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Biology of Gnathotrichus sulcatus (LeConte 1868) (Col.:Scolytidae) with special emphasis on host colonization… Zanuncio, José Cola 1981

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Biology of Gnathotrichus sulcatus (LeConte 1868)  (Col.:Scolytidae)  with Special Emphasis on Host Colonization and Brood Production  by  Jose Cola Zanuncio  For.  Eng., Federal University of Vijosa, B r a z i l M.Sc, University of Sao Paulo, B r a z i l  A thesis submitted i n p a r t i a l f u l f i l l m e n t of the requirements for the degree of Doctor of Philosophy i n the Department of Forestry  We accept this thesis as conforming to the required standard  The University of B r i t i s h August,  1981  © JosS Cola Zanuncio  Columbia  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  requirements f o r an advanced degree at the  the  University  o f B r i t i s h Columbia, I agree t h a t  the L i b r a r y s h a l l make  it  and  f r e e l y a v a i l a b l e for reference  study.  I  further  agree t h a t p e r m i s s i o n 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  department o r by h i s o r her understood t h a t  granted by  representatives.  s h a l l not  be  Department o f  Fo&GST&'l?  The U n i v e r s i t y of B r i t i s h 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5  DE-6  (2/71)  It is  allowed without my  permission.  Q c T  my  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  Date  the head of  O 3 €  ;  / ^  Columbia  1 )  written  i  ABSTRACT  The bionomics of Gnathotrichus  sulcatus (LeConte) (Col.:  Scolytidae) were studied on eight western hemlock (WH), Tsuga heterophylla (Raf.) Sarg., and eight Douglas-fir (Df), Pseudotsuga menziesii (Mirb.) Franco, trees at the UBC Research Forest, Maple Ridge, B.C. during 1978 and 1979.  Natural colonization by associated  s c o l y t i d beetles was also studied on the same trees, which were f e l l e d on May 8, 1978.  More attacks occurred on downtrees (with branches.)  than on logs (no branches),  and on WH stumps, trunks (logs and down-  trees) than on Df stumps and trunks.  WH was more suitable for c o l o n i -  zation and brood production i n the f i r s t year after f e l l i n g than Df but no differences could be demonstrated between these two hosts i n the second year. Whenever possible five fresh attacks were covered with petri dishes on every stump and trunk.  Higher quantities of frass, numbers  of brood, pupal niches, deeper penetration and longer g a l l e r i e s were recorded on WH than on Df.  Relationships between brood, frass produc-  tion and length of g a l l e r i e s were established.  I t was calculated that  one hectare of clearcut with 200 WH stumps could produce 714,860 + 417,020 beetles with 13.7 + 3.7 brood per gallery (both with 95% confidence l i m i t s ) , within two years after attack, while the estimated t o t a l brood production from the 16 trunk/stump combinations was 107,080 from 16,049 attacks. Pupal niches, length and depth of penetration of g a l l e r i e s were studied on attacks i n i t i a t e d two to seventeen months after f e l l i n g ,  ii  excluding the winter months.  For each of the three factors WH showed  higher results than Df. Traps set out i n Point Roberts, Washington, captured more beetles when baited with WH sapwood than with WH bark or heartwood. More beetles were captured on traps baited with Df phloem than those baited with Df bark, sapwood or heartwood.  These results indicate  which tissues might be extracted to determine the i d e n t i t y of primary attractants. It was concluded that WH i s preferred as a host tree over Df by G_. sulcatus during the f i r s t year, but both hosts had similar number of attacks i n the second year.  Such preference for WH poses a problem for  logging managers i n coastal B r i t i s h Columbia since WH i s 40% of the t o t a l volume processed.  If G.  sulcatus populations are allowed to  build up i n stumps, they could degrade logs i n f e l l e d and bucked timber i n adjacent areas.  WH should be removed as soon as possible after  f e l l i n g (hot logging) and the period i n dryland sorts should be minimized as logs remain vulnerable to attack 17 months following felling.  iii  DEDICATION  This thesis i s dedicated to my wife, Teresinha Vinha Zanuncio, who encouraged me to come to Canada and made a l l the efforts and s a c r i f i c e s to help me while here and also to my daughter Andressa Vinha Zanuncio.  ACKNOWLEDGEMENTS  I express my deepest gratitude to the following persons and organizations without whose contribution this thesis would not be possible.  Dr. J.A. McLean, my  supervisor, for the invaluable e f f o r t s  to introduce me to this topic, firm guidance and help; my members, Drs. J.H. Borden, R.H. G.F.  committee  E l l i o t t , B.J. van der Kamp and  Weetman for their h e l p f u l suggestions  helping and recommending the s t a t i s t i c a l  and advice; Dr. A. Kozak for  analysis used.  J . Bebyck,  J. Holman and M. J u l l for their help i n the f i e l d and laboratory work; and Mr. P. Saunders of the UBC trees used i n this study.  Research Forest for f e l l i n g and cutting  Also Mr. A. Magnuson for welcoming research  on his selectively-logged forest at Point Roberts. The Canadian International Development Agency (CIDA) and Federal University of Vicosa (UFV) Dr. V.J. Nordin and Mr. A.F.  for f i n a n c i a l support.  I thank  Shirran for their help through CIDA i n  Canada and also Dr. Arno Brune, Coordinator in Brazil.  the  of the CIDA/UFV agreement  V  TABLE OF CONTENTS Page ABSTRACT  i  DEDICATION  i i i  ACKNOWLEDGEMENTS  iv  TABLE OF CONTENTS  v  LIST OF TABLES  viii  LIST OF FIGURES  x  LIST OF APPENDICES  xiii  1.0  INTRODUCTION  1  2.0  MATERIAL AND METHODS  9  2.1  F i e l d Study Locations and Experimental Designs  9  2.1.1  UBC Research Forest  9  2.1.2  Point Roberts Host Tissue A t t r a c t i o n Studies ..  2.2  2.3  11  Host Colonization  12  2.2.1  V e r i f i c a t i o n of Attacks  12  2.2.2  Weekly Pinning  12  2.2.3  D i s t r i b u t i o n Around Logs and Pinning E f f i c i e n c y  12  Brood Production by Gnathotrichus  sulcatus on Stumps,  13  •  13  Logs and Downtrees 2.4  Gallery Dissection  16  2.5  Laboratory Rearing  16  2.6  Primary Attractants Tests  18  2.6.1  Test with Western Hemlock Stimuli  18  2.6.2  Test with Douglas-fir Stimuli  21  vi  Page  3.0  2.7  Data Analysis  22  2.8  Total Brood Emergence Pattern Over Time  22  RESULTS  24  3.1  Host Colonization by Gnathotrichus sulcatus  24  3.1.1  Attacks on Each Host Category  24  3.1.2  Comparison of Attack Densities  24  3.1.3  Seasonal Attack Rates  30  3.1.4  Attack i n Relation to Moisture Content i n  3.2  Trunks and Stumps  30  3.1.5  D i s t r i b u t i o n Around Trunks  34  3.1.6  Evaluation of Pinning E f f i c i e n c y  34  Host Colonization by Associated Scolytid Species 3.2.1  ....  Dendroctonus pseudotsugae, Hopk., the Douglasf i r Beetle  3.2.2  36  36  Scolytus unispinosus LeConte, the Douglas-fir Engraver  36  3.2.3  Scolytus tsugae (Swaine), the Hemlock Engraver  38  3.2.4  Pseudohylesinus tsugae Swaine  38  3.2.5  Trypodendron lineatum ( O l i v i e r ) , the Striped Ambrosia Beetle  40  3.3  Establishment Success of Gnathotrichus sulcatus  40  3.4  Frass Production  43  3.5  Brood Production  47  3.5.1  Stumps i n the F i e l d  47  3.5.2  Trunks i n the F i e l d  48  vii  Page  3.6  3.5.3  Logs i n Laboratory  52  3.5.4  Sex of Emerging Beetles  56  Gallery Dissections  56  3.6.1  Stumps  56  3.6.2  Trunks  61  3.6.3  Relationships between Brood, Frass and Length of G a l l e r i e s  3.6.4  Aspects of Gallery Construction by Gnathotrichus  3.7  3.8 4.0  62  sulcatus at Different Periods of  Time after F e l l i n g  62  Primary Attractants Tests  68  3.7.1  Western Hemlock Stimuli  68  3.7.2  Douglas-fir Stimuli  72  Total Brood Emergence Pattern  DISCUSSION 4.1  76  Host Selection and Colonization by Gnathotrichus sulcatus  4.2  76  Host Selection and Colonization by Associated Scolytid Beetles  81  4.3  Establishment  4.4  Aspects of Gallery Construction of Gnathotrichus  and Gallery Parameters  sulcatus i n Trunks for D i f f e r e n t Periods after F e l l i n g 4.5  4.6 5.0  72  83  87  Relationship between Brood Emergence Pattern and Attack Data  89  Implications of the Results i n B.C. Forest Industry  94  SUMMARY  96  LITERATURE CITED  98  APPENDICES  107  viii  LIST OF TABLES  Page Table I  A review of observations Gnathotrichus sulcatus.  Table II  Length and diameter at breast height (d.b.h.) for western hemlock and Douglas-fir logs and downtrees f e l l e d in the UBC Research Forest, May 8, 1978.  10  Total number of Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps, logs (L) and downtrees (DT). UBC Research Forest, Maple Ridge, B.C. 1978/79.  25  Summary of attack densities of Gnathotrichus sulcatus on western hemlock and Douglas-fir stumps, logs and downtrees. UBC Research Forest, Maple Ridge, B.C. 1978-79.  27  Bi-weekly mean attack/m^ f Gnathotrichus sulcatus on western hemlock and Douglas-fir logs and downtrees. UBC Research Forest, Maple Ridge, B.C. 1978/79.  28-29  Table III  Table IV  Table V  Table VI  Table VII  Table VIII  Table IX  on primary a t t r a c t i o n i n  Q  D i s t r i b u t i o n of Gnathotrichus sulcatus attacks by quadrants on 1 m sections of western hemlock and Douglas-fir logs. UBC Research Forest, Maple Ridge, B.C. May-November, 1978 and March-October, 1979. N = 8 for each species.  35  Number and success of Gnathotrichus sulcatus attacks monitored with p e t r i dishes on western hemlock stumps and trunks and Douglas-fir stumps and trunks i n 1978 and 197 9. UBC Research Forest, Maple Ridge, B.C.  42  Mean total frass production from 147 g a l l e r i e s of Gnathotrichus sulcatus monitored on western hemlock and Douglas-fir stumps and trunks i n the UBC Research Forest, Maple Ridge, B.C. 1978-79.  44  Brood production from 147 g a l l e r i e s of Gnathotrichus sulcatus monitored on western hemlock and Douglas-fir stumps and trunks i n the UBC Research Forest, Maple Ridge, B.C. 1978-79.  47  Total numbers of brood produced and sex r a t i o from Gnathotrichus sulcatus g a l l e r i e s established i n western hemlock and Douglas-fir under laboratory conditions, UBC 1979. Sex r a t i o of f i r s t and t o t a l Gnathotrichus sulcatus emerging from western hemlock and Douglas-fir trunks and stumps f e l l e d May 1978 the UBC Research Forest, Maple Ridge, B.C.  in  Mean egg niches (EN), pupal niches (PN), length of gallery (LG) and depth of penetration (DP) of Gnathotrichus sulcatus g a l l e r i e s on western hemlock and Douglas-fir stumps and trunks. UBC Research Forest, Maple Ridge, B.C. Relationships between brood, frass and length of g a l l e r i e s of Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps and trunks in the UBC Research Forest, Maple Ridge, B.C. Egg niches, pupal niches, length of g a l l e r i e s and depth of penetration of Gnathotrichus sulcatus on western hemlock and Douglas-fir trunks over 13 months, UBC Research Forest, Maple Ridge, B.C. 1978-79. Number of Gnathotrichus sulcatus g a l l e r i e s with and without pupal niches, and t o t a l number of pupal niches on western hemlock and Douglas-fir logs over 13 months. UBC Research Forest. 1978/79. Numbers of Gnathotrichus sulcatus caught on traps baited with stimuli prepared from western hemlock bark, sapwood and heartwood; and from Douglas-fir bark, phloem, sapwood and heartwood. Experiment set out i n a s e l e c t i v e l y logged forest i n Point Roberts, WA on June-July, 1978. Brood production p r o f i l e from the estimated 16,049 Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps and trunks from June, 1978 to June, 1980. UBC Research Forest, Maple Ridge, B.C.  X  LIST OF FIGURES Page Figures 1, 2  Pinned attacks of Gnathotrichus sulcatus and p e t r i dishes to capture brood i n successful g a l l e r i e s . 1, WH stump; 2, WH trunk.  14  Figure 3  P e t r i dishes on western hemlock showing dark colour of frass f i v e weeks after attack.  15  Figure 4  Log of Douglas-fir i n laboratory showing the five p e t r i dishes, the water container on the top and the water reservoir at the bottom of the log.  Figure 5  Modified survey trap used for testing host stimuli i n Point Roberts i n 1978.  Figures 6, 7  Bi-weekly totals of pinned attacks of Gnathotrichus sulcatus on western hemlock and Douglas-fir. UBC Research Forest. MayNovember/1978 and March-October/1979. 6, Stumps; 7, Logs and downtrees.  Figures 8, 9  Figures 10, 11  Figures 12, 13  Figures 14, 15  Climate data recorded at the gate of the UBC Research Forest from May 18, 1978 to December 31, 1979. Maple Ridge, B.C. 8, Weekly r a i n f a l l ; 9, Minimum and maximum weekly temperature. Mean moisture content of western hemlock and Douglas-fir f e l l e d May 8, 1978 i n the UBC Research Forest for the periods May 1978 November 1979. I n i t i a t i o n of sustained attacks by Gnathotrichus sulcatus indicated by solid arrows and f i r s t attack indicated by wavy arrows. Numbers refer to host p a i r s . V e r t i c a l bars represent standard errors of reported means, 10, Stumps; 11, Logs and downtrees.  17 20  31  32  33  Seasonal attack pattern of two bark beetles on Douglas-fir at the UBC Research Forest i n 1978. Maple Ridge, B.C. 12, Dendroctonus pseudotsugae; 13, Scolytus unispinosus  37  Seasonal attack pattern of two bark beetles on western hemlock at the UBC Research Forest i n 1978. Maple Ridge, B.C. 14, Scolytus tsugae; 15, Pseudohylesinus tsugae.  39  Figure 16  Total bi-weekly numbers of Trypodendron lineatum attacks pinned on western hemlock and Douglas-fir i n 1979 at the UBC Research Forest, Maple Ridge, B.C.  Figures 17, 18  Mean weekly frass production of g a l l e r i e s i n i t i a t e d at various times during 1978 and 1979 by Gnathotrichus sulcatus on western hemlock, at the UBC Research Forest. 17, Logs and downtrees, A - 5 attacks from June 2-June 30, B - 27 attacks from July 14-September 29, C - 5 attacks from May 1-June 5, D - 4 g a l l e r i e s on May 15; 18, Stumps, A - 26 attacks from June 2July 7, B - 6 attacks from May 1-May 22, C - 6 g a l l e r i e s from May 22-June 5.  Figures 19, 20  Mean weekly frass production of g a l l e r i e s i n i t i a t e d at various times during 1978 and 1979 by Gnathotrichus sulcatus on Douglas-fir, at the UBC Research Forest. 19, Df logs and downtrees, A - 8 attacks from Sept. 1-Sept. 22, B - 6 attacks from May 1-May 22; 20, Stumps, A - 5 attacks from July 28-Sept. 1; B - 11 attacks from May 15-June 5, 1979.  Figures 21, 22  Total brood production from Gnathotrichus sulcatus g a l l e r i e s monitored i n the UBC Research Forest from June 1978 to June 1980, Maple Ridge, B.C. 21, Site 1, (N = 67); 22, Site 2 (N = 80).  Figures 23, 24  Mean weekly brood production from Gnathotrichus sulcatus g a l l e r i e s established on western hemlock i n June - early July (early summer). UBC Research Forest, Maple Ridge, B.C. BP50 and BP90 are the f i f t y and ninety percentiles f o r cumulative brood production. 23, WH trunks; 24, WH stumps.  Figures 25-27  Mean weekly brood production from Gnathotrichus sulcatus g a l l e r i e s established on WH and Df from late July to October, 1978, UBC Research Forest, Maple Ridge, B.C. 25, WH stumps; 26, Df trunks; 27, Df stumps.  Figures 28-31  Mean weekly brood production from Gnathotrichus sulcatus g a l l e r i e s established on WH and on Df i n May-June, 1979. UBC Research Forest, Maple Ridge B.C. 28. WH logs and downtrees. 19, WH stumps; 30, Df logs and downtrees; 31, Df stumps.  Figure 32  Cumulative mean Gnathotrichus sulcatus brood production i n western hemlock and Douglas-fir logs i n laboratory conditions, Faculty of Forestry, UBC. Numbers i n parentheses indicate number of successful g a l l e r i e s i n each host l o g .  Figure 33  Schematic plan of Gnathotrichus sulcatus gallery i n western hemlock two years a f t e r attack. Note the presence of egg niches (EN), pupal niches (PN), dead beetles (D), and l i v e beetles (A).  Figure 34  Mean egg niche, pupal niche and brood production of Gnathotrichus sulcatus g a l l e r i e s on WH stumps and trunks and on Df stumps and trunks. UBC Research Forest, Maple Ridge, B.C.  Figures 35, 36  Mean number of egg and pupal niches of Gnathotrichus sulcatus on western hemlock and Douglas-fir trunks from June 1978 to October 1979. UBC Research Forest. 35, Egg niches; 36, Pupal niches.  Figures 37, 38  Gnathotrichus sulcatus gallery parameters on western hemlock and Douglas-fir trunks from June 1978 to October 1979. UBC Research Forest. 37, Length of g a l l e r i e s ; 38, Depth of penetration.  Figure 39  Estimates of t o t a l monthly attacks and brood production during 1978 through 1980 f o r western hemlock and Douglas-fir host material f e l l e d i n May 8, 1978. UBC Research Forest, Maple Ridge, B.C.  xiii  LIST OF APPENDICES Page  Appendix Results of the analysis of variance of Gnathotrichus sulcatus attacks/m^ on western hemlock and Douglasf i r stump i n the UBC Research Forest, 1978-79. Results of the analysis of variance for Gnathotrichus sulcatus attacks/m^ on western hemlock and Douglas-fir trunks i n the UBC Research Forest, 1978-79.  5  6  7  8  9  107  108  Results of the analysis of variance for percent of Gnathotrichus sulcatus attacks per quadrant on 1 m long western hemlock and Douglas-fir. UBC Research Forest, Maple Ridge, B.C. May-November, 1978 and March-October, 1979. N = 8 for each species.  109  Results of the analysis of variance of bark beetles t o t a l attacks on western hemlock and Douglas-fir trunks i n the UBC Research Forest, 1978-79.  110  Results of the analysis of variance of Trypodendron lineatum attacks/m2 on western hemlock and Douglasf i r trunks i n the UBC Research Forest, 1978-79.  Ill  Results of the analysis of variance of brood (BR) and frass (FR) of Gnathotrichus sulcatus g a l l e r i e s i n western hemlock and Douglas-fir i n i t i a t e d during 1978-79. UBC Research Forest, Maple Ridge, B.C.  112  Results of the analysis of variance for Gnathotrichus sulcatus productivity/gallery and mean gallery parameters i n western hemlock and Douglas-fir logs i n laboratory conditions, Faculty of Forestry, UBC 197 9".  