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Ecological factors influencing diapause in the spruce budworm, Choristoneura fumiferana (Clem.). (Tortricidae) Campbell, Douglas Kennedy 1953

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ECOLOGICAL FACTORS INFLUENCING DIAPAUSE . IH THE. SPRUCE -BUDWORM . . CHORISTONEURA FUMIFERANA (CLEM.). (TORTRICIDAE)  Douglas Kennedy Campbell  A THESIS SUBMITTED UJ PARTIAL FULFILMENT OF . - THE REQUIREMENTS FOR. -THE DEGREE OF  MASTER OF ARTS i n the Department of Zoology.  Ve accept t h i s t h e s i s as conforming t o the standard required from candidates f o r the degree of MASTER OF ARTS.  Members of the Department of THE UNIVERSITY OF BRITISH COLUMBIA April,  1955.  I ABSTRACT I n v e s t i g a t i o n s were c a r r i e d out to determine the e f f e c t of e c o l o g i c a l f a c t o r s on the i n d u c t i o n of diapause i n the spruce budworm. Experimental  rearings were conducted  at e l e v a t i o n s of 2500, 4200 and 4750 f e e t .  The  f o l i a g e of spruce, Douglas f i r and alpine f i r were used as hosts.  Progeny of Ontario,  two-  year and one-year types reared under one-year and two-year l i f e c y c l e conditions were used as experimental i n s e c t s . A trend was  observed i n emergence  from h i b e r n a t i o n w i t h the one-year type l e a d i n g , followed by the two-year and f i n a l l y the Ontario type • I t was shown that the one-year type larvae may  adopt the two-year h a b i t .  The main  f a c t o r i n f l u e n c i n g t h i s i s a prolonged development period f o r the parents.  The larvae reared  at the h i g h e r e l e v a t i o n s showed a greater p r o p o r t i o n entering diapause.  Food played  a  smaller r o l e with spruce and Douglas f i r "being more favourable f o r diapause than a l p i n e f i r . The increased percentage of larvae i n diapause in  1952  i s a t t r i b u t e d to a longer development  period f o r t h e i r parents and to a sharp drop i n temperature o c c u r r i n g about 12 days p r i o r to diapause. The Ontario m a t e r i a l may  adopt the  two-year h a b i t . The f a c t o r s c o n t r i b u t i n g to t h i s have not been c l e a r l y shown as the r e a r i n g r e s u l t s are i n c o n c l u s i v e . There were no d e f i n i t e d i f f e r e n c e s shown  i n the time f o r development among the  three foods.  The i n s e c t s at the lowest s t a t i o n  i developed i n  approximately three weeks l e s s  time than at the highest. The d i f f e r e n c e between the upper s t a t i o n s was  slight.  The i m p r a c t i c a b i l i t y of converting one-year l i f e cycle population to a two-year cycle by f o r e s t management i s noted.  a  Ill  The diapause t h e o r i e s of Wigglesworth and Andrewartha are commented on.  A  p o s s i b l e course of e v o l u t i o n l e a d i n g to the establishment of a two-year l i f e cycle population i s given.  \  IV TABLE  OP  CONTENTS  Abstract  *I  Index to Tables  VI  Introduction  ••  1  Diapause Theories .••.•.••••••.••••••••••• 7 Suggested Mechanisms. 7 A Inception of diapause 7 (a) A u t o i n t o x i c a t i o n 7 (b) Diapause f a c t o r or hormone. 8 B Termination of diapause 11 Conditions a f f e c t i n g i n c e p t i o n of ' diapause. • • • .12 A Environment «12 Ca| Temperature ...............13 l\>) Pood and water ........ ••••13 (c) Photoperiod ....•.....•••••14 B Heredity •••15 Procedure  •.•••••.••••••..••••••20  Results ••.•.•••••••••••• .28' Emergence ••........ ..28 Feeding . •... ......31 Development 32 Ontario-Bolean l a r v a e (B) ......41 One-year l a r v a e .42 Two-year l a r v a e ... ....44 Comparison of s t a t i o n s . 44 Diapause ....••••••••••••.«••••....••46 Ontario-Bolean type (B & B i ) . . . . 5 1 One-year types ...52 T r i n i t y V a l l e y type (F & F i ) 52 Bole an type (D & F ^ l ) 52  V  Comparison of one-year types.....55 Comparison of 1951 and 1952 results of one-year types.......57 Discussion  .....60  Summary •. •. • Conclusions ... •  .........  •  •••••  ... .66 68  Acknowledgments  .71  Literature cited  72  Appendic A Weather records 1951 B  Weather records 1952  «76 82  VI INDEX TO TABLES TABLE I  Dates f o r "beginning of emergence from h i b e r n a t i o n 1951  29  TABLE I I  Dates f o r beginning of emergence from h i b e r n a t i o n 1952 ..  29  TABLE I I I  Summary of r e a r i n g r e s u l t s , S t a t i o n I - 2500 f e e t 1951  35  TABLE IV  Summary o f r e a r i n g r e s u l t s , S t a t i o n I I - 4200 f e e t 1951  36  Summary of r e a r i n g r e s u l t s , S t a t i o n I I I - 4750 f e e t 1951  37  TABLE VI  Mean days from emergence from h i b e r n a t i o n t o adulthood 1951...  38  TABLE V I I  S t a t i o n I - Tabulation of oneyear and Ontario results...1952.  39  TABLE V I I I  S t a t i o n I I I - Tabulation of oneyear and Ontario r e s u l t s 1952...  40  TABLE IX  T o t a l number i n diapause or surv i v i n g to pupation and the percentage i n diapause i n 1951..  47  T o t a l number i n diapause or surv i v i n g t o pupation and the percentage i n diapause i n 1952..  48  TABLE X I  Rearing r e s u l t s condensed and expressed as percentages 1951..  49  TABLE X I I  Rearing r e s u l t s condensed and expressed as percentages 1952..  50  TABLE  V  TABLE X  INTRODUCTION  Diapause i s defined "by Wigglesworth (1950) as a spontaneous a r r e s t of development which, supervenes i r r e s p e c t i v e of the environmental c o n d i t i o n s .  Diapause  may occur i n any stage of the l i f e cycle hut the stage at which i t occurs i n any species i s as a r u l e r i g i d l y f i x e d .  In different  i n s e c t species i t exerts i t s e f f e c t under various circumstances "but u s u a l l y once the i n d i v i d u a l has entered diapause i t has t o remain i n that s t a t e f o r a c e r t a i n p e r i o d , regardless of the c o n d i t i o n s of the environment. Insects i n diapause are c h a r a c t e r i z e d by a low metabolic r a t e , g r e a t l y diminished a c t i v i t y , p r a c t i c a l cessation of development, and an increased a b i l i t y environments. to  t o survive unfavourable  They do not respond immediately  any ordinary a m e l i o r a t i o n of the e x t e r n a l  -2  c o n d i t i o n s , as do i n s e c t s whose development has "been i n h i b i t e d by t h e i r environment. Development i s resumed only a f t e r exposure t o c e r t a i n required c o n d i t i o n s , such as. c o l d , f o r a given  period.  Diapause p l a y s a major r o l e i n the l i f e cycle  of the spruce budworm.  This  species i s found i n Canada from the A t l a n t i c to  the P a c i f i c Ocean and n o r t h almost to the  limit  of timber.  I t extends down the Appala-?  chian Mountains to V i r g i n i a i n the E a s t e r n United States and has been reported as f a r south as New Mexico i n the West.  In short i t i s  d i s t r i b u t e d throughout the e n t i r e range of i t s food p l a n t s . Spruce and balsam are the p r e f e r r e d food p l a n t s over the greater part of the range of the spruce budworm.  In north-western  Ontario  and the Lake States a form that p r e f e r s Scotch pine and jack pine was studied by Graham (1935) and Brown and McKay (1943).  In B r i t i s h Columbia  Douglas f i r i s one of the main h o s t s . In Eastern America, the a d u l t s emerge from mid-June to the l a t t e r part of J u l y , commencing to l a y t h e i r eggs w i t h i n two to  f i v e days.  twelve days.  The eggs hatch i n nine to  The young l a r v a e f i n d a  sheltered niche, s p i n a cocoon or hlbernaculum, molt to the second i n s t a r and overwinter i n diapause.  The f o l l o w i n g spring the l a r v a e  emerge from or  t h e i r h i b e r n a c u l a , coincident w i t h  a few days "before the balsam buds open.  This i s g e n e r a l l y i n l a t e A p r i l or e a r l y J i a y . A large percentage of the young larvae form mines i n  the o l d needles i n spring before  a t t a c k i n g the new buds.  A f t e r passing through  f i v e i n s t a r s the larvae pupate i n l a t e Hay  or  i n June and a f t e r a pupal p e r i o d of about ten days, emerge as a d u l t s . In B r i t i s h Columbia i n the Douglas f i r regions of the I n t e r i o r and on the coast  the  -4-  l i f e cycle i s much the same as that o u t l i n e d f o r the eastern i n s e c t s .  The dates vary con-  s i d e r a b l y due t o l o c a l d i f f e r e n c e s i n climate but i n g e n e r a l , the period of a c t i v i t y i s May, June and J u l y * On the other hand, i n the sprucebalsam  f o r e s t s on the h i g h plateaux of c e n t r a l  and southern B r i t i s h Columbia, and extending i n t o the north-western States and i n the sprucebalsam  f o r e s t s o f the Rocky Mountains,, the  spruce budworm has a two-year l i f e c y c l e . This was noted and studied f i r s t by Mathers in  the B a r k e r v i l l e d i s t r i c t .  {1922)  I n t h i s case the  l a r v a e emerge from h i b e r n a t i o n about the middle of June and develop slowly u n t i l the middle or l a t t e r p a r t o f J u l y when, s t i l l i n the t h i r d i n s t a r , they s p i n h i b e r n a c u l a , molt t o the f o u r t h i n s t a r and enter diapause and overwinter a g a i n . The f o l l o w i n g s p r i n g , feeding i s resumed about the middle of June and adulthood reached by the l a t t e r  part  of July. The  p u p a l p e r i o d i s approximately  t h r e e weeks and the i n c u b a t i o n p e r i o d i s about the same l e n g t h of t i m e . Because o f t h e s y n c h r o n i z a t i o n o f the development o f t h e p o p u l a t i o n  there a r e  s m a l l , i n c o n s p i c u o u s l a r v a e one year w h i l e the next y e a r the l a r v a e a r e l a r g e and f e e d i n g voraciously.  The two-year l i f e  cycle, with  heavy f e e d i n g only i n a l t e r n a t e y e a r s ,  renders  the i n s e c t much l e s s d e s t r u c t i v e than i t i s i n a one-year c y c l e  area.  I t i s apparent t h a t , i f by f o r e s t management o r other means, the one-year c y c l e could be changed t o a two-year c y c l e the d e p r e d a t i o n s o f t h i s i n s e c t would be g r e a t l y reduced.  The crux o f t h e problem l i e s i n the  diapause i n t e r v e n i n g a t t h e c l o s e o f the t h i r d and t h e b e g i n n i n g o f the f o u r t h i n s t a r i n t h e two-year c y c l e .  The d e t e r m i n a t i o n  of the f a c t o r s  6-  causing  this diapause i s a necessary pre-  liminary step "before any practical measure may be undertaken. By observation i t i s known that the one-year type i s typically associated with Douglas f i r at lower and with spruce and alpine f i r at higher elevations.  Thus the  reasonable factors to investigate are food and altitude.  -7 DIAPAUSE THEORIES Published work on diapause i n i n s e c t s i s extensive.  3Por  comprehensive  b i b l i o g r a p h i e s the reader i s r e f e r r e d t o Uvarov (1931), Prebble (1941), Bonnemaison (1945), Dickson (1949), Wigglesworth (1950) and Andrewartha  (1952).  The w r i t e r w i l l not  attempt to review a l l the work but w i l l summarise the r e s u l t s reported, p a r t i c u l a r l y on  the b a s i s of the suggested mechanisms,  and the e c o l o g i c a l conditions a f f e c t i n g d i a pause. Suggested Mechanisms: A  Inception of diapause (a)  A u t o i n t o x i c a t i o n - the theory  of a u t o i n t o x i c a t i o n was developed by Roubaud (1922) working w i t h L u c i l i a s e r i c a t a Meig.,  who  postulated that a u t o i n t o x i c a t i o n i s caused by the accumulation of metabolic wastes which b u i l d  f  -8up f a s t e r  than they can he eliminated d u r i n g  a c t i v e growth, so that a p e r i o d of r e s t i s needed to a l l o w e l i m i n a t i o n t o c a t c h up. work  This  has "been d i s c r e d i t e d by Cousin (1932),  who showed that diapause i n L u c i l i a i s caused by environmental f a c t o r s . (b) Diapause f a c t o r or hormone Bodine (1932) studied diapause i n the eggs of Melanolplus d i f f e r e n t i a l i s (Thos.) and advanced the theory that there i s a diapause f a c t o r (X f a c t o r ) present i n the diapause type egg of that species at the time the eggs are l a i d .  If  these eggs are held at comparatively h i g h temperatures, the amount or potency of the d i a pause f a c t o r increases u n t i l i t passes a t h r e s h o l d at the "three-weeks" stage and stops embryonic development.  The diapause f a c t o r i s  g r a d u a l l y d i s s i p a t e d a f t e r t h i s point and eventually allows development t o resume. Exposure t o low temperature at any time, e i t h e r before or a f t e r the "three-weeks" stage, r a p i d l y destroys the diapause f a c t o r , and  i  development  -9-  resumes as soon as the temperature i s r a i s e d . This theory was extended "by S a l t (1947) working w i t h the wheat stem sawfly Ceuhus c i n c t u s E b r t .  He speculated that  diapause i n t h i s species i s c o n t r o l l e d not only  "by an X f a c t o r as defined by Bodine,  but also  by a Y f a c t o r , which breaks down more  slowly than does the X f a c t o r but at a constant r a t e , regardless of temperature.  He was a b l e  to r e i n s t a t e diapause by exposure t o r e l a t i v e l y h i g h temperatures (35°C) at any time before the Y f a c t o r was e l i m i n a t e d . Wigglesworth (1948) b e l i e v e s that diapause i s due t o the absence of a growthpromoting hoimone which c o n t r o l s m o l t i n g , secreted by the neuro-secretory c e l l s of the brain.  He speculates t h a t the raw m a t e r i a l s  f o r the hoimone i n Rhodnius may be vitamins produced by the symbiotic bacterium Actinomyces r h o d n i i harboured i n the gut of the i n s e c t .  •10.  Way and Hopkins (1950) consider i t probable t h a t diapause i n the pupa of D i a t a r a x i a oleracea L. i s due to the absence of a hormone responsible f o r adult d i f f e r e n t i a t i o n r a t h e r than the presence of an i n h i b i t i n g hormone. T h i s conclusion has also been reached by Williams (1946) who  found that i n Platysamia  cecropia. Telea polyphemus and  Callosamia  promethea. pupal diapause r e s u l t s from an i n t e r r u p t i o n of the normal processes of development by a f a i l u r e of the b r a i n to supply a n o n - s p e c i e s - s p e c i f i c f a c t o r necessary f o r adult differentiation. The causal agent f o r the i n h i b i t i o n of the hormone s e c r e t i o n has been postulated by Andrewartha (1952) t o be a n accumulation of an i n t r a c t a b l e food reserve occurring i n the  egg-  y o l k or, i n post-embryonic stages, i n the f a t body, which may  not be immediately broken down  i n preparation f o r the next stage i n morphogenesis.  -11  This i n t r a c t a b l e food reserve may be due t o an unbalance i n the metabolism such that the building-up processes go on normally but the breaking-down processes are reduced t o a minimum. Whether t h i s unbalance i s t o be a t t r i b u t e d t o the accumulation of a d i f f e r e n t sort of food reserve, or to the absence of a necessary enzyme system or to both, i s l e f t to be determined by p h y s i o l o g i c a l s t u d i e s .  B. Termination Recent experiments (Williams. 1946, 1947, 1948 and W i l l i a m s and Sanborn 1948, Pappenheimer and W i l l i a m s 1952) have shown the b r a i n to be the organ o f primary c o n t r o l over diapause i n pupae of Platysamia c e c r o p i a . I t was found, by i m p l a n t a t i o n techniques, that the t e r m i n a t i o n of diapause r e q u i r e s the a c t i o n of a minimum of two f a c t o r s , one a r i s i n g from the b r a i n and the other from the p r o t h o r a c i c glands (Lee 1948).  The b r a i n f a c t o r i s necessary  -12-  f o r the a c t i v a t i o n of the p r o t h o r a c i c glands. Chemical analyses showed that cytochrome c i s v i r t u a l l y absent from the diapausing pupa. During the p e r i o d when development i s dependent  on the p r o t h o r a c i c glands,  the  concentration of cytochrome c increases from l e s s than 1 to more than 50 gamma per l i v e weight. S i m i l a r l y during the p e r i o d of the "brain's secretory a c t i v i t y , the t i t r e of cytochrome oxidase increases from 40 to nearly 700 u n i t s .  approximately  As a r e s u l t of the  combined functions of both the b r a i n and  pro-  t h o r a c i c glands, the t i s s u e s of the dormant pupa, f o r the f i r s t time, come i n t o possession of a complete cytochrome system.  Conditions a f f e c t i n g i n c e p t i o n of diapause A  Environment. The environmental f a c t o r s commonly  •13-  inducing diapause may "be l i s t e d as those of temperature, food and water, and photoperiod. (a)  Temperature.  Pupal diapause may he induced i n Telea Polyphemus (Cramer) by s u b j e c t i n g the l a s t l a r v a l stadium to d e c l i n i n g temperatures (Dawson 1931).  Prebble (1941) found that  diapause i n emergent stocks of G i l p i n i a polytcma (Htg.) i s determined environmentally, and showed that l a r v a l feeding at low temperatures favours entry i n t o diapause as f u l l - f e d larvae. (b)  Food and water.  Food and water are c l o s e l y r e l a t e d i n i n s e c t d i e t a r y as most of the water taken by i n s e c t s occurs i n the food.  The c o n d i t i o n of  the food has been found to i n f l u e n c e the induct i o n of diapause. Squire (1940) reported that diapause of the f u l l - f e d l a r v a e of the pink bollworm, Pectinophora g o s s y p i e l l a  (Sound.),  -14-  i s independent of the season and depends on the moisture content of the seeds i n which they feed.  F i f e (1949) found i n the same  insect that diapause i s most abundant during periods of drought. (c)  Photoperiod.  The e f f e c t  of photoperiod i n inducing  diapause i n the o r i e n t a l f r u i t moth i s re-> ported by Dickson (1949) where diapause i s c o n t r o l l e d by temperature and d a i l y  exposure  to l i g h t during the l a r v a l f e e d i n g p e r i o d . Larvae grown i n the absence of l i g h t do not enter diapause.  As the period of l i g h t per  day i s increased to more than three hours, the percentage of diapause i n c r e a s e s , reaching 100 per cent w i t h about twelve hours of light.  