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Repellent effects of pineoil on the Sitka spruce weevil, Pissodes strobi (Peck), and an evaluation of… Carlson, Jerry A. 1987

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REPELLENT EFFECTS OF PINEOIL ON THE SITKA SPRUCE WEEVIL, Plssodes s t r o b l (Peck), AND AN EVALUATION OF LARGE SCALE AERIAL PHOTOGRAPHS FOR DETECTING WEEVIL DAMAGE by JERRY A. CARLSON A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department o£ F o r e s t r y ) We ac c e p t t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA October 1987 ®Jerry A l l e n C a r l s o n 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of FORESTRY The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date October 10, 1987 A b s t r a c t T h i s study was designed to i n v e s t i g a t e the r e p e l l e n t e f f e c t s o f p i n e o i l on the S i t k a spruce weevil (=white pine w e e v i l ) , Plssodes s t r o b l Peck, and to e v a l u a t e the u t i l i t y o f l a r g e s c a l e c o l o r a e r i a l photography f o r d e t e c t i n g w e e v i l a t t a c k e d S i t k a spruce, P l c e a s i t c h e n s l s (Bong.) C a r r . . Two f o r m u l a t i o n s o f p i n e o i l , BBR1 and BBR2, were f i e l d t e s t e d f o r t h e i r e f f e c t i n p r o t e c t i n g immature S i t k a spruce from weevil a t t a c k i n 36 twenty meter square p l o t s a t two l o c a t i o n s on Vancouver I s l a n d . The p i n e o i l f o r m u l a t i o n s were a p p l i e d both t o p i c a l l y to the t e r m i n a l l e a d e r s and i n slow r e l e a s e d e v i c e s hung a t the a p i c a l whorl of S i t k a spruce t r e e s . The t o p i c a l a p p l i c a t i o n o f BBR1 to the l e a d e r s o f a l l t r e e s i n the p l o t s reduced the number of new weevil a t t a c k s to two t r e e s compared with 24 new a t t a c k s i n the c o n t r o l p l o t s . None o f the other p i n e o i l treatments were found to d i f f e r s i g n i f i c a n t l y from the c o n t r o l s . An examination of the weevil a t t a c k h i s t o r y i n the study p l o t s showed t h a t the average number o f new w e e v i l a t t a c k s i n the p i n e o i l t r e a t e d p l o t s were p r o p o r t i o n a t e l y lower than the number o f new a t t a c k s i n the c o n t r o l p l o t s . These f i n d i n g s suggest that a p p l i c a t i o n s o f BBR1 to the t e r m i n a l l e a d e r s o f S i t k a spruce t r e e s w i l l p r o t e c t them from a t t a c k by P. s t r o b i • Large s c a l e c o l o r i n f r a - r e d (CIR) and normal c o l o r (NC) a e r i a l photograph s t e r e o t r a n s p a r e n c i e s were e v a l u a t e d f o r t h e i r u t i l i t y i n d e t e c t i n g weevil a t t a c k s i n immature S i t k a spruce stands. Four independent i n t e r p r e t e r s c o r r e c t l y 11 i d e n t i f i e d an average o f 38% more weeviled t r e e s on CIR f i l m than on NC f i l m d u r i n g a 1 minute t e s t p e r i o d . More e r r o r s were made by the i n t e r p r e t e r s with CIR f i l m than with NC f i l m . I n t e r p r e t e r e r r o r s made with CIR f i l m were mainly due to a l a c k o f a b i l i t y to d i s c r i m i n a t e between new weevil a t t a c k s and a t t a c k s made the pr e v i o u s year. E r r o r s made with NC f i l m were due mainly to m i s l d e n t i f y l n g h e a l t h y t r e e s as new weevil a t t a c k s . These f i n d i n g s suggest t h a t f o r the purpose o f d e t e c t i n g weevil a t t a c k e d S i t k a spruce t r e e s , CIR a e r i a l photographs would be both f a s t e r and more ac c u r a t e than NC photographs. i i i Acknowledgements I wish to extend my g r a t i t u d e to the f o l l o w i n g f o r t h e i r support, encouragement and guidance d u r i n g the course o£ t h i s r e s e a r c h and i n the p r e p a r a t i o n o f t h i s t h e s i s : Dr. J . A. McLean, my p r i n c i p a l a d v i s o r , f o r h i s a s s i s t a n c e and p a t i e n c e ; Dr. B. J . van der Kamp and Dr. P. H. Murtha, members o f my committee, f o r t h e i r support and c r i t i c i s m ; Dr. L. H. McMullen f o r h i s advic e and support; Hr. J . S. Hackett f o r h i s a s s i s t a n c e with the f i e l d work and h i s u n s e l f i s h f r i e n d s h i p d u r i n g times o f g r e a t need; Mr. P. M. Wood and Mr. E. M. J . J e k l i n f o r t h e i r v a l u a b l e a d v i c e and a s s i s t a n c e i n d e s i g n i n g the p r o j e c t and s e l e c t i n g the study s i t e s ; Dr. B. S. Li n d g r e n and Mr. G. H. Cushon f o r t h e i r c r i t i c a l reviews and a s s i s t a n c e with the data a n a l y s e s ; the B. C. M i n i s t r y o f F o r e s t s , Vancouver Region, and The T a h s i s Company (now C.I.P. Co. Ltd.) f o r t h e i r f i n a n c i a l support; and my parents R i c h a r d and Dorothy C a r l s o n f o r t h e i r i n t e r e s t and a s s i s t a n c e . F i n a l l y , I wish to thank K. L. Mercer C a r l s o n f o r her encouragement, support and d e t a i l e d reviews o f the manuscript. i v Table o f Contents A b s t r a c t i i Acknowledgements ............ i v L i s t o f Tables v i i L i s t o f F i g u r e s i x 1. INTRODUCTION 1 1.1 The S i t k a spruce weevil 1 1.2 P i n e o i l as a r e p e l l e n t 7 1.3 A e r i a l photography 9 1.4 Study o b j e c t i v e s .18 2. MATERIALS AND METHODS 2.1 D e s c r i p t i o n o f experimental s i t e s , p l o t s and bl o c k s 19 2.1.1 Nootka I s l a n d s i t e 19 2.1.2 U c l u e l e t s i t e 19 2.1.3 C r i t e r i a f o r e s t a b l i s h i n g the experimental p l o t s 23 2.1.4 Marking the experimental p l o t s .25 2.1.5 The experimental b l o c k s 25 2.2 The p i n e o i l study 26 2.2.1 Laboratory s t u d i e s 26 2.2.2 F i e l d s t u d i e s 27 2.2.2.1 T o p i c a l a p p l i c a t i o n 28 2.2.2.2 Slow r e l e a s e d e v i c e s 31 2.3 P l o t sampling 33 2.3.1 P h y s i c a l a t t r i b u t e s o f t r e e s 33 2.3.2 Weevil a t t a c k h i s t o r y .....34 2.3.3 Recording c u r r e n t a t t a c k s 36 v 2.4 The a e r i a l photography study 36 2.5 Data a n a l y s i s 41 2.5.1 P i n e o i l study 41 2.5.2 A e r i a l photography study 42 3. RESULTS AND DISCUSSION 3.1 P i n e o i l study 43 3.1.1 Laboratory s t u d i e s 43 3.1.2 F i e l d s t u d i e s 45 3.1.2.1 Nootka I s l a n d study s i t e 45 3.1.2.2 U c l u e l e t study s i t e 54 3.1.3 General d i s c u s s i o n 64 3.2 A e r i a l photography study 65 4. CONCLUSIONS 71 4.1 P i n e o i l study 71 4.2 A e r i a l photography study 71 5. FUTURE RESEARCH 5.1 P i n e o i l s t u d i e s 73 5.2 A e r i a l photography s t u d i e s 74 REFERENCES 75 APPENDICES 83 v i L i s t of Tables TABLE PAGE 1 Table 1. The alloc a t i o n s of p i n e o i l treatments among the plots, blocks and plantations at the Nootka Island and Ucluelet study s i t e s 29 2 Table 2. The amount of feeding by and mortality of single adult Sitka spruce weevils in six situations where they were confined with 5 cm long sections of Sitka spruce leaders treated with two types of p i n e o i l (BBR1 and BBR2) 44 3 Table 3. Sitka spruce leaders attacked by Sitka spruce weevils i n twenty-one 0.04 hectare plots on Nootka Island after t o p i c a l and slow release device treatments with p i n e o i l i n the spring of 1982 46 4 Table 4. The averages and standard deviations for height and diameter from weeviled Sitka spruce trees and a l l other trees i n the sample taken at the Nootka Island s i t e 49 5 Table 5. The t o t a l numbers of trees which had ever been attacked by the Sitka spruce weevil, the t o t a l number of leaders attacked on those trees and the t o t a l number of leaders attacked per year among the treatment groups over the six years of recorded attack at the Nootka Island s i t e . 50 6 Table 6. Sitka spruce leaders attacked by Sitka spruce weevils i n f i f t e e n 0.04 hectare plots at the Ucluelet study s i t e after treatment with p i n e o i l soaked slow release devices i n 1982 . 56 7 Table 7. The averages and their standard deviations for height and diameter (dbh) from weeviled Sitka spruce trees and a l l other Sitka spruce trees among the treatment groups at the Ucluelet study s i t e 59 8 Table 8. The t o t a l numbers of trees which had ever been attacked by the Sitka spruce weevil, the t o t a l number of leaders attacked on those trees and the t o t a l number of leaders attacked per year among the treatment groups over the seven years of recorded attack at the Ucluelet study s i t e 60 v i i 9. Table 9. Records of four I n t e r p r e t e r s ' I d e n t i f i c a t i o n s o f c u r r e n t spruce weevil a t t a c k s on normal c o l o r and c o l o r i n f r a - r e d s t e r e o p a i r s 66 10 Table 10. I n t e r p r e t e r e r r o r s i n i d e n t i f y i n g spruce we e v i l a t t a c k s on 1:1200 s c a l e a e r i a l photographs from normal c o l o r and c o l o r i n f r a - r e d f i l m s 68 v i i i L i s t o£ Figures -FIGURE PAGE 1. Figure 1. Location o£ the Nootka Island and Ucluelet study s i t e s on Vancouver Island, B r i t i s h Columbia. 20 2. Figure 2. Location o£ the experimental plots at the Nootka Island study s i t e 21 3. Figure 3. Location o£ the experimental plots at the Ucluelet study s i t e 22 4. Figure 4. The p i n e o i l applicator used for applying p i n e o i l t o p i c a l l y to the terminal leaders of treatment trees 30 5. Figure 5. Representation o£ a Sitka spruce tree which had been weeviled in 1979 35 6. Figure 6, Stereo pair prints made from the a e r i a l photograph transparencies o£ one of the plots used i n the interpretation o£ the Sitka spruce weevil attack study 38 7. Figure 7. Example of a scale plo t map showing the locations o£ a l l weeviled trees and the years of attack as determined from ground truth data 39 8. Figure 8. The d i s t r i b u t i o n o£ the t o t a l leaders attacked among the blocks at the Nootka Island s i t e 48 9. Figure 9. The percentage of trees attacked i n each year o£ attack among the treatment groups compared to the control group at the Nootka Island s i t e 51 10. Figure 10. The d i s t r i b u t i o n o£ the 1982 attack r a t i o s among the p i n e o i l treatment groups at the Nootka Island study s i t e 55 11. Figure 11. The d i s t r i b u t i o n of the t o t a l leaders attacked among the blocks at the Ucluelet s i t e 57 12. Figure 12. The percentage of trees attacked i n each year o£ attack among the treatment groups compared to the yearly attacks i n the control group at the Ucluelet study s i t e 61 13. Figure 13. The d i s t r i b u t i o n of the 1982 attack r a t i o among the p i n e o i l treatment groups at the Ucluelet study s i t e 63 ix l . IHTROPU-CTI^ 1.1. The S i t k a spruce weevil The white pine w e e v i l , P l s s o d e s s t r o b l Peck, i s a t r a n s -c o n t i n e n t a l s p e c i e s which r e g u l a r l y a t t a c k s and k i l l s the t e r m i n a l l e a d e r s o£ e a s t e r n white p i n e , Plnus strobus L., white spruce, P l c e a g l a u c a (Moench) Voss, Engelmann spruce, P.  engelmann11 Parry, S i t k a spruce, P_. s l t c h e n s l s (Bong.) C a r r . and i n t r o d u c e d Norway spruce, P. a b i e s (L.) K a r s t . Although o r i g i n a l l y c l a s s i f i e d as three separate s p e c i e s a c c o r d i n g to host; P_. s t r o b l on e a s t e r n white p i n e , P_. enaelmannl on Engelmann spruce and E- s l t c h e n s l s on S i t k a spruce, a r e v i s i o n o f the genus by Smith and Sugden (1969) p l a c e d them a l l as Plssodes s t r o b l . White pine w e e v i l , S i t k a spruce w e e v i l , and Engelmann spruce weevil are three common names which have been r e t a i n e d and are o f t e n used l o c a l l y to d e s i g n a t e the host or r e g i o n a l race (Werner 1982). E. s t r o b l was f i r s t r e c o g n i z e d by Peck (1817) as a p e s t which l i m i t e d the a v a i l a b i l i t y o f s t r a i g h t t r e e stems f o r the manufacture o f wooden masts from e a s t e r n white p i n e . The w e e v i l d i d not become a major problem, however, u n t i l the 1920's when i n c r e a s e d p l a n t a t i o n acreages o f white pine r e s u l t e d i n i n f e s t a t i o n s o f epidemic p r o p o r t i o n s . Trees harvested from stands which had recovered from weevil a t t a c k s were found to be o f l i t t l e or no economic value due to the presence o f c r o s s g r a i n s , compression wood and e x c e s s i v e knots (Spurr and F r i e n d 1941; Ostrander and S t o l t e n b e r g 1957; Marty 1 1959; Brace 1972). The problem has developed In a s i m i l a r f a s h i o n i n the West where l a r g e areas of spruce p l a n t a t i o n s , both i n the i n t e r i o r and on the c o a s t , are threatened by severe w e e v i l i n f e s t a t i o n s . Increased demands f o r S i t k a spruce products f o r a i r c r a f t c o n s t r u c t i o n d u r i n g World War I I encouraged e x t e n s i v e l o g g i n g o f the west's old-growth stands. T h i s expansive c u t t i n g i n the 1940's was f o l l o w e d i n the 1950's by l a r g e s c a l e r e g e n e r a t i o n e f f o r t s on the cutover s i t e s . The r e s u l t a n t broad i n c r e a s e i n the area o f r e l a t i v e l y even-aged, j u v e n i l e S i t k a spruce c o n t i n u e d on i n t o the 1970's. T h i s sudden, a r t i f i c i a l Increase i n immature spruce monocultures was f o l l o w e d by a c o n c u r r e n t i n c r e a s e i n the weevil p o p u l a t i o n . Today, weevil p o p u l a t i o n s s e r i o u s l y t h r e a t e n the development o f most young spruce stands and S i t k a spruce has been s e v e r e l y r e s t r i c t e d as a c h o i c e f o r r e g e n e r a t i o n (Heppner and Wood 1985). The S i t k a spruce weevil a t t a c k s S i t k a spruce throughout i t s range on the P a c i f i c c o a s t o f North America from C a l i f o r n i a to A l a s k a . The Queen C h a r l o t t e i s l a n d s are the e x c e p t i o n where &. s t r o b l has a p p a r e n t l y never become e s t a b l i s h e d (McMullen 1976a). S i t k a spruce i s the c o n i f e r o u s s p e c i e s capable o f the most r a p i d growth r a t e s i n the P a c i f i c Northwest (Ruth 1958). I t makes an e x c e l l e n t saw l o g and has good p u l p i n g c h a r a c t e r i s t i c s . I t i s a l s o r e s i s t a n t to animal browsing and t o l e r a n t of brush c o m p e t i t i o n (Phelps 1973). I t i s most v a l u a b l e as a r e g e n e r a t i o n s p e c i e s i n c o a s t a l stream bottom s i t e s where i t s growth i s e x c e l l e n t d e s p i t e o f t e n bad to extreme brush c o m p e t i t i o n ( F a r r and H a r r i s 1979). 