113  Results of the analysis of variance of mean numbers of egg niches (EN) and pupal niches (PN) of Gnathotrichus sulcatus g a l l e r i e s on western hemlock and Douglas-fir i n i t i a t e d during 1978-79. UBC Research Forest, Maple Ridge, B.C.  114  Results of the analysis of variance of mean length (LG) and depth of penetration (DP) of Gnathotrichus sulcatus g a l l e r i e s on western hemlock and Douglasf i r i n i t i a t e d during 1978-79. UBC Research Forest, Maple Ridge, B.C.  115  Results of the analysis of variance of mean numbers of egg niches (EN), pupal niches (PN), depth of penetration (DP) and length (LG) of Gnathotrichus sulcatus g a l l e r i e s i n western hemlock trunks over 13 months. UBC Research Forest, Maple Ridge, B.C. 1978-79. Results of the analysis of variance of egg niches (EN), pupal niches (PN), depth of penetration (DP) and length (LG) of Gnathotrichus sulcatus g a l l e r i e s in Douglas-fir trunks over 13 months. UBC Research Forest, B.C. 1978-79. Results of the analysis of variance for Gnathotrichus sulcatus catches on bark, phloem, sapwood and heartwood stimuli prepared from western hemlock and Douglas-fir. Set out i n Point Roberts, Washington on June and July, 1978.  1  1.0  INTRODUCTION  Ambrosia beetles t y p i c a l l y colonize recently dead or f e l l e d trees i n the coniferous forests of the P a c i f i c Northwest.  They are the f i r s t  agent of wood decomposition and they speed recycling of nutrients i n the forest.  Prior to man's logging a c t i v i t i e s , the events which  maintained supplies of suitable host material included w i l d f i r e s , wind blow down, snow press, flooding and ice breakage. These beetles comprise a l l the Platypodidae and many Scolytidae, well over 1000 species i n a l l .  They vary i n length from l i t t l e more  than 1 mm to over 10 mm i n the longest Platypodidae species (Anonymous 1972). Five species of ambrosia beetles commonly occur i n the P a c i f i c Northwest.  Among them, Gnathotrichus sulcatus (LeConte), together with  i t s associated species, Trypodendron lineatum ( O l i v i e r ) , G_. retusus LeConte, Platypus wilsoni Swaine, and Xyleborus saxeseni (Ratz.), cause considerable economic loss by degrade of wood products (McBride and Kinghorn 1960).  Degrade of wood i n B.C. was estimated at around 11% of  t o t a l volume i n 1948 (McBride 1950), and the value of better classes of timber has been reported as being reduced by 50% (Graham and Boyes 1950).  N i j h o l t (1978) stated that i n B.C., the damage due to ambrosia  beetles i n 1975-76 was estimated by the Western Forest Products Laboratory, Vancouver, B.C.*, to be around $7 m i l l i o n .  1  Now Forintek Canada Corp., Western Laboratory.  2  Additional industry losses are associated with increased slabbing and edging waste and reduced m i l l output per unit of log manufactured. T h i r d l y , there i s the effect of increased manufacturing time on the headrig when the sawyer attempts to establish a clean face on a log .before passing i t on the edger (Graham and Boyes 1950).  Finally,  interceptions of wood containing ambrosia beetles such as G_. sulcatus have caused quarantine problems i n timber importing countries such as New  Zealand ( M i l l i g a n 1970;  Bain 1974).  In extreme cases, wood  shipments to A u s t r a l i a were ordered destroyed ambrosia beetles infestations (Mathers 1935).  i n 1928 and 1930 due to Such precautions  are  advisable since McLean and Borden (1975a) have demonstrated that G_. sulcatus can survive and reproduce i n freshly sawn lumber, thus showing the very real p o s s i b i l i t y of this ambrosia beetle being introduced into foreign markets. i n a new  An example of ambrosia beetle impact  environment i s demonstrated by X. saxeseni which was  accidentally introduced i n New  Zealand ( M i l l i g a n 1969)  and now  infests  some 31 species of native trees (Hosking 1972). For e f f i c i e n t management of a pest such as G_. sulcatus, the understanding of i t s biology i s of foremost importance.  This species  does not appear i n large numbers i n a single major spring f l i g h t period as does the associated h o l o a r t i c species, T_. lineatum. beetle research i n B.C. (Nijholt 1979).  has previously concentrated  Most ambrosia  on T_. lineatum  Observations on G. sulcatus were sometimes included i n  publications as i n c i d e n t a l notes.  Daterman et a l . (1965) stated that  since much of the l i f e h i s t o r y of this insect i s unknown, i t was  3  impossible to define the seasonal f l i g h t i n terms of o r i g i n of beetles in f l i g h t during the season.  Several other authors, indicated a  bi-modal f l i g h t pattern, a peak i n the spring or early summer and a second i n September (Prebble and Graham 1957;  Chapman and Kinghorn  1958; McLean and Borden 1979), but no explanation for such bi-modality - has been given. generations  Rudinsky and Schneider (1969) suggested that were two  per year when they found CJ. sulcatus starting g a l l e r i e s i n  October. G_. sulcatus was  f i r s t described by LeConte i n 1868  as Crypturgus  sulcatus along with two other species, C^. retusus and £. asperubus. the same year Eichhoff created the genus Gnathotrichus  for (J.  cortyloides, which he believed could be Tomiscus materiarius. other new  species of Gnathotrichus  that time (Blackman 1931). Gnathotrichus i n 1918,  Three  from Chile were also described at  In 1895,  and included two new  In  Blandford redescribed the genus  species from Central America.  Later  Swaine put not only T_. materiarius but also (3. retusus LeConte  and C_. sulcatus LeConte i n this genus (Blackman 1931). Doane j 2 t a l . (1929) presented  the f i r s t data on G.  sulcatus  biology on Douglas-fir (Df), Pseudotsuga menziesii (Mirb.) Franco, when they stated i n C a l i f o r n i a that the beetles attacked the top and then the trunk of the tree, and l a t e r could also be found i n the stumps where they continued further conjectured  their borings for several generations.  They  that copulation took place i n the main and  secondary g a l l e r i e s and that eggs hatched i n about 7 or 8 days.  Doane  et a l . (1936) stated that G. sulcatus i n C a l i f o r n i a reproduced and continued  to extend g a l l e r i e s as long as the wood of their host  was  4  s u f f i c i e n t l y moist for the growth of the associated fungi.  They also  usually found two or more broods each year, but these were not regular, since larvae, pupae, and adults were present within the g a l l e r i e s at almost any season. the  Beetles were i n f l i g h t from the middle of A p r i l to  f i r s t week of September and they apparently preferred fresh timber  (Doane et a l . 1936).  Age of host material varied greatly, with several  logs being attacked within a week of the time of f e l l i n g and one log 15 months a f t e r i t was cut (Mathers 1935). Most of the more recent studies on G_. sulcatus have concentrated on primary and secondary a t t r a c t i o n .  G_. sulcatus started to emerge and  f l y i n the spring when temperatures exceeded 16°C (Daterman et a l . 1965).  Rudinsky and Schneider (1969) demonstrated that temperature and  l i g h t i n t e n s i t y regulated maximum f l i g h t a c t i v i t y .  Once i n f l i g h t ,  G_. sulcatus was guided to new habitats by odours produced by suscept i b l e host tissues (Graham and Werner 1956; Chapman 1963).  Person  (1931) hypothesized that fermentation products from dying trees were responsible for the a t t r a c t i o n of s c o l y t i d beetles which subsequently attacked and colonized them.  While the hypothesis has been substan-  t i a l l y disproved for the bark beetle, Dendroctonus brevicomis LeConte for which i t was o r i g i n a l l y erected (Moeck et a l . 1980), i t appears to be v a l i d for ambrosia beetles as proposed by Doane et a l . (1936). Ethanol has been i d e n t i f i e d as one of the primary attractants (Cade et a l . 1970); i t i s hypothesized as being formed by anaerobic respiration in host tissues (Graham 1968).  Low numbers of G_. sulcatus can be  captured at traps baited with ethanol (Cade et a l . 1970; Moeck 1971;  5  McLean 1976).  S i g n i f i c a n t l y more beetles were captured  on traps baited  with ethanolic solutions of a-pinene than on ethanol-baited (Rudinsky 1966).  Observations related to Gnathotrichus  tion are reviewed i n Table  traps  primary attrac-  1.  The presence or absence of the needles on downtrees (FordRobertson 1971) might influence primary a t t r a c t i o n .  It has been  suggested that downtrees were attacked less densely than logs by G_. sulcatus (Johnson 1964). hypothesis  However, an experiment to test the  (Johnson and Zing 1969)  f a i l e d to demonstrate any  signifi-  cant differences between attack rates on these two categories of host. Isolation procedures for i d e n t i f y i n g the primary attractants for G_. sulcatus could be greatly enhanced by demonstrating which host tissue i s the most a t t r a c t i v e .  McLean (1976) showed greatest responses  by walking beetles i n a laboratory olfactometer  to a i r passing over  sapwood sawdust prepared from western hemlock (WH),  Tsuga heterophylla  (Raf.) Sarg., than to a i r alone. Ambrosia beetles feed on ambrosia fungi carried by the adults when they emerge and f l y to a host. ported by female beetles to new  As the ambrosia fungi are trans-  tunnels during excavation and  before  oviposition, adults do not consume ambrosia fungus at this time but feed on wood as they do during the maturation feeding (Batra 1963). F a r r i s (1963) found that male G. sulcatus carry their symbiotic  fungi  i n special coxal cavities of the prothoracic legs; seasonal changes i n these mycetangial glands were described by Schneider and Rudinsky (1969).  These fungi were described by Funk (1970) as Ambrosiella  s u l c a t i Funk, Raphaella  s u l c a t i Funk and Graphium sp.  TABLE I.  A review of observations on primary a t t r a c t i o n In Gnathotrichus sulcatus  Reference  Observation  A.  General  B.  Concepts:  Primary a t t r a c t a n t s produced by fermentation of host tissue (western pine beetle)  Person  -  Sap must be i n fermentatlng condition for attack (ambrosia beetles)  Doane et a l . 1936  -  Primary a t t r a c t a n t s produced by anaerobic r e s p i r a t i o n of host tissues deprived of t r a n s l o c a t l v e oxygen  -  Graham 1968  Response to Host Tissue (odors) and Primary A t t r a c t a n t s ~  Host Tissues . Ethanol was i d e n t i f i e d as a primary a t t r a c t a n t for G. s u l c a t u s . Catches to treatments were: soaked hemlock (31), 80Z ethanol (22), 50% ethanol and non-soaked hemlock (10), water ( 0 ) . Ethanol I d e n t i f i e d as the major v o l a t i l e In soaked hemlock. In laboratory bloassays e i t h e r western hemlock sawdust or ethanol alone had a higher response for males and females of G. sulcatus than a i r c o n t r o l . When tested together the response was higher than to either a t t r a c t a n t , alone ( a d d i t i v e response)  -  -  Cade et a l . 1970  McLean 1976  Ethanol alone 282 males and 58 females were captured i n 10Z ethanol-baited traps as opposed to 7 males and 9 females i n water only control traps  Hoeck 1971  Higher response by G. sulcatus to ethanol than c o n t r o l In walking bloassays. Traps baited with ethanol with a release rate of 10.0 and 35.1 g/24 hr captured more beetles than unbalted c o n t r o l  McLean 1976  .  G_. sulcatus response to ethanol i n a sawmill study was not s i g n i f i c a n t l y greater than to unbalted c o n t r o l (test included s u l c a t o l - b a i t e d traps)  McLean & Borden 1975a  .  Response of G. sulcatus to ethanol 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 the unbalted c o n t r o l (test Included a s u l c a t o l treatment)  Borden et a l . 1980a  Ethanol + host compounds •  G. sulcatus had the higher response to, i n descending order, ethanolic s o l u t i o n s of camphene and B'pinene. No response to ethanol-baited traps Ethanol-balted logs had greater numbers of attacks than control logs In f i e l d  • C.  1931  Ethanol +  a-pinene,  experiment  Rudinsky  1966  McLean & Borden 1977 Borden et a l . 1980b  a-plnene captured s i g n i f i c a n t l y more beetles than c o n t r o l  -  Primary A t t r a c t a n t s plus Pheroaones  -  S i g n i f i c a n t l y more attacks occurred i n western hemlock logs and Douglas-fir logs and stumps baited with s u l c a t o l + ethanol than to host material s u l c a t o l - b a I t e d alone  McLean & Borden 197 7a  -  S i g n i f i c a n t l y more males responded to traps baited with (+) s u l c a t o l + ethanol + traps baited with (+) s u l c a t o l alone  Borden et a l . 1980a  ct-pinene than to  7  After successful establishment  of G. sulcatus i n a suitable host,  secondary a t t r a c t i o n (Borden 1974) i s set up. This was demonstrated i n the laboratory (Borden and Stokkink 1973).  An aggregation pheromone  present i n the boring dust of male beetles (Borden and Stokkink 1973) was i s o l a t e d , i d e n t i f i e d as 6-methyl-5-hepten-2-ol and given the t r i v i a l name s u l c a t o l (Byrne et a l . 1974).  In f i e l d t r i a l s ,  traps  baited with a racemic mixture of synthetic sulcatol attracted large numbers of both sexes of G_. sulcatus despite competition of natural host attractants (Byrne et j i l . 1974).  Primary attractants enhance the  catches at traps baited with sulcatol (Borden et a l . 1980a) and they have a s i g n i f i c a n t role i n secondary a t t r a c t i o n .  The related species  G. retusus u t i l i z e s 5-(+)-sulcatol as i t s aggregation pheromone (Borden et a l . 1980c). The objectives of this work were to: 1.  Determine the natural colonization patterns of G. sulcatus on WH and Df stumps, logs (L) and downtrees (DT) and record attacks by associated scolytids at the UBC Research Forest over two successive years.  2.  Determine when peak attack occurs especially as related to v u l n e r a b i l i t y of May-felled logs and whether there i s any d i f f e r e n t i a l attack rate between logs and downtrees.  3.  Determine frass and brood production from these attacks by placing emergence chambers over successful g a l l e r i e s on each host type and to e s t a b l i s h when brood emerged and the relationship between attacking and emergent beetles.  8  4.  Correlate frass and brood production with length of g a l l e r y to derive a developmental success  profile.  5.  Determine the success of g a l l e r i e s f o r each month of attack.  6.  Determine the host tree tissue which i s most a t t r a c t i v e to f l y i n g beetles.  9  2.0  2.1  MATERIALS AND METHODS  FIELD STUDY LOCATIONS AND EXPERIMENTAL DESIGNS 2.1.1  U.B.C. Research Forest  The research on natural colonization, brood production and effect of log age on g a l l e r y success was done i n the U.B.C. Research Forest, Maple Ridge, B.C., 60 km east of Vancouver.  This forest i s located i n  the coastal western hemlock biogeoclimatic zone (Klinka 1976).  The two  study s i t e s were located at altitudes of 110 m and 122 m i n second growth f i r e succession stands i n a Rubus - Polystichum - western red cedar ecosystem. Four pairs of trees were f e l l e d on each s i t e on May 8, 1978. Each pair consisted of one Douglas-fir (Df) and one western hemlock (WH).  At each s i t e branches were l e f t intact on two pairs of f e l l e d  trees (downtrees), while branches were removed on the other two pairs (logs).  Length, d.b.h. and other characteristics of these logs and  downtrees are l i s t e d i n Table I I . The 2 x 2 x 2  f a c t o r i a l design, which included two s i t e s , two  hosts and two conditions with two replications per site/host/condition/ situation, was used to study natural colonization patterns of Df and WH by ambrosia and bark beetles.  The experimental design enabled compari-  son to be made between attack patterns on WH and Df stumps and between logs and downtrees of the two host species at the two s i t e s . Brood and frass production was recorded for f i v e g a l l e r i e s i n each stump, log and downtree.  The effect of host age on the success of  10  TABLE I I .  Host species  Western Hemlock  Douglas-fir  Length and diameter at breast height (d.b.h.) for western hemlock and Douglas-fir logs and downtrees, Felled i n the UBC Research Forest, May 8, 1978  Site  Tree #  Condition  Length (m)  d.b.h. (cm)  Age (yrs)  1 2 3 A 5 6 7 8  DT L DT L DT L DT L  14.0 22.0 13.0 12.0 23.0 25.0 26.0 14.0  23.7 34.6 32.2 26.9 42.8 38.1 27.8 29.1  59 70 67 73 69 71 71 69  1 2 3 4 5 6 7 8  DT L DT L DT L DT L  17.0 17.0 27.0 27.0 27.0 23.0 24.0 25.0  26.0 30.9 31.9 44.5 38.5 17.2 26.8 27.9  72 74 78 73 85 71 70 73  *DT = downtree (with branches), L = log (no branches).  11  G_. sulcatus attack was  evaluated by dissecting two g a l l e r i e s i n i t i a t e d  i n each month of this study for each host  category.  Wood samples from each stump and from the third meter of each log and downtree were taken weekly using an increment borer.  The percentage  moisture on a dry weight basis of each sample determined on return to the laboratory.  Samples for moisture analysis were always taken from  the same side and area to avoid any v a r i a b i l i t y that might be associated with sunny and shady sides of the host material.  Weekly  r a i n f a l l and temperature records were obtained from the meteorological station maintained  2.1.2  by Research Forest  personnel.  Point Roberts Host Tissue A t t r a c t i o n Studies  The tests of WH and Df stimuli were set out i n a s e l e c t i v e l y logged coastal Douglas-fir wetter subzone forest i n Point Washington, U.S.A., some 30 km south of Vancouver.  Roberts,  This kind of forest  operation maintains a constant supply of forest host material for the beetle population on a year-by-year basis. This experiment was  i n s t a l l e d i n f i v e blocks, each block being  set out along a logging skid road.  A L a t i n square  randomization  pattern was used to ensure that each treatment was assigned to a d i f f e r e n t p o s i t i o n i n each block, since traps i n the ends of a row tended to catch more beetles (McLean and Borden 1977b).  12  2.2  HOST COLONIZATION 2.2.1  V e r i f i c a t i o n of Attacks  The i d e n t i t i e s of attacking scolytid beetles were v e r i f i e d by excavating new attacks u n t i l symptoms were r e l i a b l y recognized.  Such  excavations were done weekly through the end of the experiment to avoid misidentification  of species.  £. sulcatus and T. lineatum.  Ambrosia beetles monitored included Bark beetles monitored included  D. pseudotsugae Hopk., Pseudohylesinus tsugae Swaine, Scolytus tsugae (Swaine) and S^. unispinosus LeConte.  Samples of each species were sent  to the Biosystematics Research I n s t i t u t e , Ottawa to v e r i f y i d e n t i f i c a tions.  2.2.2  Weekly Pinning  Host material was checked weekly and fresh attacks pinned from May 19 to November 2, 1978 and from March 25 to October 30, 1979.  Each  week, pins were color coded so that a temporal sequence of attack could be analysed i n any area.  2.2.3  D i s t r i b u t i o n Around Logs and Downtrees and Pinning Efficiency  One meter sections were removed from each log and downtree around the t h i r d meter from the butt end at the conclusion of the study to determine d i s t r i b u t i o n of attacks on top, sides and bottom (quadrant) of the logs and downtrees, and the opportunity was also taken to  13  evaluate pinning e f f i c i e n c y for G_. sulcatus.  On the stumps pinning  e f f i c i e n c y was determined on the disks taken to assess brood production.  2.3  BROOD PRODUCTION BY Gnathotrichus  sulcatus ON STUMPS, LOGS AND  DOWNTREES Frass and brood production i n successful G_. sulcatus g a l l e r i e s were monitored by covering gallery entrances with p l a s t i c p e t r i dishes (Hosking 1972).  The base of the 5.5 cm diameter p e t r i dish had a  central hole which was placed over the gallery entrance.  To i n s t a l l  the dish, bark was f i r s t smoothed with a c h i s e l and a small quantity of p l a s t i c i n e was used to ensure a seal between the dish and the trunk or stump.  Dishes were nailed to the bark and covered a f t e r 1 week. The  delay was to allow for pair formation.  The cover was held i n place  with a small rubber band, which was stretched over the cap between two n a i l s close the edge of the p e t r i dish ( F i g . 1). Attacks were covered i n each host category u n t i l 5 successful g a l l e r i e s were obtained i n a shortest period of time after the f i r s t attack on the stump, log or downtree ( F i g . 2).  Since attack rate was far from uniform and did not  happen at the same time for every stump, log and downtree, the dish i n s t a l l a t i o n f i r s t started i n June 1978 and extended to J u l y 1979 when most host categories were f i n a l l y attacked.  One Df stump was never  attacked. A l l frass and brood were collected weekly u n t i l production ceased ( F i g . 3).  They were collected i n a small v i a l i n the f i e l d and  brought to UBC, where the beetles were sexed and the frass dried at  14  F i g u r e s 1, 2:  Pinned a t t a c k s of G n a t h o t r i c h u s s u l c a t u s and p e t r i d i s h e s to c a p t u r e brood i n s u c c e s s f u l g a l l e r i e s . 1, WH stump; 2, WH t r u n k .  15  Figure 3:  P e t r i dish on western hemlock showing dark colour of frass five weeks a f t e r attack.  16  100°C for 24 hours, allowed to cool down for one hour i n a dry desiccator and then weighed. The beetles that came out from g a l l e r i e s during the f i r s t week of emergence and t o t a l production  from a successful g a l l e r y were studied  to determine i f there was any predominance of either sex as the  first  to emerge.  2.4  GALLERY DISSECTION During the spring and summer of 1980,  10 cm thick disks were sawn  from each stump, log and downtree so that the complete g a l l e r i e s developed under a l l p e t r i - d i s h covered attacks could be brought into the laboratory.  Each g a l l e r y was  dissected and a drawing made to show  locations of egg and pupal niches, depth of penetration and length of g a l l e r i e s , as well as any dead insects. In addition, two attacks from the months of June through October, 1978  and from March to October 1979,  i n each WH and Df log and downtree  host category were dissected.  2.5  LABORATORY REARING Five pieces of log were brought to UBC,  months and then kept i n a chamber at 23°C.  A constant  hr dark regime was maintained i n the chamber. i n a shallow tray of water.  stored outside for four 14 hr light/10  Logs were placed on end  A perforated p l a s t i c 500 ml container of  water on the upper cut surface allowed water to t r i c k l e down over the log  thereby maintaining  a high moisture regime ( F i g . 4).  replenished whenever necessary.  The water  was  17  F i g u r e 4:  Log of D o u g l a s - f i r i n l a b o r a t o r y showing the f i v e p e t r i d i s h e s , the water c o n t a i n e r on the top and the water r e s e r v o i r a t the bottom of the l o g .  18  Several 3 mm diameter and 2 cm deep holes were d r i l l e d i n each ~ log,  a p e t r i dish was i n s t a l l e d over each hole and a male was put i n  each g a l l e r y .  Four to f i v e days l a t e r a female beetle was added. A l l  parent beetles used i n this experiment were brood c o l l e c t e d i n the f i e l d work.  The r e s u l t i n g brood were collected daily i n the  laboratory.  After development was completed, a l l successful and  unsuccessful  g a l l e r i e s were dissected and a drawing made of each one to  show length, depth of penetration and positions of pupal and egg niches. The sex r a t i o of first-emerging beetles and of the total brood were determined.  The number of degree-days required for development  was calculated from the day when a female joined a male i n a successful gallery u n t i l the appearance of the f i r s t brood.  This method i s  recommended when temperature i s r e l a t i v e l y stable (Mizzel and Nebecker 1978).  For the f i e l d work which was carried out under normal  fluctuating diurnal temperatures, the number of degree-days was calculated from the attack date to the average date when half the brood had been produced i n each of 37 g a l l e r i e s (Mizzel and Nebecker  2.6  1978).  PRIMARY ATTRACTANTS TESTS 2.6.1  Test with Western Hemlock Stimuli  On June 2, 1978 1 m lengths of WH were cut from each of s i x different logs f e l l e d between May 16 and May 19 i n the UBC Research Forest near Maple Ridge, B.C.  Logs from six trees were taken because  of the high v a r i a t i o n i n s u s c e p t i b i l i t y between trees within the same  19  species (Prebble and Graham 1957; were brought to UBC,  Chapman 1962).  and on June 4, 1978,  and sapwood and heartwood sawdust was bark was  the bark was  prepared  reduced to small pieces, approximately  machete.  The s i x pieces of log stripped o f f ,  using a chainsaw. 1 cm^,  The  with a  Bark pieces and sapwood and heartwood sawdust from the 6 logs  were each combined and stored i n p l a s t i c bags at 12.8°C and 74%  R.W.  These host materials were packed i n cylinders 10 cm i n diameter and cm long made of 6 mm wiremesh ( F i g . 5). through each cylinder which was pole.  put  fixed at 10 cm from the top of the  Each cylinder of stimulus was  trap (Byrne et a l . 1974)  A 1.5 m high pole was  22  surrounded by a wiremesh cylinder  coated with Stikem S p e c i a l  1  ( F i g . 5).  Empty  cylinders i n the control traps were wrapped i n brown paper to provide the same silhouettes as were present i n the other traps. F i e l d experiments were set out along logging spur roads i n a s e l e c t i v e l y logged forest i n Point Roberts, WA on June 7, 1978.  The  treatments were: bark, sapwood, heartwood, sulcatol and blank. block was  set out along a logging skid road with approximately  between traps.  The sulcatol treatment was  Each 30 m  included for 1 week to  provide a check on the presence of beetles i n the test area, and then removed so as not to overwhelm any host odour stimulus.  M i c h e l P e l t o n L t d . , Emeryville, CA.  was  20  .20*5 cm PLYWOOD SUPPORT DISCS  WIREMESH CYLINDER TO ENCLOSE STIMULI  WIREMESH CYLINDER COVERED WITH STIKEM SPECIAL®  SUPPORT POLE 1-5m HEIGHT  Figure 5:  Modified survey trap used for testing host stimuli i n Point Roberts i n 1978.  I  21  The experiment ran for f i v e weeks, without changing the s t i m u l i . (5. sulcatus were collected from the traps each week, and brought to the laboratory and their sex were determined. Two further experiments to test a t t r a c t i o n of bark, phloem, sapwood and heartwood of WH were done i n July 1979.  2.6.2  Test with Douglas-fir Stimuli  On July 7, 1978, two Df were f e l l e d at the UBC Research Forest and three pieces, each approximately 1 m long, were taken from the butt end of each l o g .  Sapwood and heartwood sawdust and bark stimuli were  prepared and stored as f o r those from WH.  The only difference was that  an additional stimulus, phloem, was prepared since i t was e a s i l y separated from the bark.  On July 12, the wiremesh cylinders were put  on a trap support pole and f i l l e d with host s t i m u l i .  Following t h i s ,  they were wrapped i n p l a s t i c bags and kept i n the cold chamber u n t i l June 16, 1978, when the experiment was set up at Point Roberts, WA. Experimental design, beetle c o l l e c t i o n and s t a t i s t i c a l analyses were the  same as for WH, except that the stimuli were bark, phloem, sapwood,  and heartwood.  Sulcatol-baited traps were not set out. The experiment  ran  for three weeks, but f i n a l analyses were done f o r catches during  the  f i r s t week only as too few beetles were captured i n weeks 2 and 3.  22  2.7  DATA ANALYSIS P r i o r to analysis of variance, the data were transformed X' = log^Q  (X + 1), except i n the case of data for the percent of attacks by quadrant, where the raw data were used since the variances were 2 homogeneous.  Data were analysed using the package ANOVAR 3  there were missing data, the GENLIN  package was used.  and when  In a l l cases  the Newman Keul's Test (Winer 1971) was used to test ranked means within main e f f e c t s .  For the regression and c o r r e l a t i o n analyses the  4 MIDAS package was used. 2.8  TOTAL BROOD EMERGENCE PATTERN Estimates of t o t a l attacks and total numbers of brood on the  stump/trunk combinations at the UBC Research Forest were calculated from data derived i n this study i n order to show the contribution of each attack period to the t o t a l brood production.  This was done as  follows: The numbers of pinned attacks (NA) (Table I I I ) were totalled by month for each host category and then converted to an estimated of t o t a l attacks (TA) using the pinning e f f i c i e n c y (PE) calculated i n Section 3.1.6. TA - NA/PE  (1)  The TA were converted to a proportion of attacks with pupal niches (PPN).  This was done by each month for the trunks,  ^UBC ANOVAR - Analysis of variance and covariance. University of B r i t i s h Columbia, 1978. 69 pp.  Computing Centre,  ^UBC GENLIN - A general least square analysis of variance program. Computing Centre, University of B r i t i s h Columbia, 1977. 55 pp. ••Michigan Interactive Data Analysis System (Fox and Guire 1976).  23  using the proportion of opened g a l l e r i e s with pupal niches (Table XV), and yearly for the stumps (Table VII).  This gave a measure  of successful attacks (SA). SA = TA x PPN  (2)  The t o t a l number of pupal niches (TPN) i n each host category and month were calculated by multiplying SA by the mean number of PN per successful g a l l e r y (MPNG) per month for the trunks (Table XV) and by the mean number of PN per successful g a l l e r y by year f o r the stumps. TPN = SA x MPNG  (3)  The estimated t o t a l number of brood (TB) were computed from t o t a l number of PN per month and the estimated number of brood/niche Table IX and XII) (BN) for the trunks and stumps. TB = TPN x BN  (4)  Equations 1-4 can be summarized as TB = (NA/PE) x PPN x MPNG x BN The estimated number of brood per month i n each host category was then divided into emergence per month according to the pattern established i n the g a l l e r i e s covered with p e t r i dishes. patterns were derived f o r three major periods:  These  early summer  attacks (Figs. 23, 24) for WH stumps and trunks, respectively; l a t e summer 1978 attacks ( F i g s . 25-27) f o r WH trunks, Df stumps, and of trunks respectively; and May, 1979 attacks for a l l four host categories (Figs. 28-31).  These results were then sum-  marized to obtain the t o t a l numbers of brood produced by month for the t o t a l G_. sulcatus attacks.  24  3.0  3.1  RESULTS  HOST COLONIZATION BY Gnathotrichus 3.1.1  sulcatus  Attacks on Each Host Category  A t o t a l of 11,490 attacks by G_. sulcatus were pinned on the stumps, logs and downtrees during this study, 5212 i n 1978 and 6278 i n 197 9 (Table I I I ) . Of the t o t a l numbers pinned, 3222 attacks were on stumps with 1651 being recorded i n 1978 and 1571 i n 1979.  Some 3561  attacks were pinned on trunks (logs plus downtrees) during 1978 and a further 4707 i n 1979 for a t o t a l of 8268 attacks.  There was a three  fold difference i n the numbers of attacks recorded i n the two study sites with 2980 and 8510 attacks being pinned on s i t e s 1 and 2, respectively (Table I I I ) . In 1978, 4285 attacks were recorded on WH as compared to 927 on Df.  In 1979, however, 3191 and 3087 attacks were  recorded on WH and Df, respectively. On the stumps, 176 and 1475 attacks were recorded on s i t e 1 and 2, respectively, during 1978, and i n 1979, 630 and 941 attacks were pinned for these same two s i t e s .  One Df stump (Df 4) was not attacked i n  either year while two stumps that were not attacked i n 1978 (Df 1 and WH 3) were successfully colonized i n 1979.  Stump DF 8 was not attacked  in 1979, but sustained 115 attacks i n 1978 (Table I I I ) .  3.1.2  Comparison of Attack Densities  For stumps, higher densities of attack were recorded on WH than on Df.  Higher densities of attacks were recorded i n s i t e 2 than i n  25  TABLE I I I .  Total number of Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps, logs (L) and downtrees (DT). UBC Research Forest, Maple Ridge, B.C., 1978/79  Pair  Host  Trunk Condition  1979  1978  l  Stump  Trunk  Total  Stump  Trunk  Total  SITE 1 1  WH Df  DT DT  70 0  78 13  148 13  216 46  10 309  226 355  2  WH Df  L L  10 19  24 18  34 37  80 31  400 40  480 71  3  WH Df  DT DT  0 1  84 66  84 67  102 90  12 8  114 98  4  WH Df  L L  76 0  11 3  87 3  65 0  248 850  313 850  Total  WH Df  156 20  197 100  353 120  463 167  670 1207  1133 1374  176  297  473  630  1877  2507  Total attacks  SITE 2 5  WH Df  DT DT  349 53  1085 127  1434 180  147 130  124 574  271 704  6  WH Df  L L  281 15  478 151  759 166  208 179  776 668  984 847  7  WH Df  DT DT  103 81  646 79  749 160  174 18  439 132  613 150  8  WH Df  L L  478 115  512 186  990 376  85 0  105 12  190 12  Total  WH Df  1211 264  2721 543  3932 807  614 327  1444 1386  2058 1713  1475  3264  4739  941  2830  3771  Total attacks  WH - Western Hemlock; Df - Douglas-fir  X  26  s i t e 1.  During the second year there were no differences i n attack  densities between the two s i t e s , but again more attacks were pinned  on  WH than on Df stumps (Table IV). For logs and downtrees there were s i g n i f i c a n t differences i n attack densities by s i t e , host and condition i n 1978  (Table IV).  Density of attack was approximtely s i x times higher on s i t e 2 than on s i t e 1.  S i g n i f i c a n t l y higher densities were recorded on WH  trunks, and on downtrees than on logs during 1978.  than on Df  None of these  differences was sustained i n 1979. On a bi-weekly basis, attack densities on trunks i n 1978  showed a  consistently and s i g n i f i c a n t l y higher attack density i n s i t e 2 from July 14 through November 2, while no s i g n i f i c a n t differences were found for the bi-weekly periods ending i n June 2 through June 30.  WH  was  more heavily attacked than Df from July 14 through November 2, but again no differences were found from June 2 to June 30. densities on downtrees were not s i g n i f i c a n t l y different  Attack from those on  logs for any bi-weekly periods (Table V), but for f i n a l attack densities i n 1978 there were s i g n i f i c a n t l y more attacks on downtrees than on logs (Table IV). For the period March 31 - May 29, 1979, higher attack densities were recorded on s i t e 2 than on s i t e 1.  Those densities were not  different from June 12, August 7, and for the periods ending August 21, and September 18 higher attack densities were recorded i n s i t e 1 (Table V).  S i g n i f i c a n t l y higher attack densities recorded on WH during  were not sustained beyond March 31, 1979,  there being no  differences between hosts for the remainder of the year.  1978  significant  27  TABLE IV. Summary of densities of Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps, logs and downtrees. U.B.C. Research Forest, Maple Ridge, B.C. 1978-79.  1.2 Total  Logs and downtrees  Stumps"  Factor  attacks/V  1979  1978  1979  23.3b 162.3a  81.1a 97.8a  3.9b 26.2a  16.1a 19.6a  150.3a 35.3b  126.2a 52.8b  25.0a 5.1b  12.7a 18.0a  13.6b 16.4a  22.4a 13.3a  1978  SITE Site 1 Site 2  HOST Western hemlock Douglas-fir  CONDITION Log Downtree  *Data transformed to X* = l o g ( X + 1 ) prior to analysis. 1 Q  ^Means within each year/factor category 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 , Neuman Keuls Test, P <0.05. AN0VA table i n Appendix 1.  3  AN0VA table i n Appendix 2.  4  TABLE V.  Bi-weekly mean attack/m2 Gnathotrichus sulcatus on western hemlock and Douglas-fir logs and downtrees. UBC Research Forest, Maple Ridge, B.C. 1978/79.  Mean number of attacks/m 19 7 8  2  J 16  30  14  28  J 11  25  A 8  S 22  6  O  1 2  0.00a 0.10a  0.04a 0.47a  0.16a 0.83b  0.18a 1.50b  0.53a 2.59b  0.50a 4.59b  0.67a 5.11b  0.81a 4.49b  0.16a 3.12b  0.42a 2.19b  0.20a 1.26b  0.09a 0.31b  WH Df  0.10a 0.00a  0.50a 0.01a  0.95a 0.04a  1.64a 0.04b  2.65a 0.47b  3.74a 0.85b  5.00a 0.78b  4.17a 1.14b  2.75a 0.53b  2.02a 0.59b  1.04a 0.42b  0.33a 0.06b  0.00a 0.10a  0.31a 0.20a  0.71a 0.28a  0.75a 0.93a  1.01a 2.12a  2.23a 2.37a  2.48a 3.30a  2.31a 2.99a  1.75a 1.53a  1.14a 1.41a  0.71a 0.80a  0.15a 0.21a  20  N 2  SITE  HOST  CONDITION L DT  Means followed by the same l e t t e r , within each year/factor category not s i g n i f i c a n t l y d i f f e r e n t , Neuman Keuls Test, P <0.05.  TABLE V.  (Cont'd)  —  T  Mean number of attacks/m 19  -  M  31  •*  13  .  ,5  2  9  12  J  26  10  J  2  7 9  24  7  "  21  4  '  18  2  16  30  SITE 0.04a  0.03a  0.15a  0.51a  2.34a  1.41a  0.87a  0.75a  1.62a  1.71a  2.27b  1.14a  1.88b  0.74a  0.48a  9.29a  0.37b  0.14b  1.02b  2.58b  8.82b  2.95a  1.99a  0.96a  0.22a  0.29a  0.07a  0.07a  0.02a  0.00a  0.01a  0.00a  0.32a  0.13a  0.73a  2.10a  5.16a  I.93a  1.45a  0.52a  0.89a  1.10a  1.49a  0.63a  0.91a  0.18a  0.08a  0.00a  0.09b  0.04a  0.45a  0.99a  6.00a  2.43a  1.40a  1.19a  0.95a  0.90a  0.85a  0.58a  1.00a  0.56a  0.41a  0.29a  0.14a  0.10a  0.90a  1.60a  5.82a  2.51a  1.68a  0.94a  1.36a  1.64  1.99a  0.95a  1.63a  0.55a  0.44a  0.29a  0.27a  0.07a  0.27a  1.49a  5.35a  1.84a  1.17a  0.77a  0.48a  0.37a  0.35a  0.26a  0.28a  0.19a  0.05a  0.00a  HOST WH Df CONDITION L DT  'Means followed by the same l e t t e r , w i t h i n each y e a r / f a c t o r category P <0.05.  not s i g n i f i c a n t l y  different,  Neuman Keuls  Test,  30  3.1.3  Seasonal Attack. Patterns  The f i r s t two attacks were recorded on WH stump 8 on May 26, 1978, while for the logs and downtrees the f i r s t attacks were recorded on June 2.  Numbers of attacks i n 1978 increased steadily during June  and highest numbers of attacks were recorded i n late July and early August for the WH stumps ( F i g . 6), and i n late August and early September for WH logs and downtrees ( F i g . 7).  Peak attacks i n Df  stumps occurred on June 20 ( F i g . 6), while the peak numbers of attacks on Df logs were recorded on September 8 ( F i g . 7).  Last attacks for  1978 were recorded for the period ending November 2 when the weekly maximum temperature was 13°C ( F i g . 9). The f i r s t attacks i n 1979 were recorded for the period ending March 25 when maximum temperature had reached 12°C.  Highest numbers of  attacks occurred on May 29 for WH and Df trunks on both sites (Figs. 6,7).  This attack was sustained on s i t e 1 trunks with a peak of  attacks on WH i n mid-August and on Df i n mid-September. A f i r s t peak of attacks i n the stumps i n 1979 occurred on WH on both s i t e s and on Df i n s i t e 1 on May 29.  There was a general increase  i n attacks on Df stumps i n s i t e 2 which reached a maximum during August and September.  The only other second peak recorded was that on August  21 f o r WH stumps i n s i t e 1. Last attacks were recorded on October 30 i n 1979 when the maximum weekly temperature reached 13°C ( F i g . 9).  3.1.4  Attack i n Relation to Moisture Content i n Trunks and Stumps  Moisture content on WH stumps was approximately Df stumps i t was around 60% ( F i g . 10).  100%, while for  Higher moisture l e v e l s i n WH  9 Figures 6, 7:  7  8  9  7  9  Bi-weekly totals of pinned attacks of Gnathotrichus sulcatus on western hemlock and Douglas-fir. UBC Research Forest. May-November/1978 and MarchOctober / l 979. 6. Stumps. 7. Logs and downtrees.  t  8:  I  RAINFALL  222  : :  y  120 ^  1  100  1  80  ~j  60  2  40  I  20  2  7  9:  M  t  •.:  S  O  N  7  8  :: • :  i — —  »..  TEMPERATURE  maximum minimum  J  J  A  1 9  F i g u r e s 8, 9:  D  J  F  M  A  M 1  J 9  J  A 7  S  O N  D  9  Climate data recorded a t the gate of the UBC Research F o r e s t from May 18, 1978 to December 31, 1979. Maple Ridge, B.C. 8. Weekly r a i n f a l l . 9. Minimum and maximum weekly temperature.  101  STUMPS  .1  Ill  -  DOUGLAS-FIN HEMLOCK  -  K  <0 Af\ 20 1  A |  Sustain**  EHplowtory attack  111  5  attack  LOGS U AND DOWNTREES fe>T]  Z  HEMLOCK  i, a. s, 7 |n)  HEMLOCK  2,4, #,8 U  DOUGLAS-FIR  \ 3. % » OT  DOUGLAS-FIR  14, •,•!.]  4.2  Ul  o  Ul  ^1 \  a.  M  J  J 1  Figures 10, 11:  9  A 7  8  S  O  N  M  M 1  9  7  9  Mean moisture content of western hemlock, and Douglas-fir f e l l e d on May 8, 1978 In the UBC Research Forest for the periods May 1978 - November 1979. I n i t i a t i o n of sustained attacks by Gnathotrichus sulcatus indicated by s o l i d u> arrows and f i r s t attack indicated by wavy arrows. Numbers refer to host pairs. V e r t i c a l bars represent standard errors of reported means. 10. Stumps; 11. Logs and downtrees.  34  were found i n May, 1978, and these levels generally decreased values i n July and August.  to lowest  Df trunks had much lower moisture levels  and varied less widely throughout the year ( F i g . 11). Peak moisture measurements generally coincided with high p r e c i p i t a t i o n levels ( F i g . 8). Sustained attack ( s o l i d arrows Figs. 10,11) showed a wide v a r i a t i o n between host categories.  Sustained attacks occurred on six  and two WH stumps and on one and s i x Df stumps i n 1978 and 1979, respectively ( F i g . 10). Five and three WH trunk and f i v e and two Df trunk had sustained attacks i n 1978 and 1979, respectively ( F i g . 11).  3.1.5  D i s t r i b u t i o n Around Trunks  S i g n i f i c a n t l y higher percentages of attacks were recorded on the r i g h t , l e f t and bottom than on the top quadrants i n WH 1 m long logs. No differences between these percentages could be demonstrated f o r Df. maximum number of attacks/m^ on WH and Df were 135.4 and 160.8 attacks/m^ respectively (Table V I ) .  3.1.6  Evaluation of Pinning E f f i c i e n c y  Pinning e f f i c i e n c y f o r the disks that were dissected was 70.0% (257/367) and 66.1% (214/324) respectively for WH and Df logs.  On WH  stumps 81.7% (428/524) of the attacks were pinned, while on Df stumps 63.0% (199/316) were marked. For the 1 m long logs, 77.6% (274/353) of the attacks on WH logs and 60.3% (140/232) of those on Df logs were pinned.  Overall pinning  e f f i c i e n c y for WH and Df combined was 70.8% (414/558).  The lowest  pinning e f f i c i e n c y f o r both hosts was recorded on the bottom quadrant  35  TABLE VI. D i s t r i b u t i o n of Gnathotrichus sulcatus attacks by quadrants on lm sections of Douglas-fir and western hemlock logs. UBC Research Forest, Maple Ridge, B.C. May-November, 1978 and March-October, 1979. N = 8 for each species.  Percent attack 2 Mean + S.D. —  Quadrant  1  2  Range  WH  Df  Top  13.3 + 9.4a  15.6 + 9.5a  Right  24.7+ 6.9b  Left Bottom  1  Attacks/m  WH  Df  0 -  80.8  0 - 62.0  28.1 + 17.4a  12.8-  92.4  0-160.8  28.2 + 4.8b  28.2 + 22.2a  17.2 - 101.2  0 - 87.6  33.6 + 10.1b  28.0 + 9.5a  8.4 - 135.4  4.8 - 78.0  Means followed by the same l e t t e r within each host not s i g n i f i c a n t l y different.  AN0VA table i n Appendix 3.  2  36  of logs where frass f e l l d i r e c t l y to the ground and so f a i l e d to accumulate and make the attack v i s i b l e , and i t was often d i f f i c u l t to observe these trunk surfaces d i r e c t l y .  3.2  HOST COLONIZATION BY ASSOCIATED SCOLYTID SPECIES 3.2.1  Dendroctonus pseudotsugae, the Douglas-fir Beetle  Two peaks of attacks were recorded. May and the second i n September.  The f i r s t after f e l l i n g i n  In both cases, logs sustained more  attacks than downtrees ( F i g . 12). After the f i r s t peak, the numbers of attacks decreased  and reached 4 attacks on downtrees and 16 attacks on  logs on August 18. There was a strong second peak of attacks on September 15. There were no attacks after October 13. No s i g n i f i c a n t differences i n t o t a l attacks between sites or between logs and downtrees were demonstrated (Appendix 4).  3.2.2  Scolytus unispinosus, the Douglas-fir Engraver  Attacks of this bark beetle started on June 9, and reached a peak of 302 on June 23. After this date, attacks decreased  and no  attacks were recorded after September 15 ( F i g . 13). S i g n i f i c a n t l y more beetles attacked downtrees than logs i n 1978 (Appendix 4).  A t o t a l of  469 attacks were recorded on s i t e 1 and 59 on s i t e 2, and 98% of the attacks recorded on s i t e 1 occurred on downtree No. 3.  On site 2, 48  were on downtree No. 7 and 9 on downtree No. 5. Attacks were concentrated material.  on the top quadrant of attacked  37  160 J  1 2 : D w i d r o c t o n u 8 pseudotsugaw  140. 120.  •  DOWNTREES  H  LOGS  100 80 60 40  o <  20  13: Q Ui  Scolytua uniaotnoaua  310 300. 1ltff 100J  OC UJ 03  2 3  90 80 70J 60 SO 40 30 20 10 26  JZL  M  Figures 12, 13:  n  n  n  23  21  18  15  13  J  J  A  S  O  1 9  7  8  Seasonal attack pattern of two bark beetles on Douglas-fir at the UBC Research Forest i n 1978. Maple Ridge, B.C. 12. Dendroctonus pseudotsugae. 13. Scolytus unispinosus.  38  3.2.3  Scolytus tsugae (Swaine) the Hemlock Engraver  Attacks started with two attacks on June 9 and reached a peak on July 7 for both downtrees and logs, after which they declined u n t i l no attacks were recorded on September 29 and beyond ( F i g . 14). number and range of attacks was  18.2  (3-41) and 70.0  and downtrees, respectively, which was 7% l e v e l (Appendix 4 ) .  significantly  Mean  (10-120) on logs d i f f e r e n t only at  For the bi-weekly periods, the only differences  appeared for the periods ending on June 23 and August 4, when s i g n i f i cantly more attacks were pinned on s i t e 1 than on s i t e 2 and on August 4, more S^. tsugae attacks were pinned on s i t e 2 than s i t e 1.  Total  attacks recorded on s i t e 1 and site 2 were 186 on 187 respectively.  3.2.4  Pseudohylesinus tsugae Swaine  Attacks started on June 9, 1978,  with a high l e v e l of attacks  from June 23 to August 4, decreasing u n t i l no attacks were recorded November 9.  When considering downtrees alone, the peak of attacks  e a r l i e r , on June 23, while for the logs the peak was August 18 ( F i g . 15). (14-161) and 104.5  was  reached only on  Mean number and range of attacks was  60.2  (6-324) for logs and downtrees respectively.  s i g n i f i c a n t differences between the number of attacks i n the two conditions were shown for any bi-weekly period (Appendix 4).  No trunk  Signifi-  cantly more attacks were pinned on s i t e 2 than on s i t e 1 for the periods ending July 23, August 4 and September 1.  on  39 14:  Scolytus  tsugae  CO  < I< O  111  u. O oc  •  DOWNTREES  £  LOGS  UJ CD  M 19  Figures 14, 15  7 8  Seasonal attack pattern of two bark beetles on western hemlock at the UBC Research Forest i n 1978. Maple Ridge, B.C. 14, Scolytus tsugae; 15, Pseudohylesinus tsugae.  40 3.2.5  Trypodendron lineatum ( O l i v i e r ) , the Striped Ambrosia Beetle  No attacks were recorded i n 1978 on either WH or Df.  In  1979  the i n i t i a l attack started on A p r i l 24, and reached a peak on May downtrees and logs.  1 for  Attack rates decreased steadily i n both downtrees  and logs u n t i l p r a c t i c a l l y no attacks were pinned from July through the end of the year ( F i g . 16).  No s i g n i f i c a n t differences were established  between sites or hosts i n the analysis of variance for total attacks per square meter (Appendix 5). were 4.2  3.3  (0-17.7) and 12.4  Mean number and range of attacks/m^  (0-43.5) for WH and Df, respectively.  ESTABLISHMENT SUCCESS OF Gnathotrichus sulcatus The percentages of successful establishment of G_. sulcatus over  two years were 82.0% and 35.5%  f o r WH and Df stumps, respectively.  Attack success was generally higher i n the second year.  In 1978  1979 the percentages of successful attacks recorded were 77.1% 82.0% for WH  and  and  stumps and 18.5% and 61.1% for Df stumps, respectively  (Table V I I ) . Out of 49 and 59 g a l l e r i e s covered on WH and Df trunks, respectively, 73.5% and 25.4% were successful over two years.  On a  yearly basis, success rates of 72.9% and 75.0% f o r WH trunks and and 85.7%  for Df trunks were achieved i n 1978 and 1979,  17.6%  respectively  (Table V I I ) . Similar rates of successful establishment were achieved i n the two trunk conditions for WH and Df. percentages of success were 75.0% 20.0%  (6/30) and 31.0%  For logs and downtrees the  (9/12) and 70.8%  (9/29) i n Df respectively.  (17/24) i n WH and Such results r e f l e c t  41  Trypodendron  1000.  en  lineatum  :  <•> 5 0 0 .  400. o  ^  WESTERN HEMLOCK  •  DOUGLAS-FIR  300. CL U. O 200. DC Ul GO Jg 1 0 0 .  J 2 13  15  12  10  7  A  M  J  J  A  1 9 79  Figure 16:  Total bi-weekly numbers of Trypodendron lineatum attacks pinned on western hemlock and Douglas-fir i n 1979 at the UBC Research Forest, Maple Ridge, B.C.  TABLE VII. Number and success of Gnathotrichus sulcatus attacks monitored with petri dishes on western hemlock stumps and trunks and Douglas-fir stumps and trunks i n 1978 and 1979, UBC Research Forest, Maple Ridge, B.C.  Western hemlock Stumps number  Succ. Unsucc. 1  Douglas-fir Trunks  Total  Succ. Unsucc. 1  Stumps Total  Succ. Unsucc. 1  Trunks Total  Succ. Unsucc. Total 1  1  5  0  5  1  5  6  0  0  0  5  2  7  2  7  1  8  4  3  7  3  6  9  1  9  10  3  8  1  9  5  1  6  2  5  7  1  7  8  4  5  0  5  6  0  6  0  0  0  0  2  2  5  4  2  6  5  1  6  5  5  10  3  5  8  6  5  1  6  5  1  6  5  0  5  5  5  10  7  2  4  6  6  0  6  0  7  7  0  6  6  8  5  0  5  4  2  6  1  6  7  0  8  8  Year Totals (percentage success f u l ) 1978  27  8  35  (77.1)  27  10  37 (72.9)  5  22  27 (18.5)  9  44  51 (17.6)  1979  14  1  15  (93.2)  9  3  12 (75.0)  11  7  18 (61.1)  6  1  7 (85.7)  Total  41  9  50  (82.0)  36  13  49 (73.5)  16  29  45 (35.5)  15  42  59 (25.4)  1  Defined as successful after producing frass for two weeks and producing four adults.  43  the steady sustained attacks on most WH during 1978, while f o r most Df sustained attacks were achieved only during the second year (Figs. 10, 11).  3.4  FRASS PRODUCTION S i g n i f i c a n t l y higher amounts of frass (FR) were recorded from  g a l l e r i e s on WH than from those on Df i n a l l host categories.  Signifi-  cantly more frass was produced from g a l l e r i e s on downtrees than from those on logs.  Generally higher frass production occurred on stumps  than on trunks (Table V I I I ) . Frass production was higher immediately  following gallery i n i t a -  tion.  The duration and length of frass production varied by attack  date.  Attacks i n the summer of 1978 produced lower amounts of frass  per week but the production was sustained throughout the spring and the summer of 1979 (Figs. 17-20). Attacks i n May 1979 produced larger quantities of frass for 6-10 weeks a f t e r which production rates declined rapidly ( F i g . 17-20). Frass was always white at the beginning of gallery construction, but a f t e r 5 weeks, on the average, i t was discolored by the presence of black fungal hyphae ( F i g . 3 ) . It became darker every week u n t i l no wood p a r t i c l e s were c l e a r l y v i s i b l e i n the f r a s s .  3.5  BROOD PRODUCTION 3.5.1  Stumps i n the F i e l d  Larger numbers of brood (BR) were produced on WH than on DF (Table IX).  44  TABLE VIII.  Mean t o t a l frass production from 147 g a l l e r i e s of Gnathotrichus sulcatus monitored on western hemlock and Douglas-fir stumps and trunks i n the UBC Research Forest, Maple Ridge, B.C. 1978-79.  Stumps No. g a l l e r i e s monitored  1,3  Trunks  1,3  mg/frass gallery  No. g a l l e r i e s monitored  mg/frass gallery  SITE 1  30  233.36a  37  130.26a  2  40  209.49b  40  142.48a  WH  40  313.84a  40  202.90a  Df  30  94.22b  37  65.00b  37  122.12b  40  140.17a  HOST  TRUNK CONDITION Logs Downtrees  Data transformed to X' = l o g ( X + 1) prior to analysis.  X  1 Q  S i g n i f i c a n c e levels indicated results of ANOVA using GENLIN, means followed by the same l e t t e r within each pair not s i g n i f i c a n t l y d i f f e r e n t , P <0.05.  2  AN0VA table i n Appendix 6.  3  0»  25 L 17: W E S T E R N  HEMLOCK  logs and downtrees 20  J  15 UJ UJ or  B-  10  UJ o. 0)  V  oc •Jt-  35  WESTERN  U- 3 0 O . 25  HEMLOCK  stumps  20 UJ  15 10  Z < UJ  5 A  Figures 17, 18:  S  O  N  M  A  M  J  J  A  S  O  N  1 9 7 8 1 9 7 9 Mean weekly frass production of g a l l e r i e s i n i t i a t e d at various times during 1978 and 1979 by Gnathotrichus sulcatus on western hemlock, at the UBC Research Forest. 17. Logs and downtrees, A - 5 attacks from June 2-June 30; B - 27 attacks from July 14-September 29; C - 5 attacks from May 1-June 5; D - 4 galleries on May 15. 18. Stumps, A - 26 attacks from June 2-July 7; B - 6 g a l l e r i e s from May 1-May 22; C - 6 g a l l e r i e s from May 22-June 5.  9:  O) E  * UJ  DOUGLAS-FIR logs and downtrees  20 -  UJ 15 .  £  DC 1 0 .  UJ Q.  (/>  5 .  1  v.. /  '*  J  x  ;•  CO  •-  <oc u.  i  stumps  u. 2 0  I  o  X  15  o  UJ 10  z  < UJ  5  A/  ••f  *L.T-\  5  j  j  A 1 9  Figures 19, 20:  S 7  8  O  N  M  A  M 1  J  J 9  7  A 9  Mean weekly frass production of g a l l e r i e s i n i t i a t e d at various times during 1978 and 1979 by Gnathotrichus sulcatus on Douglas-fir, at the UBC Research Forest. 19. Logs and downtrees, A - 8 attacks from Sept. 1Sept. 22; B - 6 attacks from May 1-May 22. 20. Stumps, A - 5 attacks from July 28-Sept. 1; B - 11 attacks from May 15-June 5, 1979.  47  TABLE IX. Brood production from 147 g a l l e r i e s of Gnathotrichus sulcatus monitored on western hemlock and Douglas-fir stumps and trunks i n the UBC Research Forest, Maple Ridge, B.C. 1978-79.  Stumps No. g a l l e r i e s monitored  1,3  Mean no. ^ brood/gallery  Trunks No. g a l l e r i e s monitored  1,3  Mean no. brood/gallery  2  SITE 30  11.6a  37  8.1a  40  6.4a  40  5.4a  WH  40  13.7a  40  10.7a  Df  30  37  2.3b  Logs  37  8.2a  Downtrees  40  5.4a  HOST  1.9b  TRUNK CONDITION  iData transformed to X' = l o g ( X + 1) prior to analysis. 1 0  2significance levels indicated results of ANOVA using GENLIN, means followed by the same l e t t e r within each main effect not s i g n i f i c a n t l y d i f f e r e n t , P <0.05. AN0VA table i n Appendix 6.  3  48  The peak number of attacks by  sulcatus i n 197 9 on s i t e 1  (Figs. 6, 7) coincided with peak brood production (Fig. 21).  On s i t e  2, the f i r s t peak of attacks coincided with high brood production but the f a l l peak of brood production was not matched by a peak of attacks at the same time (Figs. 6,7 and 22). Attacks covered i n early summer, June and early July 1978  (Figs.  23, 24) produced a major contribution of beetles to the spring 1979 flight.  In the case of WH stumps, brood started to emerge i n the same  year i n low numbers from September to November. however, 50% of the brood had emerged ( F i g . 24).  By June 5, 1979, Brood continued to  emerge from t h i s material throughout the summer and 90% had emerged by late August. Late summer attacks on Df stumps (July through October) i n 1978, produced low numbers of brood throughout the following summer with 50% of the brood being produced by August 7 and 90% by late August ( F i g . 