As the photoperiod i s increased to more  than t h i r t e e n hours per day, the percentage of diapause drops suddenly t o p r a c t i c a l l y zero. Way and Hopkins (1950) showed that the i n d u c t i o n of diapause i n the pupa of  -15 -  D i a t a r a x i a oleracea L. i s influenced by temperature and photoperiod during the l a r v a l stage, w i t h low temperatures and short photoperiods tending to induce d i a pause while h i g h temperatures and long photoperiods tend t o prevent diapause. In mites M i l l e r (1950) and Lees (1950) found that diapause i s induced by a shortening day length.  B  Heredity There are many i n s e c t species which  have but one generation per year, w i t h a cons i d e r a b l e part of each year spent i n diapause. This behaviour p a t t e r n may w e l l be g e n e t i c a l l y fixed.  The diapause o c c u r r i n g i n second  i n s t a r l a r v a e of the spruce budworm f a l l s i n t h i s category. In d i s c u s s i n g the e f f e c t of i n h e r i t a n c e on diapause, Dickson (1949) reviews two notable  -16  cases as f o l l o w s : known  "A few i n s e c t species are  i n which there a r e both single-genera-  t i o n s t r a i n s ( u n i v o l t i n e ) and m u l t i p l e generation s t r a i n s ( m u l t i v o l t i n e ) .  One of  these i s the silkworm Bombyx mori L.» i n which the diapause occurs i n the egg. The u n i v o l t i n e s t r a i n s of the silkworm have but one generation annually, and the diapause occurs i n every generation.  Multivoltine  s t r a i n s have two t o s e v e r a l generations annually; eggs l a i d i n the summer hatch i n a short time; those l a i d  i n the f a l l enter diapause.  The  i n h e r i t a n c e of v o l t i n i s m i n the silkworm i s somewhat complex,  there being some evidence  f o r somatic i n h e r i t a n c e from the mother. I t i s reported by Uyema (1926) that i f the ovaries from an i n d i v i d u a l of one race are transplanted to an i n d i v i d u a l of another race during the l a r v a l stage the eggs produced show the v o l t i n i s m of the moth i n which they are grown r a t h e r than that of t h e i r true ancestors.  -17 -  The l i k e l i h o o d t h a t a given h a t c h of eggs w i l l enter diapause i s also influenced by the temperature at which the eggs and l a r v a e of the preceding generation were h e l d . " Dickson (1949) continues:  "In the  case of Pyrausta n u b i l a l i s (Hbn.), a species which  enters diapause as f u l l - f e d l a r v a e , i t  i s w e l l known by  that some areas are occupied  one-generation s t r a i n s and others by  generation s t r a i n s .  two-  Babcock (1924) reported  t h a t when specimens of the one-generation  strain  were t r a n s f e r r e d to an area occupied by the two-generation s t r a i n , and v i c e v e r s a , they p e r s i s t e d i n r e t a i n i n g the same seasonal h i s t o r i e s that they had shown i n t h e i r o r i g i n a l environments. Arbuthnot  (1944) found that  i n Connecticut the population i s homozygous f o r m u l t i p l e generations, while i n  Ohio  i t i s mixed, c o n t a i n i n g f a c t o r s f o r both s i n g l e and m u l t i p l e generations.  He was able  to  -18 -  i s o l a t e a homozygous s i n g l e - g e n e r a t i o n : s t r a i n from the Ohio p o p u l a t i o n , and found that the genetic f a c t o r s responsible f o r the s i n g l e generation are r e c e s s i v e .  O'Kane and Lowry  (1927), working w i t h t h i s i n s e c t i n New Hamps h i r e , showed that although the population was homozygous f o r m u l t i p l e generations,  only  a part of them a c t u a l l y went through two generations per year, the r e s t having hut one. A l l the larvae from the f i r s t eggs of the season pupated that same summer and produced a second generation, while larvae from egg,s t h a t hatched a f t e r a c e r t a i n date, u s u a l l y about J u l y 20 to 25, entered diapause and so had only one annual generation.  Apparently,  environmental f a c t o r s a r e involved i n the i n duction of diapause i n t h i s species, at l e a s t in  the m u l t i p l e - g e n e r a t i o n s t r a i n . " Prebble (1941) found that i n the  European spruce sawfly, G i l p i n i a polvtoma, (Hartig)  -19-  there axe d i f f e r e n t strains within the species, with respect to the inherent tendency towards diapause or continued development. The population i n the southern areas has  two  or more annual generations while the population i n northern areas i s composed of a s t r a i n having one annual generation, diapause i n t e r vening after a single generation even under favourable environmental conditions.  -20-  PROCEDURE  The present i n v e s t i g a t i o n was p r i m a r i l y designed t o determine the e f f e c t s of environmental conditions and food on diapause and secondarily t o a s c e r t a i n the e f f e c t s of these f a c t o r s on development of the hudwoim. P r e l i m i n a r y work on t h i s p r o j e c t was s t a r t e d at L i l l o o e t , B.-C, i n 1949.  The "basic  plan was t o introduce two-year type l a r v a e i n t o a one-year area w i t h rearings made at d i f f e r e n t e l e v a t i o n s . From t h i s i t was hoped t o determine the approximate conditions under which diapause occurred.  As there were no laboratory-reared  i n s e c t s a v a i l a b l e , r e l i a n c e was placed on f i e l d collected larvae.  Due t o delays the l o c a l one-  year larvae were w e l l advanced before r e a r i n g could  be begun.  Larvae of the two-year form were  c o l l e c t e d at Bolean Lake, near F a l k l a n d , B^ C , by Mr. V. . G. Mathers, and at C a s t l e Mountain, A l b e r t a , by Dr. E. Graham on June 21 and sent t o  -21  Lillooet.  These larvae entered diapause  between June 28 and J u l y 5 although very hot weather p r e v a i l e d at that time.  This  i n d i c a t e d that the f a c t o r s producing the diapause were operative e a r l y i n the l a r v a l stage, i f not i n the preceding In 195G,  generation.  studies were c a r r i e d out  from a camp at Bolean Lake, s i t u a t e d at an e l e v a t i o n of 4750 feet i n the a l p i n e f i r Engelmann spruce f o r e s t type. h i g h endemic population  There i s a  of two-year spruce  budworm i n t h i s l o c a l i t y . Three r e a r i n g s t a t i o n s were used, located as f o l l o w s : Station I  (2500 f e e t ) i n a t y p i c a l Douglas f i r - y e l l o w pine f o r e s t type.  Station II  (4200 f e e t ) i n a t r a n s i t i o n zone w i t h a mixture of Douglas f i r , Engelmann spruce and alpine f i r .  Station I I I  (4750 f e e t ) i n a t y p i c a l Engelmamn spruce-alpine f i r f o r e s t type.  One-year stock, progeny of adults mated at L i l l o o e t , two-year m a t e r i a l which had  -22-  entered diapause a t L i l l o o e t , and Ontario stock air-expressed from Port Arthur were oonfined i n sleeve cages on Dougla-s f i r at S t a t i o n I , spruce and a l p i n e f i r at S t a t i o n I I I and on a l l three hosts at S t a t i o n I I , and i n v i a l s on the same foods at Station, I I I . Prom these s t u d i e s i t was found that food i s not a major f a c t o r i n the i n i t i a t i o n of diapause. Some i n d i v i d u a l s of the one-year type entered diapause i n the v i a l s .  Also on the b a s i s of one  specimen i t was seen that Ontario one-year m a t e r i a l may be induced t o take two years to develop. Following the f i n d i n g s of Uyema (1926) and the i n d i c a t i o n s given at L i l l o o e t i n 1949 i t was suspected that the treatment of the parents might have some e f f e c t on the diapause of t h e progeny.  I t was arranged i n 1950 t o hare  matings made of one-year a d u l t s at the T r i n i t y V a l l e y P i e l d S t a t i o n (2100 feet e l e v a t i o n ) .  The  -23-  moths were from f o r e s t Insect Survey c o l l e c t ions made i n the L i l l o o e t d i s t r i c t .  This  s e r i e s provided l a r v a e whose parents had matured under one-year c o n d i t i o n s . Matings were also made at Bole an Lake  (4750 feet e l e v a t i o n ) , of two-year,  Ontario and one-year stock from the m a t e r i a l reared there. This s e r i e s provided larvae whose parents had matured under two-year c o n d i t i o n s . The r e s u l t i n g l a r v a e , from both breeding s e r i e s , were overwintered i n v i a l s at Trinity Valley.  Thus i n 1951, the f o l l o w i n g  types of l a r v a e were on hand. Each type was given a code l e t t e r f o r convenience i n r e c o r d keeping. Two-year, l i f e cycle from,B. C. (S) progeny of budworm reared at Bolean Lake. One-year l i f e cycle from B . C . (D) frogeny of budworm reared at Bolean Lake.  -24-  One-year l i f e c y c l e from B. C. (F) progeny of f i e l d - c o l l e c t e d l a r v a e reared at T r i n i t y V a l l e y . One-year l i f e c y c l e from Ontario (B) progeny of "budworm reared at Bole an Lake. V i a l s containing the overwintering l a r v a e were d i s t r i b u t e d among the three s t a t i o n s •...on Hay 18, so that at each s t a t i o n there was a supply of each type of l a r v a . As the l a r v a e became a c t i v e they were t r a n s f e r r e d to s i x ounce j e l l y j a r s , w i t h taped-on tops. Ten l a r v a e , i n the m a j o r i t y of cases, were placed i n each j a r w i t h s u f f i c i e n t f o l i a g e t o support the feeding of that number. A s e r i e s of four or f i v e j a r s of each type of l a r v a was reared on each of the three h o s t s , spruce ( P i c e a Engelmanni P a r r y . ) , Douglas f i r (Pseudotsuga t a x i f o l i a ( P o i r . ) B r i t t e n ) , and alpine f i r (Abies l a s i o carpa (Hook.) N u t t ) . possible variation  As a means of reducing  due to food source f o l i a g e  was taken from Stati. on at S t a t i o n s I and I I I .  