e s t i n d u s t r y has been rec o g n i z e d s i n c e 1928 when p o r t i o n s of some shipments of lumber from B r i t i s h Columbia to A u s t r a l i a were ordered destroyed on a r r i v a l under quarantine r e g u l a t i o n s because of the presence of l i v e ambrosia b e e t l e s (Graham and Boyes 1950). From that date, ambrosia b e e t l e s have continued to cause economic l o s s e s due to i n s p e c t i o n c o s t s , fumigation, c l o s i n g of f o r e i g n markets, downgrading of lumber, and volume and time l o s s e s at the headsaw i n a 1 2 sawmill i f a c l e a r face was r e q u i r e d on the lumber (Graham and Boyes 1950; McMullan 1956). In l a t e 1940's, i t was estimated that about 25% of the lumber volume produced i n c o a s t a l B r i t i s h Columbia c o n t a i n e d worm-holes excavated by ambrosia b e e t l e s , and 11% was downgraded (McBride 1950). A s i m i l a r s i t u a t i o n e x i s t e d i n l a t e 1950's, and the average l o s s per M fbm was C$6.00 due to the downgrading (McBride and Kinghorn 1960). In 1975-76, the annual l o s s owing to ambrosia b e e t l e damage i n B.C. was estimated by Western F o r e s t Products Laboratory, Vancouver, B.C. to be C$7 m i l l i o n ( N i j h o l t 1978). In 1980-81, ambrosia b e e t l e downgrading of sawlogs processed through the Vancouver l o g market was estimated to be C$63.7 m i l l i o n (McLean 1985). Among the f i v e ambrosia b e e t l e s i n the c o a s t a l areas of B r i t i s h Columbia, Gnat hotri chus retusus and G. sulcatus together are a d i s t a n t second i n importance to Trypodendron lineatum ( F u r n i s s and C a r o l i n 1977). Among the three important s p e c i e s , G. retusus has r e c e i v e d the l e a s t a t t e n t i o n . The knowledge of i t s b i o l o g y and behaviour are very l i m i t e d compared with that of the other two s p e c i e s . G. retusus i s d i s t r i b u t e d i n southern B r i t i s h Columbia, the western U n i t e d S t a t e s and probably i n t o Mexico. I t s host spectrum probably i n c l u d e s a l l c o n i f e r s i n i t s range ( B r i g h t 1976). The b i o l o g y of G. retusus i s s i m i l a r to that of G. sulcatus (Doane and G i l l i l a n d 1929; Prebble and Graham 1957), and the two spe c i e s have o f t e n been t r e a t e d j o i n t l y 3 in r e l e v a n t l i t e r a t u r e . Gnat hotri chus b e e t l e s a t t a c k "green" wood, a f t e r death or i n j u r i n g of the t r e e , or a f t e r f e l l i n g and bucking i n t o l o g s , they a l s o a t t a c k f r e s h l y sawn lumber in m i l l yards and the exposed s u r f a c e of logs f l o a t i n g i n water (McLean and Borden 1975a, 1977a; Prebble and Graham 1957). D o u g l a s - f i r (D-f) logs f e l l e d from one month up to 14 months and western hemlock (WH) log s f e l l e d from one month up to 18 months may be sub j e c t to a t t a c k by Gnat hot r i chus b e e t l e s (Mathers 1935; Prebble and Graham 1957). A few a t t a c k s have been found even w i t h i n a week of f e l l i n g (Mathers 1935). The p e n e t r a t i o n of g a l l e r i e s i s r e s t r i c t e d by the depth of sapwood i n D-f but not i n WH. The deepest g a l l e r y p e n e t r a t i o n i s 8.1cm i n D-f logs and 13.5cm i n WH l o g s . A completed Gnat hot ri chus g a l l e r y system may c o n s i s t of up to s i x t r a n s v e r s e g a l l e r i e s at v a r i o u s depths, each e s s e n t i a l l y c o n c e n t r a t e d w i t h i n an annual r i n g . The maximum t o t a l l e n g t h of a g a l l e r y system can reach 73.7cm (Prebble and Graham 1957). The average diameter of a Gnat hotri chus g a l l e r y i s 1.32mm (Johnson 1958). Gnat hotri chus s p e c i e s have no true diapause; a l l stages of t h e i r l i f e c y c l e can be found d u r i n g the year, and they overwinter i n the host m a t e r i a l i n a l l stages (Chamberlin 1939; Doane et al. 1936; Prebble and Graham 1957). The f l i g h t of G. retusus b e e t l e s begins i n A p r i l and occurs c o n t i n o u s l y u n t i l September (Mathers 1935) or October to November (Daterman et al. 1965; Lindgren and Borden 1983; 4 McLean and Borden 1977b; Shore 1982; Shore and McLean 1985). One s i n g l e f l i g h t peak in May and June was recorded with the aggregation pheromone b a i t e d t r a p s (Lindgren and Borden 1983; McLean and Borden 1977b; Shore and McLean 1985), which suggests that G. retusus i s u n i v o l t i n e . However, evidence f o r the e x i s t e n c e of two gen e r a t i o n s has been found (Chamberlin 1939; Daterman et al. 1965, Doane and G i l l i l a n d 1929). According to Daterman et al . (1965), G. retusus b e e t l e s may f l y as l a t e as November 1st and g a l l e r y i n i t i a t i o n may occur i n mid-October. Two f l i g h t peaks, the f i r s t d e f i n i t e peak between mid-May and e a r l y June and a second l e s s evident peak i n J u l y , were a l s o r e p o r t e d (Daterman et al. 1965). A t t a c k s by G. retusus s t a r t i n the s p r i n g when brood emerge from g a l l e r i e s , d i s p e r s e , and i n f e s t new host m a t e r i a l . The emergence of G. retusus from host m a t e r i a l seems to be governed by d a y l i g h t s i n c e i t begins at noon and i n c r e a s e s i n i n t e n s i t y between 1600h and I800h. No emergence takes p l a c e i n the forenoon even when s u b c o r t i c a l and a i r temperatures are f a v o r a b l e (20-21.1°C) f o r emergence of other s c o l y t i d s . The lowest s u b c o r t i c a l temperature at which Gnat hot ri chus s p e c i e s was observed to emerge was 17.8°C (Rudinsky and Daterman 1964). The d i s p e r s a l f l i g h t of G. retusus b e e t l e s depends upon an i n t e r a c t i o n of temperature and l i g h t i n t e n s i t y . A temperature of 14.4°C i s necessary to i n i t i a t e f l i g h t , and the f l i g h t ceases at 15.6°C and below. Within t h i s 5 temperature range l i g h t i n t e n s i t y above 10.8 Watts/m 2 (100 f t - c 1 ) i s r e q u i r e d f o r the b e e t l e s to s t a r t f l y i n g , but they stop f l y i n g s h o r t l y before t o t a l darkness. A l i g h t i n t e n s i t y of 10.8 to 21.5 Watts/m 2 seems optimal f o r the b e e t l e f l i g h t , while temperatures between 18.3°C and 22.2°C seem to be the most f a v o r a b l e . Temperatures above 26.1°C i n h i b i t G. retusus f l i g h t (Rudinsky and Schneider 1969), and a maximum of 26.7°C f o r Gnat hot ri chus f l i g h t was e s t a b l i s h e d by Rudinsky and Daterman (1964). Gnat hot ri chus b e e t l e s have two f l i g h t peaks i n a day; a morning f l i g h t and an evening f l i g h t . The morning f l i g h t has a low temperature t h r e s h o l d of 14.4°C and a low t h r e s h o l d l i g h t i n t e n s i t y of 16.1 Watts/m 2, and an upper l i m i t f o r l i g h t i n t e n s i t y of about 215.3 Watts/m 2. The evening f l i g h t i s much g r e a t e r than the morning f l i g h t and begins when evening l i g h t i n t e n s i t y f a l l s below 215.3 Watts/m 2. A small number of b e e t l e s c o u l d be c o l l e c t e d between lOOOh and I500h (Rudinsky and Schneider 1969). A t t a c k s by Gnat hotrichus are commenced by male b e e t l e s (Borden 1974), that c a r r y symbiotic fungi c e l l s i n t h e i r f o r e c o x a l c a v i t i e s (mycetangia) ( F a r r i s 1963). The ambrosia fung i are in t r o d u c e d i n t o fungus c a v i t i e s (mycetangium) at the end of h i b e r n a t i o n , nourished by s e c r e t i o n s of the c e l l s l i n i n g the mycetangium, and begin to grow d u r i n g the d i s p e r s a l f l i g h t . A f t e r a g a l l e r y i s i n i t i a t e d , the fungus i s r e l e a s e d (Schneider and Rudinsky 1969). The primary 11 Watt/m2=9.2902 f t - c 6 s p e c i e s of fungus which G. retusus b e e t l e s feed on i s Ambrosiella gnat hot ri chi Batra (Batra 1967). G. retusus a t t a c k s are c h a r a c t e r i z e d by f i n e white f r a s s on the s u r f a c e of host m a t e r i a l s . The f r a s s p r o d u c t i o n r a t e by the male b e e t l e p r i o r to p a i r i n g with the female i s lower than that a f t e r p a i r i n g . Soon a f t e r the male i s j o i n e d by the female, f r a s s p r o d u c t i o n r i s e s to a peak. When g a l l e r i e s were d i s s e c t e d 9 days a f t e r a t t a c k , the male was always found to be at the head of the tunnel (Borden and McLean 1979). Both primary host a t t r a c t a n t s and beetle-produced secondary a t t r a c t a n t s are known to be i n v o l v e d i n a t t a c k s of host m a t e r i a l by Gnat hot ri chus b e e t l e s . G. retusus b e e t l e s respond s i g n i f i c a n t l y to l o g odors of D-f, WH, and western white pine (Chapman 1963), while G. sulcatus responds p o s i t i v e l y to sawdust from f r e s h l o g s (Borden and Stokkink 1973; McLean 1 976) . The p r o d u c t i o n of host a t t r a c t a n t s i s probably caused by anaerobic fermentation i n sapwood s i n c e a n a e r o b i c a l l y t r e a t e d logs are s i g n i f i c a n t l y more h e a v i l y a t t a c k e d by ambrosia b e e t l e s (Graham 1968). T h i s c o n c l u s i o n was f u r t h e r supported by the i n v e s t i g a t i o n by Cade et al. (1970) who found that G. sulcatus mass a t t a c k e d water soaked western hemlock lo g s but made no a t t a c k s on unsoaked l o g s . I t was concluded that a primary a t t r a c t a n t was present i n soaked l o g s , and the a t t r a c t a n t a l s o a c t e d as a b o r i n g s t i m u l a n t . 7 Gas chromatographic i s o l a t i o n and i d e n t i f i c a t i o n and f i e l d b i o a s s a y s demonstrated that ethanol was a primary host a t t r a c t a n t f o r G. sulcatus (Cade et al. 1970; Moeck 1970), and was induced by anaerobic treatments (Graham 1968; Moeck 1970). The e f f e c t s of ethanol as a host kairomone were l a t e r r e p o r t e d by other authors (Table 1). The t u n n e l l i n g (feeding) s t i m u l a t i n g e f f e c t of ethanol was demonstrated i n the ambrosia b e e t l e Xyl ebor us ferrugineus ( N o r r i s and Baker 1969). McLean and Borden (1977a) a l s o hypothesized b o r i n g s t i m u l a t i o n e f f e c t s of ethanol i n G. sulcatus a t t a c k s . Alpha-pinene i s another host chemical proposed to be a primary a t t r a c t a n t to v a r i o u s bark and ambrosia b e e t l e s i n c l u d i n g G. retusus and G. sulcatus (Rudinsky 1966). However, i n Rudinsky's study a-pinene was t e s t e d i n 95% ethanol s o l u t i o n , and ethanol has s i n c e been demonstrated to be a primary a t t r a c t a n t to ambrosia b e e t l e s but not a-pinene (Table 1). Furthermore, evidence of d e t e r r e n t e f f e c t s of a-pinene on b o r i n g by Trypodendron lineatum b e e t l e s has been found (Werner and Graham 1957). The e x i s t e n c e of secondary a t t r a c t a n t s have been demonstrated i n both G. sulcatus (Borden and Stokkink 1973) and G. retusus (Borden and McLean 1979). G. sulcatus of both sexes were found to be s i g n i f i c a n t l y responsive to male f r a s s and guts from males i n the l o g . As both sexes responded p o s i t i v e l y , the a t t r a c t a n t was d e s i g n a t e d as a p o p u l a t i o n aggregation pheromone (Borden and Stokkink 1973). Table i . Summary of e f f e c t s of a-pinene and ethanol as host kairomones or s y n e r g i s t s of aggregation pheromones for Gnat hot ri chus spp. G. retusus KAIROMONE EFFECTS: a-pinene a t t r a c t i v e (Rudinsky 1966) no a t t r a c t i o n (Borden et al ethanol 1980b) no a t t r a c t i o n (Borden et al. 1980b) G. sul cat us a t t r a c t i v e (Rudinsky 1966) no a t t r a c t i o n (Borden 1980b; Lindgren and McLean unpubl.) a t t r a c t i v e (Borden et al. 1981a; Cade et al. 1970; Lindgren and McLean unpubl.; McLean 1976; McLean and Borden 1977; Moeck 1970,1971) no a t t r a c t i o n (Borden et al. 1980b) a-pinene+ ethanol a t t r a c t i v e (Borden et al. 1981a) no a t t r a c t i o n (Borden et al. 1980b) no a t t r a c t i o n (Borden et al. 1980b; Shore and McLean 1983) SYNERGISM EFFECTS: a-pinene no e f f e c t s (Borden et al. 1980b) ethanol both sexes more responsive to ( + ) - s u l c a t o l p l u s ethanol than to ( + ) - s u l c a t o l alone (Borden et al. 1980b) a-pinene+ synergism e f f e c t s e x i s t e d f o r both ethanol sexes (Shore and McLean 1985) no e f f e c t s (Borden et al. 1980b) no e f f e c t s (Borden et al. 1980b) synergism e f f e c t s e x i s t e d f o r both sexes (Shore and McLean 1983) males responded more s i g n i f i c a n t l y to the t e r n e r y mixture than to ( i ) - s u l c a t o l alone (Borden et al. 1980b) 9 In a l a t e r study, G. retusus of both sexes a l s o showed p o s i t i v e responses to male f r a s s , gut e x t r a c t s , and male at t a c k e d l o g s (Borden and McLean 1979). T h i s i n d i c a t e s that male b e e t l e s are producers of the a t t r a c t i v e agent. However, a r i s e i n a t t r a c t i o n of f r a s s f o l l o w i n g p a i r i n g of males and females and s i g n i f i c a n t responses to f e m a l e - i n f e s t e d logs and p a i r e d b e e t l e s were re p o r t e d , and i t was suggested that both sexes might be i n v o l v e d i n secondary a t t r a c t i o n of t h i s s p e c i e s (Borden and McLean 1979). For G. sulcatus, the aggregation pheromone was i s o l a t e d from b o r i n g dust and a benzene e x t r a c t of male guts and i d e n t i f i e d to be 6-methyl-5-hepten-2-ol f o r which the name s u l c a t o l was proposed. In nature, i t e x i s t s as a racemic mixture of S - ( + ) - s u l c a t o l and R - ( - ) - s u l c a t o l enantiomers at the r a t i o of 65:35, and has been s y n t h e s i z e d (Byrne et al. 1974). Both o p t i c a l l y pure R - ( - ) - s u l c a t o l and S - ( + ) - s u l c a t o l were a l s o s y n t h e s i z e d (Johnson and S l e s s o r 1979; Mori 1975; Schuler and S l e s s o r 1977). The two enantiomers act s y n e r g i s t i c a l l y to e l i c i t a response by G. sulcatus b e e t l e s (Borden et al. 1976, 1980b). For G. retusus, Borden et al. (1980a) i s o l a t e d more than 99% o p t i c a l l y pure S - ( + ) - s u l c a t o l from male f r a s s and demonstrated i t to be an aggregation pheromone. When more than 2% of R - ( - ) - s u l c a t o l i s present i n the pheromone, the response of female G. retusus begins to be i n h i b i t e d , and the response of both sexes i s t o t a l l y i n h i b i t e d by l a r g e r amounts of R - ( - ) - s u l c a t o l . However, G. sulcatus males and 10 females respond to s u l c a t o l when l e s s than 2% R - ( - ) - s u l c a t o l i s present i n the blend. T h i s i s co n s i d e r e d to be one reason f o r the lack of response by G. retusus to G. sulcatus i n f e s t e d logs and (±)-sulcatol b a i t e d t r a p s , as w e l l as the e x i s t e n c e of c r o s s a t t r a c t i o n of G. retusus i