27)  3.5.2  Trunks i n the F i e l d  Brood production was s i g n i f i c a n t l y higher on WH than on Df and there were neither differences i n the numbers of brood produced on each s i t e nor between brood production i n logs or downtrees (Table IX).  In  addition to higher brood production, WH trunks also had higher densities of attacks (Table IX). Attacks covered i n early and l a t e summer produced no brood i n the same year on either WH or Df.  Few beetles emerged i n the spring of  1979, and most of the brood was produced from the end of June to the end of August 1979 (Figs. 23,25,26).  For the early summer, 50% of the  180  21: Sitel  160 140. 120. 100 80 J 60 Q O O  OC  40  20 g *, g I  03  9  «P  22: Site 2  L.  o  IP  1 2 0  OC Ui 1 0 o CO  3  80  z  60 40  4  18 13 15 12 10 M  A  M  J 1 9  Figures 21, 22:  J  A 7  4  S  3  30  O  9  Total brood production g a l l e r i e s monitored i n from June 197 8 to June 21. Site 1, (N = 67).  from Gnathotrichus sulcatus the UBC Research Forest 1980, Maple Ridge, B.C. 22. Site 2 (N = 80).  231 W E S T E R N  >  Attack date:  UJ  5 GALLERIES  cc 2-0  <  |BP50-5-22  H E M L O C K logs and downtrees June 1 6 - 3 0 ,  1978  1-5 IBP90«902  o  10 oc UJ a 05 Q  o o  oc 00 u. 20 O oc UJ 1-5 CO Z  1  iii 241 W E S T E R N  HEMLOCK  Attack date:  stumps  J u n e 2 - J u l y 7,  1978  26 GALLERIES BP90=13-60  BP 50  •7 43  10  Z < 05 UJ  •  5  S  O  1 9  7  F i g u r e s 23,  24:  N M 8  JL J  M 1  9  Pi J  A 7  ihh,  S 9  Mean weekly brood p r o d u c t i o n from G n a t h o t r i c h u s s u l c a t u s g a l l e r i e s e s t a b l i s h e d on western hemlock i n June - e a r l y J u l y ( e a r l y summer). UBC Research F o r e s t , Maple Ridge, B.C. B P 5 0 and BPg are the f i f t y and n i n e t y p e r c e n t i l e s f o r cumulative brood p r o d u c t i o n . 23. WH t r u n k s . 24. WH stumps. Q  51  25:WESTERN HEMLOCK logs and downtrees ATTACK DATE - July 14-Sept. 29 1978 27 GALLERIES  RY  1-5.  UJ _J  B P s o  0-5.  1 I  I  <  7  7 8  BP00- 9-89 H  I  10.  . .  l A L i  O  cc UJ  i  OD  0.  ATTACK DATE - Sept. 1-22 1978 8 GALLERIES  1-5.  BPso. 6 73  BP90 = 10 09  O  cc 1 0 . CO u.  o  0-5.  cc UJ  m D Z Z  < UJ 5  1-5.  27: DOUGLAS-FIR stumps ATTACK DATE - July 28 - Sept. 1 1978 5 GALLERIES  BP 50.38 BP 90.6-4  10 05  JL_J M  Figures 25-27:  M  J  A  1  9  9  MLi  Mean weekly brood production from Gnathotrichus sulcatus g a l l e r i e s established on WH and Df from late July to October, 1978, UBC Research Forest, Maple Ridge, B.C. 25. WH stumps. 26. Df trunks. 27. Df stumps.  52  brood was out by July 24 ( F i g . 23), while for the late summer attacks 50% was out by August 7 for WH (Fig.  25) and August 14 for Df ( F i g .  26). For  May 1979 attacks, 50% of the brood emerged by September 4  for WH (Figs. 28, 29) and August 28 for Df (Figs. 30, 31), indicating that, as for the stumps, the spring attacks made a major contribution of brood to the peak populations i n the f a l l .  3.5.3  Logs i n Laboratory  Successful g a l l e r i e s were established on three WH logs (3, 4 and 5 g a l l e r i e s ) and one Df l o g (4 g a l l e r i e s ) (Table X). On both hosts, there was steady brood production over time, with the  l a s t brood emerging on day 192 ( F i g . 32).  Higher numbers of brood  were produced on Df than on WH (Fig. 32). There were no s i g n i f i c a n t differences between these two hosts for  either length of gallery or depth of penetration into the logs. The four successful g a l l e r i e s on Df produced 56 males and 57  females, with 3 males and 2 females being the f i r s t to emerge from the galleries. logs.  For WH, 12 out of 31 g a l l e r i e s were successful i n the three  These g a l l e r i e s produced 46 males and 48 females, with 8 males  and 5 females being the f i r s t to emerge.  One gallery produced 2 males  on the f i r s t day. For  WH, the mean time to emergence the f i r s t brood was 76.6 +  13.9 days after the female was put into the gallery. time to f i r s t emergence was 90.0 + 10.42 days.  For Df the mean  53  [28i WESTERN HEMLOCK logs and downtrees ATTACK DATE - May1-June5 1979 3 >•  DC UJ  ml  I  5 GALLERIES  A  2 1  *  -J  <  o  cc u 0. Q  O  **n  2» WESTERN HEMLOCK stumps ATTACK DATE - May 8-June 12 1979 I 13 GALLERIES 3  u.  O  OC UJ CD  BPsorfO-08 BP9CMS-32  2 1  o  OC 03  •  A  30> DOUGLAS-FIR logs and downtrees ATTACK DATE - May 1-22 1979 6 GALLERIES 3 I  BPM-877  I  2  BP90J4-35  1  JL Z Z  < HI 2  3  31: DOUGLAS-FIR stumps ATTACK DATE - May 15-June 5 1979 11 GALLERIES  BPM>*-97  BP9O-13-01  2  M  J 1  Figures 28-31:  J 9  A 7  Mean weekly brood production from Gnathotrichus sulcatus g a l l e r i e s established on WH and on Dr i n May-June, 1979. UBC Research Forest,, Maple Ridge, B.C. 28. WH logs and downtrees. 29. WH stumps. 30. Df logs and downtrees. 31. Df stumps.  54  TABLE X.  Total numbers of brood produced and sex ratio from Gnathotrichus sulcatus g a l l e r i e s established on western hemlock and Douglas-fir under laboratory conditions, UBC 1979.  Sex r a t i o Gallery  1  WH 1 M  F  WH 2 M  F  WH3 M  F  M  Df 1  WH  Df  F  M:F  M:F  A  8  1  2  6  3  2  19  19  1.44  1.00  B  2  5  10  6  3  3  17  14  1.07  1.21  C  2  5  5  3  3  6  11  9  0.71  1.22  D  -  4  3  2  4  6  15  0.86  0.4  E  -  -  -  -  2  4  -  -  Totals  12  11  21  18  13  19  53  57  X  4.0  3.7  5.2  4.5  2.6  3.8  13.2  14.2  S.E.(M)  1.0  1.3  1.7  0.9  2.4  0.7  3.0  2.0  Results of the analysis of variance i n Appendix 7. - No brood were produced.  0.5 0.96  0.93  30 .  > CC  28.  UJ 2 6 . _J 2 4 . _l  < o  22 .  o o o  16 .  cc 2 0 . Ul OL 18 .  cc 14 . CO u. 12 .  o  10. 8  UM  D C UJ' CO  6  z z  4  <  UJ  z  2 70  80 DAYS  Figure 32:  90  100  AFTER  110 FEMALE  120  130  140  WAS PLACED  150 IN  160  180  190  200  GALLERY  Cumulative mean Gnathotrichus sulcatus brood production i n western hemlock and Douglas-fir logs i n laboratory conditions, Faculty of Forestry, UBC. Numbers in parentheses indicate number of successful g a l l e r i e s i n each host l o g .  210  56  Oviposition occurred i n groups on the l a t e r a l g a l l e r i e s near to the main gallery but some g a l l e r i e s had pupal niches i n the main branch ( F i g . 33).  These side g a l l e r i e s continued for several centimeters  without any pupal niches.  On WH,  the pupal niches were concentrated on  14.3% of the t o t a l length of g a l l e r i e s , the comparable figure for Df was 28.5%.  3.5.4  Sex of Emerging Beetles  The sex r a t i o of beetles reared i n the laboratory was not different  from 1:1 i n both hosts either for t o t a l or f i r s t emerging  beetles (Table X). Of the 103 g a l l e r i e s c l a s s i f i e d as successful i n the f i e l d work, 34 were on WH stumps.  trunks, 38 on WH  stumps, 15 on Df trunks and 16 on Df  F i r s t emerging beetles had a sex ratio of 1.16 males : 1  female, not s i g n i f i c a n t l y different Test P <0.05).  from a 1:1 sex r a t i o (Chi-square  Sex ratio of t o t a l brood was  1.09 males : 1 female  (Table XI).  3.6  GALLERY DISSECTIONS 3.6.1  Stumps  There were no s i g n i f i c a n t differences i n the number of egg niches (EN) per gallery either by s i t e or host (Table XII).  For the  development p r o f i l e ( F i g . 34) of G. sulcatus the egg niches represented 3.0% and 26.8% of the t o t a l number of niches (EN and pupal niches) for WH and Df respectively. The number of pupal niches (PN) was  s i g n i f i c a n t l y higher for WH  than for Df and no differences between the two sites were found.  Flo„rP 33Figure 33.  Schematic plan of Gnathotrichus sulcatus gallery in western hemlock two Schematic^ -^ET5f egg niches (EN), pupal niches (PN), N o t e  t h e  pT  dead beetles (D), and l i v e beetles (A). Ul  58  TABLE XI. Sex ratios of Gnathotrichus sulcatus emerging from western hemlock and Douglas-fir trunks and stumps f e l l e d May 1978 i n the UBC Research Forest, Maple Ridge, B.C.  Total emergence  F i r s t week* Host  Number of galleries  M  F  Sex r a t i o M:F  M  F  Sex ratio M:F  WH stumps  37  36  23  1.56  354  309  1.15  Df stumps  16  15  13  1.15  115  99  1.16  WH trunks  34  32  35  0.91  264  268  0.99  Df trunks  15  14  16  1.14  106  93  1.14  i G a l l e r i e s often produced more than one beetle during the f i r s t week.  59  TABLE XII.  Mean egg niches (EN), pupal niches (PN) length of g a l l e r y (LG) and depth of penetration (DP) of Gnathotrichus sulcatus g a l l e r i e s on western hemlock and D o u g l a s - f i T T t ^ p T and trunks. UBC Research Forest, Maple Ridge,' B.C.  monitored  niches  30  0.6a  14.0a  31.2a  5.2a  40  1.1a  8.8a  28.4a  5.3a  40  0.5a  16.2a  38.2a  7.1a  30  1.5a  4.1b  18.1b  2.8b  37  1.4a  10.3a  28.2a  4.4b  40  1.3a  7.2a  29.4a  5.3a  40  1.6a  14.1a  41.6a  7.0a  37  1.1a  2.9b  15.0b  2.5b  37  1.2a  10.0a  27.2a  4.7b  40  1.4a  7.5a  30.3a  5.0a  STUMPS Sites:  Hosts:  1 2 WH Df  TRUNKS Sites:  1 2  Hosts:  WH Df  Condition: Logs Downtrees  l a t a transformed D  to X' - l o g ( X + 1) prior to analysis. 1 0  AN0VA table i n Appendix 8 and 9.  3  M E A N IN)  PER a> j  G A L L E R Y 09  _L_  O J  rO  00  0>  09 C 1  CD OJ -P-  ••  m >f E G G N I C H E S  3  cn rr C  (B «  3 3 •a cn ro era  ft, (TO  3 a. 3—u T  rr  3" C <T> 3 ?r cn -C3 » -a 3 MIa. o 3 3 n a 3" i-h (0 cn 93 rr 3 C a. 3 "CO 3 o* o S> o 3 o. a. 1  (0 >•»  m c/> H m  c 3  LARVAL-PUPAL  0)  BROOD  33 z  m  o to  O o  a "  i  +  II  o  3  9  CD (0  it o C &. 3 c ?r o CO r r •  O  3  a 08  70  O  ft Cu l-f  rr  <COT> 3W 3" O  o•y ri tr TS  n o 3" i(D-t CCO  CO rr »  •a i— fD  CO  c ow  C  o o c o  •o  Q. M cra rt) (Tl  i  fD CO  • o  3  00  o  m  0)  a  *  (0  I  CCO  r-t H-  II  w  o  r" >  rr  1  CD  09  (0  so era  «  1  O  o i-h  3 »* "i (D (D 0)  +  3  II  o  •a n  rr  -I  NICHES  1 II W  61  Fewer brood developed than the number of pupal niches present, i n d i c a t ing l a r v a l and pupal m o r t a l i t y . The difference ranged from 15.4 to 53.7% of the t o t a l number of pupal niches on WH and Df, where mean number of pupal niches found was 16.2 and 4.1 per gallery on each of the two hosts, respectively (Table XII).  No parasites, diseases or  predators were captured, but i n several cases, dead pupal or callow adults were found i n the pupal niches. G a l l e r i e s were longer and deeper on WH than on Df (Table X I I ) . Mean length of g a l l e r i e s (LG) and depth of penetration (DP) for WH were 38.2 and 7.1 cm while f o r Df they were 18.1 and 2.8 cm respectively.  3.6.2  Trunks  No differences In number of egg niches could be demonstrated either f o r s i t e , host or condition. Mean number of egg niches were 1.6 and 1.1 for WH and Df respectively (Table XII). There was a s i g n i f i c a n t l y higher number of pupal niches i n WH than on Df, with no s i g n i f i c a n t differences related to s i t e or condition (Table X I I ) .  The number of pupal niches that f a i l e d to  develop a brood represented 24.1% and 20.7% of total pupal niches i n WH and Df respectively ( F i g . 34). The mean number of pupal niches found was 14.1 and 2.9 for WH and DF, respectively. Longer and deeper g a l l e r i e s were found i n WH than i n Df trunks. The g a l l e r i e s had mean lengths of 41.6 cm and 15.0 cm, and depths of 7.0 cm and 2.5 cm f o r WH and Df, respectively (Table XII).  62  3.6.3  Relationships  Between Brood, Frass and Length of  Galleries S i g n i f i c a n t relationships were found between brood and frass, brood and g a l l e r y length and frass and gallery length for both WH and Df trunks and stumps (Table XIII). Examination of the gradients of the regression some consistent  l i n e s suggest  relationships between the measured variables.  Highest  number of brood per cm of g a l l e r y was recorded for WH trunks and stumps, one beetle for each 2.38 and 2.86 cm of g a l l e r i e s respectively. Additionally, one beetle was recorded for every 12.35 and 22.73 mg of frass for WH trunks and stumps, respectively. was found that 1 mg of frass was equivalent  For the same species, i t  to 0.21 and 0.12 cm of  gallery for stumps and trunks, respectively. G a l l e r i e s i n Df had much lower productivity on a per cm gallery basis than those i n WH, with one beetle for each 16.95 and 27.03 mg of frass f o r trunks and stumps, respectively.  Additionally one beetle was  found f o r each 5.7 and 8.3 cm of gallery for trunks and stumps, respectively.  For frass and length of g a l l e r i e s i t was found that 1 mg of  frass was equivalent  to each 0.22 cm and 0.23 cm of g a l l e r i e s f o r Df  trunks and stumps, respectively.  3.6.4  Aspects of Gallery Construction by Gnathotrichus  sulcatus  at Different Periods of Time A f t e r F e l l i n g . A t o t a l of 269 g a l l e r i e s , approximately equally distributed between logs and downtrees, at s i t e 1 and s i t e 2 and by host were dissected.  species,  TABLE XIII.  Host  Relationships between brood production, frass production and length of g a l l e r i e s of Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps and trunks in the UBC Research Forest, Maple Ridge, B.C.  Brood and frass  category  WH stumps  Br = 0.044 F r ; * *  WH trunks  Brood and length  r = 0.51  Fr = 8.06 LG**; r = 0.71  Br - -5.81 + 0.081 Fr**; r = 0.81  Br = -6.82 + 0.42 LG**; r = 0.68  Fr = 4.86 LG**; r = 0.78  Df stumps  Br = -1.49 + 0.037 Fr**; r = 0.80  Br = 0.12 LG**;  r = 0.55  Fr - 4.39 LG*;  Df trunks  Br = -1.54  Br = 0.175 LG**;  r = 0.49  Fr = 4.47 LG**; r = 0.80  1  r = 0.72  2  + 0.059 Fr**; r = 0.84  iSignificance levels of the regression indicated: When the constant through zero.  2  Br = 0.35 LG;**  Frass and length  r = 0.59  * = P <0.05; ** = P <0.01.  i s not present i n the equation, i t was not s i g n i f i c a n t and the regression was put  On  64  There were no differences for s i t e , host, condition or month i n numbers of egg niches when analysing by host.  No differences were  found between s i t e s , conditions or months for WH, and the only difference f o r Df was the higher number of egg niches i n logs than i n downtrees.  Mean number of egg niches per month showed a high  v a r i a b i l i t y i n each host ( F i g . 35). S i g n i f i c a n t l y higher numbers of pupal niches were recorded on WH than on Df, 7.21 and 4.87, respectively.  Numbers of pupal niches  ranged from 3.12 to 9.55 per gallery per month ( F i g . 36). When considering each host separately no difference appeared  for s i t e or  month, but s i g n i f i c a n t l y more pupal niches were recorded f o r logs than for downtrees on WH (Table XIV).  For Df alone, no differences  appeared  for month and condition, but s i g n i f i c a n t l y more pupal niches were recorded for s i t e 1 than s i t e 2 (Table XIV). On WH, 141 g a l l e r i e s were opened with 83 showing pupal niches, while 58 had no pupal niches.  For Df, 128 g a l l e r i e s were dissected,  with pupal niches i n 55 g a l l e r i e s , but none i n 73 others.  The number  of g a l l e r i e s with pupal niches was higher i n WH than on Df from the beginning (Table XV).  For WH the lowest proportion of g a l l e r i e s with  pupal niches was 38.2% i n June 1978.  A l l other months except August  1978 had showed more g a l l e r i e s with pupal niches than without them. For Df, g a l l e r i e s i n i t i a t e d i n June, 1978, had no pupal niches.  Only  i n the summer of 1978 were there more g a l l e r i e s with pupal niches than without them (Table XV).  35: EGG NICHES  36 PUPAL NICHES  '"WESTERN HEMLOCK DOUGLAS- FIR  Figures 35, 36: Mean number of egg and pupal niches of Gnathotrichus sulcatus on western hemlock and Douglas-fir trunks from June 1978 to October 1979. UBC Research Forest. 35. Egg niches. 36. Pupal niches.  TABLE XIV.  Egg niches, pupal niches, length of g a l l e r i e s and depth of penetration of Gnathotrichus sulcatus on western hemlock and Douglas-fir trunks over 13 months. UBC Research Forest, Maple Ridge, B.C. 1978-79.  Mean Frequency  gallery  parameters  WH  Df  DP (cm)  LG (cm)  PN  EN  1  Df  WH"  Df  Df  WH  WH/Df  Total  WH"  1  58/62  120  0.98a  1.00a  7.43a  6.69a  24.94b  17.22a  4.85b  2.54a  2  83/66  149  0.88a  0.79a  7.06a  3.15b  28.60a  14.54a  5.68a  2.37a  WH  141  0.92a  Df  128  SITE  HOST  2  2.45b  15.84b  4.87b  0.89a  5.34a  27.09a  7.21a  CONDITION Logs  73/63  136  1.07a  1.40a  9.56a  3.93a  27.68a  Downtrees  68/65  133  0.76a  0.40b  4.68b  5.75a  26.67a  16.Ola  5.16a  2.32a  15.67a  5.53a  2.58a  ^Means followed by the same l e t t e r within each host, s i t e , condition and/or month combination not s i g n i f i c a n t l y d i f f e r e n t . 2  Data on host analysis were taken from the combined western hemlock plus Douglas-fir a n a l y s i s .  ^Results of the analysis of variance in Appendix 10. *Re suits of the analysis of variance i n Appendix 11.  TABLE XV.  Number of Gnathotrichus sulcatus galleries with and without pupal niches, and mean number of pupal niches on western hemlock and Douglas-fir trunks over 13 months. UBC Research Forest. 1978/79.  Douglas-fir  Western hemlock Month  1 With PN  No PN  Total PN  Mean 1  2 Mean 2  1 With PN  No Total PN _ PN  Mean 1  2 Mean 2  1978  June July August September October  5 8 6 7 6  8 7 8 6 4  53 81 97 88 100  10.6 10.1 16.2 12.6 16.7  4.1 5.4 6.9 6.8 10.0  0 4 1 6 5  4 4 11 9 9  0 24 4 75 28  0 6.0 4.0 12.5 5.6  0 3.0 0.3 5.0 2.0  1979  March April May June July August September October  6 6 9 8 9 7 3 3  2 2 5 7 4 3 1 1  52 84 111 171 66 73 19 24  8.7 14.0 12.3 21.4 7.3 10.4 6.3 8.0  6.5 10.5 7.9 11.4 5.1 7.3 4.7 6.0  3 3 4 7 8 7 4 • 3  3 5 10 7 4 2 3 2  41 44 73 120 128 69 16 46  13.7 14.7 18.2 17.1 16.0 9.9 4.0 15.3  6.8 5.5 5.2 8.6 10.7 7.7 2.3 9.2  83  58  73  668  Total  1019  55  ^ o t a l number of pupal niches divided by the number of g a l l e r i e s with pupal niches. T o t a l number of pupal niches divided by the total number of g a l l e r i e s (with and without pupal  2  niches (PN)).  68  G a l l e r i e s were s i g n i f i c a n t l y longer on WH than on Df but no differences appeared f o r s i t e or condition.  For WH and Df combined  there were shorter g a l l e r i e s produced by June, 1978 attacks than i n any other month, but no difference could be demonstrated i n each host alone (Table XIV). Considering WH alone, the only s i g n i f i c a n t value was longer g a l l e r i e s on s i t e 1 than on s i t e 2, but no differences appeared f o r condition or month.  For Df alone no differences appeared either for  s i t e , condition or month.  