I I t o feed the i n s e c t s  -25-  feed the i n s e c t s at S t a t i o n s I and I I I . Breeding was  c a r r i e d out  again  as the i n s e c t s reached maturity i n 1951. D i f f i c u l t y was  experienced i n obtaining  h i b e r n a t i n g larvae of the Ontario type at S t a t i o n s I I and I I I so that none was a v a i l a b l e f o r r e a r i n g i n 1952.  The one-year type f a i l e d  to hatch s a t i s f a c t o r i l y at S t a t i o n I I I but s u f f i c i e n t numbers were obtained from S t a t i o n II.  The second i n s t a r larvae from the breeding  program, and those larvae i n diapause were overwintered Thus, 1952  the experimental season  the f o u r t h i n s t a r  at T r i n i t y V a l l e y .  l a r v a e on hand f o r the  consisted of the f o l l o w i n g , coded  as i n d i c a t e d . Two-year cycle from B. C. (s) progeny of budworm reared at Bolean Lake (4750 f e e t ) i n 1950, overwintering i n the f o u r t h i n s t a r from 1951.  -26One-year cycle from B . C . (D) progeny of budworm reared at Bole an Lake (4750 f e e t ) i n 1950 and overwintering i n the f o u r t h i n s t a r from 1951. One-year c y c l e from B. G. (F) progeny of f i e l d c o l l e c t e d l a r v a e reared at T r i n i t y V a l l e y (2150 f e e t ) i n 1950 and overwintering i n the f o u r t h i n s t a r from 1951. One-year c y c l e from B• C. ( P i ) progeny of F m a t e r i a l reared and bred at S t a t i o n I (2500 feet) i n 1951. One-year c y c l e from B. 0. (.F^) progeny of F m a t e r i a l reared at S t a t i o n I I (4200 f e e t ) i n 1951. One-year cycle from Ont. (B) progeny of budworm reared at Bolean Lake (4750 f e e t ) i n 1950 and overwintering i n the f o u r t h i n s t a r from 1951. One-year cycle from Ont. (B^) progeny of B m a t e r i a l reared and bred at S t a t i o n I (2500 f e e t ) i n 1951. As the a n a l y s i s of the 1951 r e s u l t s showed that S t a t i o n I I was almost a d u p l i c a t e of S t a t i o n I I I , i t was decided t o e l i m i n a t e S t a t i o n I I from the 1952 program.  The o r i g i n a l designa-  t i o n s f o r Stations I and I I I were r e t a i n e d .  The  -27-  second year larvae from S t a t i o n I I were placed at S t a t i o n I I I to complete t h e i r development.  The r e a r i n g technique used  was the same as i n 1951 except that when the larvae were a v a i l a b l e s i x j a r s were used f o r each s e r i e s .  -28-  RESULTS  Emergence. The overwintering larvae were placed in  the f i e l d on May 18 i n 1951 and on May  in  1952.  19  The f o l l o w i n g t a b l e s ( I and I I ) g i v e  the dates f o r the f i r s t emergence f o r each type at each s t a t i o n f o r the two y e a r s .  The date  f o r the f i r s t emergence i s used as the great m a j o r i t y of the one-year larvae emerged on that day.  The emergence of the second i n s t a r two-  year type was extended over approximately f i v e days. are  In Table I i n two instances tvro dates  given and explained below.  as given above.  The coding i s  -29-  TABLE I Dates f o r beginning of emergence from h i b e r n a t i o n 1951.  1 yx.B.C. S t a t i o n reared at TV. E  l y r . B.C. 2 y r . B . C 1 yr.Ont. reared at reared at reared at Sta. I l l Sta.Ill Sta. I l l B S D  I  May  20  May  20  May  22  May  II  May  22  May  22  May  26  June  May 22 & 26  May  26  May  31  May 22 & June 4  III  22 4  TABLE I I Dates f o r beginning of emergence from h i b e r n a t i o n 1952.  Station F I III  Second i n s t a r , 1  May 20  lxjl  B,  1  • Fourth i n s t a r :E D • B :  May 21 May 24 :May 26 May 26 :  May 22 May 22 May 30 :May 29 May : 28  —  S May 22  May May 29 26  -30-  In Table I i t i s seen that the one-year c y c l e larvae came out together at the three s t a t i o n s .  The two-year larvae  were l a t e r i n each case, appearing at the same date as the Ontario-Bole an m a t e r i a l at S t a t i o n I.  At S t a t i o n I I the Ontario-Bolean m a t e r i a l  was l a t e r than the two-year l a r v a e . At S t a t i o n I I I a few Ontario-Bolean l a r v a e came out on May 22, hut the onset of a p e r i o d of cold weather delayed the main emergence u n t i l June 4. The same t h i n g happened t o the one-year T r i n i t y V a l l e y type, hut i n t h i s case emergence was resumed on May 26. In 1952 (Table I I ) there was very l i t t l e d i f f e r e n c e between the dates f o r S t a t i o n s I and I I I .  This was due probably t o the i n s e c t s  being on the verge of emergence when they were removed from storage. The Ontario type l a r v a e ,  31-  as i n 1951, were the l a s t to emerge of the second i n s t a r l a r v a e at "both s t a t i o n s .  The  f o u r t h i n s t a r one-year type l a r v a e were appreciably l a t e r than the second i n s t a r at both s t a t i o n s . The S, or two-year type, however, emerged p r i o r to the other types. These data show a trend i n the beginning of a c t i v i t y w i t h the one-year m a t e r i a l l e a d i n g , followed by two-year and f i n a l l y the Ontario stock.  Feeding. The larvae r e a d i l y accepted the three foods o f f e r e d .  Atwood (1944), i n O n t a r i o ,  reported the mining of needles by second i n s t a r larvae.  This habit has been noted also by  o f f i c e r s of the Vernon Forest B i o l o g y Laboratory; i n one-year type larvae on Douglas f i r at L i l l o o e t i n 1949,by W.G.  Mathers, and i n two-year type  l a r v a e on the same host at Heart Lake i n 1951 by  -32-  J . Grant.  I n t h i s experiment,  individuals  of a l l stocks mined needles of the three hosts at a l l s t a t i o n s i n 1951 and 1952.  Development. The r e s u l t s of the r e a r i n g are summarised and tabulated by S t a t i o n s and year (Tables I I I , IV, V, VI f o r 1951; Tables V I I , V I I I f o r 1952).  I n these t a b l e s the  f i r s t column gives the type and food. The code f o r types i s as given on pages 23 to 24 and 25 t o 26 while the foods a r e coded as follows:  spruce —  s, Douglas f i r -- d f , a l p i n e  f i r — a. The second column "emerged" shows the number o f l a r v a e o r i g i n a l l y placed i n the j a r . "Established" gives the number of larvae which began  t o feed s u c c e s s f u l l y . "Unestablished"  are those that f a i l e d to feed s u c c e s s f u l l y and died.  The "died" column gives the number of  33-  l a r v a e that d i e d a f t e r establishment. "Killed** gives those that were a c c i d e n t a l l y k i l l e d while the food was being changed i n the j a r . "Unaccounted" that disappeared:  includes those l a r v a e  many o f these were i n the  e a r l y i n s t a r s and probably represented dead l a r v a e whose cadavers could not be found but i n a few instances cannibalism may have taken place.  Under "diapause" the number of larvae  entering diapause i s given. Under the heading "pupae" the number that died as pupae, the number o f specimens of each sex, and the mean number of days from the time of emergence to pupation are found.  Under " a d u l t s " the number  of each sex and the mean number of days from pupation  t o adulthood are given. In Tables V I I and V I I I the t o t a l mean  days f o r development from emergence t o m a t u r i t y i s g i v e n . These f i g u r e s are given i n Table VI  -34-  f o r the 1951 r e s u l t s . This mean development p e r i o d i s f o r the i n d i v i d u a l s which matured and thus of course does not include the l a r v a l periods of those that died as pupae.  to W  tr)  co Pi ta  CQ  CQ ft  m  •"*»  w CD  oat) CD P.  H>  CD  hr) hrj he) P Pi CO  Hi  Type and Food  if* if* Ui O O M  -a -ocn l — cno  UI if* Ol O CO CO  if* Ol UI cD O H  Emerged  w.w  cn cn H cn  •f*rf*cd UI O CO  if*rf*W Ol <0 O  Established  cn  01  ^3 to  1  M CO if* Ol CD  l- H M O O O)  W tO CO  rf*  CO W CO  line sta b l i shed  >  CO W CO  Died  >  W M CO  H CO CO  Killed  O CO if*  W Ol if*  Unaccounted  1—  1  CO M  . hCOrf*CO  M  1  UI  CD rf*  Oi u  «  if*  1— rf* 1  <  1  ui cn if* to W CA  Diapause  U U (J)  CP W  O rf* H  W if* Ol  Died  h- M rf* CO CO  i — * 1—' 1—* CO CO O  M H H CO W CO  No. Male'  tF*  ui a i if* O O cD • • • CO CO CO  48.4 48.5 49.0  1  CJ1  ^ o> o •  •  H O Co to  M H M M  if* if* Ol UI CO CP  if* ui ai  CD c n . O  h- H W CO to 1  1— 1— 1—' O O O • • • Ol Ol o 1  M W  ^3 cn cn  No. Female  UI Ol Ol COrf*H O ) W if>  Ol Ul Ol W W CO O W to  Mean No. Days  1—• 1—• 1—' co cn o  tO h- 1— I— 03 CO  No. Male Mean No.. Days  11.1 10.8 10.5  1  J  12.1 11.6  Ol if* if*  Mean No, Days  1  a  1  1  > cj  t-l  H ^ W H if*  ID  (D tO  W -<i CO  CO  ' o o  H H  1— CD CO  O O  1  CD  O CO ^  Hie Ol M  H H  1—* 1——" 1—• O O M  •. •  cn W if*  -32-  No. Female Mean No. Days  t-3 CQ  CjJ  GO CG CG P J CO  P<  CO  H>  w  H>  ui cn  Cn  O O O  « co  H;  if>  CD  U10105  H  M H  CO  CJIOI-O  (-*  01 H UI  H  W  O  W  CD Pi  H>  CO  cn <£> cn  cnOO  hrj hrj  hij  ( B p . TO Hj  wuioi  to M  M H H '  H  H  I-  H  1  cncnW  Emerged  O  if» -a tf* w « ^ £». -<J ^3 U i O H  Type and Food  '  M  cnWtD to  CO-^H-'  Established Unestablished  >  Died  >  <i w  J—  1  M  W H  Killed  05  Holco H ^ 3 - J  if*  cnCJI-o  CJI  M ^ a o i^toco  oi i—•  (r^  t-  W  h- if*  tP*  to O  1  63.5 64,2 64.0  62.0 H  O if* CO  56.2  57.0  67.5 67.9 66.4  Mean No. Days  torf*1—'  No. Female Mean N o . Days  M lO CJI  No. Male Mean No. Days  -O  I—  1  -O  if>'  No. Female  21.0 33.8  18.8 18.4  14.0  21.7  Mean No. Days  92  .ADULTS  M  Ho. Male  20.2 21.1  •  H  to tO tO  tO  22.5 if*  Died  18 .