n f e s t e d logs to G. sulcatus (Borden and McLean 1979). S l i g h t c r o s s a t t r a c t i o n s of G. sulcatus and G. retusus to each other's aggregation pheromones were l a t e r demonstrated (Borden et al. 1981). The s u c c e s s f u l s y n t h e s i s of aggregation pheromones of ambrosia b e e t l e s has l e d to the development of present pheromone-based mass t r a p p i n g systems f o r ambrosia b e e t l e s i n c l u d i n g G. retusus and G. sulcatus. Alpha-pinene and etha n o l b a i t s are employed as s y n e r g i s t s f o r the aggregation pheromones. These systems have a l r e a d y showed promise i n survey and suppresion of G. retusus and G. sulcatus p o p u l a t i o n s (Borden and McLean 1981; Lindgren and Borden 1983; McLean 1980; McLean and Borden 1975b,1977b,1979; Shore 1982; Shore and McLean 1985). However, the e f f e c t s of a-pinene and ethanol as s y n e r g i s t s of aggregation pheromones are not c o n s i s t e n t l y agreed on by v a r i o u s authors (Table 1). A s i g n i f i c a n t s h i f t of sex r a t i o i n favor of male b e e t l e s whenever a-pinene and/or ethanol were i n c l u d e d with the aggregation pheromones was shown f o r both G. sulcatus (Borden et al. 1980b) and G. retusus (Shore and McLean 1985). T h i s r e f l e c t s the importance of host primary a t t r a c t a n t s (kairomones) to the pioneer sex (male) i n both 11 s p e c i e s of ambrosia b e e t l e s . Based on the above review, there are gaps i n our knowledge of G. retusus b i o l o g y , such as that of g a l l e r y and brood development and brood p r o d u c t i o n . There are a l s o many c o n t r a d i c t o r y r e s u l t s concerning b e h a v i o u r a l responses of the two ambrosia b e e t l e s to semiochemicals. To f u r t h e r the knowledge of G. retusus b i o l o g y , and chemical ecology of both ambrosia b e e t l e s and to manage them e f f e c t i v e l y , i t i s necessary to explore G. retusus b i o l o g y and the b e h a v i o u r a l responses of the two Gnat hotrichus b e e t l e s to semiochemicals f u r t h e r . The o b j e c t i v e s of my re s e a r c h were t o : 1. Determine attack d e n s i t i e s , g a l l e r y d i s t r i b u t i o n s , g a l l e r y s t r u c t u r e , brood p r o d u c t i o n s , and brood emergence p a t t e r n s of G. retusus f o r D-f and WH. 2. Determine the d i u r n a l and seasonal f l i g h t p a t t e r n s as measured by catches i n semiochemical b a i t e d t r a p s . 3. E v a l u a t e e f f e c t s of environmental f a c t o r s on a c t i v i t i e s of G. retusus and G. sulcatus. 4. Eval u a t e the b e h a v i o u r a l responses of G. retusus and G. sulcatus to semiochemicals. 2. MATERIALS AND METHODS 2.1 EXPERIMENTAL SITES AT THE UBC RESEARCH FOREST Two experimental- s i t e s were used at the UBC Research F o r e s t , Maple Ridge, B.C.. The f i r s t one was on Road F-3, where the f o r e s t i s a second growth f i r e s u c c e s s i o n stand and composed mainly of D o u g l a s - f i r ( D - f ) , Ps eudot suga menziesii (Mirb.) Franco, with a minor component of western hemlock (WH), Tsuga net erophylI a (Raf.) Sarg.. The a l t i t u d e i s about 270m ( F i g 1). An e i g h t hectare c l e a r cut was made i n t h i s area i n J u l y 1984, and no s i t e p r e p a r a t i o n or p l a n t i n g was undertaken to the date when experiments were conducted. The s i t e i s bordered by f o r e s t on i t s south and west s i d e s and open to o l d l o g g i n g s i t e s and F road i n i t s east and north s i d e s r e s p e c t i v e l y . A l l logs were removed from that area d u r i n g 1985. S l a s h and stumps were abundant and l e f t i n t a c t . A p r e l i m i n a r y survey conducted in e a r l y A p r i l 1986 showed heavy a t t a c k s of D-f and WH stumps by G. retusus which i n d i c a t e d there were abundant b e e t l e resources f o r v a r i o u s f i e l d experiments. The r e s e a r c h on G. retusus brood emergence, d i u r n a l f l i g h t , and b e h a v i o u r a l responses to semiochemicals and seasonal f l i g h t of G. retusus and G. sulcatus was c a r r i e d out i n that area i n 1986. In May 1986, a very small second c l e a r c u t t i n g was c a r r i e d out along the south edge of the 1984 l o g g i n g s i t e . Logs were removed d u r i n g summer 1986, and s l a s h and stumps 12 13 F i g u r e 1. Map of the experimental s i t e at the UBC Research F o r e s t . Maple Ridge, B.C. 1986. 0-. D-f stump sample. A •. WH stump sample, x-. t r a p of G. retusus 8X8 LSD experiment. ®: G. retusus m o n i t o r i n g t r a p . • l G. sulcatus monitoring t r a p . © l o c a t i o n of the t h i r d G. retusus d i u r n a l f l i g h t m o n i t o r i n g t r a p and weather r e c o r d i n g . 14 were l e f t i n t a c t . A second experimental s i t e was i n the C road area of the UBC Research F o r e s t . C l e a r c u t t i n g was c a r r i e d out during 1985 and 1986 from north to south on the east s i d e of the road. The stand i n that area i s composed mainly of D-f and WH. The a l t i t u d e i s about 320m. In August 1985, a f i e l d t r a p p i n g experiment with G. sulcatus to t e s t f o r e f f e c t s of (±)-sulcatol r e l e a s e r a t e s was c a r r i e d out i n the y a r d i n g areas. 2.2 GALLERY AND BROOD DEVELOPMENT One D-f l o g , f e l l e d i n J u l y 1984 and i n f e s t e d by G. retusus, was s e l e c t e d i n the Road E-3 area of the UBC Research F o r e s t , and cut i n t o approximately ten 1.5 meter long s e c t i o n s i n l a t e May 1985. Three s e c t i o n s were taken back to the UBC Campus f o r d e t a i l e d o b s e r v a t i o n s . The remaining s e c t i o n s were l e f t at the UBC Research F o r e s t . The two ends of each l o g s e c t i o n were se a l e d with p l a s t i c sheets to slow d r y i n g . Every two weeks, four to s i x l o g d i s c s about 10 cm t h i c k were sawn from the l o g s e c t i o n s f o r g a l l e r y d i s s e c t i o n beginning on May 31. A l l G. retusus g a l l e r i e s i n d i s c s were d i s s e c t e d and g a l l e r y maps were drawn at a s c a l e of 1:1. The numbers and p o s i t i o n s of egg n i c h e s , eggs, l a r v a e , l a r v a l n i c h e s , pupae, pupal n i c h e s , and a d u l t s i n g a l l e r i e s were recorded. S t a i n i n g a l l e r i e s was a l s o recorded. The lengths of g a l l e r i e s over depths were measured on the maps at 0.5cm i n t e r v a l s . In t h i s way d i s t r i b u t i o n s of 15 g a l l e r y l e n g t h over sapwood depth at d i f f e r e n t times were obtained. In J u l y 1985, a second G. retusus a t t a c k e d D-f l o g ( f e l l e d i n J u l y 1984) was s e l e c t e d and l o g d i s c s were sawn from the end of the top t h i r d and the top of the bottom t h i r d of the l o g i n August and e a r l y September, 1985. A l l G. retusus g a l l e r i e s i n the d i s c s were d i s s e c t e d and g a l l e r y maps were drawn at a s c a l e of 1:1. More d i s c s were taken d u r i n g the f a l l up to November 1st from the two D-f logs to check g a l l e r y and brood development. G a l l e r y d i s s e c t i o n of the f i r s t D-f l o g was done at d i f f e r e n t times to determine g a l l e r y e xtension p a t t e r n and brood development. Maximum temperature records were obtained at the gate of the UBC Research F o r e s t ( a l t i t u d e 146m) and were compared with the g a l l e r y e xtension p a t t e r n to r e v e a l any r e l a t i o n s h i p . Mature G. retusus g a l l e r i e s i n the second D-f were d i s s e c t e d to provide comparative data with mature g a l l e r i e s d i s s e c t e d from the f i r s t D-f l o g . A t o t a l of 16 mature g a l l e r i e s were d i s s e c t e d from the two D-f log s (5 from the f i r s t and 11 from the second ). D e t a i l e d g a l l e r y maps were drawn as d e s c r i b e d above and brood were sexed and counted. The r e l a t i o n s h i p between g a l l e r y l e n g t h and brood p r o d u c t i o n was eva l u a t e d by r e g r e s s i o n a n a l y s i s . 16 2.3 FRASS PRODUCTION AND GALLERY ABANDONMENT The three D-f l o g s e c t i o n s taken back from the UBC Research F o r e s t were set up on the UBC Campus on June 4. The tops were s e a l e d with p l a s t i c sheets to reduce water eva p o r a t i o n and the logs were shaded with a p i e c e of plywood to reduce e x c e s s i v e h e a t i n g . A t o t a l of 85 g a l l e r i e s on the three l o g s e c t i o n s were covered with 5cm p l a s t i c p e t r i d i s h e s ( F i g 2). The bark was f i r s t smoothed with a c h i s e l and a small amount of p l a s t i c i n e (Klean Klay) was i n s e r t e d between bark and the bottom of the p e t r i d i s h to ensure a s e a l . P e t r i d i s h e s were n a i l e d to the bark, and d i s h covers were secured with rubber bands s t r e t c h e d between n a i l s i n s e r t e d on each s i d e of them. A p i e c e of masking tape was used to pro v i d e a bridge from the g a l l e r y entrance to the bottom of the d i s h f o r those b e e t l e s which came out of the g a l l e r y . At that time, g a l l e r y d i s s e c t i o n showed that b e e t l e s had p a i r e d i n g a l l e r i e s . F r a s s was c o l l e c t e d weekly from June 11 to August 20, and kept separate by g a l l e r y , d r i e d at 70°C f o r 24 hours and weighed. B e e t l e s that came out of g a l l e r i e s were i d e n t i f i e d to s p e c i e s and sex and put back i n t o the g a l l e r i e s . Dead G. retusus b e e t l e s i n p e t r i d i s h e s were r e p l a c e d with b e e t l e s of the same sex immediately a f t e r they were found during June i n an e f f o r t to e s t a b l i s h a maximum number of s u c c e s s f u l g a l l e r i e s . Temperatures (maximum, minimum) i n the surrounding area were recorded d a i l y from June 6 to August 13, when f r a s s p r oduction almost ceased. Observations were 17 F i g u r e 2. D-f l o g set up and i n s t a l l a t i o n of p e t r i d i s h e s to monitor G. retusus f r a s s p r o d u c t i o n . UBC, Vancouver, B.C. Spring 1985. 18 made f o r any t r a c e f r a s s p r o d u c t i o n up to November 1985. Brood were c o l l e c t e d i n the s p r i n g of 1986 when they emerged from g a l l e r i e s . G a l l e r y abandonment p a t t e r n s by both sexes of b e e t l e s and the f r a s s p r o d u c t i o n p a t t e r n were obtained. The temperature r e c o r d was compared with the f r a s s p r o duction p a t t e r n to r e v e a l any r e l a t i o n s h i p between them. The l o g s e c t i o n s were used l a t e r to determine the g a l l e r y d i s t r i b u t i o n over depth. 2.4 BROOD EMERGENCE FROM DOUGLAS-FIR AND WESTERN HEMLOCK  STUMPS AND G. RETUSUS ATTACK AND BROOD PRODUCTION 2.4.1 BROOD EMERGENCE FROM DOUGLAS-FIR AND WESTERN HEMLOCK  STUMPS Ei g h t D-f and four WH stumps were sampled randomly i n the F-3 area of the UBC Research F o r e s t . S i x t y three Gnat hot ri chus g a l l e r i e s were covered with p e t r i d i s h e s on the D-f stumps on A p r i l 10, 1986 and a f u r t h e r 36 were covered on the WH stumps on A p r i l 24, 1986 (Table 2 ) . Di s t a n c e s from tops of stumps to g a l l e r y entrances covered were measured i n order to r e l a t e brood p r o d u c t i o n s to g a l l e r y p o s i t i o n s on stumps. Brood were c o l l e c t e d on a weekly b a s i s u n t i l emergence ceased, and brood were i d e n t i f i e d to s p e c i e s , sexed, and counted. Brood emergence p a t t e r n s over time were obtained f o r both D-f and WH stumps, and comparisons were made 19 Table 2. D i s t r i b u t i o n s of G. r et us us g a l l e r i e s and at t a c k d e n s i t y sampling u n i t s on D - f and WH stumps. UBC Research F o r e s t , Maple Ridge, B. C. Spri n g 1981 Stump Diam. No. of Att a c k D e n s i t y Sampling T o t a l No. (cm) G a l l e r i e s 1 E 2 S W N No. D-f stumps: 1 41 .7 6 3 3 3 3 12 2 36.0 12 4 5 3 3 15 3 48.9 7 7 5 5 5 22 4 78.8 7 7 6 4 3 20 5 65.3 6 5 5 5 5 20 6 64.2 1 1 8 6 9 5 28 7 54.4 8 3 8 5 5 21 8 66.0 4 SUM 61 3 37 38 35 28 138 WH stumps: 1 36.0 12 4 - 5 5 14 2 47.5 1 1 7 3 3 3 16 3 31.4 6 4 3 2 4 13 4 41 .9 . 6 2 3 3 4 12 SUM 35« 17 9 13 16 55 1. G a l l e r i e s monitored f o r brood emergence. 2. Aspect c a t e g o r i e s , E=east f S=south, W=west, N=north. 3. Two a d d i t i o n a l g a l l e r i e s covered produced G. sulcatus brood and were excluded. 4. One a d d i t i o n a l g a l l e r y covered produced G. sulcatus brood and was excluded. 20 between brood emergence p a t t e r n s , pheromone t r a p c a t c h p a t t e r n s , and the maximum temperature records at the gate of the UBC Research F o r e s t . The sex r a t i o of brood ready to emerge at the s t a r t of a c o l l e c t i n g p e r i o d 2 was c a l c u l a t e d f o r a l l c o l l e c t i n g dates and r e l a t e d to b e e t l e emergence and the temperature r e c o r d s . 2.4.2 BROOD PRODUCTION AND ATTACK DENSITY Unproductive g a l l e r i e s were d i s s e c t e d l a t e r to determine i f they were G. retusus or G. sulcatus g a l l e r i e s . Thereby brood d i s t r i b u t i o n s were obtained, and the average brood p r o d u c t i o n s of G. retusus were estimated f o r both D-f and WH stumps. A f t e r brood c o l l e c t i o n from both D-f and WH stumps was terminated, a l l of the 4 WH stumps and 7 D-f stumps were debarked i n order to check a t t a c k d e n s i t y on stump s u r f a c e s . Gnat hotrichus a t t a c k d e n s i t y was sampled by aspect using a 10 X 10 cm 2 paper frame. For l a r g e s u r f a c e areas, p r o p o r t i o n a l l y more measurements were made (Table 2). The d i s t a n c e from the top of a stump to the c e n t r e of the frame was measured f o r a l l g a l l e r y d e n s i t y sampling measurements i n order to evaluate any changes i n a t t a c k d e n s i t y with 2MB: No. of males c o l l e c t e d at date n. MTR: t o t a l male r e s i d u a l i n g a l l e r i e s at date n. MTR=grand t o t a l of males f o r a l l c o l l e c t i n g dates - t o t a l No. of males emerged before date n. FB: No. of females c o l l e c t e d at date n. FTR: t o t a l female r e s i d u a l i n g a l l e r i e s at date n. FTR=grand t o t a l of females f o r a l l c o l l e c t i n g dates - t o t a l No. of females emerged before date n. Sex r a t i o = FB/FTR : MB/MTR. 21 p o s i t i o n s of sample u n i t s on stumps ( d i s t a n c e s from t o p s ) . A l l Gnat hotri chus g a l l e r i e s i n the frame were counted. The average attack d e n s i t i e s and d e n s i t y d i s t r i b u t i o n s on both hosts were determined. Comparisons between G. retusus brood p r o d u c t i o n and a t t a c k d e n s i t y were made f o r D-f and WH stumps. Comparisons were a l s o made between the two hosts i n brood p r o d u c t i o n and a t t a c k d e n s i t y . 