2 In s p i t e o f these p o s i t i v e f e a t u r e s , however, the r e g e n e r a t i o n o f these extremely v a l u a b l e stream bottom s i t e s with S i t k a spruce has been d i s a p p o i n t i n g . F i r s t , some s i t e s have not been s a t i s f a c t o r i l y r e s t o c k e d . Second, some s i t e s have s u f f e r e d from poor growth r a t e s due to inten s e brush c o m p e t i t i o n . T h i r d , most o f the s i t e s which have been s u c c e s s f u l l y regenerated are being damaged by high r e s i d e n t weevil p o p u l a t i o n s (Heppner and Wood 1984). Repeated weevil a t t t a c k s r e s u l t i n the p r o d u c t i o n o f low value stands with crooked stems and m u l t i p l e tops, e l i m i n a t i n g the s p e c i e s q u a l i t i e s o f p r o d i g i o u s growth and e x c e l l e n t s t r u c t u r a l c h a r a c t e r i s t i c s (Fowells 1965). While there are few i f any ac c e p t a b l e a l t e r n a t i v e s p e c i e s to S i t k a spruce f o r r e g e n e r a t i n g many o f these high value s i t e s , there i s a r e l u c t a n c e to p l a n t i t because o f the weevil ( H a r r i s 1981). HacAloney (1930) p r o v i d e d the f i r s t complete d e s c r i p t i o n of P. s t r o b i and i t s impact on the f o r e s t r e s o u r c e . The primary t a r g e t s f o r weevil a t t a c k are the p r e v i o u s year's l e a d e r s . The i n i t i a l p e r i o d o f a t t a c k occurs i n the l a t e s p r i n g when a d u l t female w e e v i l s l a y t h e i r eggs on the one year o l d l e a d e r s . The l a r v a e hatch s h o r t l y a f t e r w a r d s . L a r v a l f e e d i n g and development g e n e r a l l y c o i n c i d e with host bud b u r s t and e l o n g a t i o n o f the t e r m i n a l l e a d e r . E s t a b l i s h e d broods from a s i n g l e female w i l l e f f e c t i v e l y k i l l two or more years o f h e i g h t growth. The l a r v a e feed w i t h i n the c o r t i c a l t i s s u e s i n an a g g r e g a t i o n around the stem o f the pr e v i o u s year's l e a d e r s e v e r i n g phloem v e s s e l s and e v e n t u a l l y completely g i r d l i n g i t . 3 Feeding c o n t i n u e s down the stem u n t i l l a r v a e are f u l l grown when they excavate pupal chambers i n the woody p o r t i o n s and p i t h o f the l e a d e r . Pupation g e n e r a l l y begins i n l a t e J u l y on c o a s t a l B.C. and new a d u l t s emerge from i n f e s t e d l e a d e r s i n l a t e August and e a r l y September (Wood and McMullen 1983). Trees become s u s c e p t i b l e to weevil attack, a f t e r the s e e d l i n g stage when the stand i s s t i l l i n open growing c o n d i t i o n s . Although s e e d l i n g s may be a t t a c k e d ( S o l e s and Gerhold 1968), stands are not g e n e r a l l y s u s c e p t i b l e to i n f e s t a t i o n before a t l e a s t 5 years of age or u n t i l the dominant t r e e s have reached a h e i g h t o f between 2 and 3 meters (Belyea and S u l i v a n 1956; S i l v e r 1968; McMullen 1976a; A l f a r o 1982). The most r e g u l a r l y r e p o r t e d f e a t u r e a s s o c i a t e d with weevil s u s c e p t i b l e t r e e s i s an above average growth r a t e as e v i n c e d by t r e e h e i g h t , crown c l a s s or l e a d e r l e n g t h and diameter. C l i n e and MacAloney (1935) f i r s t r e p o r t e d t h a t the h i g h e s t percentage o f a t t a c k e d t r e e s were o c c u r r i n g i n the uppermost or dominant crown c l a s s e s . K r i e b e l (1954) noted t h a t the most s u s c e p t i b l e t r e e s , when compared to t h e i r immediate neighbours, were those which had the most vig o r o u s growth c h a r a c t e r i s t i c s i n d i c a t e d by h e i g h t and diameter a t b r e a s t h e i g h t . The p r e f e r e n c e o f w e e v i l s to a t t a c k f a s t growing t r e e s i s w e l l documented (C o n n o l l a and Wixson 1963; Marty and Mott 1964; Gara e_t aJL. 1971; Harman 1971) where the v a r i a t i o n i n weevil a t t a c k i s h i g h l y c o r r e l a t e d to t r e e h e i g h t . Tree h e i g h t alone, however, i s o n l y a q u a l i t a t i v e i n d i c a t o r o f any g i v e n t r e e ' s p o t e n t i a l f o r weevil a t t a c k . 4 The p o s i t i o n o f a t r e e w i t h i n a stand's dominance h e i r a r c h y i s a b e t t e r i n d i c a t o r o f s u s c e p t i b i l i t y to w e e v i l i n g than t r e e h e i g h t alone (Overhulser and Gara 1981). A t r e e of a s p e c i f i c h e i g h t has a g r e a t e r r i s k o f being a t t a c k e d i f i t o c c u p i e s a dominant crown p o s i t i o n (Berry and S t i e h l 1976). Trees o f the same h e i g h t i n a lower canopy c l a s s w i l l have a much lower p r o b a b i l i t y o f being a t t a c k e d . The e f f e c t o f h e i g h t on weevil a t t a c k , t h e r e f o r e , i s not s o l e l y a f u n c t i o n o f growth r a t e . I t may Include other f a c t o r s such as topography, c o m p e t i t i o n from non-host t r e e s and t r e e n u t r i t i o n (Xydias and Leaf 1964) as they a f f e c t the p o s i t i o n s o f host t r e e l e a d e r s w i t h i n a stand. The dominant or t a l l e s t t r e e s i n a stand, r e g a r d l e s s o f t h e i r a c t u a l h e i g h t , w i l l a l s o have the l a r g e s t t e r m i n a l l e a d e r s . S e v e r a l s t u d i e s have shown t h a t one or more o f the morphological c h a r a c t e r i s t i c s of t e r m i n a l l e a d e r s are i m p l i c a t e d i n a t t a c k p r e f e r e n c e ( S u l l i v a n 1960; VanderSar and Borden 1977a; Dixon and Houseweart 1978). D o o l i t t l e (1954) emphasized the e f f e c t o f l e a d e r morphology on w e e v i l a t t a c k by showing t h a t t r e e s , which had a l l o f t h e i r l a t e r a l branches pruned away, were e x c e p t i o n a l l y a t t r a c t i v e to white pine w e e v i l s . S u l l i v a n (1961) found t h a t white pine weevils appeared to p r e f e r t h i c k l e a d e r s r e g a r d l e s s o f t h e i r l e n g t h . Harman and Kulman (1967, 1969) found t h a t although the l a r g e r , t a l l e r l e a d e r s were p r e f e r r e d , l e a d e r diameter alone was a s i g n i f i c a n t f a c t o r . In a study by W i l k i n s o n (1983) with white pine w e e v i l s . 5 the most h e a v i l y a t t a c k e d t r e e s were found to be s i g n i f i c a n t l y l a r g e r i n diameter. Although he found a d e f i n i t e a t t a c k p r e f e r e n c e f o r t a l l e r t r e e s he c o u l d not show any s i g n i f i c a n c e f o r l e a d e r l e n g t h alone. Stroh and Gerhold (1966) c o u l d f i n d no s i g n i f i c a n t r e l a t i o n s h i p s between l e a d e r diameter and white pine weevil f e e d i n g although they d i d note t h a t any apparent p r e f e r e n c e s f o r l e a d e r morphological c h a r a c t e r i s t i c s were h e a v i l y weighted by environmental c o n d i t i o n s . Host seeking S i t k a spruce w e e v i l s appear to p r e f e r t r e e s with dominant or v i g o r o u s t e r m i n a l l e a d e r s (Gara §_£. a l . 1971; VanderSar and Borden 1977a,b). In a d e t a i l e d study on l e a d e r morphology with S i t k a spruce w e e v i l s , VanderSar and Borden (1977a) showed t h a t both l e a d e r l e n g t h and diameter were s i g n i f i c a n t f a c t o r s i n l a b o r a t o r y s t u d i e s where w e e v i l s p r e f e r r e d v e r t i c a l s i l h o u e t t e s with l e n g t h and diameter dimensions w e l l above those o f the stand average. V i s u a l p e r c e p t i o n alone, however, does not appear to be enough to e x p l a i n the w e e v i l ' s apparent a b i l i t y to d i s c r i m i n a t e among c o n i f e r s with s i m i l a r s i z e d and c o l o r e d l e a d e r s ( A l f a r o and Borden 1982). S e v e r a l f a c t o r s have been found to be i m p l i c a t e d i n the host d i s c r i m i n a t i o n p r o c e s s . None o f these, however, has been abl e to d e s c r i b e the process beyond 50% o f the observed v a r i a t i o n . Species d i s c r i m i n a t i o n f o r f e e d i n g purposes has been shown to be r e l a t e d to t e r m i n a l bark c o n s t i t u e n t s and e s s e n t i a l o i l e x t r a c t s ( K r i e b e l 1954; Anderson 1956; A l f a r o §_£ a l . 1980). Other s t u d i e s have found t h a t a r e l a t i o n s h i p e x i s t s between l e a d e r bark t h i c k n e s s , c o r t i c a l r e s i n ducts and weevil 6 o v i p o s i t l o n behavior ( S u l l i v a n 1961; Stroh 1965; Overhulser 1973). These r e p o r t e d behaviors imply t h a t once a le a d e r has been s e l e c t e d , perhaps f o r i t s p h y s i c a l dimensions, a p o s i t i v e response from e x p l o r a t o r y f e e d i n g i s r e q u i r e d before the female w i l l o v i p o s i t . 1.2. pineoU as. a. R e p e l l e n t Phytophagous i n s e c t s are known to be a f f e c t e d by many o f the v o l a t i l e chemicals present i n t h e i r host p l a n t s ( D e t h i e r 1954; T h o r s t e i n s o n 1960). There i s a l a r g e a r r a y o f v o l a t i l e monoterpenes which weevils w i l l encounter when f e e d i n g on the t e r m i n a l s o f S i t k a spruce ( H r u t f i o r d a l . 1974; Bridge n e_t a l . 1979; H a r r i s e_t a l . 1983). S e v e r a l o f these compounds have been t e s t e d f o r t h e i r e f f e c t on the f e e d i n g behavior o f P_. s t r o b i (Anderson & F i s h e r 1960; A l f a r o ejt a l . 1980, 1981). Some o f these and other compounds have been shown to be e i t h e r r e p e l l e n t s or e f f e c t i v e masks o f f e e d i n g s t i m u l a n t s . A r e a d i l y a v a i l a b l e mixture o f terpene a l c o h o l s which has been shown to be an e f f e c t i v e r e p e l l e n t to s e v e r a l f o r e s t i n s e c t p e s t s i s p i n e o i l . P i n e o i l i s a commonly produced d e r i v a t i v e from the wastes of the sulphate p u l p i n g p r o c e s s . The major c u r r e n t u t i l i t y o f p i n e o i l i s as a d i s i n f e c t a n t a d d i t i v e to c l e a n i n g compounds and as a f l o a t a t i o n compound i n the mining and ore e x t r a c t i o n i n d u s t r i e s . Hore r e c e n t l y s e v e r a l i n v e s t i g a t o r s have found i t to have some u t i l i t y i n p r o t e c t i n g t r e e s , logs and wood products from i n s e c t a t t a c k . One f o r m u l a t i o n o f p i n e o i l , BBR1, was demonstrated to be a r e p e l l e n t to Trvpodendron and Gna t h o t r l c h u s ambrosia b e e t l e s 7 when a p p l i e d t o p i c a l l y to the s u r f a c e o f l o g s ( N i j h o l t 1980), T h i s mixture was a l s o found to be e f f e c t i v e i n p r o t e c t i n g l i v i n g lodgepole pine t r e e s from a t t a c k by mountain pine b e e t l e s ( N l j h o l t and McMullen 1980; McMullen and S a f r a n y i k 1985). N i j h o l t e t a l . (1981) a l s o found t h a t BBR1 sprayed to the d r i p p o i n t on the lower b o l e s o f lodgepole p i n e , Douglas-f i r and white spruce p r o v i d e d some p r o t e c t i o n from t h e i r bark b e e t l e p e s t s even when the t r e e s ' a t t r a c t i v e n e s s was enhanced by b a i t i n g with bark b e e t l e pheromones. Through l a b o r a t o r y assays, A l f a r o ejfc. al_. (1979, 1981) found t h a t r e d cedar l e a f o i l s and p i n e o i l were e f f e c t i v e f e e d i n g d e t e r r e n t s to P. s t r o b i . A l f a r o e_t al.. (1984) used an a g a r - d i s c b i o a s s a y on s t a r v e d a d u l t spruce w e e v i l s i n c h o i c e experiments with v a r y i n g c o n c e n t r a t i o n s o f BBR1. They found t h a t the amount o f a d u l t weevil f e e d i n g depended on the c o n c e n t r a t i o n s o f p i n e o i l i n the agar d i s c . Weevil f e e d i n g was reduced by 30% when p i n e o i l was a p p l i e d i n 10% c o n c e n t r a t i o n s and i t was e l i m i n a t e d completely when pure p i n e o i l was a p p l i e d . They s t a t e d t h a t w e e v i l hunger was a s i g n i f i c a n t f a c t o r i n the e f f e c t o f the p i n e o i l r e p e l l e n c y . Weevils presented with a f o r c e f e d s i t u a t i o n were ab l e to lower t h e i r acceptance t h r e s h o l d and feed on a l e s s s u i t a b l e s u b s t r a t e . Weevils presented with a ch o i c e between u n t r e a t e d and t r e a t e d s u b s t r a t e s were shown to be d e t e r r e d by much lower c o n c e n t r a t i o n s o f BBR1 than r e q u i r e d i n the no-choice t r i a l s . A l f a r o e_t ai.. (1984) concluded t h a t o p e r a t i o n a l use o f p i n e o i l on P. s t r o b i would be l e s s e f f e c t i v e i f non-choice s i t u a t i o n s were c r e a t e d by t r e a t i n g every t r e e i n a p l a n t a t i o n . 8 The above mentioned s t u d i e s suggested the p o s s i b i l i t y o f p r o t e c t i n g S i t k a spruce stands from a t t a c k by the spruce weevil through the use o f p i n e o i l s . Hypothesis 1: I f p i n e o i l v o l a t l l e s were prese n t a t the t e r m i n a l l e a d e r s of vigorous and a p p a r e n t l y s u i t a b l e S i t k a spruce t r e e s , then f e e d i n g and o v i p o s i t i o n by the weevil c o u l d be reduced or e l i m i n a t e d and the number o f c u r r e n t l y weeviled t r e e s i n the stand lowered. Two p i n e o i l d e r i v a t i v e s were e v a l u a t e d f o r use as o p e r a t i o n a l r e p e l l e n t s i n p r o t e c t i n g S i t k a spruce p l a n t a t i o n s from E< s t r o b i a t t a c k . In a d d i t i o n to t e s t i n g the r e p e l l e n c y of pine o i l , the progress of the weevil i n f e s t a t i o n from the time o f f i r s t a t t a c k was deduced through i n t e n s i v e t r e e sampling. 1.3. A e r i a l Photography P o s s i b l e methods f o r d e t e c t i n g and s u r v e y i n g the i n t e n s i t y and d i s t r i b u t i o n of P. s t r o b i i n young S i t k a spruce stands was seen as an important a d j u n c t to t h i s f i r s t g o a l of i n v e s t i g a t i n g r e p e l l e n t s . The d e t e c t i o n of P. s t r o b i damage i s most e a s i l y achieved when the i n f e c t e d t e r m i n a l begins to w i l t and the needles b e g i n to change c o l o r . The growth o f new t e r m i n a l s i s not v i s i b l y a f f e c t e d p r i o r to mid-July, although stem g i r d l i n g by the l a r v a e almost c e r t a i n l y occurs i n June. The p a l i n g and w i l t i n g o f the newly formed l e a d e r s c o i n c i d e s with the major pupation p e r i o d . The w i l t i n g i s f o l l o w e d r a p i d l y by c u r l i n g with some needle drop. The c u r r e n t year's l e a d e r becomes a withered red-brown 9 p r o j e c t i o n a t the t i p o f the young t r e e by l a t e August or September. The w i l t e d dead t e r m i n a l remains a t the top o f the t r e e u n t i l i t i s broken o f f by wind or b i r d s . V i s u a l d e t e c t i o n o f P. s t r o b i damage p r i o r to the major w i l t i n g and c o l o r change stages i s not e a s i l y accomplished. Inexperienced observers w i l l r a r e l y s u c c e s s f u l l y f i n d weevil damage bef o r e the t e r m i n a l leader c u r l s and turns brown. There has been a r e c e n t c o n c e r t e d e f f o r t on the p a r t o f f o r e s t managers to q u a n t i f y the problems r e s u l t i n g from spruce weevil a t t a c k s (Heppner and Wood 1984). The a v a i l a b l e i n v e n t o r y data fo r immature S i t k a spruce i n the Vancouver f o r e s t r e g i o n alone show an area o f around 20,000 he c t a r e s ( C a r l s o n gt. a i . 