Except f o r July, 1979, WH had consistently  longer g a l l e r i e s than Df ( F i g . 37). There were s i g n i f i c a n t l y deeper g a l l e r i e s i n WH than i n Df. Mean depth of penetration ranged from 3.56 to 4.49 cm among months ( F i g . 38) when considering WH alone, no differences appeared either for condition or month, but deeper g a l l e r i e s were recorded on s i t e 2 than on s i t e 1.  The depth of penetration on WH ranged from 3.91 to 6.01 cm.  For Df alone, no differences appeared either for s i t e , condition or month.  As f o r this l a s t factor, depth of penetration ranged from 1.67  to 3.10 cm deep; mean g a l l e r y depth exceeded 3 cm only i n July 1978 (Fig. 38).  3.7  PRIMARY ATTRACTANTS TESTS 3.7.1  Western Hemlock Stimuli  The sulcatol-baited traps were removed at the end of the f i r s t week because they were catching the majority of the beetles (2721/2747) and thus probably reduced catches i n those traps baited with host materials.  Results taken from the l a s t two weeks were not used i n the  Figures 37, 38:  Gnathotrichus sulcatus gallery parameters on western hemlock and Douglas-fir trunks from June 1978 to October 1979. UBC Research Forest. 37. Length of g a l l e r i e s . 38. Depth of penetration.  70  analysis because only 3 beetles were caught i n the fourth week and none in the l a s t week.  There were s i g n i f i c a n t differences between catches  by week (Appendix 12) with catches i n the third week being lower  than  in the f i r s t two weeks. The t o t a l catch i n three weeks to traps baited with the host stimuli was 56 beetles, of which 33 were caught i n sapwood-baited traps, s i g n i f i c a n t l y more for both sexes (P <0.01) than i n any other treatment  (excluding sulcatol-baited traps) (Table XVI).  Sulcatol-  baited trap results were not included i n the analysis because the r e l a t i v e l y large catches i n these treatments would introduce v a r i a t i o n into the analysis which could prevent differences between host stimuli being established. The interactions week x block and block x treatment were s i g n i ficant (Appendix 12).  Such interactions r e f l e c t block v a r i a b i l i t y (P  <0.01), with low catches i n block 5 during week 3 contributing greatly to the s i g n i f i c a n t week by block interaction and the low catch of treatment 4 (heartwood) i n block 3 contributing to the s i g n i f i c a n t block by treatment  interaction.  The number of beetles caught per block varied widely.  For  example, 23 beetles (13 males:10 females) were captured over three weeks i n block 3 while only 5 males were caught i n block 1.  These  results may have been a consequence of uneven d i s t r i b u t i o n of infested host material throughout  the forest.  Only 3 and 4 beetles were caught, respectively, i n the f i r s t and the second experiment i n 1979.  71  TABLE XVI. Numbers of Gnathotrichus sulcatus caught i n response to the odours of bark, sapwood and heartwood of western hemlock and i n bark, phloem, sapwood and heartwood of Douglas-fir. Point Roberts, WH. June-July, 1978.  Number of beetles captured Stimuli  Male  Female  Total  Percent of moisture content  Mean weight stimulus per trap  Beginning  End  (g)  Western hemlock experiment »-> 2  Blank control  2b  lb  3b  Bark and phloem  8b  Ob  8b  20a  13a  8b  Blank control Bark  —  —  477.0  59.5  18.1  33a  417.5  81.5  19.2  4b  12b  390.0  42.8  18.8  Ob  Ob  Ob  -  lb  Ob  lb  403.3  19a  8a  27 a  673.6  Sapwood  2b  lb  3b  422.0  65.6  Heartwood  Ob  Ob  Ob  361.8  28.7  Sapwood Heartwood  Douglas-fir experiment ,5 3  Phloem  -  33.1 -  95.3  •^Totals followed by the same l e t t e r within each column i n each experiment, not s i g n i f i c a n t l y d i f f e r e n t , Neuman-Keul's Test, P <0.05. 2  T o t a l catch of f i v e blocks run over three weeks.  3  C a t c h i n one week, i n three blocks.  ^Moisture content of fresh materials. AN0VA table i n Appendix 12.  5  72  3.7.2  Douglas-fir Stimuli  Only two beetles were caught i n block number 1 and none i n block number 2.  Since such numbers were too low to provide meaningful data  on treatment preferences, these two blocks were excluded and the analyses of variance were done using data from the three remaining blocks.  There were no s i g n i f i c a n t differences between numbers of  beetles captured i n these blocks. The numbers of beetles caught by the phloem stimuli were s i g n i f i c a n t l y higher f o r males, females and total beetles (Table XVI) than for any other treatment.  Out of 22 males caught, 19 were to this  stimulus, and of the 9 females, 8 were caught i n the same treatment (Table XVI). Again, s i g n i f i c a n t l y more males than females were caught (Appendix 12), consistent with the role of the male as the pioneer beetle.  3.8  TOTAL BROOD EMERGENCE PATTERN The overall emergence pattern from the 16 spring-felled trunks  and their stumps showed a few brood emerging i n September and October, 1978 from WH stumps attacked the previous June.  Most of the brood  emerged i n 1979 when a steady increase i n brood emergence was recorded from July, reached a peak i n August and decreased through October ( F i g . 39).  Attacks from March to June, 1979 produced most of their brood i n  the f a l l of the same year, but 5,523 beetles were produced i n 1980, along with 25,477 beetles from June to October, 1979 attacks (Table XVII).  73  30  —-  Total a t t a c k s ( x 2 )  Brood from attacks  ~25t o o o w  •  June  •  July - October  20f  initiated:  19 78  March - June  1 9 7 8 1 9 7 9  0  N M  A  1 9  Fieure 39:  M  J  8 0  Estimates of total monthly attacks and brood production during 1978 through 1980 for western hemlock and Douglas-fir host material f e l l e d i n May 8, 1978. UBC Research Forest, Maple Ridge, B.C.  TABIE XVII.  Brood production p r o f i l e from the estimated 16,049 Gnathotrichus sulcatus attacks on western hemlock and Douglas-fir stumps and trunks from June, 1978 to June, 1980. UBC Research Forest, Maple Ridge, B.C.  Early 1978  Date of attack  Late 1978  545  Estimate of t o t a l attacks  Early 1979  Early 1978  Late 1979  Early 1978  Early 1978  777  206  3,537  2,056  129  0 0 0  0 0 0  1,122  Df Trunks  Df Stumps  WH Trunks  WH Stumps  Late E a r l y 1978 1979  Early 1978  Late 1978 1,054  323  328  10  0 0 0  0 0 0  0 0 0  0 0 0  z s  0 11 22 33 109 142* 65 0  0 0 0 248 955* 775 152  0 0 0 0 0 0 0  0 0 53 53 766 818* 555 156  153  382  0 0 0 0  0 0 0 0  Early 1979  Total  2,579  12,666  Estimate of Total Brood Production (by month) 1978  s 0 N  1,,236 250 0  1979  M A  177 150 1,, 8 6 3 « 478 1,,382 774 277 119  H  J J A S 0  5 ,706  Total 1980  0 0 0  M  2  57 0 57 920 4,,259* 3,,782 2,,158 545  0 0 0 195 4,395 5,029* 1,293 10,912  11, ,778  50 0 1,450* 144  M A M J Total  Total brood from June-October 1979 a t t a c k s 3  T o t a l brood T o t a l attacks Brood per parent  1978 1979 combined  3,383  1  Additional  2  * = peak  uf brood  3  No  dishes  petri  13 0 92 66 241* 184 38 13  attacks  June-October,  production  f o reach  set o natt.irks  90 0 90 1,463 6,772* 6,014 3,431 867  647  18,727  0 0 0 0  0 0 0 0  0 0 0 186 4,699* 4,135 1,879 10,899 124 62 2,752* 248  2,130 111 27 97* 29  0 0 0 0 0  2,401 0 0 0 0  236 250 0 0 0 0 286 6,590* 4,915 707 12,498  337 161 2,177 3,013 14,444 28,353* 21,378 5,731 76,080  143 143 143 0  428 232 4,442* 421  1,644  3,186  264  429  5,523  8,710  3,005  3,278  10,484  25,477  38,750 2,983 5.2 8.1 6.5  36,464 6,466 2.6 3.1 2.8  6,207 1,236 0.6 3.6 2.5  25,812 5,364 1.1 2.7 2.4  107,080 16,049 3.3  1979. attack  fr.™ l l . i s  period.  ,.eri...l,  estimales  b.ise.l  »ii d i s k  dtssu.-t i o n s .  4^  75  The number of beetles representing attacks, i . e . corrected number of attacks pinned x 2, was higher than brood produced throughout 1978 and up to June 1979.  From July to October 1979, the brood produc-  tion was many times higher than the number of beetles representing attacks ( F i g . 39). From 1978 to 1980 a t o t a l of 107,080 brood were produced from an estimated t o t a l 16,049 attacks, which gives an average of 3.3 beetles produced for every parent. per  In a l l four host categories more beetles  parent were produced from 1979 attacks than from 1978 attacks.  76  4.0  4.1  HOST SELECTION AND An estimated  DISCUSSION  COLONIZATION BY Gnathotrichus  sulcatus  t o t a l of 16,049 attacks were recorded  on the test  materials after correcting the total pinned attacks with the pinning e f f i c i e n c y values obtained from debarked trunk and stump samples. Attempts to establish f i e l d - c o l l e c t e d brood (J. sulcatus on hosts of varying ages i n the laboratory were largely unsuccessful. hypothesized  that the beetles may  have required f l i g h t exercise before  entering a host selection/establishment behavior suggested for T. lineatum (Graham, 1959) 1966).  It was  pattern as has been  and ID. pseudotsugae (Atkins,  The more rapid colonization of s i t e 2 i n 1978  suggested that  the site was closer to the f l i g h t path or to the source of dispersing (J. sulcatus. The effect of host odour i s a close range one and may an arrestant than an attractant as was  indicated by the low catch of  G_. sulcatus to host materials (approximately compared to sulcatol (Section 3.7).  be more of  1% of total catch) as  In addition, primary attractants  are also important to females as demonstrated by the catch of 8 and females, compared with 19 and 20 males to WH respectively.  sapwood and Df phloem  This showed that the females were also attracted by host  v o l a t i l e s although to a lesser degree than the pioneer beetles. The more l i k e l y way material i s :  13  f o r G_. sulcatus to find suitable host  f i r s t , random f l y i n g , which disperses the beetles and  77  gives them f l i g h t exercise; second, close range orientation to host material releasing primary attractants; and t h i r d , establishment of secondary a t t r a c t i o n i n suitable hosts which w i l l attract beetles of both sexes to ensure f u l l host u t i l i z a t i o n . Sustained attacks occurred sooner on WH than on Df which suggested that attacking beetles were able to establish g a l l e r i e s , produce pheromone, and maintain secondary a t t r a c t i o n more easily on WH stumps and trunks.  The more rapid colonization of WH by G_. sulcatus  may be related to the fact that the source of primary a t t r a c t i o n Is located i n the sapwood, the area of g a l l e r y formation, whereas i n Df the primary attractants apparently emanate primarily from the phloem (Table XVI).  In the l a t t e r case the beetle can f l y to an a t t r a c t i v e  but, perhaps unsuitable host, thus delaying the establishment of secondary a t t r a c t i o n i n Df.  This hypothesis i s supported by the high  f a i l u r e rate of attempts to establish "successful" g a l l e r i e s i n Df trunks and the high number of short unproductive g a l l e r i e s (Table XV). Better host s u i t a b i l i t y of WH was demonstrated by higher  initial  success rates (Table VII) and higher brood production (Table IX) than on Df. Preference shown by (3. sulcatus for Df over WH reported by McLean and Borden (1977a) may  have been a result of synergist effects  between Df host attractants and the sulcatol used to bait the logs. Previously, G_. sulcatus was  shown to attack and breed more readily i n  WH green lumber than i n Df lumber (McLean and Borden 1975b). The single peak of attack i n 1978  (Figs. 6,7) indicated that the  trees were probably f e l l e d too l a t e f o r colonization by any minor  78  spring f l i g h t , while the number of attacks increased to a peak i n late summer.  This i s consistent with previous results on spring-felled host  material i n this area (McLean and Borden 1977a). hypothesized  These authors  that their host materials were unsuitable for attack in a  f a l l f l i g h t period.  My data have demonstrated that there are as many  attacks during the second year as i n the f i r s t and that the lack of a f a l l f l i g h t was more related to the lack of suitable host material during the May  attack period that would have produced brood by the  fall  than any host s u i t a b i l i t y factor per se. Higher numbers of attacks on downtrees supported  the i n i t i a l  hypothesis that downtrees would be attacked more than the logs, but disagreed with Johnson (1964) who  reported higher attacks on logs.  Later work by the same researcher f a i l e d to demonstrate any difference in attack rate on logs and downtrees (Johnson and Zing 1969).  In the  forest, downtrees created by the action of wind, snow or i c e are the natural hosts for ambrosia beetles.  These downtrees retain their crown  most of the time during the f i r s t months.  As an aid to increased  s u r v i v a l , G. sulcatus should be able to locate and colonize such trees. The response to downtrees i n this study supported  the possible explana-  tion that passive l i b e r a t i o n of host attractants was water l o s t by the needles. unbaited  increased with  This theory could be tested by placing  sticky traps near the top and near the butt of downtrees.  Moisture content i n downtrees dropped more rapidly than that i n logs, especially for WH  ( F i g . 11).  The continual loss of water may  have f a c i l i t a t e d the transport and evaporation of primary attractants.  79  The stumps, logs and downtrees i n this experiment probably never lost water to a degree at which dryness would affect survival of brood. McLean and Borden (1977b) showed that G. sulcatus readily attacked boards with a moisture content of 62.3% than 46%.  but did not attack boards d r i e r  A lack of moisture has also been suggested as a factor  l i m i t i n g attack by T. lineatum (Kinghorn  1956).  Attack densities on logs and downtrees did not reach the mean l e v e l of 182.3/m^ recorded on stumps. downtrees may  This suggested that logs and  have had a lower n u t r i t i o n a l value than stumps for fungal  growth, that they became non-attractive more quickly, or that phagostimulant production ceased at an e a r l i e r stage. downtree 5 sustained 53.7  and 6.1  attacks/m  respectively, while WH log 8 had 61.4 same periods.  2  For example, WH  i n 1978 and  and 12.6  attacks/m  1979, 2  f o r the  This indicates that logs and downtrees might have a  similar population density when attacks decrease or cease.  This  decrease of attacks agreed with past findings that G^. sulcatus does not continue attacking material already heavily infested (Prebble and Graham 1957;  McLean and Borden 1977a).  This was  further supported  in  t h i s study by an apparent switch from one host to another that occurred a f t e r June 26, 1979 when fewer beetles attacked the heavily infested WH stumps and trunks.  Borden and Stokkink (1973) suggested that a switch  off or masking mechanism might occur i n G_. sulcatus as has been reported for T. lineatum (Nijholt 1973). may  The high number of attacks  have resulted i n high l e v e l s of pheromone production that might  80  have repelled other beetles. bark and sapwood may  A l t e r n a t i v e l y , microbial degradation of  have rendered  these stumps and trunks unsuitable.  The lower attack rate i n the top quadrant for WH may  have  reflected dryness, high temperatures or higher l i g h t i n t e n s i t y (McLean and Borden 1977a).  The l a s t two are p a r t i c u l a r l y important  for this  beetle, because i t i s a crepuscular species for which f l i g h t i s inhibited by high l i g h t i n t e n s i t y (Daterman et a l . 1965); thus i t w i l l l i k e l y prefer shaded areas.  Other ambrosia beetles, such as J_.  lineatum have reduced attack rates on exposed logs (Dyer 1963a).  No  differences between quadrants could be demonstrated i n Df because t h i s species had only two trunks d i r e c t l y exposed to the sun, while WH  had  f i v e trunks, s i m i l a r l y exposed, i n the samples taken. The lowest pinning e f f i c i e n c y was because of greater d i f f i c u l t y experienced  recorded on the bottom sector i n observing fresh attacks on  surfaces where frass f e l l d i r e c t l y from the trunk.  The use of a c h i s e l  to remove part of the bark and frass around g a l l e r i e s increased pinning e f f i c i e n c y as often more than one attack was frass.  This was  found under a p i l e of  especially true on the stumps, where frass accumula-  t i o n per unit area was higher, because of the greater density of attacks.  Another advantage was  identified.  that the beetles were more p o s i t i v e l y  81  4.2  HOST SELECTION AND  COLONIZATION BY ASSOCIATED SCOLYTID BEETLES  There appeared to be no cross a t t r a c t i o n or repulsion between (J. sulcatus and P_. tsugae and S. tsugae on WH and (J. sulcatus and D. pseudotsugae and j>. unispinosus on Df. In WH,  .P. tsugae attacks during the f i r s t eight weeks were  mostly found i n downtrees, but l a t e r this trend disappeared. f l y i n g period extended into mid-September, which was recorded by McLean and Borden (1977a). t y p i c a l of  similar to that  This extended f l i g h t period i s  tsugae which overwinters at any l a r v a l stage, pupates,  and emerges i n J u l y (Bright and Stark 1973). in a WH  The  Only one attack was  found  stump, which does not confirm the preference for stumps  reported by Bright (1976).  This species always started i t s g a l l e r i e s  under bark scales, similar to the pattern reported by McLean and Borden (1977a).  About 80% of the attacks by j>. tsugae occurred on WH down-  trees, almost s i g n i f i c a n t l y more than on logs (P <0.07).  The low l e v e l  of attacks i n one of the downtrees contributed much v a r i a t i o n .  Attacks  were recorded from June to mid-September which indicated a longer f l i g h t period than that reported by Bright (1976), who f l i g h t by this species usually extended from May  reported that  to l a t e July.  When the trees were f e l l e d , the f l i g h t of JJ. pseudotsugae was probably under way  because on the f i r s t bi-weekly period, May  26, peak  numbers of attacks were recorded on logs (160 attacks) and on downtrees (66 attacks), followed by a second minor peak on September 15. f i r s t peak, probably represented  insects which overwintered  and the second peak those, which overwintered  The  as adults  as larvae or re-attacks  82  by emerging adults after e s t a b l i s h i n g a g a l l e r y (Walters Skovsgaard 1968;  Furniss and C a r o l i n 1977).  