2.5 GALLERY DISTRIBUTION AND STRUCTURE 2.5.1 DISTRIBUTION IN A DOUGLAS-FIR LOG A f t e r the brood c o l l e c t i o n from the D-f logs on the UBC Campus was f i n i s h e d i n June 1986, d i s c s were taken from a l l three l o g s e c t i o n s . Three d i s c s were taken from the top, middle, and bottom p a r t s of each l o g s e c t i o n , and each one was d i s s e c t e d r a d i a l l y i n t o 16 p a r t s . The numbers of Gnat hot r i chus g a l l e r i e s on each d i f f e r e n t r a d i a l face were counted and depths from g a l l e r i e s to the cambium and sapwood t h i c k n e s s e s were measured. A frequency d i s t r i b u t i o n of g a l l e r y depths and a g a l l e r y d i s t r i b u t i o n over percentage depths i n sapwood were ob t a i n e d . F i f t e e n G. retusus g a l l e r i e s used to monitor f r a s s p r o d u c t i o n were d i s s e c t e d to check f o r g a l l e r y development. 22 2.5.2 DISTRIBUTIONS IN DOUGLAS-FIR AND WESTERN HEMLOCK STUMPS A f t e r a t t a c k d e n s i t y measurements on D-f and WH stumps were f i n i s h e d , d i s c s were taken from 4 of the D-f and the 4 WH stumps. A l l d i s c s were taken from the middle p o r t i o n s of stumps and s p l i t r a d i a l l y i n t o 16 even p a r t s . A l l Gnat hot ri chus g a l l e r i e s on each of the r a d i a l faces were counted and d i s t a n c e s from g a l l e r y h o l e s to the cambium were measured. For D-f stumps, sapwood depths were a l s o measured for each s p l i t p i e c e . Two g a l l e r y d i s t r i b u t i o n s were p l o t t e d f o r D-f stumps, one a g a i n s t depth and the second a g a i n s t percentage depth i n sapwood. The g a l l e r y d i s t r i b u t i o n over depth i n WH stumps were a l s o p l o t t e d . Comparisons were made of g a l l e r y d i s t r i b u t i o n s among the D-f l o g , D-f stumps, and WH stumps. 2.5.3 GALLERY STRUCTURE Maps of G. retusus g a l l e r i e s i n D-f lo g s were drawn as d e s c r i b e d i n S e c t i o n 2.2. Mature G. retusus g a l l e r i e s were a l s o d i s s e c t e d from both D-f and WH stumps to determine the g a l l e r y s t r u c t u r e . A general g a l l e r y s t r u c t u r e model was developed. The D-f and WH stump samples were d i s s e c t e d along growth r i n g s to expose g a l l e r i e s and brood c r a d l e s at a l l depths. The d i s s e c t i o n s t a r t e d from the heartwood and progressed toward the cambium i n order to measure depths of g a l l e r y h o l e s i n sapwood. A l l brood c r a d l e s were counted. D i s t r i b u t i o n s of g a l l e r y l e n g t h , pupal niche, and l a r v a l 23 niche over depths, and d i s t r i b u t i o n s of pupal and l a r v a l niches per u n i t g a l l e r y l e n g t h over sapwood depths were obtained. 2.6 DIURNAL FLIGHT OF G. RETUSUS AND SEASONAL FLIGHT OF G.  RETUSUS AND G. SULCATUS Four Lindgren m u l t i p l e - f u n n e l t r a p s (Lindgren 1983) were set up i n the F-3 1984 l o g g i n g s i t e of the UBC Research Fores t on A p r i l 17, 1986 ( F i g 3). Two of them were b a i t e d with (+.)-sulcatol dOmg/day) and ethanol dOOmg/day) to monitor G. retusus b e e t l e f l i g h t , and the other two t r a p s b a i t e d with ( l ) - s u l c a t o l (5mg/day) and ethanol (I00mg/day) to monitor G. sulcatus b e e t l e f l i g h t . The four t r a p s were set out as two p a i r s at l e a s t 200m a p a r t . Each p a i r had one ( + ) - s u l c a t o l and one (±)-sulcatol b a i t e d t r a p and they were about 30m a p a r t . B e e t l e s from a l l four t r a p s were c o l l e c t e d on a weekly b a s i s , and i d e n t i f i e d to s p e c i e s and sex, and counted. For l a r g e catches, the sex r a t i o of at l e a s t one hundred b e e t l e s was recorded and the numbers of b e e t l e s were estimated v o l u m e t r i c a l l y . The same graduated c y l i n d e r was used, and the graduated c y l i n d e r was shaken to l e t the volume reading of b e e t l e s reach the lowest s t a b l e value. The f o l l o w i n g formulae were e s t a b l i s h e d . G. retusus: No. of beetles/mL=183.9. G. sulcatus: No. of beetles/mL=200.3. On May 27, 1986, a t h i r d Lindgren m u l t i p l e funnel t r a p b a i t e d with ( + ) - s u l c a t o l (lOmg/day) and ethanol (I00mg/day) 24 F i g u r e 3. M u l t i p l e funnel t r a p set up to monitor ambrosia b e e t l e f l i g h t . UBC Research F o r e s t , Maple Ridge, B.C. S p r i n g 1986. 25 was set up i n the same area to monitor G. retusus d i u r n a l f l i g h t . P a c i f i c d a y l i g h t saving time was used as the time s c a l e . B e e t l e s from the three ( + ) - s u l c a t o l b a i t e d t r a p s were c o l l e c t e d every hour and every h a l f hour d u r i n g mass f l i g h t p e r i o d s from 0700h to 2100h-2130h when the f l i g h t had ceased. Few b e e t l e s were found i n t r a p s at the 0700h c o l l e c t i o n thus i t was presumed that no f l i g h t o ccurred o u t s i d e of the o b s e r v a t i o n p e r i o d s . R e l a t i v e humidity was recorded with a hygrothermograph, and a i r temperature and l i g h t i n t e n s i t y were read with a thermometer and a l i g h t meter (Sekonic model L-398) r e s p e c t i v e l y at the time of b e e t l e c o l l e c t i o n . The l i g h t i n t e n s i t y readings were converted i n t o Watts/m 2 with a Quantum l i g h t meter (Model L1-185B ). Four day o b s e r v a t i o n s were made from May 27 to May 30. The environmental c o n d i t i o n s f o r G. retusus d i u r n a l f l i g h t were ev a l u a t e d . A f t e r the d i u r n a l f l i g h t experiment was f i n i s h e d , the t h i r d ( + ) - s u l c a t o l and ethanol b a i t e d t r a p was removed. But the four seasonal monitoring t r a p s were run c o n t i n u o u s l y through September when few b e e t l e s were caught i n t r a p s . The weather r e c o r d (maximum temperatures) at the gate of UBC Research F o r e s t was obtained and the p o s s i b l e e f f e c t s of weather on seasonal f l i g h t p a t t e r n s of the two b e e t l e s were eval u a t e d by v i s u a l comparison. A comparison between G. retusus brood emergence p a t t e r n s from D-f and WH and i t s seasonal f l i g h t p a t t e r n was a l s o made as mentioned i n the l a s t c h a p t e r . 26 2.7 EFFECTS OF SEMIOCHEMICALS ON THE BEHAVIOUR OF G. RETUSUS  AND' G. SULCATUS 2.7.1 EVALUATION OF EFFECTS OF SEMIOCHEMICAL BAIT  COMBINATIONS A 2 3 f a c t o r i a l experiment was conducted on the UBC Endowment Land Foreshore park above boomed logs i n the North Arm of the Fr a s e r R i v e r from May to September of 1985 to eval u a t e G. sulcatus responses to et h a n o l , a-pinene, and ( i ) - s u l c a t o l alone or i n combination with each o t h e r . The design of the experiment was an 8X8 L a t i n Square Design (LSD). The e i g h t treatments were: c o n t r o l , a-pinene (a-P), ethanol ( E ) , a-P+E, ( i ) - s u l c a t o l ((±)-S), a-P+(±)-S, E+(±)-S, and a-P+E+(±)-S. A second 2 3 f a c t o r i a l experiment with an 8X8 LSD was c a r r i e d out i n the F-3 area of the UBC Research F o r e s t i n May and June of 1986 to evaluate G. retusus responses to a-pinene, e t h a n o l , and ( + ) - s u l c a t o l t e s t e d alone or i n combination. The e i g h t treatments were: c o n t r o l , a-pinene, e t h a n o l , a-P+E, ( + ) - s u l c a t o l , a-P+(+)-S, E+(+)-S, and a-P+E+(+)-S. The r e l e a s e r a t e s of the semiochemicals were: a-pinene: 20-30 mg/day e t h a n o l : 100 mg/day ( l ) - s u l c a t o l : 5 mg/day ( + ) - s u l c a t o l : 10 mg/day 27 A l l r e l e a s e devices were s u p p l i e d by Phero Tech Inc., Vancouver. In each experiment, e i g h t 8-funnel t r a p s were used. Traps were hung from the tops of rebars to keep t r a p s about 50cm above ground. The d i s t a n c e between any two adjacent t r a p s was about 20m to minimize p o s s i b l e i n t e r f e r e n c e . A l l b a i t s were p l a c e d at the middle p o r t i o n s of t r a p s . The two dimensions (row and colum) of the LSD were time and t r a p l o c a t i o n . Once any t r a p caught about one hundred b e e t l e s or more, t r a p l o c a t i o n s were re-randomized w i t h i n the c o n s t r a i n t s of LSD f o r the s t a r t of the next r e p l i c a t i o n . By the end of the 8 r e p l i c a t e s , each t r a p had been set out i n each of the 8 t r a p p i n g l o c a t i o n s . For each treatment, a l l b e e t l e s were i d e n t i f i e d to s p e c i e s and sex and counted. Analyses of v a r i a n c e were c a r r i e d out with the UBC-ANOVAR program. 2.7.2 EVALUATION OF EFFECTS OF (±)-SULCATOL RELEASE RATES A 5X5 LSD experiment with (±)-sulcatol was set out i n the C-road area of the UBC Research F o r e s t i n August 1985. F i v e 8-funnel t r a p s were employed, and were set out at 20m spacing near y a r d i n g a r e a s . The f i v e treatments t e s t e d were: a-pinene+ethanol, a-P+E+(±)-S1, a-P+E+(±)-S2, a-P+E+(±)-S3, and a-P+E+(±)-S4. The r e l e a s e r a t e s of the semiochemicals were: a-pinene: 20-30 mg/day. e t h a n o l : 100 mg/day. 28 (±)-sulcatol 1: 0.5 mg/day. ( i ) - s u l c a t o l 2: 1.5 mg/day. ( i ) - s u l c a t o l 3: 5 mg/day. ( i ) - s u l c a t o l 4: 10 mg/day. The two dimensions (row and column) of the experiment were time and t r a p l o c a t i o n . Once any t r a p caught more than one hundred b e e t l e s , t r a p s were emptied and re-randomized to s t a r t the next r e p l i c a t i o n . For each treatment, a l l ambrosia b e e t l e s were separated by s p e c i e s and sex, and the numbers were counted. The UBC-ANOVAR program was used to analyse the G. sul cat us data. 3. RESULTS AND DISCUSSION 3.1 GALLERY AND BROOD DEVELOPMENT The f i r s t s i x G. retusus g a l l e r i e s d i s s e c t e d on May 31, 1985 each c o n t a i n e d one male and one female. One egg niche was found and g a l l e r i e s had no second branches and were shallow. The average g a l l e r y l e n g t h was 2.9 ±0.6 (S.E.) cm. Eggs were found on June 15 i n two g a l l e r i e s . Out of 18 g a l l e r i e s d i s s e c t e d , ten g a l l e r i e s had c o n s i d e r a b l e extensions of deep or second shallow g a l l e r y branches. Six g a l l e r i e s were n o t i c e d to have small black spots on t h e i r s u r f a c e . Larvae were found on June 28 i n one of the nine g a l l e r i e s d i s s e c t e d . Meanwhile, a new at t a c k was n o t i c e d which had only a 2.5cm long g a l l e r y c o n t a i n i n g one male b e e t l e . More l a r v a e were observed on J u l y 12 i n a l l four g a l l e r i e s d i s s e c t e d ; a few eggs were a l s o present. The f i r s t t e n e r a l a d u l t appeared on J u l y 26. The b e e t l e was l i g h t brownish c o l o u r e d , and a pupal niche was present i n the g a l l e r y . On August 9, brood were found i n a l l f i v e G. retusus g a l l e r i e s . Eleven mature G. retusus g a l l e r i e s were d i s s e c t e d from the second D-f l o g through August to e a r l y September. Two g a l l e r i e s were found to have 4 eggs which were app a r e n t l y f r e s h as w e l l as t e n e r a l a d u l t s i n September. In the l a t e s t checks i n October and November, a few short G. retusus g a l l e r i e s with a p a i r of b e e t l e s but without any brood c r a d l e s were found. 29 30 A t o t a l of 16 mature G. retusus g a l l e r i e s were d i s s e c t e d from D-f l o g s . There was a s i g n i f i c a n t l i n e a r r e l a t i o n s h i p between g a l l e r y l e n g t h and brood p r o d u c t i o n ( F i g 4). The r e g r e s s i o n equation was: Brood=-l8.9 + 1.0 Length(cm) R= 0.84 p<0.05 T h i s i n d i c a t e d that a g a l l e r y probably should have a len g t h of at l e a s t 19.9 cm i n order to be brood p r o d u c t i v e . The sex r a t i o of the brood was 1.1:1 (60 females : 54 males). Out of 16 mature g a l l e r i e s d i s s e c t e d i n August and e a r l y September, ten had n o t i c e a b l e black s t a i n on the g a l l e r y s u r f a c e , and ei g h t had s t a i n r e s t r i c t e d to g a l l e r y p o r t i o n s which were near entrances and/or i n shallow g a l l e r y branches. The extent of black s t a i n i n c r e a s e d from June to August. The d i s t r i b u t i o n of g a l l e r y l e n g t h over depth from May 31 to August 9 ( F i g 5) i n d i c a t e d that b e e t l e s bored the shallow g a l l e r y branches f i r s t , and g r a d u a l l y tended to s h i f t to b o r i n g deep g a l l e r y branches. The b o r i n g a c t i v i t y reached a peak i n June and continued u n t i l August 9 when brood had been produced. Short g a l l e r i e s found i n the f a l l were probably i n i t i a t e d i n l a t e summer or f a l l as G. retusus b e e t l e s continued f l y i n g from the s p r i n g to f a l l . B e e t l e s might overwinter as a d u l t s i n g a l l e r i e s and s t a r t to l a y eggs and excavate g a l l e r i e s or re-emerge i n the f o l l o w i n g s p r i n g . Based on g a l l e r y d i s s e c t i o n , the development from eggs to t e n e r a l a d u l t s took approximately 40 days or more; the egg stage l a s t e d about 10 days, the l a r v a l and pupal stages 31 40 • • / . y y T 100 160 200 250 300 350 400 450 600 gallery length (mm) F i g u r e 4. R e l a t i o n s h i p between G. retusus brood p r o d u c t i o n and g a l l e r y l e n g t h i n D-f l o g s . UBC Research F o r e s t , Maple Ridge, B.C. 1985. 32 D) C a> a> D) CO c <D o <D Q. 50 40 30 20 H 10 50 40-\ 30 20 10 H 50 40 30 20 10 50 40 H 30 20 10 50 40 30 20 10 0 May 31 June 15 ZZZfZLUZfZL June 28 July 12 Aug. 9 W<7\ 1"/ Si V * < * * ^ ^ ftV^ depth (mm) F i g u r e 5. C retusus g a l l e r y l e n g t h d i s t r i b u t i o n over depth of sapwood i n a D-f l o g at d i f f e r e n t time, UBC Research F o r e s t , Maple Ridge, B.C. 1985. 