1984). C u r r e n t l y a v a i l a b l e methods c a l l f o r I n t e n s i v e ground sampling to d e t e c t damaged t e r m i n a l l e a d e r s . Ground surveys, by t h e i r nature, o f t e n r e q u i r e a complete f i e l d season to generate and analyze i n f e s t a t i o n data f o r l o c a l areas. These data are o f l i t t l e use f o r p l a n n i n g or i n i t i a t i n g any o p t i o n s f o r immediate c o n t r o l . The technique i s most s u i t a b l e f o r o p e r a t i o n s where i n f o r m a t i o n on i n f e s t a t i o n p r ogress i s a l l t h a t i s necessary. For t h i s reason major c o n t r o l o p e r a t i o n s are based on h i s t o r i c data gathered d u r i n g the p r e v i o u s season. The ground survey technique (Heppner and Wood 1984) i s both time consuming and c o s t l y as i t demands c o n s i d e r a b l e s u p e r v i s i o n , c o o r d i n a t i o n and management. Recent developments i n r e l i a b l e sampling from a e r i a l photographs have shown t h a t both temporal c o n s t r a i n t s and c o s t s might be reduced with these techniques. The c o s t r a t i o o f ground s t r i p sampling to 10 a e r i a l photographic s u r v e y i n g has been q u i t e v a r i a b l e over past recorded e f f o r t s , but most i n v e s t i g a t o r s agree i t i s i n the order of 100:1 (Wear and Bongberg 1951; Meyer and French 1967; H e l l e r 1968; Wert and R o e t t g o e r i n g 1968; K l e i n 1973), Although survey c o s t s are a major c o n s t r a i n t , i t should be noted t h a t survey t i m i n g i s o f t e n o f equal or o f g r e a t e r consequence when d e a l i n g with an i n s e c t i n f e s t a t i o n . A e r i a l surveys f o r bark b e e t l e damage have been u s e f u l f o r r e c o r d i n g the h i s t o r i c a l spread o f i n f e s t a t i o n s and f o r d e l i n e a t i n g areas which have a h i g h l i k e l i h o o d of h a r b o r i n g c u r r e n t l y i n f e s t e d t r e e s . The dead, red t r e e s t h a t are e a s i l y d e t e c t e d from the a i r no longer c o n t a i n b e e t l e s but t h e i r presence, frequency and d i s t r i b u t i o n i n f e r the e x t e n t o f the a v a i l a b l e a t t a c k i n g b e e t l e p o p u l a t i o n ( H e l l e r §_t aj,. 1959). I n f e s t a t i o n s of Lt_ s t r o b i are s i m i l a r to those o f bark b e e t l e s i n t h a t red, dead t e r m i n a l s c o u l d be used f o r h i s t o r i c a l i n f e r e n c e o f the i n t e n s i t y and d i s t r i b u t i o n o f the r e s i d e n t weevil p o p u l a t i o n . E s t a b l i s h i n g weevil i n t e n s i t y and d e s c r i b i n g zones o f h i g h r i s k are e s s e n t i a l processes f o r p r e s c r i b i n g o p t i o n s f o r c o n t r o l . C o n t r o l o f the weevil and the bark b e e t l e , however, r e q u i r e s the i d e n t i f i c a t i o n o f c u r r e n t l y i n f e s t e d t r e e s p r i o r to any marked v i s i b l e m a n i f e s t a t i o n of damage symptoms. One of the the more common c o n t r o l techniques f o r d e a l i n g with spruce weevil i n f e s t a t i o n s i s to prune and then burn c u r r e n t l y i n f e s t e d l e a d e r s (Maughan 1930; D i r k s 1964; C a r l s o n e_£ a l . 1984). T h i s method serves to l i m i t p o p u l a t i o n growth by 11 d e s t r o y i n g the c u r r e n t year's brood. To achieve c o n t r o l , v i r t u a l l y a l l of the c u r r e n t l y i n f e s t e d l e a d e r s i n a stand must be r e c o g n i z e d as a t t a c k e d and c l i p p e d before the brood emerges. E f f e c t i v e l e a d e r c l i p p i n g r e q u i r e s a h i g h degree of p r e c i s i o n i n t i m i n g s i n c e the most r e l i a b l e v i s i b l e symptoms are not present u n t i l the w e e v i l s i n s i d e have pupated. T h i s o f t e n l e a v e s a very s h o r t p e r i o d between the time a t t a c k e d l e a d e r s are e a s i l y d e t e c t e d and the time the new w e e v i l s emerge. There i s a c e r t a i n r i s k t h a t some weevil a d u l t s may s u c c e s s f u l l y escape before the a t t a c k e d l e a d e r can be destroyed. A e r i a l photographs appear to have p o t e n t i a l f o r speeding up the d e t e c t i o n process by q u i c k l y d e l i n e a t i n g zones of Intense a t t a c k making c o n t r o l o p e r a t i o n s more e f f i c i e n t . A l d r i c h ejt. aL. (1959) found t h a t attempts to c o n t r o l P_. s t r o b i i n f e s t a t i o n s i n e a s t e r n white pine were hindered by problems i n a s s e s s i n g the l e v e l s o f w e e v i l damage before and a f t e r s p r a y i n g . Using c o n v e n t i o n a l ground surveys proved to be time consuming, c o s t l y and o f q u e s t i o n a b l e accuracy. They conducted a e r i a l photographic surveys u s i n g normal c o l o u r (NO f i l m to determine the e f f i c a c y , accuracy and r e l a t i v e c o s t s o f the two techniques. T h e i r s t r i p sampling scheme, a t a s c a l e o f 1:1,000, achieved 90% accuracy i n the i d e n t i f i c a t i o n o f weeviled t e r m i n a l s . The advantages o f u s i n g an a e r i a l photograph survey over c o n v e n t i o n a l ground techniques were: 1) The a e r i a l view a f f o r d s the d e t e c t i o n o f weeviled t e r m i n a l s , i n t a l l t r e e s and dense stands, t h a t are d i f f i c u l t to see from the ground. 2) The sample i s o b t a i n e d 3 times f a s t e r and i n c l u d e s many more t r e e s per p l a n t a t i o n . 12 3) Remote areas t h a t are d i f f i c u l t , c o s t l y or time consuming to reach by ground are e a s i l y sampled. 4) The c o s t s of a e r i a l sampling were equal to those o b t a i n e d by ground surveys. A l d r l c h ( 1966) suggested, t h a t the savings they r e a l i z e d with a e r i a l photographic sampling i n t h e i r small study would l i k e l y be even g r e a t e r f o r l a r g e r p r o j e c t s . Losee (1953) found t h a t a e r i a l sampling reduced measuring time and produced lower standard e r r o r s o f measurements when used f o r timber e s t i m a t e s . Weber ( 1 9 6 5 ) found no s i g n i f i c a n t d i f f e r e n c e between h i s a e r i a l sampling technique and co n c u r r e n t ground surveys f o r e s t i m a t i n g volume l o s s e s to spruce budworm i n f e s t a t i o n s . Improvements to the techniques i n u s i n g normal c o l o r (NO and c o l o r i n f r a - r e d (CIR) f i l m s have enhanced the advantages of e f f i c i e n c y , speed, accuracy and reduced c o s t s with a e r i a l photograph sampling. Large s c a l e NC and CIR a e r i a l photographs have been used e f f e c t i v e l y f o r d e t e c t i n g f o r e s t pest outbreaks (Arnberg and Wastenson 1973) and e v a l u a t i n g f o r e s t p e s t damage (Ashley SJL a l . 1976; Murtha 1 9 7 8 ) . I n f r a - r e d s e n s i t i v e f i l m s have the unique p r o p e r t y o f being a b l e to d e t e c t between-tree p h y s i o l o g i c a l d i f f e r e n c e s t h a t are not v i s i b l e with the unaided eye. The use o f CIR f i l m f o r the d e t e c t i o n o f p l a n t s t r e s s induced by i n s e c t s , d i s e a s e s and other environmental phenomena has r e c e i v e d c o n s i d e r a b l e a t t e n t i o n ( P u r i t c h 1 9 8 1 ) . A major i n t e r e s t has been to i n v e s t i g a t e the c a p a c i t y o f CIR f i l m to make changes i n the n o n - v i s i b l e i n f r a r e d r e f l e c t i o n from p l a n t t i s s u e s v i s i b l e on f a l s e c o l o r p r i n t s ( F r i t z 1967; Cochrane 1968) 13 CIR f i l m s are made up of three dye-forming l a y e r s t h a t are s e n s i t i v e on exposure to the green, r e d and near i n f r a - r e d s p e c t r a l r e g i o n s . A l l three o f these dye l a y e r s are s e n s i t i v e to e l e c t r o m a g n e t i c wavelengths i n the blue s p e c t r a l r e g i o n . To e l i m i n a t e t h i s blue exposure a yellow f i l t e r (blue l i g h t s u b t r a c t i v e ) i s comonly used ( F r i t z 1967). The developed image w i l l appear blue where exposed to green l i g h t , green from r e d l i g h t exposure and red where exposure was due to near i n f r a - r e d r e f l e c t i o n . Green p l a n t s r e f l e c t r e l a t i v e l y l a r g e amounts o f near i n f r a - r e d energy (n-IR) as w e l l as the v i s i b l e green wavelengths commonly a s s o c i a t e d with the c o l o r o f h e a l t h y p l a n t s . On CIR , f a l s e c o l o r f i l m , the magenta c o l o r o f green p l a n t s i s caused by the exposure o f the yellow and cyan dye-forming l a y e r s to the green and n-IR r e f l e c t i o n s . The r e l a t i v e amounts of n-IR r e f l e c t e d among p l a n t types causes v a r i a t i o n s i n the i n t e n s i t y o f t h e i r magenta c o l o r s on f a l s e c o l o r f i l m . D i f f e r e n c e s i n i n t e n s i t y o f n-IR r e f l e c t i o n , both w i t h i n and between p l a n t groups, are f a r more pronounced than the d i f f e r e n c e s i n green l i g h t r e f l e c t e d ( C i e s l a e t al.. 1967; Murtha and Hamilton 1969). Although some b r o a d l e a f t r e e s , grasses and c o n i f e r s show l a r g e d i f f e r e n c e s i n n-IR r e f l e c t e d from t h e i r l e a f s u r f a c e s , these same p l a n t s w i l l show o n l y s l i g h t d i f f e r e n c e s i n green l i g h t r e f l e c t e d . Since CIR f i l m i s exposed by r e f l e c t e d n-IR, the v i s u a l s e p a r a t i o n o f images from these v a r i o u s p l a n t groups i s much more apparent and should t h e r e f o r e be e v i d e n t a t much s m a l l e r s c a l e s than r e q u i r e d f o r NC f i l m s . 14 There are changes i n s p e c t r a l r e f l e c t i o n p a t t e r n s t h a t are c o n c u r r e n t to changes i n the p h y s i o l o g i c a l c o n d i t i o n o f some p l a n t s . Murtha (1978) has d e t a i l e d these changes as they apply to s t r e s s and t h e i r r e s u l t a n t e f f e c t s on the v i s i b l e image o f the a f f e c t e d p l a n t s . In some cases the changes i n n-IR r e f l e c t i o n are l i k e l y to be more pronounced than those i n the v i s i b l e spectrum d u r i n g the i n i t i a l stages o f s t r e s s . I t has been suggested that s l i g h t changes i n n-IR r e f l e c t i o n are the f i r s t i n d i c a t o r s o f p l a n t s t r e s s or l o s s of v i g o r (Murtha 1978). I f such changes do occur and they can be d e t e c t e d then the process must be termed p r e v i s u a l d e t e c t i o n of p l a n t s t r e s s . E x t r a v i s u a l d e t e c t i o n r e f e r s to the d e t e c t i o n of f o l i a r changes t h a t are not l i k e l y to become v i s i b l e (Murtha 1978). For most a p p l i c a t i o n s and c e r t a i n l y f o r p r e v i s u a l d e t e c t i o n o f p l a n t s t r e s s , the u t i l i t y o f CIR f i l m depends on i t s a b i l i t y to r e c o r d s l i g h t v a r i a t i o n s i n i n f r a - r e d r e f l e c t i o n . For t h i s reason most CIR f i l m s have the n-IR s e n s i t i v e dye l a y e r responding a t a much slower r a t e than the r e d and green s e n s i t i v e dye l a y e r s ( F r i t z 1967). I f the exposure r a t e s were e q u a l , the r e l a t i v e l y high amounts o f n-IR r e f l e c t e d would r e s u l t i n a l l f o l i a g e appearing e x c e s s i v e l y r e d and small d i f f e r e n c e s i n s p e c t r a l r e f l e c t i o n would not be e a s i l y d e t e c t e d . The p h y s i o l o g i c a l b a s i s o f s t r e s s i n green p l a n t f o l i a g e has been much s t u d i e d as have changes i n s p e c t r a l r e f l e c t i o n r e s u l t i n g from s t r e s s . Gaussman (1977) determined t h a t 8% o f the t o t a l n-IR r e f l e c t e d was due to i n t r a c e l l u l a r 15 d i s c o n t i n u i t i e s i n c l u d i n g n u c l e i , c r y s t a l s and cytoplasm i n a d d i t i o n to the c e l l - a i r i n t e r f a c e which accounts f o r the major p o r t i o n . K n i p l i n g (1967) determined t h a t changes i n these components i n s t r e s s e d f o l i a g e c o r r e l a t e d with changes i n n-IR r e f l e c t i o n . F r i t z (1967) and Murtha (1978) have suggested t h a t the f i r s t symptom o f f o l i a g e s t r e s s may be a change i n the r e f l e c t i o n of n-IR energy. Rhode and Olson (1969) r e p o r t e d on i n c r e a s e s i n n-IR r e f l e c t i o n from moisture s t r e s s e d broadleaved t r e e s . In c o n t r a s t , Weber (1965) and H e l l e r (1968) found t h a t s t r e s s e d c o n i f e r s r e f l e c t e d l e s s n-IR than h e a l t h y f o l i a g e . S e v e r a l i n v e s t i g a t o r s have s i n c e suggested t h a t although CIR f i l m o f f e r s s u p e r i o r haze p e n e t r a t i o n and c o l o r c o n t r a s t between deciduous and c o n i f e r o u s t r e e s , the technique does not a f f o r d any v i s i b l e d i f f e r e n c e s between green i n f e s t e d and h e a l t h y t r e e s i . e . p r e v i s u a l d e t e c t i o n (Meyer and French 1967; C i e s l a e t a l . 1967; H e l l e r 1968). Murtha (1985) and Murtha and Cozens (1985) however, have shown t h a t f a l s e c o l o u r f i l m can be used e f f e c t i v e l y f o r d e s c r i b i n g green t r e e s a t t a c k e d by the spruce b e e t l e . Arnberg and Wastenson (1973) d e s c r i b e d v i s i b l e d i f f e r e n c e s i n CIR and NC photographs o f h e a l t h y versus green a t t a c k e d Norway spruce i n a bark b e e t l e i n f e s t a t i o n . They p o s t u l a t e d t h a t the d i f f e r e n c e s i n s p e c t r a l r e f l e c t i o n r e s u l t e d from n u t r i e n t d e f i c i e n c i e s which a f f e c t e d needle p h y s i o l o g y . They s t a t e d t h a t any m o d i f i c a t i o n s i n c h l o r o p h y l l due to s t r e s s should appear as an i n c r e a s e i n blue and r e d r e f l e c t i o n s i n c e the c h l o r o p h y l l a b s o r p t i o n spectrum peaks i n the blue and red 16 s p e c t r a l r e g i o n s . H e l l e r (1968) a l s o recorded t h i s i n c r e a s e i n r e d r e f l e c t i o n but s t a t e d t h a t the d i f f e r e n c e s were too s m a l l to be d e t e c t a b l e when the i n h e r e n t v a r i a t i o n s w i t h i n a s p e c i e s are taken i n t o account. More s o p h i s t i c a t e d analyses of CIR photographs of s t r e s s e d f o l i a g e by m i c r o d e n s i t o m e t r i e techniques have been conducted (Murtha and Hamilton 1969). They were ab l e to s u c c e s s f u l l y i d e n t i f y m e c h a n i c a l l y s t r e s s e d t r e e s by dye l a y e r d e n s i t y a n a l y s i s o f f a l s e c o l o r (CIR) t r a n s p a r e n c i e s . Murtha and McLean (1981), u s i n g d e n s i t o m e t r l c a n a l y s e s , suggested a technique whereby CIR photography c o u l d be used to determine e x t r a v i s u a l l y the h e a l t h and growth c o n d i t i o n s o f D o u g l a s - f i r stands. In summary, p r e v i s u a l d e t e c t i o n r e l i e s on the presence o f measurable changes i n s p e c t r a l r e f l e c t i o n s due to p h y s i o l o g i c a l changes r e s u l t i n g from s t r e s s . In the case o f P. s t r o b i i n f e s t a t i o n s the t e r m i n a l l e a d e r s of a t t a c k e d t r e e s w i l l e v e n t u a l l y w i l t and change c o l o r so e a r l y d e t e c t i o n would be termed p r e v i s u a l . The c o l o r changes are from the b r i g h t , dark green o f a h e a l t h y l e a d e r to a p a l e green, then yellow-green and f i n a l l y o n l y the red-brown withered s t i c k remains. Weeviled S i t k a spruce l e a d e r s would begin to be s t r e s s e d soon a f t e r the l a r v a e hatch and b e g i n f e e d i n g . The major s t r a i n here probably comes from a r e d u c t i o n i n a v a i l a b l e n u t r i e n t s r e s u l t i n g from the s e v e r i n g of phloem v e s s e l s . The most obvious c h a r a c t e r i s t i c s o f l a r v a l f e e d i n g are a drooping l e a d e r and the yellow hue imparted to the f o l i a g e ( K l i n e and 17 M i t c h e l l 1979). Major w i l t i n g o f a t e r m i n a l due to moisture l o s s then does not g e n e r a l l y occur u n t i l l a t e i n the we e v i l ' s development p e r i o d when c o n s i d e r a b l e damage has a l r e a d y been wrought. Hypothesis 2: Large s c a l e normal c o l o u r (NC) and c o l o u r i n f r a - r e d (CIR) a e r i a l photographs c o u l d be u t i l i z e d f o r the e a r l y d e t e c t i o n and su r v e y i n g o f weevil a t t a c k . T e s t i n g o f t h i s h y p othesis was the second goal o f t h i s p r o j e c t ; t h a t i s , to ev a l u a t e NC and CIR a e r i a l photographic techniques f o r d e t e c t i n g and s u r v e y i n g the i n t e n s i t y and d i s t r i b u t i o n o f P. s t r o b l i n young S i t k a spruce stands. 