-5 ' 18.1 17.7  tO  to  63 ;0 66;2 66. 6  if*  1  P U P A E  CJI CJI  Diapause  64.0 65.9 64.-2  M  Unaccounted  W O O fD Pi CD H>  cd Cd tx)  CO CQ CQ  CO p . CD  p3 p . CO  rf*rf*to  if* cn ui a w » O H iD UI O  O ID 00  OJ 03 H rf* CO CO CO H Oi O M UI  if* co co  CO  01  M H 0-N3-3  CO  CO • OJ CO CO CO O CO  Type and Food  o> Q I m H-> if* O  emergence  W M W 03 if* UI  ^ Ol « CO O -O  Established  criH-'oi  torf*O J  Unestablished  M CO Ol  H-rf*Ol  Died  1  rf* H-  I—' M  OJ Oi to  1  rf* 01  cn  cnrf*Ol  H- H-" UI H «  H-'M  rf* H- OJ  co -o cn  1  1  CQ CO Hi <<  Killed  O H>  Unaccounted  <+ g"  Diapause  |X> CD 03 H-  ti H CW  Died  cd  cO  UI H Ui M • O  to Co cn  kr) hrj hrj CB P> CD H>  «  cn rf* Ol CD • • O 03  Ol cn Cn 01 H -<3 -3  • • •  H- O rf* 1  No. Male  H M H cn Oi if*  Mean No. Days  1  CDrf*CO  H-" ^ COrf*Ol  H- H Oi CO CO  No. Female  UI o> on O J CD O  S en<3 cn Ol  cn  Mean No. Days  • • • O cn to  W H  U  f I •if* cn • •co O O OJ 1-1  - 1  H~0  1  CO  oi O -3  -O  Mrf*Ol  CD  i= Hc+  1  en cn -<J rf* -O H. . . CO CO cn 1  Ol ft) H-" CD  OJ  O CO CD  No. Male  co Ol OJ  co to to O H K l O OJ o  Mean No. Days  CD  CQ c+ 05 c+  O H HH rf*  -<J Ol o  isO c!  |__J  | I  cOrf*CO  CDrf*rf*  OJ  co co  H M H -<] to -o  H CO CO co cn cn Ol Ol UI  CO CO to M H O  Ol Ol Ol  -L2-  Oi Ol O  No. Female  tr  1  02  Mean No. Days  H> CD CD c+  TABLE VI Mean Days of Development from Emergence from Hibernation to Adulthood 1951  S P R U C E  Food Stat ion  Station  I  II  Station I I I  One-year Trinity T&lley Male Female No. Days No. Days  BUD? 0 R M  T Y P E  A N D  0 R I G I N  One-year Bolean Male Female No. Days No. Days  Ontario -Bolean Male Female No. Days No. Days  Sprue e D. f i r Abi es  12 13 21  60. 6' 11 60.1 22 60.5 15  62.4 63.2 62.8  10 16 12  60.3 61.7 61.1  12 9 10  61.1 64.4 62.9  2 12 13  60.5 56.5 54.7  4 11 3  62.2 59.3 55.6  Sprue e D. f i r Abies  15 9  85.1 85. 6  4 12  87.5 86.4  2 21 9  82.0 82.1 80.7  12 7  85.1 85.4  2  82.0  4  78.2  Spruce D.' f i r Abies  8 18 10  97.6 89.5 84.9  3 13 13  87.5 91.8 90.3  4 4 8  91.5 94.0 82.5  3 1 3  3  92. 6'  11 "78.2  60.6 81.0 66.0  2 4 8  68,0 90.7 72.8  Two-year Bolean Male Female No. Days No. Days 2  55.5  1  71.0  Cd  ^  H « ^  ^  Ml-' H HH H HH H > « CO "3  •<] O  fcrj  Cn Cn CJ> O O O  h=f taj  H  H H CO >"j  J» 0  ->3 O O O  0 1 <T>  Type and Food  Emerged  u irf*cn B cn O  Established  CP H rf* ui cn o  H H co if* o  Unestablished  H CO 63 H U Cf> ^3 ->3 • H H H  Died  OJ  CO  Hrf*H  Killed  H I—  -H H H <o <T>  Ul UD co  Unaccounted  H rf* CO H  H  H  Male  rf* CO <J  H  H  Female  1  1  H CO CO  H  H  H CO H (P-  H Cfl  H H H H H U (Jl Urf*rf*-CO-  cn -a co  51.2 58; 7 51.9  54.3 58.8 50.5  53; 5 Ul  03  CO rf*>  Days No'. Female  64,2 61.8 56.1  54.0 58.4 53.5  55.0  H H CO CJ1  H Cfl •• H  I—' H cn tp> •• O O  H H M cnrf*rf* Days . . . CO cn Ol  Ul  Cn <3 CO  Ulrf*CP  11.4  15.0 12.8 14.3  11.0 11.7 14.2  Days  67.1  0 70.2 64.7  72.3 72.1 67.1  Total Mean Days MALE  66.4  69.0 71,2 67.8  73.6 75.4 70.4  (D © ID  o p o  H H> CO Ul O CO P  Total Mean Days FEMALE  *<1 CD CO  CO  P Pi O  p >-l H-  o 4  No. Male  No. Female  CO I  d05  A D U L T S  -62  H-  Days  H CO  O P  H P c+  Died No. Male  %  cr P  P U P A E  H H H  co  i-3 55  Diapause  tD  L A R V A E  rf* cn cn cn cn Cflrf*O  CD CO  P H c+ CO  <!  H H  cd  bj  H  Hxj hx)  H  P  t—* 1—* }—"  H  H  H  P  *j ^ m  M M  hg  Jo O CO  €  M  Jt> O CO  Type and Food  if* if* 03 O O Ol  cn cn cn  if* CJl  to N M •o ro o i  Oltoif* tO N I H  Established  M  H  03 M CO 03 tO  Unestablis hed  Ol  co  H  03 CO Cn  M  M  co  H  Oi Cd  CO  M  03 -<1  if*  A  Ol  cn  Died  Male  03  Female  -3 03  M  if*  M  CO  M  CO 03 cn  M  ?  I- 1  O  P  o  M H> tO Ol o  CO p CD  No. Male Days  I  a  No. Female  CD  4 fed  Days  16,7  tO 03 CO M O "<3 » »• . 03 Ol if*  Days  90.3  89.5  CO  104.4 110.0 94.2  88.2  98.5  -07-  <<i CD 03  cn ., cn  M  o  p  P  Died  No. Female  o  c+ H*  M CO ct  CD  Days  O  co  03  Total Mean Days MALE Total Mean Days FEMALE  P P> O P c+ (B 4 O 4 CD CO  >  tO  C+  i-3  No. Male  03  CO  M M  CO  M  CO to Ol  to  >  Unaccounted  if*  CT>  > O  Killed  cn  20.1  • 22.5  H  Emerged  apau  to  M  79.5 83.0 73.1  CQ  1  o  w  75.0 81.0 71.7  if*  oo. u  70.4 i—  M  Ol to W  71 P.  54.8 if*  O  CO CO  if*  H  O  M  03  cn if* 01  cn  H  if*  H  CO H O  O  M  H O  03  tO  O  ci t-" t-3 CO  p M ct • CO  0 cd  <1  H M H  -41  Ontario-Bolean Larvae ( B ) . The data f o r the development p e r i o d of the Ontario-Bolean type are inadequate f o r d e f i n i t e a n a l y s i s , notably at Stations I I and I I I i n 1951, and due t o the low number a v a i l a b l e f o r r e a r i n g i n 1952. However, Table VI shows that at S t a t i o n I the food apparently had some e f f e c t on fir  the time f o r development w i t h a l p i n e  being the most favourable, followed by  Douglas f i r , w i t h spruce the l e a s t favourable. On  spruce the number of days taken was a p p r o x i -  mately the same as that f o r the one-year stock. On Douglas f i r and a l p i n e f i r the time was roughly f i v e days l e s s .  I n 1952 the time f o r the  Ontario-Bolean type on Douglas f i r was much the same as that taken f o r the one-year type on a l p i n e f i r . Comparing the time i n 1951 f o r the two female adults recovered from the two-year l a r v a e , w i t h the Ontario m a t e r i a l on a l p i n e f i r and Douglas f i r , shows that these are somewhat s i m i l a r .  -42-  One-yeax larvae Again, Table VI shows that at S t a t i o n I the d i f f e r e n c e s i n days f o r development "between foods and between types were s l i g h t .  An a n a l y s i s  of variance of the mean days f o r development f o r the two types was made, based on f i v e r e a r i n g j a r s on each of three foods f o r both sexes of the two types.  The mean f o r four j a r s was used  as a f i f t h i n the case of the male T r i n i t y V a l l e y type on spruce, and f o r a female on Douglas f i r i n the Bolean type.  The mean f o r three j a r s was  s u b s t i t u t e d f o r the m i s s i n g two i n the Bolean type on a l p i n e f i r . The a n a l y s i s showed that the d i f f e r e n c e s between the means f o r food and types were not s i g n i f i c a n t at the 5 per cent l e v e l .  The  d i f f e r e n c e f o r sex was s i g n i f i c a n t at 1 per cent. A f u r t h e r a n a l y s i s was done of the days f o r development of the two types at the three s t a t i o n s on  alpine f i r . This host was chosen as having  -43-  the best d i s t r i b u t i o n of a d u l t s , n e c e s s i t a t i n g s u b s t i t u t i o n of means i n only three cases. The analysis  showed that the d i f f e r e n c e s due to  sex were h i g h l y s i g n i f i c a n t and those due t o s t a t i o n were s i g n i f i c a n t at the 5 per cent l e v e l . The  i n t e r a c t i o n s of type and s t a t i o n were  s i g n i f i c a n t at the 5 per cent l e v e l .  The  d i f f e r e n c e s due to type were not s i g n i f i c a n t . The r e s u l t s f o r the other foods are e r r a t i c and somewhat c o n t r a d i c t o r y . This may be due t o the small numbers of i n d i v i d u a l s i n some cases and to the f a c t that the larvae were being reared i n an environment d i f f e r i n g from t h e i r natural  one. The d a t a f o r 1952 are not adequate f o r  a n a l y s i s but i n s p e c t i o n of the days f o r development as given i n Tables V I I and V I I I suggest that the P - j ^ type developed more q u i c k l y than the F^. I t i s suggested that a d i e t of a l p i n e f i r favoured more r a p i d development.  -44-  Two-year l a r y a e . Because of the very few recovered from t h i s type, no regarding drawn. The  adults  conclusions  the period of development can  he  s i g n i f i c a n t f a c t i s established  that some i n d i v i d u a l s  of the two-year l i f e  cycle type can develop i n one year. The two-year larvae completed t h e i r l i f e cycle i n 1952  and were bred.  worthy data were obtained  No note-  on t h e i r development  as i t proved impossible to t r a c e the development of i n d i v i d u a l s as emergence was several days i n the s p r i n g .  spread over  The main object i n  r e a r i n g t h i s type i n 1952 was to obtain progeny for use i n  1953.  Comparison of S t a t i o n s . In comparing the e n t i r e r e s u l t s from the three s t a t i o n s , i t i s evident that development was markedly f a s t e r at S t a t i o n I than at  -45-  S t a t i o n s I I and I I I "but the l a t t e r two showed very l i t t l e d i f f e r e n c e .  