33 30 days or more. But a t t a c k and egg l a y i n g l a s t e d over s e v e r a l months. T h i s r e s u l t e d i n p o o r l y synchronized brood development. Those eggs found i n September probably c o u l d not develop to t e n e r a l a d u l t s before temperatures f e l l below the t h r e s h o l d f o r brood development. T h i s seems to support e a r l i e r s p e c u l a t i o n that Gnat hot ri chus may overwinter i n a l l stages (Chamberlin 1939; Doane et al. 1936; Prebble and Graham 1957). Asynchronous brood development a l s o o c c u r r e d w i t h i n a g a l l e r y ; both eggs and t e n e r a l a d u l t s were found i n the same g a l l e r y i n September. However, t h i s was not a common phenomena. The overwhelming m a j o r i t y of g a l l e r i e s examined had synchronized brood development among and w i t h i n g a l l e r i e s . One f e a t u r e of G. retusus as w e l l as G. sulcatus g a l l e r i e s i s that the p r o d u c t i v e g a l l e r y l e n g t h (the p o r t i o n of a g a l l e r y with brood c r a d l e s ) only r e p r e s e n t s a small p o r t i o n of the t o t a l g a l l e r y l e n g t h , and brood c r a d l e s are r e s t r i c t e d to the s e c t i o n of the g a l l e r y near the entrance. In comparison, g a l l e r i e s of Trypodendron lineatum do not have an apparent non-brood p r o d u c t i v e g a l l e r y p o r t i o n (personal o b s e r v a t i o n ) . Comparing t h e i r h a b i t a t s , T. lineatum b e e t l e s overwinter i n d u f f . However, G. retusus as w e l l as G. sulcatus overwinter i n host m a t e r i a l s and remain i n g a l l e r i e s much longer than T. lineatum b e e t l e s . T h e r e f o r e , the non-brood p r o d u c t i v e g a l l e r y p o r t i o n may be an important o v e r w i n t e r i n g h a b i t a t and maturation f e e d i n g area f o r brood. The s i g n i f i c a n t p o s i t i v e l i n e a r r e l a t i o n s h i p 34 between G. retusus brood p r o d u c t i o n and g a l l e r y l e n g t h supports t h i s h y p o t h e s i s . To produce one more brood, may r e q u i r e an a d d i t i o n a l g a l l e r y l e n g t h from the present f i n d i n g s . S i m i l a r l i n e a r r e l a t i o n s h i p s between brood pr o d u c t i o n and g a l l e r y l e n g t h were a l s o found f o r G. sulcatus (Zanuncio 1981). The gradual s h i f t of b o r i n g a c t i v i t i e s of b e e t l e s from shallow to deep p o r t i o n of sapwood over time may be an a d a p t a t i o n to seasonal environmental changes. C o n s i d e r a b l e d i f f e r e n c e s i n moisture content among d i f f e r e n t sapwood depths (Chapman and Dyer 1969), as w e l l as seasonal sapwood moisture changes have been r e p o r t e d (Chapman and Dyer 1969; Johnson and Zingg 1969). These changes may cause b e e t l e s to develop t h e i r g a l l e r i e s i n t o new p a r t s of the sapwood in order to maintain a s u i t a b l e growing environment f o r the ambrosia f u n g i . 3.2 FRASS PRODUCTION AND GALLERY ABANDONMENT Out of 85 g a l l e r i e s monitored ( f i v e of which were G. sul cat us) only e i g h t G. retusus g a l l e r i e s produced f r a s s c o n t i n u o u s l y up to mid-August, 1985. Yet, t r a c e f r a s s p r o d u c t i o n d i d not cease u n t i l e a r l y November, 1985. The f r a s s p r o d u c t i o n p a t t e r n from those e i g h t g a l l e r i e s ( F i g 5) showed a peak i n mid-June. The peak c o i n c i d e d with the time of maximum g a l l e r y extension obtained at the UBC Research F o r e s t ( F i g 6,7). There were no obvious c o r r e l a t i o n s between f r a s s p r o d u c t i o n or g a l l e r y e x t e n s i o n and maximum 4 0 - r XL 3 5 -O we 3 0 -2 5 -E, 2 0 -CO 1 5 -CO 1 0 -< DC 5 -T&-<D 60 a> 6 0 1 CM 40-1 E 30-1 I 2 0 -a 10-z UJ - J 0 -6-7. 6: G. retusus f r a s s production p a t t e r n and i t s r e l a t i o n s h i p with maximum temperature. UBC, Vancouver, B.C. 1985. 7: G. retusus g a l l e r y extension p a t t e r n and i t s r e l a t i o n s h i p with maximum temperature. UBC Research F o r e s t , Maple Ridge, B.C. 1985. CO U l 36 temperature f l u c t u a t i o n s ( F i g 6,7). The number of g a l l e r i e s which ceased f r a s s p r o d u c t i o n i n c r e a s e d from June to August, and f o r most of them, at l e a s t one b e e t l e emerged from the g a l l e r y before or a f t e r the c e s s a t i o n of f r a s s p r o d u c t i o n . A l l f i r s t - e m e r g e d b e e t l e s in June and J u l y were females, and a small number of males were the f i r s t to emerge from g a l l e r i e s through August to October ( F i g 8). F i f t e e n of the g a l l e r i e s d i s s e c t e d i n June 1986 showed that none of the g a l l e r i e s had any c r a d l e s f o r progeny p r o d u c t i o n , and seven of them had a s l i g h t l y black s u r f a c e . The l e n g t h of the g a l l e r i e s ranged from 3.9 cm to 15.2 cm with a average of 8.9±0.9 (S.E.) cm. Fr a s s c o l o u r became n o t i c e a b l y b l a c k e r from June on ( F i g 9). Two g a l l e r i e s , which were among those that produced f r a s s c o n t i n u o u s l y , had brood which emerged i n A p r i l and May 1986. The numbers of brood were e i g h t and nine r e s p e c t i v e l y . F r a s s c o l l e c t i o n and g a l l e r y d i s s e c t i o n from the D-f l o g s e c t i o n s on the UBC Campus r e v e a l e d that most g a l l e r i e s were u n s u c c e s s f u l . The reason might be that the wood became too dry f o r the fungus and/or b e e t l e s to grow as time progressed. As the l o g s e c t i o n s were only about 1.5m long, water l o s s would be c o n s i d e r a b l e even though the tops were se a l e d with p l a s t i c sheets and the l o g s e c t i o n s were shaded with a p i e c e of plywood. A second reason might be that the d e s i c c a t i o n of the wood h a l t e d anaerobic fermentation i n the wood and t h e r e f o r e prevented the p r o d u c t i o n of e t h a n o l . 14 JUNE 1985 28 5 JULY "t" ' i r " r "i • i — i • i - " i — i — i — r 12 19 26 2 9 16 23 SO 6 13 20 27 4 11 AUGUST SEPTEMBER F i g u r e 8. G a l l e r y abandonment by G. retusus a d u l t s i n a D-f l o g . UBC, Vancouver, B.C. 1985. 38 F i g u r e 9. G. retusus f r a s s c o l o u r changes over time i n a D-f l o g . UBC, Vancouver, B.C. 1985. 39 Ethanol has been i d e n t i f i e d as a b o r i n g s t i m u l a n t f o r Xyleborus furregineus ( N o r r i s and Baker 1969), a p o s s i b l e b o r i n g s t i m u l a n t f o r G. sulcatus (McLean and Borden 1977a), and l i k e l y c o u l d be a bori n g s t i m u l a n t f o r G. retusus. The short g a l l e r y lengths found d u r i n g d i s s e c t i o n support t h i s hypothesi s. The lack of s i g n i f i c a n t c o r r e l a t i o n between weekly f r a s s p r o d u c t i o n and maximum temperature i n d i c a t e s that there i s no obvious r e l a t i o n s h i p between f r a s s p r o d u c t i o n and maximum temperature w i t h i n the range of temperatures recorded. There may be a s u i t a b l e temperature range f o r b e e t l e a c t i v i t i e s . Further i n c r e a s e s i n temperature may a c t u a l l y i n h i b i t a c t i v i t i e s of b e e t l e s and so i n h i b i t f r a s s p r o d u c t i o n and g a l l e r y e x t e n s i o n . In t h i s study, maximum temperatures on June 19 , 20, and J u l y 3, 8 , 9, 10, 11 were w e l l above 30°C which was above the upper l i m i t (26.7°C) f o r G. retusus f l i g h t (Rudinsky and Schneider 1969), and would a l s o season the a l r e a d y dry log s f u r t h e r . The two peaks of g a l l e r y abandonment by female b e e t l e s around June 19, 20, and J u l y 3 support the above e x p l a n a t i o n . For Trypodendron lineatum, i t has been s t a t e d that a f t e r b e e t l e s have entered the wood, inadequate moisture undoubtedly i n f l u e n c e s parent a d u l t abandonment of g a l l e r i e s and s u r v i v a l of the broods (Kinghorn 1956). As male G. retusus are u s u a l l y at the heads of g a l l e r i e s (Borden and McLean 1979), the f a c t that females are the f i r s t sex to abandon g a l l e r i e s seems l o g i c a l . 40 B i o l o g i c a l l y , females may be more s e n s i t i v e to host q u a l i t y than males as females c a r r y eggs and determine progeny p r o d u c t i o n . Abandonment of u n s u i t a b l e g a l l e r i e s or host m a t e r i a l s may l e a d to higher success r a t e s of brood development as females may e v e n t u a l l y f i n d s u i t a b l e host m a t e r i a l s i n which to r a i s e t h e i r brood. T h i s should be advantageous f o r the development of G. retusus p o p u l a t i o n s . For those g a l l e r i e s from which males emerged i n the l a t e r summer and f a l l , females might have d i e d i n g a l l e r i e s before emergence of males, s i n c e no evidence of the e x i s t e n c e of l i v e b e e t l e s i n those g a l l e r i e s were found a f t e r the emergence. 3.3 BROOD EMERGENCE FROM DOUGLAS-FIR AND WESTERN HEMLOCK  STUMPS AND G. RETUSUS ATTACK AND BROOD PRODUCTION 3.3.1 BROOD EMERGENCE FROM DOUGLAS-FIR AND WESTERN HEMLOCK  STUMPS G. retusus brood emergence from D-f stumps began a f t e r A p r i l 17, and brood were c o l l e c t e d from WH stumps immediately a f t e r the i n s t a l l a t i o n of p e t r i d i s h e s on A p r i l 24. The emergence peak occurred between May 15 and May 29, and the emergence ceased on June 19 f o r D-f stumps and on June 26 f o r WH stumps ( F i g 10). However, there was a g a l l e r y i n a D-f stump that had 15 brood which emerged i n May and June and an a d d i t i o n a l 3 brood emerged i n l a t e J u l y . The emergence peak from D-f stumps came a l i t t l e e a r l i e r than 41 10 17 24 1 8 16 12 29 6 12 19 28 8 APRIL MAY JUNE JULY 1986 F i g u r e 10. G. retusus brood emergence p a t t e r n from D-f and WH stumps (middle), and i t s r e l a t i o n s h i p with temperature (top) and the seasonal f l i g h t p a t t e r n (bottom). UBC Research F o r e s t , Maple Ridge, B.C. 1986. 42 that from WH stumps. F r a s s p r o d u c t i o n was of c o n s i d e r a b l e q u a n t i t y f o r many g a l l e r i e s i n both D-f and WH stumps beginning i n l a t e A p r i l . The f l u c t u a t i o n of brood emerging over time was p o s i t i v e l y r e l a t e d to the f l u c t u a t i o n of maximum d a i l y temperatures recorded at the gate of the UBC Research F o r e s t . The f l i g h t peak of G. retusus recorded with ( + ) - s u l c a t o l p l u s ethanol b a i t e d Lindgren m u l t i p l e funnel t r a p s c o i n c i d e d with the brood emergence peak recorded from D-f and WH stumps ( F i g 10). However, a f t e r the brood emergence ceased, the f l i g h t was s t i l l at a high l e v e l and l a s t e d f o r q u i t e a long time. Reasons f o r t h i s continued f l i g h t may be the search f o r s u i t a b l e hosts and abandonment of u n s u i t a b l e hosts by b e e t l e s , e s p e c i a l l y females, and the l a t e emergence of brood from host m a t e r i a l s . The average sex r a t i o of emergent G. retusus b e e t l e s from D-f and WH stumps was 0.9:1 (388 females:429 males) which 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 (p^0.05). I t v a r i e d over time i n s y n c h r o n i z a t i o n with the maximum temperature f l u c t u a t i o n , and showed s l i g h t i n c r e a s e s over time ( F i g 11). Brood emergence of G. retusus from D-f and WH stumps l a s t e d about one and h a l f months. T h i s suggests that a c o n s i d e r a b l y l a r g e p o r t i o n of brood feed and develop to mature a d u l t s i n g a l l e r i e s before emergence i n the s p r i n g and e a r l y summer. Some g a l l e r i e s had f r a s s p r o d u c t i o n i n l a t e A p r i l , and brood emergence i n e a r l y June. I t appears that the brood may overwinter i n stages other than a d u l t and 43 17 24 1 8 15 22 29 5 12 19 APRIL MAY JUNE 1986 F i g u r e 11. R e l a t i o n s h i p between the sex r a t i o of G. retusus brood ready to emerge and temperature. UBC Research F o r e s t , Maple Ridge, B.C. 1986. 44 develop i n t o mature a d u l t s i n the s p r i n g and summer. T h i s agrees with the c o n c l u s i o n made e a r l i e r (from g a l l e r y d i s s e c t i o n s ) that small numbers of b e e t l e s may overwinter i n stages other than a d u l t , and a l s o agrees with Chamberlin (1939), Doane et al. (1935), and Prebble and Graham (1957). The s y n c h r o n i z a t i o n between the sex r a t i o of brood i n g a l l e r i e s ready to emerge and temperature suggests that female emergence i s more s e n s i t i v e to temperature f l u c t u a t i o n than male emergence. Female b e e t l e s have g r e a t e r f l u c t u a t i o n s i n numbers emerging r e l a t i v e to temperature changes than do males. The s l i g h t g eneral i n c r e a s e i n sex r a t i o over time a l s o supports t h i s c o n c l u s i o n as temperature shows a general i n c r e a s e over time i n the p e r i o d . B i o l o g i c a l l y , t h i s suggests that males may have a wider temperature range and lower t h r e s h o l d than females f o r emergence, and be b e t t e r adapted to g e n e r a l l y h o s t i l e environments than females. 3.3.2 BROOD PRODUCTION AND ATTACK DENSITY Of 63 Gnat hot ri chus g a l l e r i e s covered with p e t r i d i s h e s on D-f stumps, two were G. sulcatus g a l l e r i e s , 41 were G. retusus g a l l e r i e s , and 20 d i d not have brood emerged. For WH stumps, of 36 g a l l e r i e s covered with p e t r i d i s h e s , one was a G. sulcat us g a l l e r y , 22 were G. retusus g a l l e r i e s , and 13 d i d not have brood emerged. The d i s s e c t i o n of s i x and seven of those*unproductive g a l l e r i e s from the four D-f and four WH stumps sampled r e s p e c t i v e l y r e v e a l e d that those 45 unproductive g a l l e r i e s were e i t h e r immature g a l l e r i e s without pupal niches or mature g a l l e r i e s with dead G. retusus t e n e r a l a d u l t s . G. sulcatus i s b i v o l t i n e (Prebble and Graham 1957; Zanuncio 1981). If the stumps were a t t a c k e d in the s p r i n g of 1985 or e a r l i e r , the brood would have emerged by the f a l l of 1985, and empty mature g a l l e r i e s should have been found i n g a l l e r y d i s s e c t i o n s . A l s o , among pr o d u c t i v e g a l l e r i e s , G. sulcatus g a l l e r i e s represented only a very small p o r t i o n ( 3 % ) . I t i s t h e r e f o r e reasonable to presume that G. sulcatus g a l l e r i e s would a l s o represent a very small p o r t i o n of those immature g a l l e r i e s . T h i s i m p l i e s that both D-f and WH stumps i n that area were overwhelmingly c o l o n i z e d by G. retusus, and most of those unproductive g a l l e r i e s were G. retusus g a l l e r i e s . Based on t h i s c o n c l u s i o n , the G. retusus brood d i s t r i b u t i o n s f o r both D-f and WH stumps were obtained ( F i g 12) and brood p r o d u c t i o n s were estimated (Table 3 ) . There were no s i g n i f i c a n t d i f f e r e n c e s i n average brood p r o d u c t i o n between D-f and WH stumps. However, s i g n i f i c a n t d i f f e r e n c e s were found among D-f and WH stumps i n brood p r o d u c t i o n (Table 4). The average a t t a c k d e n s i t y (±S.E.) on D-f stumps was 3.35±0.18/100 cm 2 ( 3 1 . 1 / f t 2 ) which was s i g n i f i c a n t l y higher than the average a t t a c k d e n s i t y 1.53±0.27/100 cm 2 ( 1 4 . 2 / f t 2 ) (p^0.05) on WH stumps. There was a l s o a manifest d i f f e r e n c e i n d i s t r i b u t i o n of g a l l e r y d e n s i t y between the two hosts ( F i g 13). S i g n i f i c a n t d i f f e r e n c e s i n at t a c k d e n s i t y e x i s t e d Legend EZ2 D-f stump n=61 WH stump n=35 . *> a $ q O rfr tSi €& w *P number of brood F i g u r e 12. G. retusus brood d i s t r i b u t i o n s f o r D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986. T a b l e 3. G. retusus g a l l e r y success and brood p r o d u c t i o n s i n D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. June 1986. Species No. of Success R a t e 1 Average Brood 1 G a l l e r i e s ±S.E.