1956;  Most of the attacks by  S.  unispinosus, the other bark beetle i n Df, were recorded i n late spring and early summer, which agrees with Bright (1976). attacks occurred on downtrees than on logs. attacks occurred i n a single downtree.  O v e r a l l , more  A heavy concentration of  The major difference between  the two most attacked downtrees and the other two was pair was  i n f u l l sunlight, which may  that the  first  have increased l i b e r a t i o n of  chemical attractants from these downtrees and attracted beetles i n higher numbers to them.  This agrees with Deyrup (1981), who  reported  that this bark beetle prefers trunks under f u l l sunlight while i t s ecological twin P. nebulosus prefers shaded trunks. The other ambrosia beetle recorded in the study was T_. lineatum. No attacks were recorded i n 1978 because the logs were f e l l e d on May 8 and this beetle attacks only logs that have aged (Prebble and Graham, 1957).  The quick build-up of attacks i n 1979 was  c h a r a c t e r i s t i c of  T_. lineatum ( F i g . 16), when the temperature reached 15.5°C i n the spring, which i s the threshold for f l i g h t (Chapman and N i j h o l t 1980), and the beetles l e f t hibernation sites in the forest duff (Hadorn 1933).  Even with higher attack rates i n s i t e 2 and on Douglas-fir no  •differences could be demonstrated either for s i t e or host.  This was  probably due to the high v a r i a t i o n that existed within the same host. For example the attacks for Douglas-fir were concentrated on Douglasf i r No. 5, a downtree, an aggregation probably mediated by secondary attraction.  83  4.3  ESTABLISHMENT AND  GALLERY PARAMETERS  The most v i s i b l e difference between the two years was attacks i n 1979 had a quicker establishment frass production i n the f i r s t ten weeks.  that  with higher amounts of  Such higher frass production  and success r a t i o i n 1979 indicated a better s u i t a b i l i t y of the host or a stronger beetle a f t e r a long maturation feeding period through the winter, thus allowing £. sulcatus to make g a l l e r i e s more rapidly. After this period of ten weeks, frass production gradually decreased during the remainder of the year indicating that the main phase of gallery construction was  completed.  Low  levels of frass from August to  November might be mainly frass produced by larva enlarging their niches. Frass was  steadily produced from successful g a l l e r i e s which  indicated that when such a g a l l e r y was leave i t .  established the parents did not  On the other hand, many g a l l e r i e s , especially those i n Df  stumps and trunks covered with p e t r i dishes, stopped producing  frass i n  three weeks to two months a f t e r attack when one or both of the beetles abandoned the g a l l e r y .  This demonstrated that the establishment  phase  proposed by Borden (1974) takes several weeks before successful establishment  occurs.  The presence of black fecal material i n frass  from successful g a l l e r i e s was  recorded  f i v e weeks a f t e r commencement of  attacks indicating that at this time the beetle had already started eating black hyphae.. In a l l four host categories, frass production started to drop at the end of July for 1979 attacks when brood started to emerge.  It  84  i s hypothesized necessary  that a maturation  feeding period (Batra 1963) i s  and with brood walking through the gallery system further  boring by parents i s i n h i b i t e d .  In many cases i t was observed that one  of the parents blocked the gallery entrance and prevented from re-entering  any brood  the g a l l e r y once they were i n the p e t r i dish.  The production of very low levels of frass, mostly black material i n 1979,  from 1978  attacks, indicated that at this point the  parents were only removing f e c a l material and frass produced by larvae excavating their niches.  A l l g a l l e r i e s opened were clear of frass  showing that these materials are routinely removed. The only host category that produced similar amounts of frass per g a l l e r y for the attacks i n both years was WH other three host categories were not completely  stumps.  Thus, the  suitable for beetle  reproduction during the f i r s t months after f e l l i n g .  This i s confirmed  by the fact that WH stumps showed the highest number of attacks per square meter and also the highest number of brood per gallery.  One i s  a consequence of the other, because i f the i n i t i a l beetles are successful they w i l l attract others. Approximately 300 old attacks i d e n t i f i e d by colour-coded which had stopped producing August and October 1978,  pins,  frass, produced fresh white frass between  indicating r e a c t i v a t i o n . Such r e a c t i v a t i o n  had to be done by beetles from outside, rather than brood from the same g a l l e r i e s , because no covered unsuccessful attack produced any fresh material l a t e r i n the season.  A consequence of such r e a c t i v a t i o n i s  85  that should the beetle abandon a previously pinned g a l l e r y and  then  reattack i t would be counted twice. Many g a l l e r i e s , opened after frass production had ceased, empty egg niches.  had  There are four possible explanations for the  presence of empty egg niches: lack of oviposition following niche -  construction, i n f e r t i l i t y , a direct host effect preventing egg hatch, and cannibalism.  There was no evidence to support the third hypo-  thesis, since there were no differences i n number of egg niches per g a l l e r y between hosts, even though WH supported much more successful brood production.  If cannibalism by brood was a factor, i t should have  been proportional to numbers of brood and no such c o r r e l a t i o n could be obtained.  The most probable explanation i s that the female made the  egg niche, but no egg was l a i d i n i t . Since the potential for egg production should be similar i n a l l females within WH or Df, lower numbers of pupal niches i n the l a t t e r , probably indicated that the female may  have obtained better nutrients  from WH woodsap than from Df during gallery construction, resulting i n greater production of eggs i n WH.  A l t e r n a t i v e l y , i t could have  indicated poor establishment of the fungi, and that the females lay eggs only after feeding on their fungi. The greater depth of G_. sulcatus g a l l e r i e s i n WH was a consequence of much deeper sapwood and lack of fungitoxic heartwood i n this tree species. the p i t h .  In some of the WH  trunks, g a l l e r i e s extended almost to  The longer g a l l e r i e s not only produced more brood but also  caused greater degrade to WH than to Df.  In the l a t t e r species  86  g a l l e r i e s were confined to the sapwood and they terminated at the well d i f f e r e n t i a t e d heartwood. S i g n i f i c a n t l y negative constants on the brood and frass relationships equations (Table XIII) indicated some loss of frass since p e t r i dishes were put on one week after attack and covered one week after i n s t a l l a t i o n . A s p e c i f i c gravity was calculated f o r stumps and trunks on both hosts using the relationships between frass and volume of g a l l e r i e s . For WH stumps and trunks s p e c i f i c g r a v i t i e s of 0.62 and 0.37 were found, respectively.  Since i n this species the early wood zone usually  occupies two-thirds or more of the r i n g , and t r a n s i t i o n from early to late wood i s more or less gradual (Panshin and Zeeuw 1980), s p e c i f i c gravity of the early wood should be smaller but closer to the s p e c i f i c gravity f o r the whole log, which varies from 0.429 to 0.487 (Jessome 1977).  Specific gravity of early wood i s about 0.25 (Wilson 1968).  The s p e c i f i c gravity f o r trunks of 0.37 i s intermediate between these values as would be expected  f o r g a l l e r i e s which crossed annual  rings.  As for the stumps an unusually high s p e c i f i c gravity of 0.62 was found, which could not be explained.  Even though the number of pupal niches  in stumps was the highest o v e r a l l , equal to 16.25 per g a l l e r y as compared to 14.10 f o r the trunks, t h i s alone does not explain the high s p e c i f i c gravity found i n the stumps.  There may have been a higher  contribution of fungal biomass i n the WH g a l l e r i e s . Specific gravity f o r Df stumps and trunks were both 0.34.  This  i s consistent with Parker et al. (1976) who reported s p e c i f i c gravity  87  values ranging from 0.313  to 0.346 f o r early wood which contrasts with  the average value of 0.20  found by Wilson (1968).  The early wood zone  i n Douglas-fir i s usually several times wider than the band of late wood (Panshin and Zeeuw, 1980) and most of the G_. sulcatus g a l l e r i e s w i l l be constructed i n the early wood, which i s reflected by the s p e c i f i c gravity values.  These r e s u l t s again suggested some contribu-  t i o n to frass weight by the beetle digestive residues.  4.4  ASPECTS OF GALLERY CONSTRUCTION OF Gnathotrichus sulcatus IN TRUNKS FOR DIFFERENT PERIODS AFTER FELLING Few s t a t i s t i c a l l y s i g n i f i c a n t differences could be demonstrated  i n the data because of high v a r i a b i l i t y i n the r e l a t i v e l y few numbers of observations but some trends are worth mentioning. pupal niches for WH and Df were 7.21 compared to 14.10  and 2.89,  and 4.81,  Mean numbers of  respectively, as  found for the brood production work.  The  l a t t e r value f o r WH i s probably overestimated, since p e t r i dishes continued to be i n s t a l l e d u n t i l successful g a l l e r i e s had been established whereas the f i r s t reported means above are averaged a l l dissected g a l l e r i e s .  over  Much lower numbers of PN per g a l l e r y i n WH  and Df logs were found by McLean and Borden (1977a) than those registered here, because they opened g a l l e r i e s before brood production had been completed.  Mortality within g a l l e r i e s due to natural enemies  i s probably not important f o r G. sulcatus since the mean PN per gallery were similar i n covered g a l l e r i e s (successful + unsuccessful) on WH and  88  i n uncovered g a l l e r i e s .  For Df, even though many p e t r i dishes were set  up (Table VII), they were i n the most part put on during 1978 when this host was not completely  suitable as demonstrated by the low number of  pupal niches found for g a l l e r i e s i n i t i a t e d i n 1978 (Table XV). Probably f o r this reason, mean numbers of PN were lower i n the g a l l e r i e s covered with p e t r i dishes, than the mean PN found when g a l l e r i e s were opened on a monthly basis. For WH, no numerical  trend by month was apparent, but i n Df i t  was clear that lower numbers of pupal and egg niches and shorter g a l l e r i e s were recorded from 1978 attacks (Table XV) which demonstrated that spring-felled  logs of this l a t t e r host are not suitable for  colonization during the f i r s t year.  This trend confirmed  host  u n s u i t a b i l i t y as indicated by a lower number of attacks during 1978 i n Df (Table I I I ) . No differences were demonstrated for months within either host. No g a l l e r i e s were opened u n t i l August 1980, by which time a l l attacking beetles including those of October 1979 should have completed construction and brood production.  gallery  Beetles that attacked WH and Df i n  October 1979, 17 months after f e l l i n g , were able to successfully complete the cycle and cause damage similar to that of e a r l i e r attacks (Table XV). About 70% of t o t a l length of g a l l e r i e s had no pupal niches and most pupal niches were adjacent to the r a d i a l entrance of the gallery. It i s possible that the whole g a l l e r y i s b u i l t to enable more fungus c u l t i v a t i o n for the adult and l a r v a l feeding.  I f this were the case,  89  the larvae of G. sulcatus would need to move i n the g a l l e r y system i n a similar manner as those of Xyleborus  celsus (Gagne and Kearby 1979).  The difference between these two species i s that X. celsus larvae feed communally i n a single chamber, while G_. sulcatus have i n d i v i d u a l "cradles" to which they would need to return after any feeding. The a b i l i t y of G. sulcatus to colonize logs and downtrees i n the second year after f e l l i n g as observed during this study i s i n agreement with other authors (Mather 1935;  Prebble and Graham 1957).  Dyer and  Chapman (1965) further commented that (3. sulcatus preferred Df f e l l e d in the previous year meaning that Df needs considerable aging  before  being completely suitable for G_. sulcatus attacks.  4.5  RELATIONSHIP BETWEEN BROOD EMERGENCE PATTERN AND The estimated  ATTACK DATA  t o t a l of 107,080 brood produced over a two  year  period i n these 16 stumps and trunks probably represented more than one generation, because attacks i n the f a l l 1978  and during 1979  been by brood produced by the e a r l i e s t attacks ( F i g . 39). attacking WH  stumps i n the second year had an eight fold  could have  G. sulcatus generation  increase but on Df stumps the brood would only replace the o r i g i n a l parents.  Thus, WH  production.  stumps provided a better environment for brood  Similar results were found for logs and downtrees.  Brood production i n the laboratory showed a steady pattern of emergence throughout 200 days with no peaks similar to those seen i n the f i e l d .  A similar pattern was reported by Hosking (1972) for  X. saxeseni i n New  Zealand, i n laboratory conditions.  This result  90  suggested that brood emergence i n the f i e l d must be co-ordinated by an interaction between environmental factors, such as temperature and light intensity.  It has been demonstrated by Rudinsky and Schneider  (1969) that few G. sulcatus f l y i f l i g h t i n t e n s i t i e s exceed 21,520 lux. No meaningful degree-day calculations could be made using the lab  and f i e l d r e s u l t s .  It may have been that the laboratory  ture used was above the optimum for development  tempera-  of the brood or the  symbiotic fungi. Numbers of brood per parent i n the f i e l d ranged from 0.6 to 8.1, depending on the host and time of attack (Table XVII), as compared to an overall 4.5 brood per parent found by Dyer (1963b) for T_. lineatum on stumps, logs, chunks and tops of Df i n a clearcut.  Probably the  shade and the p a r t i a l shade conditions i n which trees were f e l l e d i n this experiment might have contributed to the high numbers of successf u l attacks and brood production. More pupal niches per gallery were found for J_. lineatum by Gibson et^ al. (1958) on shaded than on exposed s i t e s i n logs of Df.  Also, more brood per g a l l e r y were found for _T.  lineatum on shaded than on s u n l i t sides of logs, trunks, tops and stumps of Df (Dyer 1963b).  Further studies could elucidate the brood  productivity pattern i n stumps and logs i n shaded and exposed clearcut s i t e s , as well as by season of the year i n which logs were cut. In this study, brood production was very low i n late summer and f a l l , 1978, when the highest numbers of attacks were recorded.  These  attacks probably represented a c t i v i t y by migrating beetles that completed their development elsewhere.  The brood production and attack  91  peaks i n May  1979  showed a greater contribution of brood from WH  than from any other host material.  This suggests that brood were  re-attacking material i n the same general area. attacks i n 1979,  stumps  Peak numbers of  for a l l host materials (Figs. 6,7), were higher than  that i n 1978 due to brood production from g a l l e r i e s established the previous year plus improved host s u s c e p t i b i l i t y .  Brood would attack i n  the same area provided they had s u f f i c i e n t f l i g h t exercise. time of attack a pattern of brood emergence was emergence was  combined i t was  When a l l  shown that G_. sulcatus had a f i r s t peak  of emergence i n the spring, dropping and decreasing again through October. study i t was  observed.  For each  i n June, reaching a peak i n August Under f i e l d conditions of this  demonstrated that June 1978 attacks i n WH stumps produced  a peak of brood i n May  1979.  beetles pinned at this time.  These beetles may  have been the attacking  The high brood population from August to  September could be accounted for mainly by late summer, 1978  and  spring, 1979 attacks and beetles from attacks up to June, 1979  contri-  buted to the July to October, 1979 emerging population, with additional production i n the following spring. From July to October 1979,  t o t a l brood production exceeded the  number of pinned attacks ( F i g . 39) which indicated a net production of G. sulcatus, which would have dispersed to other areas.  The  emigration  of beetles, as indicated by lower attack rate during summer and spring, 1979,  indicated a decrease i n host s u i t a b i l i t y .  Most material i s  apparently unsuitable for heavy attack 15 months beyond a May date.  1  felling  92  The data (Table XI) do not support the hypothesis that the pioneer beetle i s the f i r s t to emerge to ensure outbreeding 1981)  non-  (Borden  since 97 males and 87 females were the f i r s t to emerge from a l l  successful g a l l e r i e s i n the f i e l d and this i s not different from 1:1 sex ratio (Chi-square  test).  On the other hand, i t i s d i f f i c u l t  to v i s u a l i z e inbreeding i n a  G_. sulcatus population since there are thousands of beetles and  they  a l l do not attack the same log year after year and have to move out, thus favouring outbreeding.  S l i g h t l y more males than females were  recorded (83 9 males : 769 females), which could allow for higher mortality among the pioneer beetles since the female can f l y d i r e c t l y to a male occupied gallery after emergence, decreasing f l y i n g time and thus decreasing mortality among them. The o v e r a l l brood production pattern during 1979 very similar to the pattern of pinned attacks i n 1978 that reported by McLean and Borden (1977a).  ( F i g . 39), i s  (Figs. 6,7)  This shows that i n a  forest setting where a (3. sulcatus population can be maintained t i o n after generation, the expected from July to September.  