1.4. Study O b j e c t i v e s The s p e c i f i c o b j e c t i v e s o f t h i s study were t o : 1) I n v e s t i g a t e the e f f i c a c y o f two f o r m u l a t i o n s o f p i n e o i l i n p r o t e c t i n g young, second growth S i t k a spruce stands from a t t a c k by P. s t r o b l . 2) Determine whether P. s t r o b l a t t a c k e d stands can be sampled f o r damage by a l a r g e s c a l e a e r i a l photograph survey. 3) I n v e s t i g a t e the d i f f e r e n c e s i n e f f i c a c y between normal c o l o r and c o l o r i n f r a - r e d s e n s i t i v e f i l m s f o r d e t e c t i n g P_. s t r o b l damage on l a r g e s c a l e a e r i a l photographs. 18 2. MATERIALS AND METHODS The s t u d i e s were conducted at two l o c a t i o n s on the west c o a s t of Vancouver I s l a n d ( F i g . l ) d u r i n g the summer o f 1982. One o f the s i t e s was l o c a t e d w i t h i n B r i t i s h Columbia F o r e s t Products L t d . t r e e farm l i c e n c e #22 near the v i l l a g e of U c l u e l e t . The other s i t e was l o c a t e d i n The T a h s i s Company's T.S.H.L. #A006003 on Nootka I s l a n d . Both of the s i t e s c o n s i s t e d of p r i m a r i l y pure S i t k a spruce stands, from 8 to 12 years a f t e r p l a n t i n g , which were h e a v i l y a t t a c k e d by P. s t r o b l . 2.1 D e s c r i p t i o n of the Experimental S i t e s , P l o t s and Blocks 2.1.1 Nootka I s l a n d S i t e The Nootka I s l a n d study s i t e was l o c a t e d along the upper reaches o f Beano Creek on west c e n t r a l Nootka I s l a n d ( F i g . 2). T h i s area was chosen f o r i t s w e l l documented h i s t o r y of weevil i n f e s t a t i o n . I t s i n l a n d l o c a t i o n was p r o t e c t e d by low mountains from the d i r e c t i n f l u e n c e of the marine c l i m a t e . The dominant s i t e type was medium to good i n the wetter subzone o f the c o a s t a l western hemlock b i o g e o c l i m a t i c zone. The s i t e c o n s i s t s mainly of even-aged S i t k a spruce i n f i v e c u t b l o c k p l a n t a t i o n s . P l a n t a t i o n S ( p l o t s 1 to 10) was e s t a b l i s h e d i n 1971 and p l a n t a t i o n s R (11 to 15), Q (16, 17), N (18, 19) and M (20, 21) were e s t a b l i s h e d i n 1974. 2.1.2 U c l u e l e t S i t e The U c l u e l e t study s i t e was l o c a t e d along Staghorn Creek i n two S i t k a spruce p l a n t a t i o n s ( F i g . 3). One p l a n t a t i o n , 19 F i g u r e 1. L o c a t i o n of the Nootka I s l a n d and U c l u e l e t study s i t e s on Vancouver I s l a n d , B r i t i s h Columbia. 20 F i g u r e 3. L o c a t i o n o f the experimental p l o t s a t the U c l u e l e t study s i t e . 22 p l a n t e d i n 1970 ( p l o t s 1 to 5), was p r i m a r i l y D o u g l a s - f i r with pure S i t k a spruce p l a n t e d i n the lowlands and the other p l a n t a t i o n was pure S i t k a spruce p l a n t e d i n 1972 ( p l o t s 6 to 15). The U c l u e l e t s i t e was chosen f o r i t s documented a t t a c k h i s t o r y and f o r i t s c o n t r a s t with the Nootka I s l a n d s i t e . The area was a medium to poor s i t e type i n the wetter subzone of the c o a s t a l western hemlock b i o g e o c l i m a t i c zone. Both the U c l u e l e t and Nootka I s l a n d s i t e s are i n the "low weevil hazard" c o a s t a l fog b e l t s , as d e s c r i b e d by McMullen (1976a,b), however, the U c l u e l e t s i t e i s somewhat c l o s e r to the ocean. U n l i k e the Nootka I s l a n d s i t e , i t i s not surrounded by mountainous t e r r a i n and i t i s more d i r e c t l y i n f l u e n c e d by marine c o n d i t i o n s . 2.1.3 C r i t e r i a f o r E s t a b l i s h i n g the Experimental P l o t s The experimental p l o t s a t both study s i t e s were e s t a b l i s h e d as 20 meter by 20 meter square u n i t s . T h i s p l o t s i z e was based on the f i n d i n g s t h a t host seeking P. s t r o b l tend to remain w i t h i n 20 meters of t h e i r brood t r e e (McMullen and Condrashoff 1973; Harman 1975; Dixon e t al.. 1979). An attempt was made to a t t a i n c o n s i s t e n c y among p l o t s by adhering to the f o l l o w i n g s e l e c t i o n c r i t e r i a : 1) A minimum o f two 1981 weevil a t t a c k e d t r e e s were present w i t h i n the p l o t . 2) At l e a s t one of the a t t a c k e d t r e e s was l o c a t e d w i t h i n one meter of the p l o t c e n t e r . 3) The S i t k a spruce component was a t l e a s t 80 percent of the p l o t stand. 4) P l o t s were c o n s i s t e n t with regard to drainage, aspect and exposure. 5) The p l o t boundaries were l o c a t e d on or near f e a t u r e s t h a t would be v i s i b l e on a e r i a l photographs. 23 C u r r e n t l y a t t a c k e d t r e e s w i t h i n each p l o t were r e q u i r e d to ensure t h a t a p o p u l a t i o n o f host seeking weevils was present. T h i s assumption i s supported by the above mentioned r e p o r t s on a d u l t d i s p e r s a l and a r e p o r t on weevils o v e r w i n t e r i n g i n a t t a c k e d t e r m i n a l s (VanderSar 1977). A minimum o f two c u r r e n t l y a t t a c k e d t r e e s was chosen i n case one t r e e d i d not produce any l i v e a d u l t w e e v i l s . Some of the a t t a c k s were on t r e e s which had been weeviled p r e v i o u s l y suggesting t h e i r brood p r o d u c t i o n c o u l d be minimal (Overhulser e_t al_. 1972). I t was assumed t h a t a l l p l o t s meeting t h i s c r i t e r i o n would c o n t a i n s i g n i f i c a n t numbers of l i v e , h e a l t h y w e e v i l s , some of which would s e l e c t a s u i t a b l e host w i t h i n the p l o t . A l a r g e component of S i t k a spruce w i t h i n the p l o t would ensure t h a t host seeking weevils were not i n f l u e n c e d by the presence of non-host t r e e s . I t was assumed t h a t a non-host presence of l e s s than 20 percent would not s e r i o u s l y a f f e c t the host seeking behavior o f the w e e v i l s . P l o t s were a l s o s e l e c t e d f o r c o n s i s t e n c y i n drainage, aspect and exposure to minimize any e f f e c t s of m i c r o s i t e on weevil host seeking behavior. Wherever p o s s i b l e , p l o t s were s e l e c t e d i n l o c a t i o n s which c o u l d be i d e n t i f i e d e a s i l y on a e r i a l photographs. Most o f the p l o t s were l o c a t e d near roadways, small creeks and open areas which were v i s i b l e on 1:20,000 a e r i a l photographs. P l o t s which c o u l d not be p l a c e d i n these areas were l o c a t e d i n s t r a i g h t l i n e s from the other more e a s i l y i d e n t i f i e d p l o t s . 24 2.1.4 Marking the Experimental P l o t s The p l o t s were marked a t each corner and each s i d e was surveyed to 20 meters u s i n g a hand compass and a 30 meter surveyor's tape. Trees along the p l o t boundaries were i n c l u d e d i n the p l o t i f t h e i r stem was on or w i t h i n the l i n e . The p l o t s were separated by a minimum of 50 meters. The c e n t e r of each p l o t was a l s o marked f o r a e r i a l d e t e c t i o n by s e c u r i n g a one meter square p i e c e of cheese c l o t h which d i s p l a y e d a b o l d b l a c k number. These markers were p l a c e d i n a l l p l o t s a t both study l o c a t i o n s i n June 1982. Each p l o t was then surveyed f o r i t s exact l o c a t i o n on 1:20,000 s c a l e a e r i a l photographs and f o r e s t cover maps. The f l i g h t l i n e s and f i l m exposure sequences f o r the a e r i a l photographs were planned from these r e f e r e n c e s . 2.1.5 The Experimental Blocks During the p l o t e s t a b l i s h m e n t procedure, i t became obvious t h a t areas with a s i n g l e uniform s i t e type e i t h e r d i d not have enough weeviled t r e e s or were too small to accommodate a l l of the p l o t s . An attempt was made to overcome t h i s l a c k o f s i t e c o n t i n u i t y by i d e n t i f y i n g three b l o c k s with s i m i l a r w i t h i n block gross environmental c h a r a c t e r i s t i c s . P l o t s were a l l o c a t e d e q u a l l y among the b l o c k s . On Nootka I s l a n d , the p l o t s i n block 1 (1 to 7) were on w e l l d r a i n e d lowlands with f l a t a s p e c t s . The b l o c k 2 p l o t s , 8 to 14, were on w e l l d r a i n e d upper s l o p e s with s o u t h e a s t e r n a s p e c t s . Block 3 p l o t s , 15 to 21, were on w e l l d r a i n e d upper s l o p e s with e a s t e r n a s p e c t s . 25 At U c l u e l e t , the p l o t s i n block 1 (1 to 5) c o n s i s t e d o f S i t k a spruce p l a n t e d i n and along the bottoms of narrow g u l l i e s i n the 1970 p l a n t a t i o n where the upper s l o p e s and surrounding t e r r a i n were occupied by a D o u g l a s - f i r p l a n t a t i o n o f the same age. Block 2 p l o t s (6 to 10) were p l a n t e d i n and along the bottoms of narrow g u l l i e s i n the 1972 p l a n t a t i o n with S i t k a spruce occupying the high ground. P l o t s i n block 3 (11 to 15) c o n s i s t e d o f S i t k a spruce p l a n t e d on l e v e l ground. A l l b l o c k 3 p l o t s were w i t h i n the 1972 p l a n t a t i o n except f o r p l o t 15, which was i n the 1970 p l a n t a t i o n . 2.2. The P i n e o i l Study The e f f e c t o f p i n e o i l as a spruce weevil r e p e l l e n t was t e s t e d i n two f o r m u l a t i o n s ; BBR1, which was u n a l t e r e d Norpine 65, and BBR2, a mixture o f s y n t h e t i c p i n e o i l s (Safer Agro-Chem L t d . ) l * . 2.2,1. Laboratory S t u d i e s A l a b o r a t o r y f e e d i n g b i o a s s a y was conducted to determine the r e l a t i v e r e p e l l e n c y o f the two p i n e o i l s to S i t k a spruce w e e v i l s on host f o l i a g e . S i t k a spruce l e a d e r s were c o l l e c t e d a t the U n i v e r s i t y o f B r i t i s h Columbia Research F o r e s t i n March, 1982 and c u t i n t o 5 cm l e n g t h s . To prevent r a p i d d e s s i c a t i o n the ends of the c u t t i n g s were dipped i n melted wax. The spruce c u t t i n g s were randomly assi g n e d to three groups; treatment with BBR1, treatment with BBR2 and u n t r e a t e d . 1*. Both f o r m u l a t i o n s o f p i n e o i l were ob t a i n e d from Safer Agro-Chem L t d . 6761 K i r k p a t r i c k Crescent, V i c t o r i a , B r i t i s h Columbia V8X 3X1 26 The treatment c u t t i n g s were submerged i n a f l a s k c o n t a i n i n g the p i n e o i l and then p l a c e d on paper t o w e l l i n g f o r 24 hours to allow the excess p i n e o i l to d r i p o f f . The weevils used f o r the study were c o l l e c t e d on Nootka I s l a n d i n September of 1981 and maintained on cut f o l i a g e u n t i l the experiment date. Tests f o r weevil v i g o r were performed by p l a c i n g weevils on the f l o o r c e n t e r of a screened cage with f r e s h l y c ut S i t k a spruce l e a d e r s s t a n d i n g u p r i g h t around the perimeter. Weevils which s u c c e s s f u l l y moved acr o s s the f l o o r and up a le a d e r i n a 24 hour p e r i o d were s e l e c t e d f o r study. The experiment c o n s i s t e d o f 10 r e p l i c a t i o n s i n each o f which a s i n g l e weevil was c o n f i n e d to a 300 ml styrofoam cup co n t a i n g the treatment c u t t i n g s . S i x s i t u a t i o n s were t e s t e d : 1) a s i n g l e c u t t i n g dipped i n BBR1. 2) a s i n g l e c u t t i n g dipped i n BBR2 3) two c u t t i n g s , one dipped i n BBR1 and the other u n t r e a t e d . 4) two c u t t i n g s , one dipped i n BBR2 and the other u n t r e a t e d . 5) a s i n g l e u n t r e a t e d c u t t i n g . 6) two c u t t i n g s , both untreated. The cups c o n t a i n i n g the wee v i l s and c u t t i n g s were p l a c e d i n a fume hood and examined a f t e r 48 hours. The t o t a l number of fe e d i n g punctures excavated by the wee v i l s on both the p i n e o i l t r e a t e d and the un t r e a t e d c u t t i n g s were recorded f o r a n a l y s i s . Observed we e v i l m o r t a l i t y was recorded a f t e r 48, 72, 120 and 168 hours. 2.2.2. F i e l d S t u d i e s . The pine o i l s were a p p l i e d i n two treatments. The f i r s t treatment was a d i r e c t , t o p i c a l a p p l i c a t i o n to the t e r m i n a l 27 l e a d e r s of a l l t r e e s i n the p l o t . The second treatment was to pl a c e a slow r e l e a s e d e v i c e (SRD) soaked i n p i n e o i l near the te r m i n a l l e a d e r s on s i n g l e dominant t r e e s . The SRDs were a p p l i e d a t one t r e e per p l o t and a t f i v e t r e e s per p l o t . Each treatment was r e p l i c a t e d three times. There were s i x treatments p l u s a c o n t r o l a t the Nootka I s l a n d s i t e and four treatments p l u s a c o n t r o l a t the U c l u e l e t s i t e . The a l l o c a t i o n of p i n e o i l treatments to p l o t s i n both study areas are o u t l i n e d i n Table 1. The Nootka I s l a n d p l o t s were e s t a b l i s h e d by the t h i r d week of A p r i l 1982 and were t r e a t e d d u r i n g the second week of May. The U c l u e l e t p l o t s were e s t a b l i s h e d by the f i r s t week i n A p r i l 1982 and were t r e a t e d d u r i n g the t h i r d week o f A p r i l . T o p i c a l a p p l i c a t i o n s o f the p i n e o i l s were admi n i s t e r e d o n l y at the Nootka I s l a n d s i t e . The p i n e o i l SRDs were a p p l i e d a t the U c l u e l e t s i t e u s i n g the same methods employed a t the Nootka I s l a n d s i t e . 2.2.2.1. T o p i c a l A p p l i c a t i o n The p i n e o i l s were t o p i c a l l y a p p l i e d to the t e r m i n a l l e a d e r s o f the treatment t r e e s with a s p e c i a l l y c o n s t r u c t e d a p p l i c a t o r ( F i g . 