(%) ±S.E. D-f 61 67.2±6.0 8.30±1.53 WH 35 62.9±8.2 7.29±1.84 1. No s i g n i f i c a n t d i f f e r e n c e between s p e c i e s , t - t e s t p<0.05. 48 Table 4. G. retusus a t t a c k d e n s i t y and brood p r o d u c t i o n i n D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. June 1986. D-f 1 WH1 Stump No. d e n s i t y 2 b r o o d 3 d e n s i t y brood 1 2.75 ab" 5.67 ab 0.69 a 17.50 b 2 2.07 a 4.75 ab 1 .00 a 1 1 .50 ab 3 4.96 ab 3.71 a 6.06 b 6.00 ab 4 5.40 b 6.00 ab 1 .07 a 1 .25 a 5 3.40 ab 14.83 ab 6 3.46 ab 9.46 ab 7 5.05 ab 15.63 b 8 7.25 ab 1. Data transformed t o X'=Log(X+1) p r i o r to ANOVA. 2. D e n s i t y : No. of entrances per 100cm 2. 3. Brood: average brood p r o d u c t i o n per g a l l e r y . 4. 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 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 , p^0.05. 49 45 40 3 5 -3 0 -Legend EZ2 D-f stump n=138 WH slump n=55 o c 9 25 2 0 -T—i—I—i—i—i—i—I—i—r 0 10 11 12131416161718192021222324 gallery/100 sq cm. F i g u r e 13. G. retusus g a l l e r y d e n s i t y d i s t r i b u t i o n s on D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986. 50 among both D-f and WH stumps (Table 4). No s i g n i f i c a n t d i f f e r e n c e s i n g a l l e r y d e n s i t y among d i f f e r e n t aspects of e i t h e r D-f or WH stumps were d e t e c t e d . No s i g n i f i c a n t c o r r e l a t i o n between brood p r o d u c t i o n and g a l l e r y d e n s i t y c o u l d be d e t e c t e d f o r the sample of e i t h e r host s p e c i e s , and n e i t h e r were there any s i g n i f i c a n t c o r r e l a t i o n s between stump diameter and brood p r o d u c t i o n or a t t a c k d e n s i t y f o r e i t h e r of the host s p e c i e s . Within stumps, d e f i n i t e trends of i n c r e a s e s i n at t a c k d e n s i t y and brood p r o d u c t i o n from the tops to the bottoms of D-f stumps were found. For WH stumps, there was a l s o a tr e n d of i n c r e a s e s i n at t a c k d e n s i t y from stump tops to the bottoms ( F i g 14). But the brood p r o d u c t i o n i n WH stumps had a very weak negative c o r r e l a t i o n with d i s t a n c e s from stump tops to g a l l e r y entrances. L i n e a r models were a l s o c o n s t r u c t e d f o r above r e l a t i o n s h i p s ( F i g 14). The higher a t t a c k d e n s i t y of G. retusus on D-f stumps than on WH stumps i n d i c a t e s that D-f stumps are p r e f e r r e d by G. retusus b e e t l e s . T h i s may be due to a p o s s i b l e higher p r o d u c t i o n r a t e of the host a t t r a c t a n t ethanol i n D-f stumps. D-f stumps have much t h i c k e r bark than WH stumps and t h e r e f o r e may have b e t t e r anaerobic fermentation c o n d i t i o n s i n the bark and sapwood than do WH stumps. T h i s w i l l probably enhance p r o d u c t i o n of ethanol and induce mass a t t a c k by G. retusus b e e t l e s . But the d i f f e r e n c e i n ethanol p r o d u c t i o n l e v e l between the two hosts may not cause a s i g n i f i c a n t d i f f e r e n c e i n b o r i n g a c t i v i t y i n sapwood even £ o o o CO c CD o O) TJ O O 14-] 12 S" 10 8 6 4 2 H 40 H 35 30-25-20-, 15-10-5-D-f stump D=0.97+0.14H(cm) r-0.48, p<0.01 n=138 D-f atump B—3.93+0.57H(cm) r=0.39, p<0.01 n=61 * & & $«{? £ # & #«? # WH stump D=0.14+0.13H(cm) r-0.41. p<0.001 n=55 i r WH stump B-19.63-4.08H(cm) r=0.34, p<0.05 n=35 J> <§> t ? & F i g 14 distance from top (cm) distance from top (cm) R e l a t i o n s h i p between G. retusus a t t a c k d e n s i t y , brood p r o d u c t i o n and p o s i t i o n s on D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986. H: di s t a n c e from the top of a stump t o the g a l l e r y entrance or a t t a c k d e n s i t y sampling u n i t on the stump. 52 though ethanol i s a p o s s i b l e b o r i n g s t i m u l a n t of G. retusus. The s u i t a b i l i t i e s of D-f and WH stumps seem to be the same f o r G. retusus brood development s i n c e there are no s i g n i f i c a n t d i f f e r e n c e s i n average g a l l e r y success r a t e s and average brood p r o d u c t i o n between the two h o s t s . The lack of c o r r e l a t i o n between stump diameter and at t a c k d e n i s t y or brood p r o d u c t i o n i m p l i e s that the range of t r e e diameters i n t h i s study i s not s u f f i c i e n t to cause d i f f e r e n c e s in a t t a c k d e n s i t y and brood p r o d u c t i o n . The lack of s i g n i f i c a n t d i f f e r e n c e s i n at t a c k d e n s i t y among d i f f e r e n t a spects of D-f stumps i m p l i e s that d i f f e r e n c e s among d i f f e r e n t aspects are not b i g enough f o r b e e t l e s to d i s c r i m i n a t e by aspect once they are o r i e n t e d to stumps. The lack of s i g n i f i c a n t c o r r e l a t i o n between a t t a c k d e n s i t y and brood p r o d u c t i o n f o r D-f or WH stumps may be due to l a r g e v a r i a n c e s w i t h i n stumps i n at t a c k d e n s i t y and brood p r o d u c t i o n s i n c e trends of a t t a c k d e n s i t y and brood p r o d u c t i o n i n r e l a t i o n to p o s i t i o n s on stumps have been demonstrated. The same trends of i n c r e a s e s i n a t t a c k d e n s i t y and brood p r o d u c t i o n from tops to bottoms w i t h i n D-f stumps seems to i n d i c a t e a p o s i t i v e r e l a t i o n s h i p between a t t a c k d e n s i t y and brood p r o d u c t i o n . The trends of i n c r e a s e s i n at t a c k d e n s i t y and brood p r o d u c t i o n f o r D-f and i n a t t a c k d e n s i t y f o r WH with d e c r e a s i n g d i s t a n c e s from stump tops to bottoms r e f l e c t i n c r e a s e s i n host q u a l i t y f o r G. retusus. A f t e r l o g g i n g , water and v o l a t i l e o i l s w i l l evaporate from the top of 53 stumps much f a s t e r than from other p a r t s of stumps. But water may be r e p l e n i s h e d through a b s o r p t i o n by the r o o t s . T h i s w i l l r e s u l t i n a moisture g r a d i e n t from the tops to the bottoms of stumps i n the sapwood. Moisture c o n d i t i o n i n the sapwood i s a very important f a c t o r i n f l u e n c i n g a t t a c k s and brood p r o d u c t i o n of ambrosia b e e t l e s (Kinghorn 1956; McLean and Borden 1977a). In the top of a stump, as wood i s c o n s i d e r a b l y dehydrated, anaerobic fermentation w i l l be reduced. T h i s w i l l r e s u l t i n a decreased p r o d u c t i o n of e t h a n o l , the primary host a t t r a c t a n t and p o s s i b l e t u n n e l l i n g s t i m u l a n t f o r G. retusus. On the other hand, dehydration w i l l a l s o render the wood d i f f i c u l t to bore in and u n s u i t a b l e f o r growth of ambrosia f u n g i . Other micro-organisms w i l l c e r t a i n l y c o l o n i z e sapwood through cut s e c t i o n s and may a l s o make the wood i n t h e i r v i c i n i t y u n s u i t a b l e to grow ambrosia f u n g i . A l l t h i s may r e s u l t i n low attack d e n s i t i e s and low brood .production near the top of a stump. In a d d i t i o n , v o l a t i l e o i l s e x t r a c t e d from wood has been found to r e t a r d or deter a t t a c k s of c o n i f e r l o g s by Trypodendron lineatum ( N i j h o l t 1973; Werner and Graham 1957). For G. retusus, emission of v o l a t i l e o i l s from cut s e c t i o n s of stumps may a l s o be a cause of low a t t a c k d e n s i t i e s near the tops of stumps. However, the brood p r o d u c t i o n t r e n d i n WH stumps does not f i t the above h y p o t h e s i s . Brood p r o d u c t i o n had a very weak negative c o r r e l a t i o n with d i s t a n c e from the top of a WH stump. T h i s may w e l l be an a r t i f a c t caused by the small 54 sample s i z e . 3.4 GALLERY DISTRIBUTION AND STRUCTURE 3.4.1 GALLERY DISTRIBUTIONS IN A DOUGLAS-FIR LOG, DOUGLAS-FIR STUMPS, AND WESTERN HEMLOCK STUMPS G a l l e r y d i s t r i b u t i o n s i n a l l three host c a t e g o r i e s had a peak frequency at depths of 11-20mm in sapwood. Beyond t h i s peak, f r e q u e n c i e s decreased s t e a d i l y with i n c r e a s i n g sapwood depth ( F i g 15). The d i s t r i b u t i o n s of g a l l e r y depths were dependent on sapwood depths. Except f o r a small p o r t i o n of g a l l e r y h oles i n h e a v i l y a t t a c k e d D-f stumps d i s t r i b u t e d in heartwood, most g a l l e r y h oles i n the D-f l o g and stumps d i d not penetrate deeper than the sapwood ( F i g 15). The d i s t r i b u t i o n i n the D-f l o g was the same as those r e p o r t e d f o r Gnathori chus s p e c i e s or G. sulcatus (McLean 1985; Prebble and Graham 1957). For D-f and WH stumps, g a l l e r y d i s t r i b u t i o n s over depth of sapwood were s i m i l a r to those c o n s t r u c t e d f o r Gnat hotri chus s p e c i e s or G. retusus i n D-f and WH lo g s except f o r much deeper p e n e t r a t i o n s were found i n the stumps (McLean 1985; Prebble and Graham 1957). Comparing percentage depth d i s t r i b u t i o n s of g a l l e r i e s between the D-f l o g and D-f stumps ( F i g 16), there were no g a l l e r y h o l e s i n the f i r s t 10% of sapwood depth and only a very small p o r t i o n i n the second 10% of sapwood depth f o r the D-f l o g and decreases i n frequency a f t e r 40% of sapwood depth. T h i s may due to the small sapwood depth i n the D-f "3 H O, —• o • ft. "^ 3 —-<« G "* » W c o *> b o - c o ~ < O 3 0> a n i -• • o M c » G < ^ CO <D •< - a SO M-n> to in tn • r t n> o n 0) . M. o — c 00 T] CJ1 O 0 • 3 1 in r t O < 01 (II I—1 r t W a (V a o 00 ON O in o> •a « o o a Ol to Ol O l Q l CD "D CO ~o o o OL 3 3 Ol CO Ol o - l Ol C3 N) - | Ol Ol CO Ol 0» Ol fO o H Ol IO «o -\ Ol ro H oi percentage frequency _ l rO _ l _» N> M _ l w cn cn o m o c n o c n o c n o o o o o o i i i- i t I \ \ w \ w I* CO ^1 CO cn - i " c - 3 ] =J O II I C O " 1 cot/). W W W W N D O II I 99 56 25 percentage depth of sapwood F i g u r e 16. G. retusus g a l l e r y d i s t r i b u t i o n s over percentage depth of sapwood i n a D-f l o g and D-f stumps. top: UBC, Vancouver, B.C. 1985. bottom: UBC Research F o r e s t , Maple Ridge, B.C. 1986. 57 l o g compared with D-f stumps and the lack of success of most G. retusus g a l l e r i e s i n the D-f l o g . The D-f l o g had an average sapwood depth of 34.2±0.9(S.E.)mm. However, D-f stumps had an average sapwood depth of 65.4±8.8(S.E.)mm. The f i r s t 10% of sapwood depth i n the D-f log ranged only from 0 to 4 mm, and the second 10%, 4 to 7 mm. G. retusus g a l l e r y d i s s e c t i o n s r e v e a l e d that most g a l l e r i e s were immature g a l l e r i e s which had only one short shallow g a l l e r y branch and l i t t l e e x t ension of deep g a l l e r y branches. T h i s c o u l d r e s u l t i n a decrease of frequency of g a l l e r y h o l e s i n the deep p o r t i o n of the sapwood. The sapwood of D-f stumps was used more evenly by G. retusus b e e t l e s except f o r low f r e q u e n c i e s of g a l l e r y holes i n the f i r s t 10% and the l a s t 10% of sapwood depth. The f i r s t 10% sapwood depth took a depth range of 0 to 7 mm, i n which range the ab s o l u t e depth d i s t r i b u t i o n a l s o showed a low frequency of g a l l e r y h o l e s . The even d i s t r i b u t i o n p a t t e r n of G. retusus g a l l e r i e s and presence of g a l l e r y h o l e s i n heartwood i n D-f stumps seem to r e f l e c t i n t r a - s p e c i e s space competition i n the sapwood. The competition r e s u l t e d i n f u l l usage of the m a j o r i t y of the sapwood. The high g a l l e r y d e n s i t y and i n t e r - g a l l e r y c r o s s i n g s d i s c u s s e d l a t e r appear to support t h i s e x p l a n a t i o n . 58 3.4.2 GALLERY STRUCTURE A mature G. retusus g a l l e r y , which i s s i m i l a r to a G. sulcatus g a l l e r y i n s t r u c t u r e (McLean 1975a; Zanuncio 1981), u s u a l l y has at l e a s t one shallow and one deep g a l l e r y branch which very o f t e n extend i n opp o s i t e d i r e c t i o n s i n the l e s s dense s p r i n g wood of annual growth r i n g s . More main branches can o f t e n be observed and they may have s e v e r a l short sub-branches ( F i g 17). The complexity of g a l l e r y s t r u c t u r e seems to be r e l a t e d to brood p r o d u c t i o n . G a l l e r i e s which have a l a r g e brood p r o d u c t i o n o f t e n have complicated g a l l e r y s t r u c t u r e . Brood p r o d u c t i o n of G. retusus appears to be c o n f i n e d to the p o r t i o n of the g a l l e r y c l o s e s t to the main r a d i a l g a l l e r y ( F i g 17). The depth d i s t r i b u t i o n s of brood c r a d l e s ( F i g 18) demonstrated that both pupal and l a r v a l n i c h e s had a c o n c e n t r a t i o n from 10 to 20 mm depth of sapwood in D-f and from 20-30mm depth i n WH stumps. Both shallow and deep branches have c o n s i d e r a b l e d i s t a l l e ngths without any egg or l a r v a l n i c h e s . The t o t a l l e n g t h of non-brood p r o d u c t i v e p o r t i o n s i n a mature g a l l e r y i s s e v e r a l times that of the brood p r o d u c t i v e p o r t i o n s . A s t r i k i n g d i f f e r e n c e i n g a l l e r y s t r u c t u r e was that G. retusus g a l l e r i e s i n D-f stumps had c o n s i d e r a b l e e l o n g a t i o n of pupal n i c h e s and i n t e r - g a l l e r y c r o s s i n g s e s p e c i a l l y i n h e a v i l y a t t a c k e d ones ( F i g 19,20). The e l o n g a t i o n of pupal niches was never observed i n D-f logs but was q u i t e common in D-f stumps and o c c a s i o n a l l y o c c u r r e d i n WH stumps. F i g u r e 17. A model of a G, retusus g a l l e r y i n D-f l o g s . E: egg niche; L: l a r v a l n i c h e ; P: pupal n i c h e . Scale*1:1. 60 D-F STUMP Legend EZ3 larval niche 197 • I pupal niche 1026 ED length 13.415m Legend EZ2 larval niche pupal niche l 1 1 1 1 r Legend EZ3 larval niche 145 pupal niche 529 ED length 10.123m J3. Legend EZ2 larval niche pupal niche T 1 r 15 25 35 45 55 65 75 85 95 105 115 125 136 145 DEPTH IN SAPWOOD (mm) F i g u r e 18. D i s t r i b u t i o n s of G. retusus g a l l e r y l e n g t h , l a r v a l n i c h e , and pupal niche over sapwood depth and d i s t r i b u t i o n s of l a r v a l n iche and pupal niche d e n s i t y per u n i t g a l l e r y l e n g t h over sapwood depth i n D-f and WH stumps. UBC Research F o r e s t , Maple Ridge, B.C. 1986. 61 F i g u r e 19. C. retusus g a l l e r y s t r u c t u r e i n D-f stumps: e l o n g a t i o n of pupal niches i n t o maturation f e e d i n g tunnels and i n t e r - g a l l e r y c r o s s i n g s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. 