I n an attempt t o evaluate  these d i f f e r e n c e s the means f o r the sexes at each s t a t i o n were c a l c u l a t e d , combining the d a t a f o r the four s t a t i o n s .  The f o l l o w i n g means were  obtained, Kale  Female  59.5 days  60.9 days  II  82.9 days  84.5 days  III  81.3 days  85.4 days  68.9 days  70.5 days  90.2 days  99.0 days  Station I 1951  1952  Station I III  Thus development at S t a t i o n I was f a s t e r by  about 23 days i n 1951 and 25 days i n 1952  than at S t a t i o n I I I .  S t a t i o n s I I and I I I were  p r a c t i c a l l y the same i n 1951.  - 4 6 -  Diapause The number of l a r v a e s u r v i v i n g i n diapause or t o pupation and the number and percentage of these entering diapause i s g i v e n by type,  food, and s t a t i o n i n Table IX  f o r 1951 and i n Table X for. 1952.  Table X I  presents the d a t a given i n Tables I I I , IV and V and Table X I I presents the data i n Tables V I I and V I I I i n condensed form showing the t o t a l number of l a r v a e reared and t h e i r f a t e expressed i n percentages.  TABLE DC Total number i n diapause or surviving to pupation and the percentage i n diapause i n 1951. Picea Sngelmanni  in Diapause  No. of Survivors  No. in Diapause  F D S B  29 26 43 6  1 6 43 0  3.4 23.1 100.0 0  39 32 65 26  0 3 63 0  •0 9.3 96.9 0  39 36 59 19  0 13 59 0  0 36.1 100.0 0  Station  II  F D S B  3 24 10  1 18 10  33.3 75.0 100.0  25 57 17 12  5 19 17 5  20; 0 33.3 100.0 41.6  21 25 32  0 4 31  0 8.0 96.8  Station III  F D S B  16 23 22 12  0 13 22 7  0 56.5 100.0 58.3  37 16 20 22  1 11 20 17  2.7 68.7 100.0 77.2  32 28 39 33  0 5 39 20  0 17.8 100.0 60.6  •  CO OJ •H  cd  •..  cd  O  PH  -H  % in Diapause  No. in 'Diapause  I  % in Diapause  No. of Survivors  Station  •  fa  Type  No. Of Survivors-  Abies lasiocarpa  —  —  Pseudotsuga taxifolia  TABLE X Total number i n diapause or surviving to pupation and the percentage i n diapause f o r one-year and Ontario types i n 1952.  Picea Engelmanni  Abies lasiocarpa  12  B  S  60 100  fo in Diapause  20 8  F  No. in Diapause  Station I I I  No. of Survivors  *1 lll l  B  23 38 23  2 16 5  8.7 42.1 21.7  25 26  3 7  12.0 26.9  12 14 27  8 14 3  66. 6 100 11.1  35 25  9 16  25.7 64.0-  0  20.0 28.5  in Diapause  4 2  F  f  20 7  F  No. in Diapause  I  No. of Survivors  in Diapause  Station  fo.  No. in Diapause  l lll l  Type  No. of Survivors  •  Pseudotsuga taxifolia  TABLE XL Rearing Results Condensed and Expressed as Percentage 1951 Fate of Larvae Established Failed to Establish Rearing Total Rearing History of No. Environment Parents 1 yr. B.C. Stock 150 Reared at T.V. 1 y r . B.C. Stock Station I Reared at Sta. I l l 151 . 2,500' 2 yr, B.C. & A l t a . Reared at Sta. I l l 207 1 yr. Ont. Reared 131 at Sta. I l l 1 yr. B.C. Reared 141 at T.V. Station II 1 .yr. B.C. Reared 206 at Sta. I l l 2 yr. B.C. Reared 150 4,200' at Sta. I l l 1 yr. Ont. Reared 36 at Sta. I l l 1 yr. B.C. Reared 175 at T.V. Station III 1 yr. B.C. Reared 124 at Sta. I l l .2 yr. B.C. Reared 153 at Sta. I l l 4,750' 1 yr. Ont. Reared 117 at Sta. I l l  Died A f t e r Established  Diapaused  Pupated As % Of . Larvae Establ.  No,  As $ Of Total  18.3  1  .33  26  20.8  22  15.9  7  4.0  165  48  36.6  32  38.5  0  0  0  51  39.0  28  19.9  64  56.5  6  4.2  5.3  43  30.4  37  18.0  63  37.2  41  19.9  24.3  65  31.5  47  31.-4  44  42.7  58  38.6  56.3  1  18  50.0  6  33.3  5  13.8  27.7  7  19.4  39  22.3  50  36,5  2  1.1  85  48.5  32  25.8  25. .27.2  29  12.0  31.-5  38  30,6  66  43.0  6  6.9  81  52.2  93.1  - 0  34  29.0  16  19.3  44.  37.6  53.0  23  No.  %  19  12.65  24  28  18.55  33  No.  .76  No.  i Of Total  106  70.7 49.0  14 .-6  17.6  75  79.7  95.0  2  1.46  .96  .53  0 19.6  TABLE XII Rearing Results, Condensed and Expressed as Percentages 195B  Fate of Larvae Established F a i l e d to . Establish Rearing Environment Station I  Station I I I  Rearing History of Parents 1 yr. B;C. Reared at Sta-, I 1 yr. B.C. Reared at Sta. I l l 1 yr. Ont. Reared at Sta. I 1 y r . B.C. Reared at Sta. I 1 yr. B.C. Reared at Sta. I l l 1 yr-. Ont. Reared at Sta. I  Total No. No.  Died A f t e r Established No.  lo  Diapaused No.  As % Of Total 4.7  Pupated As % Of Larvae Establ.  No.  % Of Total  5.6  59  21; 0  27.1  46  25.5  6  8.5  190  32  16.8  91  57.6  9  180  21  11.3  88  55; 3  " 25  70  24  34.2  23  50.0  5  7.1  180  60  33.3  53  44.1  29  16.1  24.1  38  21.1  115  51  44.3  17  26.5  38  33.0  59.3  9  7.8  58  13  22.4  18  40.0  3  5.1  6.6  24  41.7  • 13.8  • 10.8  -51  Ontario-Bolean type (B and B ^ ) . The diapause r e a c t i o n of the OntarioBolean type i n 1951 was d i f f e r e n t front both the one-year Bolean and the two-year type.  At  S t a t i o n I I I the m a j o r i t y of these i n s e c t s entered diapause.  As can be seen i n Table IX  food appeared t o be an i n f l u e n c e , Douglas f i r "being more favourable t o diapause than a l p i n e f i r or spruce. U n f o r t u n a t e l y , the d a t a f o r S t a t i o n I I are incomplete but from those a v a i l able i t i s seen that approximately 41 per cent went i n t o diapause.  At S t a t i o n I none of the l a r v a e  entered diapause* Because of the p a u c i t y of m a t e r i a l i t was not f e a s i b l e t o use three foods i n 1952. The behaviour of the i n s e c t s reared was cont r a d i c t o r y t o that of 1951 i n that a higher percentage (Table X I I ) entered diapause at S t a t i o n I than at S t a t i o n I I I .  Ho explanation of t h i s  anomaly i s offered other than t o s t r e s s the small number of l a r v a e i n v o l v e d .  The r e s u l t was  -52-  unexpected as i t was thought that "being the progeny of parents reared under oneyear conditions very few of the larvae would enter diapause.  One-year types* T r i n i t y V a l l e y type (F and I^) Of the i n d i v i d u a l l y - r e a r e d l a r v a e at Station  I I I i n 1950, f i v e of the one-year l a r v a e  went i n t o diapause.  In 1951, at the three  s t a t i o n s , a t o t a l of eight one-year T r i n i t y V a l l e y l a r v a e entered diapause.  In 1952 a t o t a l  of 44 l a r v a e entered diapause, 15 at S t a t i o n I and 29 at S t a t i o n I I I .  The r e s u l t s f o r S t a t i o n  I I I (Table X ) , i n d i c a t e that a l p i n e f i r tended to reduce the percentage entering diapause. was not apparent at S t a t i o n I .  This  The e f f e c t of  the higher e l e v a t i o n i n i n c r e a s i n g diapause i s demonstrated* Bolean type (D and  P-^^)  As w i l l be seen from Table IX i n d i v i d u a l s of  the one-year Bolean type entered diapause  -53-  at a l l s t a t i o n s and on a l l foods i n 1951. An a n a l y s i s of variance was made t o determine the e f f e c t of foods and s t a t i o n s and t h e i r interactions. used. on  The means of f i v e j a r s were  At S t a t i o n I I , w i t h s i x j a r s a v a i l a b l e  spruce and a l p i n e f i r , one was d i s c a r d e d  from each.  I n "both cases these were of the same  value as another j a r used i n the c a l c u l a t i o n . There were nine j a r s a v a i l a b l e f o r Douglas  fir.  In t h i s case the odd numbered ones were used. The c a l c u l a t i o n s were based on the percentage of l a r v a e not going i n t o diapause.  This device  was used t o reduce the number of zeroes. I t was shown that the d i f f e r e n c e s between the means f o r S t a t i o n s were s i g n i f i c a n t at the 5 per cent l e v e l , and those f o r Poods at the 1 per cent l e v e l . The mean percentages not entering diapause f o r s t a t i o n s and food are given  below.  The mean d i f f e r e n c e required f o r  s i g n i f i c a n c e was c a l c u l a t e d and i s shown below.  -54STATIOHS  I  FOODS  MEAN DIFFERENCE  80.08^  II  61.24%  III  51.22%  alpine " f i r Douglas f i r spxuce  76.50^ 63.23$ 46.81%  at 5 per cent  18.75$  at 1 per cent  25.30$  Thus i n the case of s t a t i o n s the d i f f e r e n c e between I and I I i s s i g n i f i c a n t a t 5 per cent, hut the d i f f e r e n c e between I I and I I I i s not s i g n i f i c a n t . The d i f f e r e n c e between I and I I I i s s i g n i f i c a n t at 1 p e r cent. I t was shown that alpine f i r and spruce d i f f e r e d s i g n i f i c a n t l y at 1 per cent but a l p i n e f i r and Douglas f i r d i d not d i f f e r s i g n i f i c a n t l y neither d i d Douglas f i r and spruce. The f a c t that a l p i n e f i r markedly reduced t h e  -55-  percentage of diapausing larvae i s somewhat anomalous, as i t i s one of the foods on which the two-year cycle l a r v a e normally feed. Douglas f i r , the host commonly supporting a one-year c y c l e p o p u l a t i o n showed a higher percentage of diapausing l a r v a e than d i d spruce, hut the d i f f e r e n c e was not s i g n i f i c a n t . Due t o the uneven s u r v i v a l i n the r e a r i n g j a r s i n 1952, s t a t i s t i c a l analyses of the data have not been undertaken.  Inspection  of Table X, however, shows that the r e s u l t s obtained i n 1951 are v e r i f i e d w i t h a higher percentage of larvae entering diapause at the higher eleva/tion and a d i e t of alpine f i r reducing the number i n diapause at both s t a t i o n s .  