4a). The a p p l i c a t o r head was a f f i x e d to the top o f a f i v e meter t e l e s c o p i n g p o l e . I t was designed such t h a t when presented to the t e r m i n a l o f a four meter t a l l t r e e , i t s sponge l i n i n g was p a r a l l e l to the stem. The sponge was made of s o f t polyurethene which was e a s i l y compressed to 1/4 of i t s t h i c k n e s s . T h i s a p p l i c a t o r c o u l d accommodate l e a d e r s up to 4 cm i n diameter without appearing to cause any mechanical i n j u r y to t h e i r bark or needles. 28 Table 1. The a l l o c a t i o n s of p i n e o i l treatments among the p l o t s , b l o c k s and p l a n t a t i o n s a t the Nootka I s l a n d and U c l u e l e t study s i t e s . P l a n t a t i o n S i t e Treatment (1) Block P l o t No. Age ( y r s . ) Nootka BBR1-1 1 1 11 Nootka BBR1-5 1 7 11 Nootka BBR1-T 1 3 11 Nootka BBR2-1 1 5 11 Nootka BBR2-5 1 6 11 Nootka BBR2-T 1 4 11 Nootka C o n t r o l 1 2 11 Nootka BBR1-1 2 10 11 Nootka BBR1-5 2 12 8 Nootka BBR1-T 2 11 8 Nootka BBR2-1 2 9 11 Nootka BBR2-5 2 13 8 Nootka BBR2-T 2 8 11 Nootka C o n t r o l 2 14 8 Nootka BBR1-1 3 21 8 Nootka BBR1-5 3 17 8 Nootka BBR1-T 3 20 8 Nootka BBR2-1 3 18 8 Nootka BBR2-5 3 15 8 Nootka BBR2-T 3 16 8 Nootka C o n t r o l 3 19 8 U c l u e l e t BBR1-1 1 5 12 U c l u e l e t BBR1-5 1 3 12 U c l u e l e t BBR2-1 1 1 12 U c l u e l e t BBR2-5 1 2 12 U c l u e l e t C o n t r o l 1 4 12 U c l u e l e t BBR1-1 2 10 10 U c l u e l e t BBR1-5 2 6 10 U c l u e l e t BBR2-1 2 8 10 U c l u e l e t BBR2-5 2 9 10 U c l u e l e t C o n t r o l 2 7 10 U c l u e l e t BBR1-1 3 12 10 U c l u e l e t BBR1-5 3 14 10 U c l u e l e t BBR2-1 3 15 12 U c l u e l e t BBR2-5 3 11 10 U c l u e l e t C o n t r o l 3 13 10 (1) E x p l a n a t i o n o f treatment codes: BBR1-1 = a s i n g l e BBR1 SRD per p l o t BBR1-5 = 5 BBR1 SRD's per p l o t BBR1-T = BBR1 a p p l i e d t o p i c a l l y to a l l t r e e s i n p l o t , note: codes are the same f o r BBR2 treatments. 29 F i g u r e 4. The p i n e o i l a p p l i c a t o r used f o r a p p l y i n g p i n e o i l t o p i c a l l y to the t e r m i n a l l e a d e r s of treatment t r e e s . a. Schematic drawing of the a p p l i c a t o r head. b. pine o i l being i n j e c t e d on to the a p p l i c a t o r i n the f i e l d . c. d. The a p p l i c a t o r i n use i n the f i e l d on the l e a d e r of a treatment t r e e . 30 The s o f t sponge on the a p p l i c a t o r head was s a t u r a t e d with p i n e o i l a t the beginning of each treatment ( F i g . 4b). The sponge s u r f a c e was kept s a t u r a t e d by p e r i o d i c a l l y r e a p p l y i n g p i n e o i l when dry areas were v i s i b l e . When p l a c e d on t e r m i n a l s from 1 to 4 cm i n diameter, the p i n e o i l soaked sponge would c o n t a c t three s i d e s . Each of the t e r m i n a l s to be t r e a t e d were g i v e n two a p p l i c a t i o n s of p i n e o i l , one from e i t h e r s i d e of the t r e e . T h i s ensured t h a t the p i n e o i l s were a p p l i e d to a l l s i d e s of the t e r m i n a l leaders.The sponges were examined f o r dry areas a f t e r each t e r m i n a l was t r e a t e d . Resoakings g e n e r a l l y r e q u i r e d 25 ml o f p i n e o i l which was s u f f i c i e n t to t r e a t approximately e i g h t 50 cm long t e r m i n a l l e a d e r s . In t h i s manner, the average t e r m i n a l l e a d e r r e c e i v e d a c o a t i n g o f approximately 3 ml of p i n e o i l . The a p p l i c a t i o n process began by manouvering the a p p l i c a t o r to surround the t e r m i n a l j u s t above the p r e v i o u s year's l a t e r a l whorl ( F i g . 4 c ) ; t h a t i s , a t the lower or proximal p o r t i o n of the c u r r e n t t e r m i n a l l e a d e r . Pushing s t e a d i l y and evenly upwards on the a p p l i c a t o r pole moved the sponge head along the l e n g t h of the t e r m i n a l leader and a p p l i e d a l i g h t coat o f p i n e o i l . The a p p l i c a t o r head was removed from the l e a d e r j u s t p r i o r to r e a c h i n g the t e r m i n a l bud c l u s t e r to a v o i d any p o s s i b l e p h y s i c a l damage or p h y t o t o x i c e f f e c t s to the expanding shoots. 2.2.2.2. Slow Release Devices P i n e o i l slow r e l e a s e d e v i c e (SRD) treatments were designed 31 to have p i n e o i l v o l a t i l e s envelope the t e r m i n a l l e a d e r area without the t e r m i n a l i t s e l f a c t u a l l y r e c e i v i n g any p i n e o i l d i r e c t l y . The m a t e r i a l used f o r the SRD's was F l o t h r u (Reg. T.M.), a r e i n f o r c e d spun c e l l u l o s e m a t e r i a l , commonly used i n n u r s e r i e s to support seeds d u r i n g germination. The 4 mm t h i c k F l o t h r u was c u t i n t o 10 cm square pads. A 40 cm loop of g a l v a n i z e d wire was passed through a 5 mm hole punched i n one corner of each pad. Each pad was soaked with 25 ml o f p i n e o i l j u s t p r i o r to being hung from the base of a l a t e r a l branch i n the topmost whorl of the treatment t r e e s . The SRDs were s e t out i n two treatments. In the f i r s t , the s i n g l e SRD treatment, an SRD was hung i n the t r e e with the dominant t e r m i n a l l e a d e r n e a r e s t the p l o t c e n t r e . In the second, the f i v e SRD treatment, an SRD was hung i n the dominant t r e e i n the c e n t r e of each p l o t quadrant as w e l l as the dominant t r e e near the p l o t c e n t r e . These treatment t r e e s were s e l e c t e d on the b a s i s of t h e i r s u i t a b i l i t y as w e e v i l hosts as i n d i c a t e d by the s i z e and crown c l a s s o f t h e i r t e r m i n a l l e a d e r s . The SRD's were secured to the topmost whorls of the s e l e c t e d t r e e s . Tree top access was gained by c l i m b i n g on a t h r e e - l e g g e d o r c h a r d s t y l e step l a d d e r . These l a d d e r s s t r a d d l e d the crown and minimized c o n t a c t with the treatment t r e e . 32 2.3 P l o t Samplinq During the second and t h i r d weeks of June, when i t was assumed t h a t a l l weevil mating and o v i p o s i t i o n a l a c t i v i t y had ceased, the p l o t s were r e v i s i t e d . D e t a i l e d o b s e r v a t i o n s were made of the p h y s i c a l a t t r i b u t e s o f the t r e e s and the weevil a t t a c k h i s t o r y of the p l o t s . 2.3.1 P h y s i c a l A t t r i b u t e s o f Trees Each t r e e i n every p l o t was i n d i v i d u a l l y marked, numbered and l o c a t e d on a p l o t map. The f o l l o w i n g f i v e o b s e r v a t i o n s were made a t each t r e e : 1) l o c a t i o n w i t h i n the p l o t 2) diameter a t b r e a s t h e i g h t (dbh) 3) h e i g h t 4) l e n g t h o f the l a s t three t e r m i n a l l e a d e r s 5) canopy s t a t u s ; clumped or s i n g l e Tree l o c a t i o n s were e s t a b l i s h e d by measuring t h e i r displacement from the p l o t boundaries and t r a n s f e r r i n g the i n f o r m a t i o n to a gr i d d e d s c a l e map of the p l o t . Tree diameters were recorded i n cen t i m e t e r s u s i n g a standard metal diameter tape. Tree h e i g h t s were measured with a seven meter r u l e s t i c k (5 cm increments) p l a c e d next to the b o l e . T h i s s t i c k was a l s o used to measure l e a d e r l e n g t h s . Due to l i m i t a t i o n s i n time and access to the Nootka I s l a n d s i t e a l l the above o b s e r v a t i o n s were made onl y f o r p l o t s 1, 3, 8, 12, 14, 15, and 18. These p l o t s were chosen randomly from each o f the seven treatment groups. The other p l o t s were sampled i n an a b b r e v i a t e d method i n which the time consuming measurements o f h e i g h t and l e a d e r l e n g t h were omitted. 33 2.3.2 Weevil Attack. H i s t o r y Each t r e e i n every p l o t was examined f o r evidence o f pre v i o u s s u c c e s s f u l a t t a c k s by we e v i l s . Both the t o t a l number of p r e v i o u s a t t a c k s and the estimated year o f a t t a c k were recorded. The h i s t o r y o f weevil a t t a c k s was determined by examining the boles o f a l l t r e e s f o r any d e f o r m i t i e s and i r r e g u l a r i t i e s i n d i c a t i v e o f t e r m i n a l l e a d e r death. The de f o r m i t y was recorded as having r e s u l t e d from w e e v i l i n g i f p o r t i o n s o f the dead t e r m i n a l c o n t a i n i n g o l d c h i p cocoons c o u l d s t i l l be found. A l l crooked and forke d t r e e s without t h i s p o s i t i v e evidence o f weevil a t t a c k were recorded as having had t h e i r t e r m i n a l s d i e from other causes. Trees t h a t were forked a t l e s s than 50 cm from the ground were regarded as clumped t r e e s . The years o f a t t a c k were e s t a b l i s h e d by e i t h e r c o u n t i n g growth segments along a l i v e branch or back down along the succeeding nodes of the l a t e r a l which assumed a p i c a l dominance ( F i g . 5). The age or year o f a t t a c k on the dead t e r m i n a l was assumed to be the same as the i n i t i a l growth of the l a t e r a l branches a t i t s base. I t should be noted t h a t many of the t r e e s i n the Nootka I s l a n d p l o t s had been a t t a c k e d d u r i n g the year p r i o r to t h i s study. These t r e e s had been " t r e a t e d " by having t h e i r i n f e s t e d l e a d e r s removed i n 1981. The t r e e s which had been " c l i p p e d " were not counted as weevil a t t a c k s . In p l o t 16 f o r example, there were 16 c l i p p e d t r e e s and 3 t r e e s which s t i l l had i n f e s t e d t e r m i n a l s . T h i s p l o t was recorded as having o n l y three 1981 weeviled t r e e s although 19 t r e e s were a t t a c k e d . 34 1981 1980 1979 1977 F i g u r e 5. R e p r e s e n t a t i o n o f a S i t k a spruce t r e e which had been weeviled i n 1979. The c i r c l e s i n d i c a t e the nodes which were counted to determine the year o f a t t a c k . The t r e e ' s l e a d e r grew i n 1978 and was a t t a c k e d i n 1979. 35 2.3.3 Recording Current Attacks The p l o t s a t both s i t e s were r e v i s i t e d i n September 1982. I t was assumed t h a t most of the weevil l a r v a e would have f i n i s h e d f e e d i n g a t t h i s time and t h a t the p o p u l a t i o n would c o n s i s t mainly of pupae and c a l l o w a d u l t s . The t e r m i n a l l e a d e r s of a l l t r e e s i n a l l p l o t s were cu t from the t r e e s and taken to the l a b o r a t o r y f o r e v a l u a t i o n . Each t e r m i n a l was c a r e f u l l y examined f o r evidence o f weevil a t t a c k . Only those t e r m i n a l s which were found to c o n t a i n a d u l t brood w e e v i l s were counted as s u c c e s s f u l 1982 a t t a c k s . 2.4 The A e r i a l Photography Study The a e r i a l photographs were to have been taken d u r i n g the l a s t two weeks of J u l y and the f i r s t week of August when weevil development was a t v a r i o u s stages between e a r l y l a r v a l i n s t a r and c a l l o w a d u l t . During t h i s p e r i o d a wide range of a t t a c k symptoms would be v i s i b l e on the photographs. The frequency of inclement weather and the i n f l e x i b i l i t y o f the c o n t r a c t e d photographer's other commitments, however, delayed the photography. The U c l u e l e t study area was photographed on August 15 and the Nootka I s l a n d s i t e on September 2, 1982. Stereo photographs were taken with w i n g t i p mounted V i n t e n 492-70 mm reconnaisance cameras with L e l t z l e n s e s s e t a t f/7.5. The study p l o t s were photographed with Kodak Aerochrome MS Type 2448 normal c o l o r f i l m and rephotographed on the same date with Kodak Aerochrome type 2443 i n f r a r e d c o l o r f i l m u s i n g Wratten 12 and CC 20m f i l t e r s . Camera f o c a l l e n g t h and f l i g h t e l e v a t i o n 36 were a d j u s t e d to achieve a photo s c a l e o f 1:1200. The d e v e l o p i n g , p r o c e s s i n g and p r e l i m i n a r y checking o f the photographs was done by the c o n t r a c t e d photographer. The exposed f i l m t r a n s p a r e n c i e s were r e t u r n e d on October 18. P o s i t i v e c o l o r enlargements were made of each p l o t f o r use i n the f i e l d . During the f i r s t two weeks of November the p l o t c e n t e r s , boundaries and any apparent a b n o r m a l i t i e s were checked on the ground with the c o l o r enlargements. Trees occupying the corner p o s i t i o n s o f each p l o t were i d e n t i f i e d and marked on the photographs. The normal c o l o r (NC) and c o l o r i n f r a - r e d (CIR) photographs o f each p l o t were examined under a stereoscope f o r the purpose o f s e l e c t i n g the most s u i t a b l e f o r i n t e r p r e t a t i o n t e s t i n g . NC and CIR st e r e o photographs of s i x p l o t s from each s i t e were chosen f o r t e s t i n g . The twenty four photographs were s e l e c t e d because o f t h e i r c o n s i s t e n c y with r e s p e c t to s c a l e and t h e i r complete i n c l u s i o n o f a l l the p l o t boundaries. F i g u r e 6 shows NC and CIR p r i n t s made from the s t e r e o p a i r s o f one o f the s e l e c t e d p l o t s . A l l f r e s h l y a t t a c k e d t r e e s , as noted by the ground data, were i d e n t i f i e d on the photographs o f the twelve s e l e c t e d p l o t s . Scale maps showing the l o c a t i o n s o f weeviled t r e e s , p l o t boundaries, the n o r t h e a s t corner and the p l o t markers f o r each o f the twelve p l o t s were made from the photographs ( F i g . 7). These s c a l e maps were used f o r s c o r i n g the i n t e r p r e t a t i o n s . Four i n t e r p r e t e r s were employed i n the t e s t . The i n t e r p r e t e r s ' experience with a e r i a l photographs and weevil a t t a c k symptomology v a r i e d . One of the i n t e r p r e t e r s had 37 Figure 6. Stereo pair p r i n t s made from the normal color and color Infra-red a e r i a l photograph transparencies of p l o t one at the Nootka Island s i t e . The c i r c l e d tree i s a Sitka spruce weeviled i n 1982. 38 PLOT STEM HAP STUDY AREA: NOTKA PLOT No.! 1 TREATMENT: BBRl-t _ NE 1 !~~. ----------------------------- - 81182! 2 S .. . .81. .79. . . . . i 3! .81. . . . .80. S 4 5 ! . . . 6 ! . .82. 7 ! .81. 8 ! . . . . .82. i l a . . . * • • . . • . . . . I I I I I 9: .80 : 10: 81! 11 I • • • • • • • ( • • • • • • WmL. i81. 12 I . . P . . . . . . £82 13 14; IS16 17 182 ! is : .81. . . . . . . . . . . . . . . .so. . : 19 I i 20 l _ . . . . . . . J 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 Ii 17 18 19 20 F i g u r e 7 . Example of a s c a l e map o f p l o t one a t the Nootka I s l a n d study s i t e showing the l o c a t i o n s of a l l weeviled t r e e s and the years o f a t t a c k as determined from ground t r u t h d a t a . Trees i n d i c a t e d with an * were weeviled more than once. The years o f a t t a c k are presented on e i t h e r s i d e o f the *. 