62 F i g u r e 20. G. retusus g a l l e r y s t r u c t u r e i n D-f stumps: e l o n g a t i o n of pupal niches i n t o maturation f e e d i n g tunnels and i n t e r - g a l l e r y c r o s s i n g s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. 63 Pupal niches i n D-f stumps c o u l d be elongated up to three c e n t i m e t e r s , and i n t e r - g a l l e r y c r o s s i n g s occurred through c o n j u c t i o n s of pupal niches or elongated pupal niches of two or more g a l l e r i e s . In WH stumps, elongated pupal niches were much s h o r t e r ( F i g 21) than those i n D-f stumps. The i n t e r - g a l l e r y c r o s s i n g s are a consequence of the high a t t a c k d e n s i t y of D-f stumps as w e l l as e l o n g a t i o n of pupal n i c h e s . The elongated pupal niches may f u n c t i o n as maturation feeding t u n n e l s to cope with overcrowding and shortage of feeding areas i n main tunnels r e s u l t i n g from space competition and s u c c e s s f u l l a r g e brood p r o d u c t i o n . Since g a l l e r y d e n s i t y was very high i n some host m a t e r i a l s , the e x t e n s i o n of main g a l l e r y branches c o u l d be l i m i t e d c o n s i d e r a b l y . As no c o n j u c t i o n s of two g a l l e r i e s i n main branches were found, a d u l t s seem to a v o i d g a l l e r y c r o s s i n g s by d e t o u r i n g or stopping g a l l e r y e x t e n s i o n . A c o u s t i c communication has been demonstrated i n bark b e e t l e s (Rudinsky et al. 1978a,1978b), and i t may a l s o e x i s t i n ambrosia b e e t l e s and enable them to d e t e c t b o r i n g a c t i v i t i e s i n t h e i r v i c i n i t y . In a e a r l i e r p a r t of t h i s t h e s i s , a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n between g a l l e r y l e n g t h and brood p r o d u c t i o n was demonstrated, and the v i t a l f u n c t i o n of non-brood p r o d u c t i v e g a l l e r y p o r t i o n s as f e e d i n g areas has been suggested. In the present case, c o m p e t i t i o n f o r space c o u l d r e s u l t i n r e d u c t i o n of non-brood p r o d u c t i v e g a l l e r y 64 F i g u r e 21. G. retusus g a l l e r y s t r u c t u r e i n WH stumps: s l i g h t e l o n g a t i o n of pupal n i c h e s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. 65 p o r t i o n s , crowdedness of brood, and shortage of feed i n g areas i n g a l l e r i e s . In a d d i t i o n , i n t e r - g a l l e r y brood movement was p o s s i b l e s i n c e g a l l e r y c r o s s i n g s were q u i t e common. T h i s c o u l d r e s u l t i n i n a c c u r a t e e s t i m a t i o n of g a l l e r y brood p r o d u c t i o n and i n overcrowding i n some g a l l e r i e s . I t i s a l s o p o s s i b l e that a b e e t l e might d i e i n a g a l l e r y , and t h i s c o u l d r e s u l t i n the r e s t of brood being i s o l a t e d t e m p o r a r i l y i n some p a r t s of the g a l l e r y . The excav a t i o n of maturation feeding tunnels at the heads of pupal niches by t e r n e r a l a d u l t s probably can not only secure t h e i r own food supply but a l s o l e s s e n the crowdedness and shortage of feeding space i n main branches. 3.5 DIURNAL FLIGHT OF G. RETUSUS AND SEASONAL FLIGHT OF G.  RETUSUS AND G. SULCATUS 3.5.1 DIURNAL FLIGHT OF G. RETUSUS G. retusus had c r e p u s c u l a r f l i g h t h a b i t s and showed a bimodal f l i g h t p a t t e r n . The f i r s t f l i g h t , i n the morning, occu r r e d about 0700h and reached a peak between 0800 and 0900h which was very small and c o n s t i t u t e d only 3.3% to 10% of the t o t a l c a t c h i n a day. In the morning of a c l e a r day du r i n g the experiment, l i g h t i n t e n s i t y i n c r e a s e d from about 70 Watts/m 2 at 0700h to about 120 Watts/m 2 at 0800h, temperature i n c r e a s e d from around 14°C at 0700h to 17 or 19°C at 0800h, and r e l a t i v e humidity decreased from 87% at 0700h to 58% at 0800h. The dusk f l i g h t was much gr e a t e r than 66 the morning f l i g h t and c o n s t i t u t e d more than 90% of the t o t a l c a t c h d u r i n g a day. I t o c c u r r e d between I800h and 2100h or 2130h ( F i g s 22-25). From I800h, the number of b e e t l e s f l y i n g i n c r e a s e d r a p i d l y over time and reached a peak between 2000h and 2030h, and then terminated q u i c k l y . During t h i s mass f l i g h t p e r i o d , l i g h t i n t e n s i t y decreased d r a m a t i c a l l y from 120 Watts/m 2 to about 12 Watts/m 2, temperature decreased from about 24.7°C to 14.5°C, and r e l a t i v e humidity i n c r e a s e d from 40% to 83% at 2l00h. The lowest temperature at or above which b e e t l e s flew was 14°C. Between the two f l i g h t peaks, l i g h t i n t e n s i t y on a c l e a r day i n c r e a s e d from a low l e v e l i n the morning up to 199 Watts/m 2 at noon and then decreased g r a d u a l l y . Temperature a l s o i n c r e a s e d from a low l e v e l i n the morning to a peak at about I500h, which v a r i e d from 24.1°C to 30.5°C, and r e l a t i v e humidity decreased from a high l e v e l i n the morning to the lowest l e v e l at about 1700h, which v a r i e d from 40% to 28% on d i f f e r e n t days, and then i t i n c r e a s e d d r a m a t i c a l l y as l i g h t i n t e n s i t y decreased. During t h i s p e r i o d , very few b e e t l e s were caught. At 0700h, l i g h t i n t e n s i t y was almost i d e n t i c a l to that at I900h to I930h when mass f l i g h t s t a r t e d . But temperatures up to 0700h were lower than temperatures d u r i n g the dusk f l i g h t s . Although temperature i n c r e a s e d to reach a s u i t a b l e range f o r b e e t l e f l i g h t as the day progressed, l i g h t i n t e n s i t y a l s o i n c r e a s e d to above the upper l i m i t f o r mass f l i g h t . T h i s may w e l l be an important reason why morning 35 ^ 3 0 -U 1+ 2 5 -iime (hour) F i g u r e 22. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 27, 1986. UBC Research F o r e s t , Maple Ridge, B.C. 35 time (hour) F i g u r e 23. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 28, 1986. UBC Research F o r e s t , Maple Ridge, B.C. 30-=1000 = u o u Q_ O IOOt Legend' A male time (hour) F i g u r e 24. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 29, 1986. UBC Research F o r e s t , Maple Ridge, B.C. 70 35 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 time (hour) F i g u r e 25. Record of temperature, r e l a t i v e humidity, l i g h t i n t e n s i t y , and G. retusus f l i g h t on May 30, 1986. UBC Research F o r e s t , Maple Ridge, B.C. 71 f l i g h t peaks of G. retusus were much smaller than dusk f l i g h t s . On May 27, l i g h t i n t e n s i t y and temperature reached only 80 Watts/m 2 and 17°C r e s p e c t i v e l y at I300h as a r e s u l t of heavy fog i n the morning ( F i g 20). Although t h i s l i g h t i n t e n s i t y and temperature combination was not i d e n t i c a l to that under which mass f l i g h t s o c c u rred, i t was i n a s i m i l a r range. However, few b e e t l e s were caught before 1300h on t h i s date. The major d i f f e r e n c e between t h i s date and other three dates was i n r e l a t i v e humidity which decreased from 100% i n the morning to 80% at 1300h on May 27. For the other three days, i t was sunny a l l day, l i g h t i n t e n s i t y and temperature were high, and r e l a t i v e humidity was very low before the i n i t i a t i o n of the evening mass f l i g h t . The peak on May 27 was the s m a l l e s t among the four dusk f l i g h t peaks recorded. I t appears that warm days with low r e l a t i v e humidity are r e q u i r e d f o r the b e e t l e s to f l y i n the evening. Comparing dusk f l i g h t peaks of G. retusus i n the four days, the f l i g h t rhythm was probably e n t r a i n e d by l i g h t i n t e n s i t y s i n c e a l l dusk f l i g h t peaks oc c u r r e d at a constant l i g h t i n t e n s i t y but v a r i o u s temperatures and r e l a t i v e h u m i d i t i e s . A l i g h t i n t e n s i t y of 120 Watts/m 2 seems to be an upper l i m i t f o r b e e t l e s to i n i t i a t e dusk mass f l i g h t , and 12 Watts/m 2 a low t h r e s h o l d . In the four days, the temperature p r o f i l e showed steady i n c r e a s e s . But there was no d e t e c t a b l e advance or delay of the dusk f l i g h t . A temperature of 14°C seems to be a low t h r e s h o l d f o r b e e t l e f l i g h t . The 72 temperature range duri n g dusk f l i g h t s was from 17°C to 25°C which was wider than the 18.8 to 22.2°C range r e p o r t e d by Rudinsky and Schneider (1969). The upper l i g h t i n t e n s i t y l i m i t f o r b e e t l e f l i g h t e s t a b l i s h e d i n t h i s study was much lower than 2000 f t - c (215 Watts/m 2) repo r t e d by Rudinsky and Schneider (1969). E c o l o g i c a l l y , the dusk f l i g h t rhythm c o u l d be advantageous to t h i s s p e c i e s . L i g h t i n t e n s i t y decreases d r a m a t i c a l l y from l a t e a f t e r n o o n to evening so that b e e t l e s may be able to e a s i e r d i f f e r e n t i a t e changes i n l i g h t i n t e n s i t y . A l s o , as a r e s u l t of higher temperature and higher l i g h t i n t e n s i t y d u r i n g the day p r i o r to a dusk f l i g h t , s y n t h e s i s of aggregation pheromone i n s i d e the bodies of b e e t l e s may be enhanced, as i s anaerobic fermentation i n s i d e host m a t e r i a l s . I t c o u l d be that the a c c e l e r a t e d anaerobic fermentation d u r i n g warm hours which u s u a l l y l a s t s from l a t e morning to l a t e a f t e r n o o n would r e s u l t i n a h i g h c o n c e n t r a t i o n of host kairomone (ethanol) d u r i n g the dusk f l i g h t p e r i o d . A l s o , b e e t l e s may become dehydrated d u r i n g the hot daytime hours and be b e t t e r able to f l y long d i s t a n c e s at dusk. Mass f l i g h t at dusk may a l s o minimize l o s s e s of b e e t l e s to p r e d a t o r s by reducing exposure time, v i s i b i l i t y , and s y n c h r o n i z a t i o n with p r e y i n g p e r i o d s of p r e d a t o r s . V a r i o u s p r e d a t o r s i n c l u d i n g b i r d s have been r e p o r t e d to exert i n f l u e n c e s on bark b e e t l e p o p u l a t i o n s at a d u l t stages (Moeck and S a f r a n y i k 1984). 73 3.5.2 SEASONAL FLIGHT OF G. RETUSUS AND G. SULCATUS The f i r s t emergent G. retusus and G. sulcatus b e e t l e s caught i n t r a p s o c c u r r e d between A p r i l 17 and A p r i l 24 when the maximum temperature recorded at the gate of the UBC Research F o r e s t reached only 13.5°C. From then on, numbers of both G. retusus and G. sulcatus b e e t l e s captured i n tr a p s i n c r e a s e d over time. The f l i g h t peaks of both s p e c i e s o c c u r r e d between May 22 and May 29 when the weekly mean maximum temperature reached 22.6°C and the hi g h e s t d a i l y maximum temperature reached 25°C. Catches of G. retusus remained high u n t i l mid-July and decreased g r a d u a l l y from then on. However, catches of G. sulcatus dropped more d r a m a t i c a l l y a f t e r t h i s peak but i n c l u d e d a second small peak on J u l y 24, and then decreased s t e a d i l y but more slow than G. retusus c a t c h e s . The seasonal f l i g h t s ceased i n e a r l y October when weekly mean maximum temperatures dropped below 15°C ( F i g 26). The f l u c t u a t i o n of both G. retusus and G. sulcatus b e e t l e captures c o i n c i d e d with the f l u c t u a t i o n of maximum temperatures. Changes i n sex r a t i o s of both s p e c i e s a l s o c o i n c i d e d with the maximum temperature f l u c t u a t i o n ( F i g 26). In the d i u r n a l f l i g h t experiment with G. retusus, i t has been concluded that low r e l a t i v e humidity and high daytime temperatures are very important f o r the dusk f l i g h t . T h i s a l s o appears to be a major cause of f l u c t u a t i o n s of b e e t l e catches i n the seasonal f l i g h t p a t t e r n s . High temperatures u s u a l l y correspond to c l e a r sunny days with low r e l a t i v e tO NJ Cft ft G Q> 00 3 re n ( 1 3 X3 re • en Oi (D n rr 01 C C i~l — >-» O n ro 3- IS —* 0) O «> o O f0 ~\ cn 3 a rr —• - O. -— —-1— re W 3 ro Qi cn O o> ro 3 Qi l—• to o • 3 i-*> n o» \-> • t—> U3 — cn 3* >J3 fD rr 03 X cn • n QJ 0) rr rr rr »-< • ro O 3 l-h cn t-1 c o o f-h rr C w rr O 3 *••» in e Co e O O • catch/trap*week sex ratio (f:m) - giaxtemp.(C) O u ^ N M U tt o © at o <n o oi 75 h u m i d i t i e s , and these c o n d i t i o n s w i l l enhance dusk f l i g h t s . The c o i n c i d e n c e of the sex r a t i o f l u c t u a t i o n with the temperature f l u c t u a t i o n confirms the same r e l a t i o n s h i p i n brood emergence, and supports the c o n c l u s i o n that males are b e t t e r adapted to environmental extremes than females. As the male i s the pioneer sex, t h i s enable males more time to explo r e host m a t e r i a l s . Another f a c t o r which may a l s o c o n t r i b u t e to high sex r a t i o s i n seasonal f l i g h t on warm days i s the abandonment of g a l l e r i e s by female b e e t l e s , s i n c e peak abandonment by G. retusus females on the D-f l o g was recorded on days with high temperatures. The seasonal f l i g h t p a t t e r n of G. retusus observed h e r e i n agrees with those r e p o r t e d by Lindgren and Borden (1983), McLean and Borden (1977b), and Shore and McLean (1985), and confirms the o b s e r v a t i o n from g a l l e r y d i s s e c t i o n work with D-f log s that G. retusus i s p r i m a r i l y u n i v o l t i n e . G. sulcatus had an evident second f l i g h t peak duri n g mid-July . But i t was f a r smal l e r than those r e p o r t e d by Lindgren and Borden (1983), McLean and Borden (1975b), and Shore and McLean (1985). Comparing experimental s i t e s , a l l other surveys were conducted i n d r y l a n d s o r t s and sawmills where f r e s h logs were r e p l e n i s h e d c o n t i n u o u s l y over time. In the present study i n the f o r e s t , most host m a t e r i a l s were l e f t i n 1984 except f o r a small l o g g i n g o p e r a t i o n i n May 1986. Most of these host m a t e r i a l s l e f t i n 1984 whether a t t a c k e d or not probably became u n s u i t a b l e f o r ambrosia b e e t l e s to a t t a c k i n the s p r i n g 1 986. T h e r e f o r e , emergent G. 76 sulcatus b e e t l e s i n s p r i n g would probably not be able to f i n d adequate s u i t a b l e host m a t e r i a l s to maintain i t s p o p u l a t i o n i n that area. T h i s seems a l s o to be a reason f o r long l a s t i n g f l i g h t of G. retusus. In a d d i t i o n , G. sulcatus would face a s t r o n g competition from G. retusus s i n c e G. retusus was the dominant ambrosia b e e t l e s p e c i e s i n that a r e a . For p o p u l a t i o n suppression of Gnat hotrichus s p e c i e s with pheromone-based mass t r a p p i n g systems, t r a p s should be set out before a weekly mean maximum temperature of 15°C i s reached i n the s p r i n g . 