Comparison of the one-year types R e f e r r i n g t o Tables I X and X i t i s apparent that the l a r v a e (D and Fixi) whose  -56-  parents had "been reared at S t a t i o n I I I i n 1950 and S t a t i o n I I i n 1951 went i n t o diapause i n considerably greater numbers than d i d those and 3?i) whose parents had been reared at T r i n i t y Valley i n 1950 or Station I i n 1951. In each case the two stocks were overwintered under the same c o n d i t i o n s .  In the r e a r -  ing experiments they were t r e a t e d i d e n t i c a l l y . The only d i s s i m i l a r i t y l i e s i n the treatment of the parents. The matings of the T r i n i t y V a l l e y (p) type were made from J u l y 1 3 t o 26, 1950, w h i l e those f o r the Bolean (D) type were made from August 3 1 t o September 5, 1950.  These l a t t e r averaged 75.1 days  f o r males and 76.2 days f o r females f o r development from emergence t o adulthood. The one-year type reared i n cages at S t a t i o n I i n 1950 took 52.5 and 52.8 days f o r development f o r males and females:  these matured from J u l y 1 2 to 2 1 .  Thus  the dates o f e c l o s i o n f o r the T r i n i t y V a l l e y (p) type and those reared at S t a t i o n I are roughly comparable.  I t i s assumed that the days f o r  development are s i m i l a r l y  comparable.  57  Then the development p e r i o d f o r the parents of the Bolean (D) type was 25 and 24 days longer than f o r the T r i n i t y V a l l e y (F) type. The parents of the ^  type averaged  60.4 days f o r males and 62.8 days f o r females at S t a t i o n I i n 1951. The parents of the  'FjU.  type averaged 85.3 days f o r males and 86.8 days f o r females at S t a t i o n I I . Thus the development p e r i o d f o r the  parents was 24 and 25 days  longer than that of the jF-^ parents. This shows t h a t prolonging the development  p e r i o d of the parents by about 24 days has  a profound e f f e c t on the a b i l i t y of the l a r v a e t o enter diapause.  Comparison of 1951 and 1952 r e s u l t s of oneyear types. The percentage of l a r v a e entering diapause i n 1952 was higher than that found i n 1951.  One  f a c t o r c o n t r i b u t i n g to t h i s d i f f e r e n c e may be the  -58-  longer development p e r i o d of the parents of the 1952 l a r v a e than of the 1951 m a t e r i a l . This d i f f e r e n c e i s about 8 days, the p e r i o d being approximately 52 days i n 1950 and 60 days i n 1951 at T r i n i t y V a l l e y and S t a t i o n I r e s p e c t i v e l y , and 75 days i n 1950 and 84 days i n 1951 at Stations I I I and I I r e s p e c t i v e l y . There was a f u r t h e r increase i n 1952 w i t h a mean  f o r S t a t i o n I of 70 days and f o r S t a t i o n  I I I of 95 days. Another f a c t o r may be the weather c o n d i t i o n s occurring p r i o r t o the larvae entering diapause.  An examination of the d a i l y  mean temperatures (Appendix B) shows that at S t a t i o n I i n 1952, the mean d a i l y temperature f e l l from 59.6°F on June 9 t o 41.8°F on June 12. There was no s i m i l a r change i n 1951 (Appendix A) during t h i s p e r i o d . The l a r v a e at S t a t i o n I entered diapause from June 24 t o J u l y 14 approximately.  Thus there was a drop, w i t h i n three days  -59-  of 18° I? i n the mean temperature roughly 12 days before the appearance of diapause.  A  second depression, from J u l y 5 t o 5 from  61.60]?  t o 45.2° I , i n 1952, corresponds t o one i n 1  1951 of 10° F d i f f e r e n c e between 66.1° F f o r J u l y 3 and 56.8° F f o r J u l y 4. At S t a t i o n I I I i n 1952 from J u l y 3 to 5, the mean f e l l from 55.89 F t o 38.00F, or 17.8° F i n two days.  The s i m i l a r d e c l i n e i n  1951 was from 57.5° F f o r J u l y 3 t o 45.1° F on J u l y 7, or a drop of 12° F over a period of 5 days. The l a r v a e at S t a t i o n I I I entered diapause from approximately J u l y 16 t o August 1.  Thus  there was, i n 1952, a drop of 17.8° F i n two days roughly 13 days before diapause was observed. The f a c t that at both s t a t i o n s there was a decrease i n the d a i l y mean temperature of 18° F, about 12 days before diapause was noted, could be a f a c t o r i n causing some l a r v a e t o enter diapause that would have developed i n one year i n the absence of t h i s stimulus.  -60DISCUSSIOl  One  o b j e c t i v e of t h i s p r o j e c t was  to determine the p o s s i b i l i t y of converting a population from the p o t e n t i a l l y h i g h l y destruct i v e one-year c y c l e t o the l e s s d e s t r u c t i v e twoyear cycle by changing the f o r e s t composition. The r e s u l t s , showing that food i s a minor f a c t o r , that Douglas f i r and spruce are equally  favour-  able foods, and that alpine f i r tends t o reduce diapause i n c e p t i o n , i n d i c a t e that i t would not be p o s s i b l e t o e f f e c t t h i s change. Some i n t e r e s t i n g observations may be made regarding diapause and the t h e o r i e s put forth  t o e x p l a i n i t s i n c e p t i o n on the b a s i s of  the l i f e c y c l e of the budworm.  One theory,  postulated by V. B. Wigglesworth (1948), i s that diapause i s due t o the absence of a growthpromoting hormone,  which c o n t r o l s m o l t i n g ,  secreted by neuro-secretory c e l l s i n the b r a i n .  -61-  T h i s theory i s substantiated "by the observation  that diapause occurs at the c l o s e of a  l a r v a l i n s t a r or i n the pupa, never i n t e r r u p t i n g a stage o f a c t i v e growth, and the completion of diapause i s followed by a l a r v a l molt or the beginning of the next stage i n metamorphosis. The budworm shows c o n t r a d i c t i o n s t o t h i s theory i n i t s h a b i t of m o l t i n g , from f i r s t to second, and t h i r d to f o u r t h i n s t a r .  While  i t i s d i f f i c u l t t o determine e x a c t l y when a l a r v a i s i n diapause, the cessation of feeding, the search f o r a sheltered niche, and the cons t r u c t i o n of a hibernaculum are behaviour patterns d e f i n i t e l y associated w i t h diapause. The molt i n the hibernaculum, f o l l o w i n g t h i s bahaviour pattern s t r o n g l y suggests that diapause can not be due to the absence of the hormone that controls molting. I f we ignore the associated behaviour p a t t e r n and assume that diapause begins a f t e r the  -62-  molt, then i t might he due t o the absence of the hormone and t h i s i s due i n t u r n t o complete u t i l i z a t i o n of the hormone i n the m o l t i n g process. However, i f t h i s were t r u e , then i t would be l o g i c a l to expect diapause a f t e r each molt i n the l i f e  of the l a r v a due t o d e p l e t i o n of the  hormone. Andrewartha (1952) has p o s t u l a t e d that diapause i s caused by the accumulation of a reserve of i n t r a c t a b l e food i n the fat-body or egg y o l k .  That the food supply i s not a v a i l a b l e  for metabolism may be due t o the q u a l i t y of the food reserve, t o the absence of a necessary enzyme system, or t o both, i s l e f t open f o r p h y s i o l o g i c a l determination. The i n t r a c t a b l e food supply, i t i s suggested, f a i l s t o stimulate the neuro-secretory c e l l s to produce the molting hormone, whose absence i n t u r n causes diapause.  The w r i t e r  has no information on the q u a l i t y or q u a n t i t y of the food reserves of the budworm l a r v a .  These  -63-  reserves could play a part i n the diapause r e a c t i o n hut i t may w e l l he a secondary one as t h i s experiment has shown that the maternal physiology has an important e f f e c t on the i n cidence of diapause i n the progeny which must he due to some substance c a r r i e d i n the c y t o plasm of the egg. This substance may be of, the nature of an enzyme system which acts d i r e c t l y t o cause diapause, or as a stimulus to  a t i s s u e which i n t u r n secretes a hormone  which causes diapause.  I t i s simpler t o t h i n k  of the i n t r a c t a b l e food supply as part of the diapause r e a c t i o n r a t h e r than as a causal l i n k i n the chain of events l e a d i n g t o diapause. The two-year l i f e c y c l e , occurring i n regions w i t h a r e l a t i v e l y short f r o s t - f r e e season and low d a i l y mean temperatures, permits the budworm t o r e g u l a r l y complete i t s l i f e c y c l e . The development of the l a r v a e i s arrested p r i o r t o the advent of cold weather by the i n t e r v e n t i o n  -64-  of  diapause and thus the danger of f r o s t -  k i l l i n g i s g r e a t l y reduced.  The f o l l o w i n g  s p r i n g the l a r v a e are small enough t o f i n d the developing "buds of the host t r e e s a s a t i s f a c t o r y food source, y e t are able t o complete t h e i r development i n time f o r the new generation of l a r v a e to enter diapause before being endangered by f r o s t . The evolutionary process leading t o the e s t a b l i s h ment o f two types o f population of the i n s e c t , each adapted t o i t s environment, i n v i t e s speculation. I f i t i s assumed that the one-year cycle i s p r i m i t i v e , the f o l l o w i n g explanation may be given: Consider a mountain slope with Douglas f i r growing at the lower e l e v a t i o n s , and the upper slope l e v e l i n g o f f i n t o a plateau w i t h spruce and  alpine f i r .  