3 9 s e v e r a l years experience i n t e r p r e t i n g a e r i a l photographs but t had no p r i o r knowledge of P. s t r o b l a t t a c k symptoms. Each of the other three i n t e r p r e t e r s had s e v e r a l years o f experience i n d e t e c t i n g P. s t r o b l symptoms but had very l i t t l e experience with a e r i a l photographs. The i n t e r p r e t e r s were s u p p l i e d with a Bausch and Lomb zoom 70 stereomicroscope f o r the i n t e r p r e t a t i o n e x e r c i s e to h e l p e l i m i i n a t e any v a r i a t i o n due to the small d i f f e r e n c e s i n photo s c a l e between the s t e r e o p a i r s . The three I n t e r p r e t e r s who had never used a zoom stereomicroscope before were allowed to f a m i l i a r i z e themselves with i t p r i o r to the t r a i n i n g s e s s i o n . The four i n t e r p r e t e r s were each g i v e n a f i f t e e n minute t r a i n i n g s e s s i o n i n the photographic evidence o f weevil a t t a c k e d S i t k a spruce. The t r a i n i n g c o n s i s t e d o f examining f r e s h l y weeviled t r e e s , y e a r - o l d a t t a c k s , h e a l t h y S i t k a spruce, h e a l t h y D o u g l a s - f i r and h e a l t h y Western hemlock on NC and CIR d u p l i c a t e s t e r e o photographs o f a study p l o t . One s e t of photographs had the t r e e s marked and the other d i d not. P l o t photographs used f o r t r a i n i n g were not used i n t e s t i n g . The i n t e r p r e t e r s were then presented with the twelve s t e r e o photographs i n a sequence randomly s e l e c t e d f o r the f i r s t and maintained f o r each subsequent i n t e r p r e t e r . They were allowed one minute to view each s t e r e o p a i r and r e c o r d the p o s i t i o n s o f the c u r r e n t l y weeviled S i t k a spruce t r e e s t h a t they saw w i t h i n each p l o t ' s boundaries. The p l o t boundaries were c l e a r l y marked with white l i n e s on the photographs. For each s t e r e o photograph, the i n t e r p r e t e r s were s u p p l i e d with blank p l o t maps having o n l y the n o r t h e a s t e r n corner and 40 the p l o t marker i d e n t i f i e d . They were to l o c a t e what they thought to be a c u r r e n t l y a t t a c k e d S i t k a spruce t r e e on the photograph and t r a n s f e r i t s p o s i t i o n to the map us i n g the p l o t boundaries, p l o t c e n t e r and n o r t h e a s t e r n corner as r e f e r e n c e p o i n t s . Each i n t e r p r e t e r was allowed 15 seconds a f t e r viewing each photograph to reassure themselves t h a t the o r i e n t a t i o n of t h e i r map was c o r r e c t . I f an e r r o r had o c c u r r e d the i n t e r p r e t e r ' s o r i e n t a t i o n was marked on the map before the t e s t proceeded. The p l o t maps drawn by the i n t e r p r e t e r s were compared with the o r i g i n a l s made from the ground t r u t h data. The number of c o r r e c t l y i d e n t i f i e d c u r r e n t l y a t t a c k e d t r e e s was recorded f o r each f i l m type. E r r o r s made by the i n t e r p r e t e r s were recorded and c a t e g o r i z e d i n t o three e r r o r types: 1) c l a i m i n g a non-attacked S i t k a spruce to be a c u r r e n t a t t a c k 2) c l a i m i n g a t r e e s p e c i e s other than S i t k a was a c u r r e n t l y a t t a c k e d S i t k a spruce 3) c l a i m i n g a p r e v i o u s l y a t t a c k e d S i t k a spruce was a c u r r e n t l y a t t a c k e d S i t k a spruce. 2.5 Pat a. A n a l y s i s 2.5.1 P i n e o i l Study For the l a b o r a t o r y study, the number of fe e d i n g punctures a f t e r 48 hours per treatment was analysed by an a n a l y s i s o f v a r i a n c e (ANOVA) performed on the model: FEEDING PUNCTURES = TREATMENT + ERROR The treatment means were t e s t e d f o r e q u a l i t y with a Newman-Keul's t e s t . 41 For the f i e l d study, a randomized block d e s i g n , the c u r r e n t 1982 weevil a t t a c k e d t r e e s were scored and transformed by loglO (X+l) to normalise the d i s t r i b u t i o n s of the data. The a n a l y s i s of v a r i a n c e was performed on the model: LOG10 (CURRENT ATTACK + 1) = TREATMENT + BLOCK + ERROR Orthogonal c o n t r a s t s were performed to compare treatment means. An a t t a c k r a t i o v a r i a b l e was c r e a t e d f o r i n t e r p r e t i n g weevil a t t a c k h i s t o r y and i t s e f f e c t on c u r r e n t a t t a c k s . The a t t a c k r a t i o , equal to the t o t a l c u r r e n t a t t a c k s d i v i d e d by the average number of a t t a c k s over the p r e v i o u s two y e a r s , was expressed as a percentage. 2.5.2 A e r i a l Photography Study The data recorded f o r each i n t e r p r e t e r were compared to the ground t r u t h data. The i n t e r p r e t e r s were scored on the percent of true a t t a c k s i d e n t i f i e d . These data were transformed by a r c s i n to normalize the d i s t r i b u t i o n . An a n a l y s i s of v a r i a n c e was performed on these transformed data i n the model: ARCSIN (% ATTACKS IDENTIFIED) = FILM(A) + SITE(B) + PLOT(C) + INTERPRETER(D) + AB + AC + BC + ABC + AD + CD + ERROR 42 3.RESULTS AND DISCUSSION 3.1 P i n e o i l Study 3.1.1. Laboratory S t u d i e s The number o f f e e d i n g punctures a f t e r 24 hours was s i g n i f i c a n t l y l e s s on the p i n e o i l t r e a t e d c u t t i n g s than on the u n t r e a t e d c o n t r o l s (Table 2). In a d d i t i o n to reduced f e e d i n g , weevil m o r t a l i t y was much higher i n the p i n e o i l t r e a t e d s i t u a t i o n s than i n the c o n t r o l s . A f t e r 72 hours 80% o f the weevils presented with one u n t r e a t e d c u t t i n g were s t i l l a l i v e , whereas 80% o f the w e e v i l s c o n f i n e d with a s i n g l e p i n e o i l t r e a t e d c u t t i n g had d i e d (Table 2). In s i t u a t i o n s where the w e e v i l s c o u l d choose between c u t t i n g s which had been t r e a t e d with p i n e o i l and those which had not, f e e d i n g punctures were found o n l y on the u n t r e a t e d c u t t i n g s d u r i n g the f i r s t 48 hours. The number o f f e e d i n g punctures was lower on the u n t r e a t e d c u t t i n g s i n the c h o i c e b i o a s s a y s which i n c l u d e d a p i n e o i l treatment. Feeding punctures were found on the t r e a t e d c u t t i n g s i n the c h o i c e s i t u a t i o n s a f t e r 72 hours. Presumably the u n t r e a t e d c u t t i n g s were no longer s u i t a b l e as a food source and the weevils were f o r c e d to e i t h e r feed on the t r e a t e d c u t t i n g s or s t a r v e . These r e s u l t s have s i n c e been c o r r o b o r a t e d by A l f a r o (1984) where he showed t h a t p i n e o i l was l e s s e f f e c t i v e as a f e e d i n g d e t e r r e n t i n no-choice s i t u a t i o n s . Although the weevils began to make fe e d i n g puctures i n the t r e a t e d c u t t i n g s a f t e r 72 hours the weevil m o r t a l i t y a t each o b s e r v a t i o n i n 43 Table 2. The amount of f e e d i n g by and m o r t a l i t y o f s i n g l e a d u l t S i t k a spruce weevils i n s i x s i t u a t i o n s where they were c o n f i n e d with 5 cm long s e c t i o n s of S i t k a spruce l e a d e r s t r e a t e d with two types o f p i n e o i l (BBR1 and BBR2). Each s i t u a t i o n was r e p l i c a t e d 10 times. P i n e o i l Feeding Punctures % M o r t a l i t y A f t e r : C u t t i n g s Treatment Mean + SD 48hrs 72hrs 120hrs 168hrs 1 BBR1 0.4 + 1.2a 0 80 80 100 1 BBR2 1.1 + 2. 2a 0 80 90 100 1 none 5.6 + 4.4b 0 20 40 100 2 ( l ) B B R l + none 3.0 + 3. la b 0 30 60 90 2 (DBBR2 + none 2.9 + 3. Oab 0 40 40 90 2 none + none 6.3 + 1.7b 0 0 10 80 (1) No f e e d i n g punctures were found, a f t e r 48 hours, on the c u t t i n g s t r e a t e d with e i t h e r type o f p i n e o i l i n the two c u t t i n g c h o i c e t r i a l s . (2) Means fo l l o w e d by the same l e t t e r were not s i g n i f i c a n t l y d i f f e r e n t , Newman-Keul's t e s t , (P < 0.05). (3) For ANOVA t a b l e , see Appendix 1. 44 these c h o i c e s i t u a t i o n s was higher i n comparison to the 2 c u t t i n g c o n t r o l (Table 2). T h i s r e s u l t i m p l i e s that the p i n e o i l treatments reduced the s u i t a b i l i t y o f the c u t t i n g s as a food source. The weevil m o r t a l i t y a s s o c i a t e d with the presence o f p i n e o i l and i t s v o l a t i l e s i n d i c a t e t h a t i t e i t h e r a c t s d i r e c t l y as a p o i s o n or i n d i r e c t l y as a fe e d i n g d e t e r r e n t . In e i t h e r case both the reduced f e e d i n g and i n c r e a s e d m o r t a l i t y o f S i t k a spruce w e e v i l s i n the presence o f p i n e o i l supports the c o n t e n t i o n t h a t i t may have some u t i l i t y i n p r o t e c t i n g S i t k a spruce from weevil a t t a c k . 3.1.2. F i e l d S t u d i e s 3.1.2.1. NQQtKfl Island. Study s i t s The a n a l y s i s o f v a r i a n c e (ANOVA) on the LoglO t r a n s f o r m a t i o n o f the c u r r e n t a t t a c k data d i d not show any s i g n i f i c a n t d i f f e r e n c e s between e i t h e r the treatments or the b l o c k s (Table 3). The orthogonal c o n t r a s t s performed with the treatment mean squares from the above ANOVA showed t h a t the only treatment s i g n i f i c a n t l y d i f f e r e n t from the ot h e r s was the BBR1 t o p i c a l a p p l i c a t i o n (BBR1-T). The BBR1-T treatment was 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) from the c o n t r o l s . T h i s a n a l y s i s supports the c o n c l u s i o n t h a t the t o p i c a l a p p l i c a t i o n o f BBR1 to the l e a d e r s o f s u s c e p t i b l e t r e e s w i l l p r o t e c t them from weevil a t t a c k . The SRD treatments were 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 c o n t r o l s . N e v e r t h e l e s s , none o f the t r e e s b e a r i n g SRD's 45 Table 3. S i t k a spruce l e a d e r s a t t a c k e d by S i t k a spruce weevils i n twenty-one 0,04 hectare p l o t s on Nootka I s l a n d a f t e r t o p i c a l (T) and slow r e l e a s e d e v i c e (SRD) treatments with p i n e o i l i n the s p r i n g o£ 1982. 1982 A t t a c k s Der treatment Treatment (1) P l o t a t t a c k s T o t a l Mean (2) BBR2-1 5 18 BBR2-1 9 6 BBR2-1 18 2 26 8.7 C o n t r o l 19 16 C o n t r o l 2 5 C o n t r o l 14 3 24 8.0 BBR1-5 17 11 BBR1-5 7 7 BBR1-5 12 5 23 7.7 BBR2-5 6 14 BBR2-5 13 3 BBR2-5 15 0 17 5.7 BBR1-1 10 8 BBR1-1 1 5 BBR1-1 21 1 14 4.7 BBR2-T 16 9 BBR2-T 4 3 BBR2-T 8 1 13 4.3 BBR1-T 3 2 BBR1-T 11 0 BBR1-T 20 0 2 0.7 S i t e t o t a l 119 5.7 (1) E x p l a n a t i o n o f treatment codes: BBR1-1 = a s i n g l e BBR1 SRD per p l o t BBR1-5 = 5 BBR1 SRD's per p l o t BBR1-T = BBR1 a p p l i e d t o p i c a l l y to a l l t r e e s i n p l o t , note: codes are the same f o r BBR2 treatments. (2) ANOVA f a i l e d to show s i g n i f i c a n t F-value f o r the treatment main e f f e c t . Orthogonal c o n t r a s t s i n d i c a t e d t h a t the mean number o f a t t a c k s i n the BBR1-T treatment was s i g n i f i c a n t l y l e s s (P < 0.05) than the c o n t r o l , BBR2-1 and BBR1-5 treatment means (ANOVA on LOG10 ( X + l ) ) . (3) For ANOVA t a b l e , see Appendix 2. 46 were a t t a c k e d . Since the t r e e s were among the l a r g e s t i n the p l o t s i t i s reasonable to suggest t h a t they would have a high p r o b a b i l i t y o£ being a t t a c k e d (Gara g £ al.. 1971; Barry and S t i e h l 1976). The SRD's were not e f e c t i v e i n a l t e r i n g the weevil a t t a c k r a t e s f o r the whole p l o t but they may have pro v i d e d p r o t e c t i o n f o r i n d i v i d u a l t r e e s . The l a c k o f s i g n i f i c a n t e f f e c t s between b l o c k s from the ANOVA suggests t h a t the b l o c k i n g c r i t e r i a were inadequate to e x p l a i n any v a r i a t i o n s i n weevil a t t a c k r a t e s due to s i t e types. Although the s i t e d i s c o n t i n u i t i e s were not e x p l a i n e d by the b l o c k i n g , i t i s i n t e r e s t i n g to note t h a t b l o c k 1 p l o t s had higher o v e r a l l a t t a c k r a t e s than e i t h e r b l o c k s 2 or 3 ( F i g u r e 8). T h i s r e s u l t might have been expected s i n c e the b l o c k 1 p l o t s were i n an o l d e r p l a n t a t i o n with a l a r g e r average t r e e s i z e and fewer clumped t r e e s . These data support the c o n t e n t i o n t h a t P. s t r o b l p r e f e r s l a r g e r t r e e s i n open growing c o n d i t i o n s (Berry and S t i e h l 1976; Gara e t al.. 1971; W i l k i n s o n 1983). The data c o l l e c t e d on the p h y s i c a l a t t r i b u t e s o f the t r e e s show t h a t the a t t a c k e d t r e e s were above the p l o t averages i n diameter a t b r e a s t h e i g h t (dbh) while being a t or near the p l o t average i n h e i g h t (Table 4). These data are c o n s i s t e n t with the above r e p o r t s which a t t e s t to the l a r g e r , " f r e e to grow" stems being more s u s c e p t i b l e to weevil a t t a c k . Table 5 and F i g u r e 9 show the data o b t a i n e d from a t t a c k h i s t o r y o b s e r v a t i o n s a t the Nootka I s l a n d s i t e . The f i r s t evidence o f a t t a c k i n any p l o t was found to be i n 1977 where 47 t o 1B77 1178 197t 1980 1981 1771 BLOCK 1 Y777X BLOCK 2 POq BLOCKS F i g u r e 8. The d i s t r i b u t i o n o f the t o t a l l e a d e r s a t t a c k e d among the b l o c k s a t the the Nootka I s l a n d s i t e . 48 Table 4. Means and standard d e v i a t i o n s f o r h e i g h t s and diameters (dbh) from weeviled S i t k a spruce t r e e s and a l l other t r e e s i n the sample taken a t the Nootka I s l a n d s i t e . P l o t Number Weeviled Trees A l l Other Trees No. Ht. s.d. dbh s.d. No. Ht. s.d. dbh s.d. 1 15 4.5 0.9 9.2 2.2 32 4.7 1.5 7.7 3.1 3 16 4.7 0.8 9.3 2.3 23 4.7 1.3 8.3 3.5 8 33 3.9 0.7 6.9 2.2 71 3.8 1.0 5.4 2.0 12 17 3.4 0.9 6.8 1.8 46 3.6 0.8 5.5 2.1 14 10 3.0 0.7 5.6 1.7 28 3.6 0.6 5.1 1.5 15 2 2,9 0.6 5.8 1.5 51 3.6 0.7 4.9 1.9 18 13 3.8 0.7 8.1 1.3 48 4.3 0.9 6t9 2.2 S i t e 106 3.7 7.4 299 4.0 6.3 49 Table 5. The t o t a l numbers o f t r e e s which had ever been a t t a c k e d by the S i t k a spruce w e e v i l , the t o t a l number of l e a d e r s a t t a c k e d on those t r e e s and the t o t a l number of l e a d e r s a t t a c k e d per year among the treatment groups over the s i x years o f recorded a t t a c k a t the Nootka I s l a n d s i t e . Treatment Trees Leaders Leaders a t t a c k e d per year Group T o t a l Attacked a t t a c k e d 1977 1978 1979 1980 1981 1982 C o n t r o l 125 63 72 0 0 3 20 25 24 BBR2-1 164 54 97 6 4 11 24 26 26 BBR1-1 172 40 47 1 1 1 8 22 14 BBR2-5 159 44 66 1 2 9 15 22 17 BBR1-5 192 90 111 2 6 18 28 34 23 BBR2-T 228 109 132 3 4 24 33 55 13 BBR1-T 158 52 59 1 5 5 17 29 2 per p l o t 57 22 28 0.7 1.0 3.4 6.9 10,1 5.7 T o t a l 1198 452 465 14 22 71 145 213 119 (1) E x p l a n a t i o n o f treatment codes: BBR1-1 - a s i n g l e BBR1 SRD per p l o t BBR1-5 = 5 BBR1 SRD's per p l o t BBR1-T » BBR1 a p p l i e d t o p i c a l l y to a l l t r e e s i n p l o t , note: codes are the same f o r BBR2 treatments. 50 1977 1978 1979 1980 1981 1982 1977 1978 1979 1980 1981 1982 I *T !