3.6 EFFECTS OF SEMIOCHEMICALS ON THE BEHAVIOUR OF G. RETUSUS  AND G. SULCATUS 3.6.1 EFFECTS OF SEMIOCHEMICAL BAIT COMBINATIONS Both G. retusus and G. sulcatus of both sexes responded s i g n i f i c a n t l y to ethanol and t h e i r aggregation pheromones, ( + ) - s u l c a t o l and ( t ) - s u l c a t o l r e s p e c t i v e l y (Table 5-8). S i g n i f i c a n t s y n e r g i s t i c e f f e c t s of ethanol with ( + ) - s u l c a t o l f o r G. retusus of both sexes e x i s t e d (Table 5,6). But no s i g n i f i c a n t s y n e r g i s t i c e f f e c t s of ethanol with (±)-sulcatol were v e r i f i e d f o r G. sulcatus of e i t h e r sex s i n c e there was no a s i g n i f i c a n t i n t e r a c t i o n between ethanol and (±)-sulcatol (Table 8 ) . Ne i t h e r G. retusus nor G. sulcatus of e i t h e r sex responded s i g n i f i c a n t l y to a-pinene b a i t e d t r a p s . No s y n e r g i s t i c e f f e c t s of a-pinene with s u l c a t o l or ethanol Table 5. ANOVA of G. retusus 8X8 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. 1986. Source D.F. Male 1 MS F Female 1 MS F Sex r a t i o (f:m) MS F EMS; Time 7 P o s i t i o n 7 S u l c a t o l 1 a-Pinene 1 S+P Ethanol S+E P+E S+P+E E r r o r 42 0.04681 7.53** 0.00486 0.78 0.64173 103.21** 0.00001 0.002 0.00125 0.20 0.66836 107.49** 0.07810 12.56** 0.00852 1.37 0.00304 0.49 0.00622 0.02548 4.21** 25.333 1.44 0.01025 1.69 14.178 0.81 1.51098 249.36** 418.144 23.78** 0.00536 0.88 25.048 1.42 0.00483 0.79 27.886 1.59 0.39529 65.24** 33.245 1.89 0.07496 12.37** 67.698 3.85 0.02337 2.38 76.045 4.32* 0.00196 0.32 59.205 3.37 0.00606 17.584 e t i m e o 2+64a 2 ... 6 p O S l t a 2+256a 2 6 S a 2+256o 2 e P " e + 1 2 8 ° S P a 2+256o 2 e E a e + l 2 8 ° S E a ^ 1 2 8 a 2 E " e + 6 4 " s P E 1. Data transformed to X'=log(log(X+1) +1 ) p r i o r to ANOVA, 2. Expected mean square. *. S i g n i f i c a n c e l e v e l pS0.05. **. S i g n i f i c a n c e l e v e l pSO.01. 78 Table 6. A n a l y s i s of f a c t o r i a l e f f e c t s i n G. retusus 8X8 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. 1986. F a c t o r 2 Mean c a t c h 1 Male Female Ethanol-0 Ethanol-1 1 1 .2 77.6 a 3 b 28.2 a 158.8 b Sucatol-0 Sucatol-1 12.2 76.6 a b 10.4 a 186.6 b E-0 + S-0 E-1 + S-0 E-0 + S-1 E-1 + S-1 0.4 23.9 22.0 131.2 a b b c 0.4 a 20.3 b 75.9 c 297.3 d 1. Data transformed to X'=log(log(X+1)+1) p r i o r to ANOVA. 2. 0 i n d i c a t e s absence of the treatment f a c t o r . 1 i n d i c a t e s presence of the treatment f a c t o r . 3. 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 not s i g n i f i c a n t l y d i f f e r e n t , Newman-Keuls t e s t , p^O.05. Table 7. ANOVA of G. sulcatus 8X8 L a t i n Square experiment. UBC Endowment Lands, Vancouver, B.C. 1985. Source D.F. Male i Female i Sex r a t i o (f :m) EMS 2 MS F MS F MS F Time 7 0.452 3.76** 0.480 4.19** 0.601 0.58 o 2+64o*. e time P o s i t i o n 7 0.137 1.14 0.223 1 .94 0.511 0.49 o'+64o* • e p o s i S u l c a t o l 1 8.166 67.84** 15.077 131.60** 40.877 39.22** a 2+256o 2 a-Pinene 1 0.263 2.18 0.466 4.06 0.004 0.00 aj+256a| S+P 1 0.078 0.65 0.001 0.01 0.51 1 0.49 a 2+128o| p Ethanol 1 5.643 46.88** 4.616 40.29** 2.569 2.46 c 2+256a 2 S+E 1 0.040 0.33 0.009 0.08 2.328 2.23 ffe+128oSE P+E 1 0.000 0.00 0.008 0.07 0.015 0.01 a e + 1 2 8 a P E S+P+E 1 0.046 0.38 0.099 0.86 0.804 0.77 ° e + 6 4 ° S P E E r r o r 42 0.120 0.115 1.042 a 2 e 1. Data transformed to X'=log(X+1) p r i o r to ANOVA. 2. Expected mean square. *. S i g n i f i c a n c e l e v e l p£0.05. **. S i g n i f i c a n c e l e v e l p^O.Ol. 80 Table 8. A n a l y s i s of f a c t o r i a l e f f e c t s i n G. sulcatus 8X8 L a t i n Square experiment. UBC Endowment Lands, Vancouver, B.C. 1985. F a c t o r 2 Mean c a t c h 1 Sex r a t i o (f :m) Male Female a-Pinene-0 a-Pinene-1 8.6 13.0 a 3 a 15.0 19.8 a a 1.18 1.20 a a Ethanol-0 Ethanol-1 4.6 17.1 a b 10.3 25.5 a b 0.99 1 .39 a a S u l c a t o l - 0 S u l c a t o l - 1 3.0 18.7 a b 2.5 32.3 a b 0.39 1 .99 a b 1. Data transformed to X' = log(X+1) p r i o r t o ANOVA. 2. 0 i n d i c a t e s absence of the treatment f a c t o r . 1 i n d i c a t e s presence of the treatment f a c t o r . 3. 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 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. 81 were found f o r e i t h e r G. retusus or G. sulcatus (Table 5-8). The sex r a t i o s of both G. sulcatus and G. retusus f o r any treatments with e i t h e r (±)-sulcatol or ( + ) - s u l c a t o l present were s i g n i f i c a n t l y higher than those f o r treatments i n c l u d i n g only host odors (a^0.05). A l l treatments c o n t a i n i n g only host odors had sex r a t i o s smaller than one, and a l l treatments c o n t a i n i n g aggregation pheromones had sex r a t i o s l a r g e r than one (range 1.79 to 10.6). T h i s experiment r e p r e s e n t s the f i r s t time that G. retusus of both sexes have been found to respond s i g n i f i c a n t l y to ethanol alone, although ethanol had been demonstrated to be a primary host kairomone f o r ambrosia b e e t l e s f o r q u i t e a long time. The r e s u l t s f o r a-pinene e f f e c t s agree with Borden et al. (1980b), and i n d i c a t e that a-pinene does not p l a y a s i g n i f i c a n t r o l e i n e i t h e r G. retusus or G. sulcatus o r i e n t a t i o n . Ethanol i s a major product of anaerobic fermentation i n dead or dying wood t i s s u e (Graham 1968; Moeck 1970). However, a-pinene i s a major n a t u r a l l y - o c c u r r i n g terpene component i n both l i v e and dead t r e e t i s s u e (Fengel and Wegner 1984; Kurth 1952). Apparently, ethanol i s more c h a r a c t e r i s t i c of the dead or dying t r e e s which ambrosia b e e t l e s a t t a c k than a-pinene, and i s t h e r e f o r e a b e t t e r host i n d i c a t o r . I f ambrosia b e e t l e s used a-pinene as a major host kairomone,"they would be a t t r a c t e d to l i v e t r e e s which c e r t a i n l y were not s u i t a b l e hosts f o r them. Based on the above d i s c u s s i o n , and the r e s u l t s of f i e l d experiments, i t 82 can be concluded that a-pinene i s n e i t h e r a major host a t t r a c t a n t nor a s y n e r g i s t of aggregation pheromones f o r the two Gnat hotri chus s p e c i e s . I t would thus seem unnecessary to in c l u d e an a-pinene b a i t i n mass t r a p p i n g systems f o r Gnat hotrichus s p e c i e s . The s i g n i f i c a n t d i f f e r e n c e s i n sex r a t i o between host odor treatments and treatments c o n t a i n i n g aggregation pheromones imply that females of both s p e c i e s are more responsive to aggregation pheromones than are males, and males of both s p e c i e s are more responsive to ethanol than are females. T h i s appears l o g i c a l s i n c e males are the pioneer sex which i n i t i a t e s a t t a c k s and females are the responding sex. 3.6.2 EFFECTS OF (±)-SULCATOL RELEASE RATES (±)-sulcatol at a 1.5mg/day r e l e a s e r a t e i n combination with ethanol (I00mg/day) and a-pinene (20-30mg/day) caught the l a r g e s t numbers of both male and female G. sulcatus b e e t l e s . Catches of male b e e t l e s decreased s t e a d i l y and more d r a m a t i c a l l y than female catches as the (±)-sulcatol r e l e a s e r a t e i n c r e a s e d beyond 1.5mg/day ( F i g 27). But catches of males and females f o r a l l treatments with (±)-sulcatol were not s i g n i f i c a n t l y d i f f e r e n t . However, the sex r a t i o showed s i g n i f i c a n t i n c r e a s e s with (±)sulcatol r e l e a s e r a t e s (Table 9). The l a c k of s i g n i f i c a n t d i f f e r e n c e i n sex r a t i o between the combination of ethanol with a-pinene and the t e r n a r y 83 450 (+-)-sulcatol release rate (mg/day) F i g u r e 27. R e l a t i o n s h i p between (±)-sulcatol r e l e a s e r a t e and G. sulcatus t r a p c a t c h . UBC Research F o r e s t , Maple Ridge, B.C. 1986. Table 9. Mean catches of G. sulcatus b e e t l e s i n r e l a t i o n to (±)-sulcatol r e l e a s e r a t e s . UBC Research F o r e s t , Maple Ridge, B.C. 1985. Mean c a t c h 1 Treatment 2 (±)-sulcatol Sex r a t i o r e l e a s e r a t e (mg/day) Male Female P+E 0.0 3.0 a 3 1.2 a 0.71 a P+E+S1 0.5 162.8 b 267.0 b 1.63 ab P+E+S2 1.5 211.8 b 411.6 b 2.06 b P+E+S3 5.0 154.4 b 356.4 b 2.41 c P+E+S4 10.0 112.2 b 376.6 b 3.74 c 1. Data transformed t o X'=log(X+1) p r i o r to ANOVA. 2. P+E«=a-pinene+ethanol; r e l e a s e r a t e s : a-pinene 20-30mg/day, ethanol I00mg/day. 3. Numbers w i t h i n a column followed by the same l e t t e r 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 , p£0.05. 85 mixture with (±)-sulcatol at a r e l e a s e r a t e of 0.5mg/day was appa r e n t l y due to low catches i n the ethanol and a-pinene b a i t e d t r a p which r e s u l t e d i n the absence of sex r a t i o s i n three of the f i v e L a t i n Square r e p l i c a t e s , and a l a r g e v a r i a n c e . Although there were no s i g n i f i c a n t d i f f e r e n c e s i n t r a p catches of both males and females, the s i g n i f i c a n t d i f f e r e n c e s i n sex r a t i o among d i f f e r e n t (±)-sulcatol r e l e a s e r a t e s demonstrated e f f e c t s of the aggregation pheromone on behaviour of both males and females. High r e l e a s e r a t e s of (±)-sulcatol seems to i n h i b i t responses by male b e e t l e s . With respect to G. sulcatus p o p u l a t i o n management and survey using aggregation pheromone based systems, these r e s u l t s suggest that the 1.5mg/day r e l e a s e r a t e s of (±)-sulcatol may be used s i n c e i t would be more economical and a p p a r e n t l y an optimal r e l e a s e r a t e f o r both sexes of G. sulcatus. 3.6.3 ALLELOCHEMIC ACTIVITY OF AGGREGATION PHEROMONES  BETWEEN C7. RETUSUS AND G. SULCATUS R e l a t i v e l y l a r g e numbers of G. retusus b e e t l e s of both sexes were caught i n the two seasonal f l i g h t m o n i t o r i n g t r a p s b a i t e d with ethanol and (±)-sulcatol. In these t r a p s , G. retusus b e e t l e s made up 10.7% of the t o t a l c a t c h , but the p r o p o r t i o n of G. retusus v a r i e d over time. The f l u c t u a t i o n of numbers of G. retusus b e e t l e s i n the ethanol and (±)-sulcatol b a i t e d t r a p s was s i m i l a r to the G. retusus 86 catches i n the ethanol and ( + ) - s u l c a t o l b a i t e d t r a p s ( F i g 28). During the peak f l i g h t of both s p e c i e s , G. retusus b e e t l e s i n the ( i ) - s u l c a t o l made up 14.3% of the t o t a l c a t c h , and then decreased as the f l i g h t peaks passed. As the tr a p s were b a i t e d with both ethanol and (±)-sulcatol, and ethanol has been demonstrated to be a primary host a t t r a c t a n t of G. retusus, i t i s not r e l i a b l e to c l a i m a c r o s s a t t r a c t i o n of G. retusus to (±)-sulcatol because the ( i ) - s u l c a t o l e f f e c t s can not be d i s t i n g u i s h e d from ethanol e f f e c t s . But, at l e a s t , i t can be concluded that G. retusus can t o l e r a t e ( - ) - s u l c a t o l to a c e r t a i n extent. As hosts c o l o n i z e d by G. sulcatus w i l l have the primary host kairomone ethanol emitted by hosts and (±)-sulcatol excreted by the b e e t l e s , t h i s m a t e r i a l c o u l d be at t a c k e d by G. retusus b e e t l e s based on r e s u l t s r e p o r t e d here. But i t has been r e p o r t e d that C7. retusus was never found to a t t a c k logs i n f e s t e d by G. sulcatus (Borden et al. 1979) although s l i g h t c r o s s a t t r a c t i o n of (±)-sulcatol to G. retusus was l a t e r r e p o r t e d (Borden et al. 1981a). A small number of G. sulcatus was caught i n the ethanol and ( + ) - s u l c a t o l b a i t e d t r a p s . But due to the same reason s t a t e d above, the data were not adequate to reach the c o n c l u s i o n r e p o r t e d by Borden et al. (1981a) that ( + ) - s u l c a t o l has s l i g h t c r o s s a t t r a c t i o n to G. sulcatus. 87 210 £ 180 CO 150 Legend C. retusus / 22 MAY 1986 - 6 i ; i 29 5 JUNE —I— 12 T-19 l I 26 3 JULY 15 12 CO -H 3 o -o 10 F i g u r e 28. Comparison between G. retusus c a t c h e s i n ( t ) - s u l c a t o l and etha n o l b a i t e d t r a p s (top) and G. retusus c a t c h e s i n ( + ) - s u l c a t o l and etha n o l b a i t e d t r a p s (bottom). UBC Research F o r e s t , Maple Ridge, B.C. 1986. 4. SUMMARY T h i s r e s e a r c h was conducted i n 1985 and 1986 at the UBC Research F o r e s t and at UBC. The scope of the r e s e a r c h covered the b i o l o g y of G. retusus and b e h a v i o u r a l responses of G. retusus and G. sulcatus to semiochemicals. The main r e s u l t s are summarized as f o l l o w s : 1. G. retusus brood development from egg to a d u l t i n D-f logs i n the s p r i n g and summer takes 40 days or more. T h i s s p e c i e s i s p r i m a r i l y u n i v o l t i n e , but a small p o r t i o n of the p o p u l a t i o n may take more than one year to complete the l i f e c y c l e . I t overwinters mainly as an a d u l t , but other l i f e stages may a l s o be found. 2. Boring a c t i v i t i e s s h i f t e d g r a d u a l l y from shallow sapwood in the s p r i n g to deep sapwood i n l a t e summer. Ne i t h e r f r a s s p r o d u c t i o n nor g a l l e r y e x t e n s i o n had a c o n s i s t e n t r e l a t i o n s h i p with maximum temperature, and both showed a s i m i l a r p a t t e r n . 3. G a l l e r y abandonment occurred mainly i n June and J u l y and was commenced by females. T h i s i m p l i e s a high s e n s i t i v i t y of females to host q u a l i t y . The abandonment seems to be induced d i r e c t l y and/or i n d i r e c t l y by high temperatures. 4. Fr a s s c o l o u r changed from white i n June to completely black i n August. T h i s r e f l e c t e d s t a i n development i n g a l l e r i e s . S t a i n g e n e r a l l y i s r e s t r i c t e d i n shallow branches and g a l l e r y p o r t i o n s near entrances. 5. G. retusus brood p r o d u c t i o n i n D-f logs had a 88 89 s i g n i f i c a n t l i n e a r r e l a t i o n s h i p with g a l l e r y l e n g t h . T h i s i m p l i e s a v i t a l f u n c t i o n of the l a r g e p r o p o r t i o n of non-brood p r o d u c t i v e p a r t s of g a l l e r i e s . 6. S t r u c t u r e of G. retusus g a l l e r i e s i s s i m i l a r to that of G. sulcatus g a l l e r i e s . Brood niches were r e s t r i c t e d to g a l l e r y p o r t i o n s near entra n c e s . A mature g a l l e r y system u s u a l l y had at l e a s t one shallow and one deep branch or s e v e r a l branches d i s t r i b u t e d at d i f f e r e n t depths. Pupal niches had a c o n c e n t r a t i o n i n I0~20mm depth of sapwood in D-f stumps and i n 20-30mm depth i n WH stumps. Many G. retusus g a l l e r i e s i n D-f stumps showed unique s t r u c t u r e : pupal niches were elongated which may f u n c t i o n as maturation feeding t u n n e l s , and i n t e r - g a l l e r y c r o s s i n g s were q u i t e common. S l i g h t e l o n g a t i o n of pupal niches was a l s o found i n WH stumps. 