and  genera-  pattern w i l l be high population  The peak of attacks recorded i n May,  1979  was  minor compared with the brood emergence numbers from J u l y to September. Numbers of attacks probably did not build up to a real high peak during the summer and early f a l l of 1979, already heavily colonized. the recorded May  because the host materials were  For this reason the r e l a t i v e importance of  1979 peak was  overestimated  because i t was compared  with 1978 peaks of attack when populations i n the area were lower than  93  In 1979.  This demonstrated that i f suitable host material  was  available i n an area from year to year, population build up of (J. sulcatus could be considerable. Bi-modality i n numbers of attacks as recorded by McLean and Borden (1975b; 1979)  i n a sawmill happened because the beetles caught  are from outside populations (McLean 1980b). modality can be explained as follows: sulcatus i n May  I suggest that the b i -  f i r s t , high numbers of f l y i n g (3.  come from logs that were cut and attacked i n the  previous summer; second, logs processed  during the summer period were  cut during the winter, w i l l have few attacks and produce few brood; f i n a l l y , logs processed  i n August and September were cut during winter,  yarded and attacked i n the spring and w i l l produce a high number of beetles i n l a t e summer and early f a l l .  Additional evidence  to support  this theory was  shown by McLean and Borden (1977b) when no second  f l i g h t peak was  recorded during a mid-summer m i l l shutdown and no logs  were coming from the forest. i n October i t was  By the time the industry started up again  too cold for beetles to emerge from logs attacked i n  the spring. The results of this study, wherein 107,080 brood were estimated to have been produced from 16 stump/trunk combinations, showed that 42% were produced by stumps and 58% by logs.  In the forest this would mean  that stumps could sustain a r e l a t i v e l y high number of G_. sulcatus and further, that f i e l d - i n f e s t e d logs transported to dryland sorting areas and m i l l s could contain many thousands of beetles.  Approximately 25  infested logs would be needed to produce the 50,000 beetles captured i n  94  a pheromone-baited trap survey of the Shawnigan and Port McNeil dryland sorting areas (McLean 1980a). transport phase to the mill? Chemainus Sawmill i n 1974  How  many beetles survive the water  A 1 week per month survey of the  caught 3,098 (J. sulcatus (McLean and Borden  1975b) while e f f o r t s to suppress the population, captured (McLean and Borden 1977b) and 42,907 i n 1976  4.6  5,796 i n  1975  (McLean and Borden 1979).  IMPLICATIONS OF THE RESULTS FOR THE B.C.  FOREST INDUSTRY  High attack rates and brood production on WH stumps and  trunks  poses a potential major threat to the forest industry, since WH makes up 40% of the volume processed i n coastal B r i t i s h Columbia (B.C.M.F. 1980).  The rapid b u i l d up of (3. sulcatus i n WH,  the extensive g a l l e r y  construction and resultant serious degrade of this tree species emphasizes the need for rapid removal of WH logging) and rapid inventory turnover  from forest settings (hot  i n storage and processing  areas.  The potential for (2. sulcatus b u i l d up i n f e l l e d and bucked areas i s immense as demonstrated by the production of 107,080 brood from 16,049 attacks.  This number of attacks i s probably an over-  estimation since a beetle which attacked an unsuitable stump or trunk and re-emerged could have attacked another stump or trunk, and thus been counted twice.  Another way  to look at the reproductive  capacity  of £. sulcatus i s that a single one meter high p a r t i a l l y shaded WH stump can produce 3,574.3 + 2,085.1 beetles. f i e l d of 200 WH  This suggests that a  stumps could, produce 714,860 + 417,020 beetles.  If a trap log or trap bundle t a c t i c i s to be used to capture (J. sulcatus i n dryland sorting areas then i t i s recommended that  WH  95  logs should be used as they received a mean of 18.2 sustained attacks/m , while Df received only 0.9 sustained attacks/m 2  the f i r s t year.  during  Two types of WH e x i s t , one with furrowed bark and the  other with flaky bark (Walters et a l . 1960). has a purple phelloderm -  2  The furrowed bark type  and should be used f o r trap logs, because my  observations have indicated that i t i s preferred by ( 3 . the flaky barked type.  sulcatus over  Data developed i n this study suggest that four  month old WH logs can be used as trap logs at two different times of the year.  F i r s t , they should be set out i n March to remove G_. sulcatus  from the spring f l i g h t , but most of the attacks w i l l probably be _T. lineatum.  These logs would need to be removed by the end of June to  prevent emergence of T_. lineatum brood.  A second set of trap logs  should be set out at the beginning of July to receive attacks from the heavy summer and early f a l l G_. sulcatus f l i g h t and then removed f o r processing before the following February. The increased use of dryland sorting and storage areas as opposed to water sorting as well as the planned increase i n the use of barges for log transport w i l l almost certainly increase beetle tion.  popula-  Protection gained by water storage and transport as well as  mortality caused by submergence of logs which drowned any brood present (Dyer and Chapman 1962, McLean and Borden 1977b) w i l l be greatly reduced.  A d d i t i o n a l l y , most of the logs i n a barge are shaded, which  w i l l lead to higher survival of G_. sulcatus.  96  5.0  SUMMARY  Aspects of G. sulcatus biology and host colonization c l a r i f i e d i n this study. For spring-felled logs and downtrees as well as their stumps: 1.  Western hemlock was  the preferred host over Douglas-fir in the  f e l l i n g year as indicated by numbers of attacks and success of establishment.  No differences between trunks of the two  species  appeared in the second year, but again western hemlock stumps were preferred over Douglas-fir stumps. 2.  More attacks were pinned on downtrees than on logs i n the f i r s t year, but no differences were demonstrated i n the second year.  3.  Highest numbers of attacks were recorded September of 1978  4.  and on May,  1979  during July, August and  for a l l host categories.  More brood, as well as longer and deeper g a l l e r i e s were found i n WH than on Df.  5.  Peak of t o t a l brood emergence was September, 1979.  recorded  i n August and  Peaks of brood emergence from each host  category varied by time of attack. 6.  Western hemlock sapwood and Douglas-fir phloem were shown to be the most a t t r a c t i v e host tissues and suggested starting points for further elaboration of primary attractants f o r (2. sulcatus.  97  Implications related to management of G!. sulcatus suggest that: 7.  It i s very important to trap the minor spring f l i g h t of G_. sulcatus, because spring attacks i n this study produced 63.4% of t o t a l brood production i n August and September.  8.  Western hemlock, rather than Df, should be used i n trap bundles, as i t i s more readily colonized.  9.  Stumps produced 42% of the total brood production i n this study showing that they are major sources of continuing infestation i n the f i e l d .  10.  Logs, especially western hemlock, should be removed as soon as possible after f e l l i n g (hot logging) to minimize degrade losses and the build up of G. sulcatus populations.  98  6.0  LITERATURE CITED  Anonymous, 1972. Damage by ambrosia  (pinhole borer) beetles.  Technical Note No. 55. Princes Risborough Laboratory. Aylesbury, Bucks. England. Atkins, M.D.  8 pp.  1966. Laboratory studies on the behavior of the  Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins.  Can.  Entomol. 98:953-991. Bain, J . 1974. Overseas wood- and bark-boring insects intercepted at New Zealand ports. Batra, L.R.  N.Z. For. Serv. Tech. Pap., No. 61. 24 pp.  1963. Ecology of ambrosia fungi and their dissemination  by beetles. Trans. Kans. Acad. S c i . 66:213-236. Blackman, M.W.  1931. A revisioned study of the genus Gnathotrichus  Eichhoff i n North America. Borden, J.H.  1974. Aggregation pheromones i n the Scolytidae. In:  M.C. Birch (ed.). Borden, J.H.  J . Wash. Acad. S c i . 21:265-276.  Pheromones. North Holland, Amsterdam.  1981. Aggregation pheromones. _In: J.B. Mitton and K.B.  Sturgeon (Eds.) (E.D.S.).  Bark Beetles i n North American  Conifers, Ecology and Evolution. Univ. Texas Press, Austin. (In press). Borden, J.H. and E. Stokkink.  1973. 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McGraw-Hill Book Company.  907  pp.  7. designs.  107  APPENDIX 1:  Results of the analysis of variance of Gnathotrichus sulcatus attacks/m on western hemlock and Douglas-fir stumps i n the UBC Research, Forest, 1978-79. 2  Source of Variation  1978 D.F.  1979  1  Mean square  F  D.F.  1  Mean square  F  Site  1 •  6.043  16.64**  1  0.0285  0.06  Host  1  2.181  6.01*  1  2.1478  4.71*  Site x host  1  0.02154  0.06  1  0.00000976  0.00  12  0.3631  Error  2  12  0.4556  ^Data transformed to X' = logio(X + 1) 2  S i g n i f i c a n c e levels indicated:  * = P <0.05, ** = p <0.01.  108  APPENDIX 2:  Results of the analysis of variance of Gnathotrichus sulcatus attacks/m on western hemlock and Douglas-fir trunks i n the UBC Research Forest, 1978-79. 2  19781 Source of Variation  D > F >  M e a T 1  19791 D.F.  F  square  Mean square  Site  2.1767  73.81**'  0.1989  0.62  Host  1.0413  35.31**  0.01663  0.05  Condition  0.1820  6.17*  0.3545  1.11  Site x Host  0.09772  3.31  0.0349  0.11  Site x Condition  0.3008  10.20*  0.5109  1.60  Host x Condition  0.1125  3.81  0.4789  1.50  Site x Host x Condition  0.000391  0.013  0.03118  0.10  Error  8  0.02949  8  *Data transformed to X' = logio(X + 1) Significance  levels indicated:  * = P <0.05;  ** = P <0.  0.3190  109  APPENDIX 3:  Results of the analysis of variance for percent of Gnathotrichus sulcatus attacks per quadrant on 1 m long western hemlock and Douglas-fir logs. UBC Research Forest, Maple Ridge, B.C. May-November, 1978 and March-October, 1979. N = 8 per each species.  WESTERN HEMLOCK  Source of Variation,  D > F >  M  e  a  n  DOUGLAS-FIR Mean square  F  square  Percent of attacks per quadrant* Aspect  3  589.72  Error  28  94.65  iRaw d a t a .  6.23**  310.28 244.55  No t r a n s f o r m a t i o n as B a r t l e t t ' s Test showed homogeneous  variances. Probability  2  level indicated:  ** = P <0.01.  0.30  f Yv,rk beetles t o t a l attacks on  DOUGLAS-FIR WESTERN HEMLOCK Source of Variation D.F.  4.59  0.079  0.014  4.59  0.758  1  0.0007  0.003  4  0.248  Condition Site x Condition  l a t a transformed to X' - l o g D  2  P r o  bability  level indicated:  1 0  (  0.772 0.130  X  +  U  * - * <0- ' 05  S. nnlspinosus Mean square  Mean square  Mean square  Mean square  1.141  Site  Error  S. tsugae  P. tsugae  D. pseudotsugae  F  0.734  3.37  0.049  0.11  0.367  3.652  8.37*  5.84  1.69 0.01  0.189  0.43  5.94  0.003  0.61  0.022  0.436  2  Ill  APPENDIX 5:  Results of the analysis of variance of Trypodendron lineatum attacks/ro.2 t e r n hemlock and Douglasf i r trunks in the UBC Research Forest, 1978-79. o  Source of Variation  n  w e s  1  D.F.  Mean square  Site  F  0.536  1.51  Host  1  0.352  0.99  Site x Host  1  0.0523  0.15  Condition  1  0.107  0.30  Site x Condition  1  0.481  1.36  Host x Condition  1  0.0163  1.78  Error  8  1  Data transformed to X' = l o g i f j (  0.354  x  +  112  APPENDIX 6: APPbNUlA o.  Results of the analysis of variance of brood (BR) *es ^ sulcatus g a l l e r i e s (  f  r  )  o  f  G  a  t  h  o  t  r  l  c  h  u  s  on western hemlock and Douglas-fir i n i t i a t e d during 1978-79, UBC Research Forest, Maple Ridge, B.C.  BR Source of Variation  M D , F  *  e  a  FR  1  1  Mean square  n  square  TREES: 0.13  0.2538  1.76  Site  1  0.01966  Host  1  7.6047  50.58**  Site x Host  1  0.1473  0.98  0.0953  Condition  1  0.0261  0.17  1.9857  Site x Condition  1  0.1906  1.27  0.000027  Host x Condition  1  1.764  11.73**  3.5204  24.48**  Site x Host x Cond.  1  1.794  11.93**  0.807  5.62*  Tree (Site,Host,Cond)  8  0.3360  0.5174  3.60**  61  0.1503  Site  1  0.3040  Host  1  9.4935  Site x Host  1  Stump (Site,Host)  Error  Error  2.23*  11.968  83.23** 0.66 13.81** 0.00019  0.1438  STUMP: 0.6475  4.93*  94.29**  6.7968  51.8**  0.3570  3.55  0.3400  2.59  10  0.4787  4.75**  0.2813  2.14*  56  0.1007  *Data transformed to X' - l o g ( X 1 0  Significance  levels indicated:  +  3.01  ^  * = P <0.05;  0.1312  APPENDIX 7: APPENDIX  Source of Variance  Host Tree  Error  Results of the analysis of variance for Gnathotrichus sulcatus productivity/ gallery parameters i n western hemloc^ana bouglas-fir logs i n laboratory conditions. Faculty of Forestry, UBC 1978-79. l  l  e  r  y  a  n  d  m  e  a  n  D.F.  1  28.9  2  0.80  16  8.07  3.58*  592.9  2  0.099  13.07  52.97  11.9** 0.25  756.9 8.60  56.82  *Data transformed to X' = l o g ^ C X  +  Significance  * = P <0.05; ** - P <0.01.  levels indicated:  ^  Mean square  Mean square  Mean square  Mean square  Mean square  DP  LG  BR  PN  EN  13.32** 0.15  97.34 136.8 127.9  0.76  0.016  0.007  1.07  5.70  2.56  2.22  114  APPENDIX 8:  Results of the analysis of variance of mean numbers of egg niches (EN) and pupal niches (PN) of Gnathotrichus sulcatus g a l l e r i e s on western hemlock and Douglas-fir i n i t i a t e d during 1978-79, UBC Research Forest, Maple Ridge, B.C.  EN  Source of Variation D , F  *  Mean square  PN  1  F  1  Mean square  TREES: Site  1  0.0068  0.08  0.07650  0.048  Host  1  0.285  3.20  9.1018  57.61**  Site x Host  1  0.0003  0.004  0.3042  1.93  Condition  1  0.133  1.50  0.00701  0.44  Site x Condition  1  0.010  0.12  0.1077  0.68  Host x Condition  1  0.0054  0.06  1.5181  9.61**  Site x Host x Cond.  1  0.075  0.84  2.2443  14.21**  Tree (Site,Host,Cond)  8  0.233  2.62  0.4702  2.98**  61  0.089  Error  0.1580  STUMP: Site  1  0.000194  0.054  0.1200  0.98  Host  1  0.05864  1.65  7.3561  59.60*  Site x Host  1  0.03613  1.01  0.2750  2.06  Stump (Site,Host)  10  0.3139  8.81**  0.6768  2.09**  Error  56  0.3563  1  0.1333  Data transformed to X' = log Q(X + 1) 1  2 i g n i f i c a n c e levels indicated: S  * = P <0.05; ** « P <0.01.  115  APPENDIX 9:  Results of the analysis of variance of mean length (LG) and depth of penetration (DP) of Gnathotrichus sulcatus g a l l e r i e s on western hemlock and Douglas-fir i n i t i a t e d during 1978-79, UBC Research Forest, Maple Ridge, B.C.  LG Source of Variation D , F  '  Mean square  DP  1  1  Mean square  F  TREES: 0.053  Site  1  0.003436  Host  1  6.8474  105.79**  Site x Host  1  0.1479  2.28  Condition  1  0.7155  Site x Condition  1  Host x Condition  2  0.1019  8.53**  2.5002  210.79**  0.02613  2.20  11.05**  0.09059  7.63**  0.01061  0.164  0.02304  1.94  1  1.2083  18.67**  0.03910  3.30  Site x Host x Condi  1  0.1420  1.19  0.006688  0.56  Tree (Site,Host,Cond)  8  0.2251  3.48**  0.04329  3.65**  61  Error  0.001186  0.064728  STUMP: 0.21  0.00917  0.26  Site  1  0.02081  Host  1  3.2892  33.74**  1.6745  48.32**  Site x Host  1  0.1404  1.44  0.09328  2.69  Stump (Site,Host)  10  0.2702  0.04931  1.42  Error  56  0.09750  *Data transformed to X' » l o g ( X + 1 0  Significance  levels indicated:  2.77  0.03465  D  * = P <0.05; ** = P <0.01.  APPENDIX 10:  Results of the analysis of variance of mean number of egg niches (EN), pupal niches (PN), depth of penetration (DP) and length (LG) of Gnathotrichus sulcatus g a l l e r i e s i n western hemlock trunks over 13 months. UBC Research Forest, Maple Ridge, B.C. 1978-79.  EN  Source of Variance  PN  1  DP  1  LG  1  1  Mean square  F  7.20**  0.416  4.14*  0.025  1.19  0.013  0.13  0.67  0.034  1.61  0.100  1.00  0.735  3.43  0.0088  0.41  0.013  0.13  1.19  0.455  2.16*  0.030  1.39  0.176  1.76  0.080  1.32  0.641  3.04**  0.022  1.02  0.389  3.88*  6  0.086  1.42  0.171  0.81  0.032  1.50  0.200  1.99  Tree (Site,Cond., Month)  34  0.115  1.91**  0.400  1.89**  0.039  1.81*  0.210  2.09**  Error  66  0.060  Mean square  F  Mean square  0.16  0.600  2.85  0.154  0.0086  0.14  2.129  10.ii**  12  0.068  1.13  0.140  Site x Cond.  1  0.115  1.91  Site x Month  9  0.072  Cond. x Month  10  D.F.  Mean square  Site  1  0.0096  Cond.  1  Month  Site x Cond. x Month  F  0.211  ^Data transformed to X' = l o g i ( X + 1) Q  Significance  levels indicated:  * = P'<0.05; ** = P <0.01.  2  0.021  F  0.100  ™  x^^^^^s^^^^^^  t  g a l l e r i e s i n Douglas-fir trunks over 13 months. Maple Ridge, B.C.  UBC Research Forest,  1978-79.  Mean square  Site  1  0.047  0.74  Cond.  1  0.330  Month  12  Site x Cond.  Mean square  Mean square  Mean square  D.F.  LG  DP  PN  EN  Source of Variance  '  (PN)  1.064  5.20*  0.021  1.44  0.335  1.96  5.16*  0.621  3.03  0.376  2.52  0.030  0.17  0.051  0.81  0.449  2.19*  0.015  1.03  0.245  1.44  1  0.183  2.86  0.671  3.27  0.0378  2.46  1.05  6.14**  11  0.138  2.17*  0.324  1.58  0.013  0.84  0.159  0.93  Site x Month  12  0.102  1.60  0.285  1.39  0.024  1.60  0.087  0.51  Cond. x Month  7  0.106  1.66  0.213  1.04  0.024  1.60  0.086  0.51  Tree (Site,Cond, Month)  28  0.091  1.43  0.340  1.66  0.032  2.12**  0.189  1.11  Error  54  0.063  Site x Cond. x Month  2  0.205  iData transformed to X' = l o g ( X + 1) 1 Q  Significance  levels indicated:  * = P <0.05; ** = P <0.01.  0.015  0.171  118  APPENDIX 12: Results of the analysis of variance for Gnathotrichus sulcatus catches on bark phloem, sapwood and heartwood stimuli prepared from western hemlock and Douglas-fir. Set out i n Point Roberts, Washington on June and July, 1978,  Source of Variation  Degrees of freedom  Mean square  Western hemlock experiment 5.07**'  Week  2  0.094  Sex  1  0.192  10.35**  Block  4  0.101  5.45*  Treatment  3  0.218  11.74**  Week x block  8  0.044  2.39*  12  0.088  4.76*  89  0.018  Block x treatment 3 Error  Douglas-fir  experiment  1  Sex  1  0.0715  5.00*  Block  2  0.0026  0.18  Treatment  4  0.536  3  22  Error  *Data transformed to X' = l o g ( X 1 Q  S i g n i f i c a n c e l e v e l s indicated:  +  37.49**  0.0142  ^  * = P <0.05; ** = P <0.01.  ^ A l l other interactions were pooled i n the error term because they were non-significant.  

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