• i i i « »— i t — • • » 1977 1978 1979 1980 1981 1982 1977 i978 1979 1980 1981 1982 • - Treatment group + - Control group F i g u r e 9 . The percentage o f t r e e s a t t a c k e d i n each year f o r each treatment group compared to the y e a r l y a t t a c k s i n the c o n t r o l group a t the Nootka I s l a n d s i t e . f o u r t e e n a t t a c k s o c c u r r e d i n 6 p l o t s . These f o u r t e e n a t t a c k s amounted to an i n f e s t a t i o n r a t e of 1% o f a l l t r e e s sampled. In a l l p l o t s the a t t a c k r a t e began to n o t i c e a b l y i n c r e a s e a f t e r 1978 with f i f t e e n of the 21 p l o t s a t the Nootka I s l a n d s i t e having a t l e a s t one weeviled t r e e by 1979. Combined data from a l l p l o t s showed an i n c r e a s e i n weeviled t r e e s of approximately 6 percentage p o i n t s per year up to 1981, the pretreatment year. In 1981, a f t e r 4 years o f recorded a t t a c k , 393 t r e e s or 33% o f a l l stems had been weeviled a t l e a s t once. The number o f t r e e s a c t u a l l y a t t a c k e d i n 1981 was 212, an 18% c u r r e n t a t t a c k r a t e . These r e s u l t s are s l i g h t l y lower than those found by A l f a r o (1982), where 30% of the stems i n an i n t e n s e l y weeviled stand were a t t a c k e d d u r i n g the f o u r t h year of i n f e s t a t i o n . McMullen (1976a), r e p o r t e d s i m i l a r f i n d i n g s where stands over 3 meters i n h e i g h t were a t t a c k e d a t a 27% annual r a t e . The t o t a l number o f stems recorded i n t h i s study, however, i n c l u d e s those which a r i s e from a common stump and those which were growing under suppressed c o n d i t i o n s r e s u l t i n g from t h e i r b e i n g covered by the crown of a d j a c e n t neighbours. There were 575 of these clumped t r e e s , 48% of a l l stems, i n 238 clumps a t the Nootka I s l a n d s i t e . The presence o f these l a r g e numbers o f clumped or suppressed t r e e s i n an otherwise open canopied stand would tend to d e f l a t e the percentage f i g u r e s f o r c u r r e n t a t t a c k s . Assuming t h a t each clump would produce a s i n g l e stem with a dominant weevil s u s c e p t i b l e l e a d e r , then the number o f s u s c e p t i b l e stems w i t h i n the Nootka I s l a n d sample would be reduced from 1198 to 1198 -(575-238) = 861. T h i s adjustment f o r clumped stems would a l t e r 52 the c u r r e n t r a t e and t o t a l a t t a c k s In 1981 to 25% and 46% r e s p e c t i v e l y . These a d j u s t e d f i g u r e s suggest t h a t the Nootka I s l a n d stand was approaching the 30% annual a t t a c k p l a t e a u ( A l f a r o 1982; McMullen 1976a) and s i g n i f i c a n t l y higher a t t a c k r a t e s would not be expected to occur i n 1982. In 1981, the pretreatment year, a l l of the treatment groups experienced i n c r e a s e s i n a t t a c k r a t e s over the p r e v i o u s year. A f t e r a d j u s t i n g f o r clumped stems the c o n t r o l group had an a t t a c k r a t e of 25% i n 1981, the pretreatment year. The post-treatment a t t a c k r a t e f o r the c o n t r o l group was 24%, a r e s u l t t h a t i s c o n s i s t e n t with the above r e p o r t s where a t t a c k r a t e s tend to p l a t e a u a t between 25 and 30% per year. S i t k a spruce weevils have an average l i f e span o f two years with some i n d i v i d u a l s l i v i n g and r e p r o d u c i n g f o r up to four years (McMullen & Condrashoff 1973). Since a l l of the p l o t s but two had a t t a c k e d t r e e s i n 1980, i t was assumed t h a t most o f the r e s i d e n t a d u l t weevil p o p u l a t i o n w i t h i n each p l o t were the o f f s p r i n g from 1980 and 1981 a t t a c k s . The e f f e c t of r e c e n t a t t a c k h i s t o r y was i n c o r p o r a t e d i n the c u r r e n t a t t a c k data by c r e a t i n g a r a t i o between the number o f c u r r e n t a t t a c k s and the t o t a l number of a t t a c k s d u r i n g the p r e v i o u s two years. These a t t a c k r a t i o s are an i n d i c a t i o n of the progress o f an i n f e s t a t i o n s i n c e they i n c l u d e the e f f e c t s o f the two most r e c e n t years o f a t t a c k . P l o t s with a t t a c k r a t i o s o f 1.0 would be expected from areas where the weevil p o p u l a t i o n i s s u s t a i n i n g i t s e l f , i n terms o f l e a d e r s a t t a c k e d per year, and c u r r e n t a t t a c k s are 53 equal to the average o f the past two years a t t a c k s . P l o t s with r a t i o s over 1.0 would i n d i c a t e areas where the number o f l e a d e r s a t t a c k e d per year i s i n c r e a s i n g , while those below 1.0 would i n d i c a t e a d e c l i n e . The d i s t r i b u t i o n o f the p o s t -treatment a t t a c k r a t i o s among the p i n e o i l treatment groups ( F i g . 10) show a trend o f fewer new a t t a c k s i n the p l o t s with 8BR1 treatments. The a t t a c k r a t i o s d e c l i n e c o n s i s t e n t l y with p i n e o i l treatments from 1 BBR1 SRD to 5 BBR1 SRD's to the t o p i c a l treatments. Although o n l y the BBR1 t o p i c a l treatment was s i g n i f i c a n t l y d i f f e r e n t , the a t t a c k r a t i o s f o r both BBR1-T and BBR2-T were both w e l l below the a t t a c k r a t i o f o r the Nootka I s l a n d s i t e i n g e n e r a l . T h i s d e c l i n i n g a t t a c k r a t e with i n c r e a s i n g c o n c e n t r a t i o n s o f p i n e o i l suggests t h a t the weevil p o p u l a t i o n w i t h i n the treatment groups was a f f e c t e d to some degree by the pine o i l treatments. 3.1.2.2. U c l u e l e t Study S i t e The ANOVA performed on the l o g l O transformed data showed t h a t n e i t h e r the p i n e o i l treatments nor the b l o c k s d i f f e r e d s i g n i f i c a n t l y (Table 6). Ne v e r t h e l e s s , none o f the t r e e s b e a r i n g SRD's were at t a c k e d . T h i s f i n d i n g i s c o n s i s t e n t with the r e s u l t obtained a t the Nootka I s l a n d s i t e . A l s o c o n s i s t e n t with the r e s u l t s from the Nootka I s l a n d study was the f i n d i n g t h a t the b l o c k i n g c r i t e r i a d i d not e x p l a i n any v a r i a t i o n s due to s i t e type. The b l o c k i n g data from both study areas were s i m i l a r , however, i n t h a t the p l o t s e s t a b l i s h e d i n the o l d e r p l a n t a t i o n s (block 1) had higher o v e r a l l y e a r l y a t t a c k r a t e s p r i o r to the treatment year ( F i g u r e s 8 and 11). 54 F i g u r e 10. The d i s t r i b u t i o n o f the 1982 a t t a c k r a t i o s among the p i n e o i l treatment groups a t the Nootka I s l a n d study s i t e . The a t t a c k r a t i o i s equal to the 1982 w e e v i l a t t a c k s d i v i d e d by the sum o f the 1980 and 1981 weevil a t t a c k s . 55 Table 6. S i t k a spruce l e a d e r s a t t a c k e d by S i t k a spruce weevils i n f i f t e e n 0.04 hectare p l o t s a t the U c l u e l e t study s i t e a f t e r treatment with p i n e o i l soaked slow r e l e a s e d e v i c e s (SRD) i n 1982. 1982 At t a c k s Der treatment Treatment (1) P l o t a t t a c k s T o t a l Mean (2) BBR2-1 1 10 BBR2-1 8 6 BBR2-1 15 4 20 6.7 C o n t r o l 13 9 C o n t r o l 7 4 C o n t r o l 4 1 14 4.7 BBR2-5 2 9 BBR2-5 11 2 BBR2-5 9 1 12 4.0 BBR1-5 3 7 BBR1-5 6 4 BBR1-5 14 0 11 3.7 BBR1-1 5 7 BBR1-1 10 2 BBR1-1 12 1 10 3.3 S i t e t o t a l 67 4.5 (1) E x p l a n a t i o n o f treatment codes: BBR1-1 = a s i n g l e BBR1 SRD per p l o t BBR1-5 = 5 BBR1 SRD's per p l o t note: codes are the same f o r BBR2 treatments. (2) ANOVA f a i l e d to show any s i g n i f i c a n t d i f f e r e n c e s i n l e v e l o f a t t a c k . (3) For ANOVA t a b l e , see Appendix 3. 56 48 -40 -33 -SKCO SO -1 25 -< 8 20 -§ 15 -10 -S -0 -1976 JB. -C2Q T 1977 L V7\ BLOCK 1 r 1978 1979 1980 1981 fZZl BLOCK 2 KZI BLOCKS F i g u r e 11. The d i s t r i b u t i o n o f the t o t a l l e a d e r s a t t a c k e d among b l o c k s a t the U c l u e l e t s i t e . 57 A summary o f the p h y s i c a l a t t r i b u t e s o f the t r e e s a t the U c l u e l e t s i t e shows the same trends apparent a t the Nootka I s l a n d s i t e (Table 7). Among a l l o f the treatment groups the average dbh f o r the weeviled t r e e s was g r e a t e r than the average dbh f o r non-attacked t r e e s . The data o b t a i n e d from the a t t a c k h i s t o r y o b s e r v a t i o n s a t the U c l u e l e t s i t e are summarized i n Table 8 and F i g u r e 12. The f i r s t evidence of weevil a t t a c k was found to occur i n 1976 when 3 t r e e s were a t t a c k e d i n one p l o t i n the 12 year o l d p l a n t a t i o n (6 years a f t e r p l a n t i n g ) . The f i r s t a t t a c k s found i n p l o t s i n the 10 year o l d p l a n t a t i o n s were i n 1979 where a s i n g l e a t t a c k o c c u r r e d i n one p l o t . In 1979 the number of a t t a c k e d t r e e s amounted to 3% of a l l t r e e s i n a l l p l o t s . Nine percent o f a l l t r e e s were a t t a c k e d i n 1980 and 11% were a t t a c k e d i n 1981. At the end of 1981, 21% of the t r e e s a t the s i t e had been a t t a c k e d a t l e a s t once. These data show t h a t the weevil p o p u l a t i o n a t the U c l u e l e t s i t e was c o n t i n u i n g to i n c r e a s e up to 1981, the pretreatment year. At the U c l u e l e t s i t e 33% of the t r e e s were i n clumps as compared to the 48% i n clumps a t the Nootka I s l a n d s i t e . A f t e r a d j u s t i n g f o r clumped stems, which would have a lower p r o b a b i l i t y o f being a t t a c k e d , the 1981 pretreatment a t t a c k r a t e was 13%. These r e s u l t s i n d i c a t e t h a t the weevil p o p u l a t i o n a t the U c l u e l e t s i t e was w e l l below both the 25 to 30% annual a t t a c k r a t e s r e p o r t e d by A l f a r o (1982) and McMullen (1976a) and the a t t a c k r a t e o f 25% a t the Nootka I s l a n d s i t e . The a t t a c k r a t e s a t U c l u e l e t c o u l d t h e r e f o r e be expected to i n c r e a s e . A l l of the treatments, except f o r the BBR2-1 and the 58 Table 7. Means and standard d e v i a t i o n s f o r h e i g h t s and diameters (dbh) from weeviled S i t k a spruce t r e e s and a l l other S i t k a spruce t r e e s among the treatment groups a t the U c l u e l e t study s i t e . Treatment Weeviled Trees A l l Other Trees Group No. Ht. s.d. dbh s.d. No. Ht. s.d. dbh s.d. c o n t r o l 29 4.0 0.9 6.6 1.9 118 4.3 1.2 5.9 2.0 BBR2-1 57 4.0 0.8 7.1 2.1 78 3.9 1.1 5.4 2.3 BBR2-5 43 3.8 0.7 6.7 1.9 101 3.9 0.9 5.2 1.7 BBR1-1 24 4.4 0.9 6.9 1.4 131 4.3 0.9 6.0 1.9 BBR1-5 44 4.0 1.0 7.1 2.1 105 3.9 1.1 5.5 2.5 S i t e 197 4.0 0.9 6.9 2.0 533 4.1 1 5.6 2.1 59 Table 8. The t o t a l numbers of t r e e s which had ever been a t t a c k e d by the S i t k a spruce w e e v i l , the t o t a l number o f l e a d e r s a t t a c k e d on those t r e e s and the t o t a l number o f l e a d e r s a t t a c k e d per year among the treatment groups over the seven years o f recorded a t t a c k a t the U c l u e l e t s i t e . Treatment Trees Leaders Leaders Attacked per Year Group A l l A ttacked Attacked 1976 •77 •78 • 7 9 •80 •81 •82 C o n t r o l 147 29 30 0 0 0 1 6 9 14 BBR2-1 135 57 79 3 8 2 6 16 24 20 BBR1-1 155 24 24 0 0 1 0 3 10 10 BBR2-5 144 43 63 0 1 7 10 22 11 12 BBR1-5 149 44 58 0 0 1 3 17 26 11 per p l o t 49 13 17 0.2 0.6 0.7 1.3 4.3 5.3 4.5 T o t a l 730 197 254 3 9 11 20 64 80 67 (1) E x p l a n a t i o n o f treatment codes: BBR1-1 = a s i n g l e BBR1 SRD per p l o t BBR1-5 = 5 BBR1 SRD's per p l o t note: codes are the same f o r BBR2 treatments. 60 F i g u r e 12. The percentage o f t r e e s a t t a c k e d i n each year f o r each treatment group compared to the y e a r l y a t t a c k s i n the c o n t r o l group a t the U c l u e l e t study s i t e . and the BBR1-5 groups, experienced i n c r e a s e d a t t a c k r a t e s i n the post-treatment year. Although other treatment groups c o n t a i n e d p l o t s which showed a decrease i n a t t a c k r a t e i n 1982, the onl y group i n which none o f the p l o t s showed an i n c r e a s e i n a t t a c k r a t e was the BBR1-5 treatment. These data c o u l d be i n t e r p r e t e d as i n d i c a t i n g t h a t some measure o f c o n t r o l was achieved a t the U c l u e l e t s i t e with the 5 SRD treatment with BBR1. F i g u r e 13 shows the r e l a t i o n s h i p among the a t t a c k r a t i o s f o r each o f the f i v e treatments. The c o n t r o l p l o t s and the s i n g l e SRD treatments a l l had a t t a c k r a t i o s over 1.0 i n d i c a t i n g t h a t the post treatment weevil p o p u l a t i o n s i n these p l o t s were i n c r e a s i n g . The o v e r a l l post treatment a t t a c k r a t i o f o r the U c l u e l e t s i t e was 0.94. T h i s apparent post treatment r e d u c t i o n i n the a t t a c k r a t i o suggests t h a t the weev i l p o p u l a t i o n s i n the study p l o t s may have been reduced s l i g h t l y . The p l o t s which had been t r e a t e d with f i v e SRD's had the lowest post treatment a t t a c k r a t i o s a t the U c l u e l e t s i t e . Treatment 5, BBR1 i n 5 SRD's per p l o t had a lower a t t a c k r a t i o (0.5) than treatment 4, BBR2 i n 5 SRD's per p l o t (0.72). These r a t i o s would both i n d i c a t e t h a t the post treatment a t t a c k r a t e w i t h i n the p l o t s was d e c l i n i n g . None o f the t r e e s t r e a t e d with an SRD, r e g a r d l e s s o f type, were a t t a c k e d i n 1982. 62 2.0 CONTROL BBR2-1 BBR1-1 BBR2-5 BBR1-5 F i g u r e 13. The d i s t r i b u t i o n o f the 1982 a t t a c k r a t i o among the p i n e o i l treatment groups a t the U c l u e l e t study s i t e . The a t t a c k r a t i o i s equal to the 1982 w e e v i l a t t a c k s d i v i d e d by the sum o f the 1980 and 1981 w e e v i l a t t a c k s . 63 3.1.3 General D i s c u s s i o n The t o p i c a l a p p l i c a t i o n of BBR1 to a l l stems was the o n l y treatment shown to be s i g n i f i c a n t l y e f f e c t i v e i n r e d u c i n g S i t k a spruce weevil a t t a c k s i n pure S i t k a spruce stands. Although the slow r e l e a s e d e v i c e (SRD) treatments were not shown to be s i g n i f i c a n t l y e f f e c t i v e , none o f the t r e e s i n which they were a p p l i e d were a t t a c k e d . An examination o f the a t t a c k h i s t o r i e s a t both the U c l u e l e t and Nootka I s l a n d s i t e s i n d i c a t e d t h a t some e f f e c t on the weevil a t t a c k r a t e s may have been achieved through the deployment of SRD's soaked i n BBR1. The block 1 p l o t s a t both study areas were i n o l d e r p l a n t a t i o n s which had been a t t a c k e d i n p r e v i o u s years and which had higher y e a r l y a t t a c k r a t e s . The b l o c k 1 p l o t s a t Nootka I s l a n d c o n t a i n e d the l a r g e s t t r e e s on the s i t e . In c o n t r a s t , the t r e e s i n the block 1 p l o t s a t U c l u e l e t were not over the s i t e averages f o r h e i g h t and dbh. These U c l u e l e t p l o t s were unique i n t h a t they occupied the bottoms o f g u l l i e s which were surrounded by non-host t r e e s . The higher a t t a c k r a t e s shown f o r these p l o t s , i n s p i t e o f t h e i r not being among the l a r g e s t a t the s i t e , were l i k e l y a r e s u l t of a d u l t weevil d i s p e r s a l being c o n f i n e d to an area with l i m i t e d host t r e e s . These r e s u l t s support the f i n d i n g s of Harman (1975) and Overhulser and Gara (1975) who found t h a t weevil d i s p e r s a l tended to f o l l o w p l a n t a t i o n rows and non-host borders. The weevil a t t a c k h i s t o r y r e c o r d s i n d i c a t e t h a t the U c l u e l e t s i t e had been a t t a c k e d e a r l i e r than the Nootka I s l a n d s i t e , however, the a t t a c k r a t e proceeded a t a much slower pace. 64 The lower a t t a c k r a t e s a t U c l u e l e t may be a t t r i b u t a b l e to the poorer s i t e type c l a s s and the more d i r e c t i n f l u e n c e o f the marine environment. These r e s u l t s would support the f i n d i n g s of McMullen (1976a,b) and Heppner and Wood (1984) who suggested t h a t areas under the d i r e c t i n f l u e n c e of c o a s t a l marine c o n d i t i o n s are o f t e n not s u i t a b l e f o r optimal P. s t r o b i brood p r o d u c t i o n . 