7. D-f stumps were s i g n i f i c a n t l y more h e a v i l y a t t a c k e d by G. retusus than WH stumps. There were no s i g n i f i c a n t d i f f e r e n c e s i n g a l l e r y success rate and brood p r o d u c t i o n between the two host s p e c i e s . S i g n i f i c a n t d i f f e r e n c e s were found i n at t a c k d e n s i t y and brood p r o d u c t i o n among D-f and WH stumps. Within D-f stumps, i n c r e a s e s i n at t a c k d e n s i t y and brood p r o d u c t i o n were noted from tops to the root c o l l a r zone. Within WH stumps, only a t t a c k d e n s i t i e s showed a s i m i l a r g r a d i e n t . 8. G. retusus was the dominant ambrosia b e e t l e s p e c i e s i n the F-3 area of the UBC Research F o r e s t c o l o n i z i n g D-f and WH stumps. Brood emergence from D-f and WH stumps 90 s t a r t e d i n l a t e A p r i l when maximum d a i l y temperatures reached about 13.5°C, reached a peak i n l a t e May when • weekly mean maximum temperature reached 22.2°C, and •ceased i n e a r l y June. But a few brood might emerge as l a t e as the end of J u l y . The number of brood emerged and the sex r a t i o of brood i n g a l l e r i e s ready to emerge were p o s i t i v e l y r e l a t e d to maximum temperatures. 9. G. retusus showed a bimodal d i u r n a l f l i g h t rhythm: a very small morning f l i g h t and a l a r g e r dusk f l i g h t . F l i g h t seems to be t r i g g e r e d mainly by l i g h t i n t e n s i t y and o c c u r r e d w i t h i n a l i g h t i n t e n s i t y range of 12 Watts/m 2 to 120 Watts/m 2. Temperature and r e l a t i v e humidity a l s o i n f l u e n c e d the d i u r n a l f l i g h t . Temperatures above 14°C were e s s e n t i a l f o r b e e t l e s to f l y . Temperatures from 17 to 25°C were a s u i t a b l e range f o r the dusk f l i g h t . High temperature and low r e l a t i v e humidity d u r i n g the day a l s o appeared to enhance the dusk f l i g h t . 10. Seasonal f l i g h t s of both G. retusus and G. sulcatus s t a r t e d i n l a t e A p r i l when maximum d a i l y temperatures only reached 13.5°C, reached peaks i n l a t e May which c o i n c i d e d with the brood emergence peak, and ceased i n October when weekly mean maximum temperatures dropped below 15°C. G. retusus showed only one f l i g h t peak, and G. sulcatus showed a small second f l i g h t peak i n l a t e J u l y . The f l i g h t s and sex r a t i o s of both s p e c i e s were p o s i t i v e l y r e l a t e d with maximum temperatures. 91 11. G. retusus and G. sulcatus of both sexes responded s i g n i f i c a n t l y to e t h a n o l . S i g n i f i c a n t s y n e r g i s t i c e f f e c t s of ethanol with ( + ) - s u l c a t o l i n c a t c h i n g G. retusus of both sexes were v e r i f i e d . No s y n e r g i s t i c e f f e c t s of ethanol with (±)-sulcatol were found. Alpha-pinene d i d not have s i g n i f i c a n t e f f e c t s as e i t h e r a primary host a t t r a c t a n t or a s y n e r g i s t of aggregation pheromones. 12. Sex r a t i o s of both G. retusus and G. sulcatus s h i f t e d from l e s s than one f o r treatment with only host odors to above one f o r treatments i n c l u d i n g a g g r e g a t i o n pheromones. For G. sulcatus, the sex r a t i o i n c r e a s e d with i n c r e a s e s of (±)-sulcatol r e l e a s e r a t e . 13. 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Measurement of a damage index i n logs i n f e s t e d by ambrosia b e e t l e . B.C. Lumberman 34(8):43,89. Graham, K. 1968. Anaerobic i n d u c t i o n of primary chemical a t t r a c t a n c y f o r ambrosia b e e t l e s . Can. J . Zoo l . 46:905-908. Johnson, B.D. and K.N. S l e s s o r . 1979. F a c i l e s y n t h e s i s of the enantiomers of s u l c a t o l . Can. J . Chem. 57:233-235. 94 Johnson, N.E. 1958. F i e l d i d e n t i f i c a t i o n of ambrosia b e e t l e a t t a c k i n g c o n i f e r o u s timber i n the D o u g l a s - f i r r e g i o n . Can. Entomol. 90:236-240. Johnson, N.E. and J.G. Zingg. 1969. T r a n s p i r a t i o n a l d r y i n g of D o u g l a s - f i r : e f f e c t s on moisture content and i n s e c t a t t a c k . J . F o r e s t r y 67(11):816-819. Kinghorn, J.M. 1956. Sapwood moisture i n r e l a t i o n to Trypodendron a t t a c k s . Can. Dep. A g r i . , F or. B i o l . Div. Bi-mon. Prog. Rep. 12(5):3-4. Kurth, E.F. 1952. The v o l a t i l e o i l s , i n : L.E. Wise and E.C. Jahn (eds.) Wood Chemistry. Reinhold, New York. Volume 1. pp. 548-589. Lindgren, B.S. 1983. A m u l t i p l e funnel t r a p f o r S c o l y t i d b e e t l e s ( C o l e o p t e r a ) . Can. Entomol. 115:299-302. Lindgren, B.S. and J.H. Borden. 1983. Survey and mass t r a p p i n g of ambrosia b e e t l e s ( C o l e o p t e r a : S c o l y t i d a e ) i n timber p r o c e s s i n g areas on Vancouver I s l a n d . Can. J . For. Res. 13:481-493. Lindgren, B.S. and J.A. McLean, unpubl. data. F l i g h t responses by Gnat hot ri chus sulcatus to semiochemicals i n a wind t u n n e l . A s c i e n t i f i c note f o r Can. Entomol. 10 pp. Mathers, W.G. 1935. Time of f e l l i n g i n r e l a t i o n to i n j u r y from ambrosia b e e t l e s , or pinworms. B.C. Lumberman 19(8):14. McBride, C.E. 1950. The e f f e c t of ambrosia b e e t l e damage upon lumber v a l u e . B.C. Lumberman 34(9):46-48. McBride, C.E. and J.M. Kinghorn. 1960. Lumber degrade caused by ambrosia b e e t l e s . B.C. Lumberman 44(7):40-52. McLean, J.A. and J.H. Borden. 1975a. Gnat hot ri chus sulcatus a t t a c k and breeding i n f r e s h l y sawn lumber. J . Econ. Entomol. 68:605-606. McLean, J.A. and J.H. Borden. 1975b. Survey f o r Gnat hotri chus sulcatus ( C o l e o p t e r a : S c o l y t i d a e ) i n a commercial sawmill with the pheromone, s u l c a t o l . Can. J . For. Res. 5:586-591. McLean, J.A. 1976. Primary and secondary a t t r a c t i o n i n Gnat hotrichus spp. and t h e i r a p p l i c a t i o n i n pest management. Ph.D. T h e s i s , Simon F r a s e r U n i v e r s i t y . 108 pp. McLean, J.A. and J.H. Borden. 1977a. Attack by Gnat hotrichus 95 sulcatus ( C o l e o p t e r a r S c o l y t i d a e ) on stumps and f e l l e d t r e e s b a i t e d with s u l c a t o l and e t h a n o l . Can. Entomol. 109:675-686. McLean, J.A. and J.H. Borden. 1977b. Suppression of Gnat hot richus sulcatus with s u l c a t o l - b a i t e d t r a p s i n a commercial sawmill and notes on the occurrence of G. retusus and Trypodendron lineatum. Can. J . For. Res. 7:348-356. McLean, J.A. and J.H. Borden. 1979. An o p e r a t i o n a l pheromone-based suppression program f o r an ambrosia b e e t l e Gnat hotri chus spp. i n a commercial sawmill. J . Econ. Entomol. 72:165. McLean, J.A. 1980. Survey using pheromone t r a p s , of Gnat hotri chus sulcatus ( C o l e o p t e r a : S c o l y t i d a e ) i n two Vancouver I s l a n d d r y l a n d s o r t i n g areas. J . Entomol. Soc. B.C. 77:20-24. McLean, J.A. 1985. Ambrosia b e e t l e s : A m u l t i m i l l i o n d o l l a r degrade problem of sawlogs i n C o a s t a l B r i t i s h Columbia. Fo r . C h r o n i c l e Aug. 1985. Moeck, H.A. 1970. Ethanol as the primary a t t r a c t a n t f o r the ambrosia b e e t l e Trypodendron lineatum ( C o l e o p t e r a : S c o l y t i d a e ) . Can. Entomol. 102:985-995. Moeck, H.A. 1971. F i e l d t e s t of ethanol as a S c o l y t i d a t t r a c t a n t . Can. Dep. F i s h , and For. Bi-Mon. Res. Notes 27(2):11-12. Moeck, H.A. and L. S a f r a n y i k . 1984. Assessment of predator and p a r a s i t o i d c o n t r o l of bark b e e t l e s . E n v i r o n . Can., For. Serv., Inform. Rep. BC-X-248, P a c i f i c For. Res. Centre, 24 pp. Mori, K. 1975. Synt h e s i s of o p t i c a l l y a c t i v e forms of s u l c a t o l . Tetrahedron 31:3011-3012. N i j h o l t , W.W. 1973. Ambrosia b e e t l e a t t a c k s delayed by t u r p e n t i n e o i l . Can. Dep. F i s h , and For., Bi-mon. Res. Notes 29(6):36. N i j h o l t , W.W. 1978. Ambrosia b e e t l e , a menace to the f o r e s t i n d u s t r y . Can. For. Serv. Rept. BC-P-25 V i c t o r i a , B.C.. 8 pp. N o r r i s , D.M. and J.M. Baker. 1969. N u t r i t i o n of Xyl eborus ferrugineus ( C o l e o p t e r a : S c o l y t i d a e ) . I. Ethanol i n d i e t s as a t u n n e l l i n g (feeding) s t i m u l a n t . Ann. Entomol. Soc. Amer. 62:592-594. Prebble, M.L. and K. Graham. 1957. Studie s of at t a c k by 96 ambrosia b e e t l e s i n softwood logs on Vancouver I s l a n d , B r i t i s h Columbia. For. S c i . 3:90-112. Rudinsky, J.A. and G.E. Daterman. 1964. F i e l d s t u d i e s on f l i g h t p a t t e r n s and o l f a c t o r y responses of ambrosia b e e t l e s i n D o u g l a s - f i r f o r e s t s of Western Oregon. Can. Entomol. 96:1339-1352. Rudinsky, J.A. 1966. S c o l y t i d b e e t l e s a s s o c i a t e d with D o u g l a s - f i r : response to terpene. Science 152:218-219. Rudinsky, J.A. and I.A. Schneider. 1969. E f f e c t s of l i g h t i n t e n s i t y on the f l i g h t p a t t e r n of two Gnat hotri chus ( C o l e o p t e r a : S c o l y t i d a e ) s p e c i e s . Can. Entomol. 101:1248-1255. Rudinsky, J.A., P.T. Oester, and L.C. Ryker. 1978a. G a l l e r y i n i t i a t i o n and male s t r i d u l a t i o n of the polygamous spruce bark b e e t l e Polygraphus rufipennis ( C o l e o p t e r a : S c o l y t i d a e ) . Ann. Entomol. Soc. Amer. 71:317-321. Rudinsky, J.A., V. V a l l o , and L.C. Ryker. 1978b. Sound pr o d u c t i o n i n S c o l y t i d a e : A t t r a c t i o n and s t r i d u l a t i o n of Scolytus mali ( C o l e o p t e r a : S c o l y t i d a e ) . Sonderdruck aus Bd. 86(1978), H.4,S.381-391. Schneider, I.A. and J.A. Rudinsky. 1969. Anatomical and h i s t o r i c a l changes i n i n t e r n a l organs of a d u l t Tr ypode ndr on lineatum, Gnat hot r i chus retusus, and G. sulcatus ( C o l e o p t e r a : S c o l y t i d a e ) . Ann. Entomol. Soc. Amer. 62:995-1003. Shore, T.L. 1982. A pheromone-mediated mass-trapping program for three s p e c i e s of ambrosia b e e t l e i n a commercial sawmill. Ph.D. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia. 163 pp. Shore, T.L. and J.A. McLean. 1983. 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 Trypodendron lineatum and Gnat hotri chus sulcatus ( C o l e o p t e r a : S c o l y t i d a e ) . Can. Entomol. 115:1-5. Shore, T.L. and J.A. McLean. 1985. A survey f o r the ambrosia b e e t l e s Trypodendron lineatum and Gnat hot ri chus retusus ( C o l e o p t e r a : S c o l y t i d a e ) i n a sawmill u s i n g pheromone-baited t r a p s . Can. Entomol. 117:49-55. Werner, A.E. and K. Graham. 1957. V o l a t i l e wood c o n s t i t u e n t s i n r e l a t i o n to ambrosia b e e t l e s . Can. Dep. A g r i . For. B i o l . D iv., Bi-mon. Prog. Rep. 13(4):3. Wood, S.L. 1982. The bark and ambrosia b e e t l e s of North and C e n t r a l America: A taxonomic monograph. Great Basin 97 N a t u r a l i s t Memoirs, Number 6. Brigham Young U n i v e r s i t y . 1359 pp. Zanuncio, J.C. 1981. B i o l o g y of Gnat hotrichus sulcatus (LeConte 1968) ( C o l e o p t e r a : S c o l y t i d a e ) with s p e c i a l emphasis on host c o l o n i z a t i o n and brood p r o d u c t i o n . Ph.D. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, Canada. 118 pp. 98 Appendix 1. ANOVA of G. retusus a t t a c k d e n s i t y 1 on D-f stumps and t h e i r a s p e c t s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. Source D.F. Mean Square F value Stump Aspect SA E r r o r 6 3 18 1 10 0.2579 0. 1746 0.0949 0.0609 4.23** 2.86* 2 1 .56 1. Data transformed to X'=Log(X+1) p r i o r to ANOVA. 2. No s i g n i f i c a n t d i f f e r e n c e s were de t e c t e d among d i f f e r e n t a s p e c t s , Newman-Keul's t e s t , p^0.05. *. S i g n i f i c a n c e l e v e l p<0.05. **. S i g n i f i c a n c e l e v e l p<0.0l. 99 Appendix 2. ANOVA of G. retusus attack d e n s i t y 1 on WH stumps and t h e i r a s p e c t s . UBC Research F o r e s t , Maple Ridge, B.C. 1986. Source D.F. Mean Square F value Stump 3 0.9529 10.76** Aspect 3 0. 1 183 1 .34 SA 8 0.0702 0.79 E r r o r 41 0.0886 1. Data transformed to X'=Log(X+l) p r i o r to ANOVA. **. S i g n i f i c a n c e l e v e l p^O.01. Appendix 3. Layout and data of G. retusus 8X8 Latin Square experiment. UBC Resaerch Forest, Maple Ridge, B.C. 1986. Trap Location 1 2 3 • 4 5 6 7 8 Date treatment 1 treatment treatment treatment treatment treatment treatment treatment M2 F 3 M F M F M F M F M F M F M F May 8 C P+E S+E P E S S+P S+P+E 1 0 93 49 190 546 4 2 73 116 12 36 28 198 326 818 May 22 S+P S+P+E E S S+E P C P+E 79 252 461 753 85 64 135 159 636 593 0 0 0 0 40 16 May 27 E S S+P S+P+E C P+E S+E P 40 16 6 0 5 34 30 55 0 0 17 10 63 147 0 . 0 May 29 S+E P C P+E S+P S+P+E E s 110 296 1 1 0 0 7 6 22 60 206 419 6 4 9 34 May 30 S+P+E S+P S E P S+E P+E C 16 81 8 60 2 6 4 4 0 2 188 437 5 5 0 1 May 31 P+E C P S+E S E S+P+E S+P 6 6 0 1 0 0 3 16' 11 15 18 34 48 185 4 135 June 1 P S+E P+E C S+P+E S+P S E 0 0 9 146 3 0 0 0 14 65 17 149 1 14 17 7 June 2 S E S+P+E S+P P+E C P S+E 6 13 3 2 12 29 1 15 0 2 . 0 0 0 0 60 170 1. C=control, S=(+)-sulcatol, P=a-pinene, E=ethanol. 2. M=male catch. 3. F=female catch. Appendix 4. Layout and data of G. sulcatus 8X8 L a t i n Square experiment. UBC Endowment Lands, Vancouver, B.C. 1985. Trap Location 1 2 3 4 5 6 7 8 Date treatment 1 treatment treatment treatment treatment treatment treatment treatment M 2 F 3 M F M F M F M F M F M F M F May 16 C 0 0 3 P+E 6 S+E 20 14 P 0 0 E 1 1 S 1 0 S+P 1 4 S+P+E 2 4 May 19 S+P 45 89 S+P+E 20 49 E 26 21 S 4 10 S+E 23 44 p 0 2 C 0 0 P+E 11 14 May 25 E 4 8 14 S 30 S+P 23 38 S+P+E 66 69 C 0 0 P+E 19 9 S+E 21 38 P 0 0 May 31 S+E 43 79 0 P 0 C 0 0 P+E 1 1 8 S+P 8 15 S+P+E 36 46 E 4 2 S 3 5 June 2 S+P+E 79 95 0 S+P 0 S 0 2 E 0 0 P 0 0 S+E 4 21 P+E 3 1 C 0 0 July 8 P+E 2 3 0 C 0 p 0 0 S+E 45 52 S 7 13 E 5 1 S+P+E 21 42 S+P 15 26 Aug 14 P 0 0 32 S+E 64 P+E 2 3 C 0 0 S+P+E 19 36 S+P 7 12 S 1 2 E 5 1 Sept 13 S 13 69 0 E 0 S+P+E 20 49 S+P 4 13 P+E 0 1 C 0 0 P 0 0 S+E 1 3 1. C=control, S=(±)-sulcatol, P=a-pinene, E=ethanol. 2. M=male catch. 3. F=female catch. 1 02 Appendix 5. Layout and data of ( i ) - s u l c a t o l r e l e a s e rate 5X5 L a t i n Square experiment. UBC Research F o r e s t , Maple Ridge, B.C. August 1985. Trap l o c a t i o n 1 2 3 4 5 Date t r e a t 1 t r e a t t r e a t t r e a t t r e a t M 2 F 3 M F M F M F M F 1 PE PES 2 PES 1 PES3 PES 4 7 1 360 649 147 260 90 230 261 795 2 PES4 PES3 PE PES2 PES 1 171 580 75 228 1 1 85 200 98 157 3 PES 3 PES 1 PES2 PES4 PE 230 493 164 251 148 253 46 1 1 3 1 2 4 PES2 PE PES4 PES 1 PES 3 282 416 5 2 49 202 102 162 271 619 5 PES 1 PES 4 PES 3 PE PES 2 303 505 34 193 106 212 1 0 184 540 1. treat=treatment: P=a-pinene; E=ethanol; S=(±)-sulcatol; l-4=release r a t e l e v e l s ; 2. M=male c a t c h . 3. F=female c a t c h . 

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