3.2 The A e r i a l Photography Study The success r a t e s o f the four i n t e r p r e t e r s i n c o r r e c t l y i d e n t i f y i n g c u r r e n t l y a t t a c k e d S i t k a spruce are summarized i n Table 9, These data show t h a t the observers c o r r e c t l y i d e n t i f i e d 38% more 1982 a t t a c k e d t r e e s on c o l o r i n f r a - r e d (CIR) f i l m than on normal c o l o r (NO f i l m . During the one minute o b s e r v a t i o n p e r i o d the i n t e r p r e t e r s d e t e c t e d an average o f 60% of the c u r r e n t a t t a c k s on CIR f i l m compared with 43% on NC f i l m . An ANOVA was performed on the a r c s i n t r a n s f o r m a t i o n o f the percent a t t a c k s c o r r e c t l y i d e n t i f i e d by the i n t e r p r e t e r s . The ANOVA, see Appendix 4, i n d i c a t e d t h a t the i n t e r p r e t a t i o n o f c u r r e n t weevil a t t a c k s from the two f i l m types was s i g n i f i c a n t l y d i f f e r e n t . There were no s i g n i f i c a n t f i l m , s i t e , observer or p l o t i n t e r a c t i o n s i n d i c a t e d by the ANOVA. I t may be concluded from t h i s a n a l y s i s t h a t c u r r e n t a t t a c k s on S i t k a spruce t r e e s are more e a s i l y d e t e c t e d on CIR f i l m than on NC f i l m . 65 Table 9. Records of four i n t e r p r e t e r s ' i d e n t i f i c a t i o n s o f c u r r e n t spruce weevil a t t a c k s on normal c o l o r (NO and c o l o r i n f r a - r e d (CIR) s t e r e o p a i r s . ( 1 ) A t t a c k s A t t a c k s I d e n t i f i e d bv I n t e r p r e t e r F i l m S i t e V i s i b l e A B C D T o t a l NC Nootka 21 15 12 13 12 52 NC U c l u e l e t 28 11 7 9 6 33 T o t a l 49 26 19 22 18 85 % of v i s i b l e 53% 39% 45% 37% 43% CIR Nootka 21 18 14 18 17 67 CIR U c l u e l e t 28 11 12 17 10 50 T o t a l 49 29 26 35 27 117 % of v i s i b l e 59% 53% 71% 55% 60% (1) As determined from ground t r u t h i n g and checking of photo t r a n s p a r e n c i e s . F a i l u r e to i d e n t i f y an a t t a c k e d t r e e are e r r o r s of omission (Murtha 1985). 66 Although the CIR f i l m was shown to be s u p e r i o r f o r d e t e c t i o n , more e r r o r s were made i n i t s i n t e r p r e t a t i o n (Table 10). The e r r o r s made with the CIR f i l m were mainly e r r o r type 3; t h a t i s , i n c o r r e c t i n t e r p r e t a t i o n o f the age of weevil a t t a c k . There were no type 3 e r r o r s made with the NC f i l m . A l l type 3 e r r o r s r e s u l t e d from the i n t e r p r e t e r s i d e n t i f y i n g two year o l d a t t a c k s as c u r r e n t a t t a c k s . These r e s u l t s are c o n s i s t e n t with the c o n c l u s i o n s reached by C i e s l a (1977) t h a t CIR f i l m i s l e s s s u i t a b l e f o r d i f f e r e n t i a t i n g between year o f a t t a c k . Most of the e r r o r s made with the NC f i l m were e r r o r type 1; t h a t i s i n t e r p r e t i n g a h e a l t h y S i t k a spruce as a c u r r e n t a t t a c k . I n t e r p r e t e r B who had no p r i o r t r a i n i n g i n ob s e r v i n g the symptomology o f S i t k a spruce weevil a t t a c k s , was r e s p o n s i b l e f o r 67% of t h i s e r r o r , 73% of NC f i l m e r r o r s and 69% o f a l l e r r o r s made. The more experienced i n t e r p r e t e r s made only type 3 e r r o r s with CIR f i l m and o n l y type 1 e r r o r s with NC f i l m . The a e r i a l photographs were not taken u n t i l September when most of the weevils had completed t h e i r development. The newly a t t a c k e d t e r m i n a l s had changed c o l o r to a dark r e d brown and most of the needles had a l r e a d y been shed. In t h i s regard there would have been fewer d i f f e r e n c e s between the s p e c t r a l r e f l e c t a n c e from c u r r e n t a t t a c k s and one year o l d a t t a c k s s i n c e both types would c o n s t i t u t e a dead, r e d brown s h o r t stem a t the tops o f t r e e s . T h i s problem o f m i s s i d e n t i f i c a t i o n does not occur with a t t a c k s over 2 years o l d because the l a t e r a l s a t the base o f the a t t a c k have grown up and t h e i r f o l i a g e covers the 67 Table 10. I n t e r p r e t e r e r r o r s i n i d e n t i f y i n g spruce weevil a t t a c k s on 1:1200 s c a l e a e r i a l photographs from normal c o l o r (NC) and c o l o r i n f r a - r e d (CIR) f i l m s . E r r o r E r r o r s by I n t e r p r e t e r % of F i l m Type A B C D T o t a l T o t a l NC 1 1 6 2 0 9 82 NC 2 0 2 0 0 2 18 NC 3 0 0 0 0 0 0 T o t a l 1 8 2 0 11 100% % o f T o t a l 9 73 18 0 CIR 1 0 3 0 0 3 9 CIR 2 0 4 0 0 4 12 CIR 3 5 16 6 0 27 79 T o t a l 5 23 6 0 34 100% % of T o t a l 15 68 17 0 E x p l a n a t i o n of e r r o r types: Type 1 - c l a i m i n g a non-attacked S i t k a spruce to be a c u r r e n t a t t a c k . Type 2 - c l a i m i n g a t r e e s p e c i e s other than S i t k a spruce to be a c u r r e n t a t t a c k . Type 3 - c l a i m i n g a p r e v i o u s l y a t t a c k e d S i t k a spruce to be a c u r r e n t a t t a c k . 68 dead t e r m i n a l . I f the photographs had been taken i n e a r l y August as o r i g i n a l l y planned, much of the d i s c o l o r e d f o l i a g e would s t i l l be v i s i b l e on the c u r r e n t a t t a c k s . The presence o f t h i s d i s c o l o r e d f o l i a g e would f u r t h e r enhance the d i f f e r e n c e s i n s p e c t r a l r e f l e c t a n c e between one and two year o l d a t t a c k s . T h i s might have s i g n i f i c a n t l y reduced type 3 e r r o r s which accounted f o r 79% of a l l the e r r o r s made i n i d e n t i f y i n g c u r r e n t a t t a c k s on CIR f i l m . A l l o f the type 1 and type 2 e r r o r s with CIR f i l m were made by i n t e r p r e t e r B, the l e a s t experienced i n weevil a t t a c k symptomology. E r r o r types 1 and 2 would be f a r more c o n s e q u e n t i a l to the i n t e r p r e t a t i o n o f weevil survey i n f o r m a t i o n s i n c e they i n d i c a t e weevil a t t a c k s which do not i n f a c t e x i s t . The types o f i n t e r p r e t e r e r r o r s made with the CIR f i l m might be a v o i d a b l e through the proper t r a i n i n g o f i n t e r p r e t e r s on spruce weevil a t t a c k symptomology and a e r i a l photograph i n t e r p r e t a t i o n . Although CIR f i l m e r r o r s may be s u c c e s s f u l l y reduced or e l i m i n a t e d , i t seems d o u b t f u l t h a t the type 1 e r r o r s made by both t r a i n e d and u n t r a i n e d i n t e r p r e t e r s with NC f i l m c o u l d be as e a s i l y avoided. I t i s i n t e r e s t i n g to note here, however, t h a t i n t e r p r e t e r D d i d not make any e r r o r s with e i t h e r type o f f i l m . The number of a t t a c k s i d e n t i f i e d by i n t e r p r e t e r D, however, was below the average o f 60% f o r CIR f i l m and 43% f o r NC f i l m . In summary, t h i s study has shown t h a t i n f e s t a t i o n s o f the S i t k a spruce weevil can be s u c c e s s f u l l y sampled with a e r i a l 69 c o l o r photographs a t a s c a l e o f 1:1200. The use o f CIR f i l m f o r t h i s purpose i s s u p e r i o r to NC f i l m i n percentage o f stems i d e n t i f i e d . Since the i n t e r p r e t e r s ' time was l i m i t e d to 1 minute per p l o t , the l a r g e r number of c o r r e c t a t t a c k s i d e n t i f i e d on CIR f i l m makes i t more e f f i c i e n t than NC f i l m . 70 4. CQHCLVSIQHS 4.1. P i n e o i l S t u d i e s (1) The l a b o r a t o r y study showed t h a t S i t k a spruce weevil f e e d i n g was reduced and m o r t a l i t y was i n c r e a s e d when the weevils were presented with p i n e o i l t r e a t e d l e a d e r c u t t i n g s . (2) The weevils avoided the p i n e o i l t r e a t e d c u t t i n g s u n t i l they were f o r c e d to e i t h e r feed on them or s t a r v e . (3) Only the l e a d e r s t o p i c a l l y t r e a t e d with BBR1 i n the f i e l d s t u d i e s were p r o t e c t e d from a t t a c k . (4) None o f the dominant t r e e s with the SRD's c o n t a i n i n g p i n e o i l s , were at t a c k e d . (5) The a n a l y s i s o f the a t t a c k h i s t o r y data and the a t t a c k r a t i o v a r i a b l e showed t h a t the numbers of new a t t a c k s i n the p i n e o i l t r e a t e d p l o t s were reduced when compared to the unt r e a t e d c o n t r o l s . (6) A t r e n d was noted towards lower a t t a c k r a t i o s a f t e r treatment with i n c r e a s i n g c o n c e n t r a t i o n s o f p i n e o i l . 4.2 A e r i a l Photography Study (1) T h i s study showed t h a t c u r r e n t a t t a c k s by the S i t k a spruce weevil on immature S i t k a spruce t r e e s are d e t e c t a b l e on 1:1200 s c a l e c o l o r a e r i a l photographs. (2) In a comparison of normal c o l o r (NC) and c o l o r i n f r a - r e d (CIR) f i l m t r a n s p a r e n c i e s , CIR f i l m was found to be the more e f f e c t i v e f o r d e t e c t i n g weeviled t r e e s w i t h i n a p r e s c r i b e d time p e r i o d . 71 (3) The analysis of interpreters' errors showed that the t o t a l number of errors made with CIR f i l m was higher than with NC film. (4) The errors with CIR f i l m were primarily misinterpretations of weevil attack year while the errors with NC f i l m were i d e n t i f i c a t i o n s of non-attacked trees as current weevil attacks. 72 5. FUTURE RESEARCH 5.1 P i n i o n s t u d i e s The a p p l i c a t i o n of BBR1 to the t e r m i n a l l e a d e r s of f u t u r e c r t r e e s may be an e f f e c t i v e technique f o r p r o t e c t i n g stands from the l o s s e s a s s o c i a t e d with S i t k a spruce weevil a t t a c k . The frequency of a p p l i c a t i o n s w i l l depend on the r e s i d u a l e f f e c t of the p i n e o i l present on the stem of treatment t r e e s . N i j h o l t et. a l . (1981) suggest that p i n e o i l may have some r e s i d u a l a c t i v i t y f o r s e v e r a l years a f t e r a p p l i c a t i o n . I f p i n e o i l has a r e s i d u a l e f f e c t on S i t k a spruce, then s i n g l e a p p l i c a t i o n s to the stem with BBR1 c o u l d be e f f e c t i v e i n l i m i t i n g weevil access to the te r m i n a l l e a d e r s of crop t r e e s f o r more than one year. Although the t o p i c a l a p p l i c a t i o n of BBR1 g r e a t l y reduced weevil a t t a c k i n 20 meter square p l o t s the q u e s t i o n s t i l l remains whether the same r e s u l t c o u l d be achieved i f a l l stems i n a p l a n t a t i o n were t r e a t e d . P r i o r to any o p e r a t i o n a l use of p i n e o i l i n a r e p e l l e n t t r i a l , a s u i t a b l e mechanism f o r deployment and r e l e a s e of p i n e o i l v o l a t i l e s a t or near the tops of s p e c i f i e d t r e e s would have to be developed. In a d d i t i o n the e f f e c t s of p i n e o i l on the weevil p o p u l a t i o n and the changes i n t h e i r host seeking behaviour i n the presence of p i n e o i l t r e a t e d t r e e s r e q u i r e s f u r t h e r study. I t should be determined whether the presence of p i n e o i l t r e a t e d crop t r e e s would f o r c e weevils to f i n d s u i t a b l e host m a t e r i a l i n the codominant or suppressed t r e e s . By a v o i d i n g the s i t u a t i o n where host seeking weevils have no c h o i c e but to a t t a c k t r e e s t r e a t e d with p i n e o i l the dominant crop t r e e s c o u l d be p r o t e c t e d from c u r r e n t and f u t u r e a t t a c k s . F u r t h e r i n v e s t i g a t i o n s o f the r e p e l l e n t and r e s i d u a l e f f e c t s o f p i n e o i l , i n which on l y s e l e c t e d crop t r e e s o f a S i t k a spruce stand are t r e a t e d , seem warranted. 5.2 A e r i a l photography s t u d i e s The study presented i n t h i s r e p o r t was a p r e l i m i n a r y assessment of the u t i l i t y f o r l a r g e s c a l e NC and CIR photographs i n d e t e c t i n g spruce weevil damage. The major q u e s t i o n o f the p o t e n t i a l f o r e r r o r s o f omi s s i o n i n the i n t e r p r e t a t i o n o f the photographs was not addressed. In order f o r t h i s technique to be used o p e r a t i o n a l l y , the r i s k o f not d e t e c t i n g w e e v i l a t t a c k s which i n f a c t e x i s t must be assessed. 74 r LITERATURE CITED A l d r i c h , R. C. 1966. F o r e s t r y a p p l i c a t i o n s o£ 70 mm c o l o r . Photog. Eng. 32: 802-810. A l d r i c h , R. C , W. F. 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No. 2. 81 as, G. K. and A. L. Leaf. 1964. Weevil i n f e s t a t i o n i n r e l a t i o n to f e r t i l i z a t i o n o f white p i n e . For. S c i . 10 428-431. 82 Appendix 1. ANOVA of the number o f fe e d i n g punctures made by a d u l t spruce weevils c o n f i n e d with l e a d e r c u t t i n g s i n the l a b o r a t o r y f e e d i n g b i o a s s a y Mean Source D.F. Square F Value Treatment 5 55.497 6.3939 * E r r o r 54 8.679 * Treatment i s s i g n i f i c a n t a t alpha=0.05 83 Appendix 2. ANOVA of the number of spruce l e a d e r s a t t a c k e d i n 1982 among the p i n e o i l treatments and c o n t r o l s a t the Nootka I s l a n d study s i t e . Source D.F. Mean Square F Value Treatment 6 0.204 1.513 E r r o r 14 0.135 T o t a l 20 84 Appendix 3. ANOVA of the number o f spruce l e a d e r s a t t a c k e d i n 1982 among the p i n e o i l treatments and c o n t r o l s a t the U c l u e l e t study s i t e . Source D.F. Mean Square F Value Treatment 4 0.052 0.453 Block 2 0.148 1.291 E r r o r 8 0.114 T o t a l 14 85 Appendix 4. ANOVA f o r i n t e r p r e t e r successes i n d e t e c t i n g c u r r e n t spruce weevil a t t a c k s on NC and CIR s t e r e o p a i r s . Source D.F. Hean Square F Value F i l m (ft) 1 1.055 7.816 * S i t e (B) 1 4.224 2.931 AB 1 1.350E-7 1.350E-7 I n t e r p r e t e r (C) 3 7.948E-2 0.444 AC 3 2,276E-2 0.551 BC 3 1.791E-1 1.755 ABC 3 4.133E-2 0. 219 P l o t (D) 10 1.441 7.650 * AD 10 6.532E-2 0, 347 CD 30 1.021E-1 0.542 E r r o r 30 1.883E-1 T o t a l 95 * S i g n i f i c a n t a t alpha=0.05 86 

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