The budworm population on the  Douglas f i r has a one-year c y c l e . As t h i s p o p u l a t i o n reaches the l i m i t of i t s range a t the  -65-  upper e l e v a t i o n s , the retarded development of one generation w i l l cause some of the next t o adopt a two-year c y c l e . This c y c l e permits the m i g r a t i o n of the i n s e c t onto the plateau where the conditions are such that only the two-year c y c l e can survive due to the l a t e spring and e a r l y autumn f r o s t s .  A c o l d , wet summer may now i n t e r -  vene and e l i m i n a t e the one-year type from the t r a n s i t i o n zone.  Thus the two-year type i s  i s o l a t e d on the higher regions.  The i n d i v i d u a l s  adopting the two-year cycle i n an area favourable to "the one-year w i l l be eliminated probably by a combination of d e s i c c a t i o n and p r e d a t i o n , as they w i l l be i n t h e i r h i b e r n a c u l a from mid-July onwards and w i l l thus have t o withstand some of the h o t t e s t weather of the season, and also w i l l be a v a i l a b l e t o the s t i l l a c t i v e predators f o r at l e a s t two and p o s s i b l y three months.  As the  populations remain separate, s e l e c t i o n w i l l  favour  those i n d i v i d u a l s whose genetic c o n s t i t u t i o n predisposes them t o the appropriate l i f e c y c l e .  -66-  SIMMARY I n v e s t i g a t i o n s were c a r r i e d out t o determine the e f f e c t of e c o l o g i c a l f a c t o r s on the i n d u c t i o n of diapause and development i n the spruce "budworm. Experimental r e a r i n g s were conducted at e l e v a t i o n s of 2500, 4200 and 4750 f e e t i n 1951  and at 2500 and 4750 f e e t i n 1952.  The  f o l i a g e o f spruce, Douglas f i r and a l p i n e f i r was used as food. Progeny of Ontario, twoyear and  one-year types reared under one-year  and two-year c o n d i t i o n s , was used. Conclusions are drawn as t o the e f f e c t s of  the treatment o f the parents, food, a l t i t u d e  and weather on diapause i n the budworm l a r v a e and the e f f e c t s of food and a l t i t u d e on development. The growth-promoting hormone theory of diapause by Wigglesworth and the i n t r a c t a b l e food supply theory by Andrewartha are commented on.  The i m p r a c t i c a b i l i t y of converting a one-year c y c l e population of budworm to a two-year c y c l e i s shown. Speculation i s made as t o the probable cause of e v o l u t i o n l e a d i n g t o the establishment of a two-year cycle population.  •68-  COUCLUSIONS  A trend was noted i n emergence from h i b e r n a t i o n w i t h the one-year m a t e r i a l l e a d i n g , followed by the two-year and f i n a l l y the Ontario stock. The three types of l a r v a e can adopt the habit of mining needles i n the second instar. There was no s i g n i f i c a n t d i f f e r e n c e i n the time f o r development of the one-year types on the three foods at S t a t i o n I i n 1951. However, i t i s suggested by the data f o r 1951 and 1952 t h a t a l p i n e f i r favoured more r a p i d development i n the one-year and Ontario types than d i d spruce or Douglas f i r . Females took s i g n i f i c a n t l y longer than males t o develop. The d i f f e r e n c e i n time f o r development between S t a t i o n I I and I I I i n 19531 was not marked but these two d i f f e r e d from S t a t i o n I .  69-  Development at S t a t i o n I was f a s t e r by 23 days i n 1951 and by 25 days i n 1952 than at S t a t i o n III. On the b a s i s of three i n d i v i d u a l s i t i s seen that the two-year type can develop i n one year.  I t was shown i n 1951 and amply  v e r i f i e d i n 1952 that the one-year B r i t i s h Columbia and the Ontario type mayadopt the twoyear h a b i t . The e l e v a t i o n of the r e a r i n g s i t e i s a f a c t o r i n promoting diapause i n the one-year type. A d i e t of spruce or Douglas f i r i s more favourable t o diapause than one of a l p i n e f i r f o r the  one-year types. The i m p r a c t i c a b i l i t y of changing a one-  year cycle  population t o a two-year c y c l e by  f o r e s t management i s i n d i c a t e d . Prolonged development of the parents is  a major f a c t o r i n causing the one-year type  to adopt the two-year h a b i t .  -70-  The higher percentage of larvae entering diapause i n 1952 may he a t t r i b u t e d to a longer development period of the parents of the 1952 larvae or t o a drpp of 18° j i n the mean d a i l y temperature about 12 days p r i o r to the appearance of diapause, or t o a combinat i o n of these two f a c t o r s . The growth-promoting hormone theory of diapause, as p o s t u l a t e d by Wigglesworth, i s untenable f o r the budworm.  I t i s suggested  t h a t an enzyme, c a r r i e d over i n the cytoplasm of  the egg, i s more probable as a causal agent  than i s the i n t r a c t a b l e food supply suggested by  Andrewartha.  -71-  ACIOJ0¥JbEDGS£EinT S  Indebtedness  i s expressed to the  U n i t of Forest Zoology o f the Forest B i o l o g y D i v i s i o n . o f the Science Service of the Canada Department of A g r i c u l t u r e , of conducting the r e s e a r c h .  f o r the p r i v i l e g e Thanks are extended  to Mr. ¥. G. Mathers of Vernon f o r advice and encouragement throughout the work. Acknowledgment i s made t o D r . R. H. Handford of Kamloops and Dr. G. B• Oakland of Ottawa f o r o u t l i n i n g the s t a t i s t i c a l a n a l y s i s ; to Dr. S. G. Smith of Sault Ste. Marie f o r advice on experimental design and record keeping; and to Mr. T. F. Rutherford of V i c t o r i a f o r able assistance i n the f i e l d s t u d i e s . G r a t e f u l a p p r e c i a t i o n i s expressed by the author t o Dr. ¥. A. Clemens, P r o f e s s o r G.J. Spencer and Dr. Kenneth Graham of the Department of Zoology, U n i v e r s i t y of B r i t i s h Columbia, f o r t h e i r help and encouragement and f o r t h e i r v a l u a b l e c r i t i c i s m of the manuscript.  -72-  LITERATUHE CITED Andrewartha, H. G. 1952. Diapause i n r e l a t i o n to the ecology of. insects.. B i o l . Rev. 27: 50-107. Arhuthnot, K. D. 1944. S t r a i n s of the European corn borer i n the United States. U. S. Dept. Agr. Tech. B u i . 869: 1 - 2 0 . Atwood, C.E. 1944. The feeding h a b i t s of young spruce budworm l a r v a e . Can. Ent. 76: 64-66 Babcock, K. ¥. 1924. Environmental s t u d i e s on the European corn borer (Pyrausta n u b i l a l i s Hubn.). (Abstract) Jour.Ec on. Ent. 17: 120-125. Bodine, J . H. 1932. Hibernation and diapause i n c e r t a i n Orthoptera. I I I . D i a p a u s e — a theory of i t s mechanism. .Physiol. Z o o l . 5: 549-554. Bonnemaison, L. 1945. A r r e t s de development et diapauses. Ann. des E p i p h y t i e s (n.s.) 11: 19-56. Brown, A. W. A., and M. M• HcKay. 1943. The j a c k pine budworm and the spruce budworm Cacoecia fumiferana Can. Ent. 75: 207-211. Cousin, G.  1932. Etude experimental de l a diapause des i n s e c t s . B u i . B i o l , de l a Prance et B e l g . Sup 15: 1-341.  Dawson, R.¥. 1931. The problem of v o l t i n i s m and dormancy i n the polyphemus moth, ( f e l e a polyphemus Cramer). Jour. E x p t l . Z o o l . 59V  87-132'.  -73Dickson, R. C. 1949. Factors governing the i n d u c t i o n of diapause i n the o r i e n t a l f r u i t moth. Ann. E n t . Soc.Amer. 42: 511-537. F i f e , L. G. 1949. Studies of the diapause i n the pink bollworm i n Puerto R i c o . XJ. S. Dept. Agr. Tech. B u i . 977: 1-26. Graham, S. A. 1935. The spruce budworm- on Michigan' p i n e . U n i v . of Mich. School of For. and Cons. B u l l . Ho. 6. Lee, H. T.  1948. 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Chosen Is 1-26.  Way, M.J. and B • A. Hopkins. 1950. The i n f l u e n c e of photoperiod and temperature on the i n d u c t i o n of diapause i n D i a t a r a x i a o l e r a c e a L. (Lepidoptera). Jour. Exp. B i o l o g y 27: 365-374. Wigglesworth, V. B. 1948. The i n s e c t as a medium f o r the study of physiology. Proc. Roy. Soc. S e r i e s B. 135: 430-446. Wigglesworth, V. B. 1950. P r i n c i p l e s of i n s e c t physiology 4 t h ed. Methuen and Co. London.  75-  Williams, C M . 1946. P h y s i o l o g y of i n s e c t diapause: the r o l e of the b r a i n i n the p r o d u c t i o n and t e r m i n a t i o n of pupal dormancy i n the g i a n t silkworm P l a t y s a m i a c e r c o p i a B i o l . B u l l . 90:  234-245.  Williams, C M . 1947. P h y s i o l o g y of i n s e c t diapause: I I I n t e r a c t i o n between t h e pupal b r a i n and p r o t h o r a c i c glands i n the metamorphosis of t h e g i a n t s i l k worm P l a t y s a m i a c e c r o p i a B i o l . B u l l .  93: 89-98.  W i l l i a m s , C. M. 1948. P h y s i o l o g y of i n s e c t diapause: I I I The p r o t h o r a c i c glands i n the C e c r o p i a silkworm, w i t h s p e c i a l reference to t h e i r s i g n i f i c a n c e i n embryonic and postembryonic development. B i o l . B u l l . 94: 60-65. Williams, C M . and R. c. Sanborn. 1948. The cytochrome system i n r e l a t i o n t o diapause and development i n the C e c r o p i a silkworm Samia c e c r o p i a . B i o l . B u l l . 95: 282-283.  -76APPEWDIX A Wea t h e r  Re cords  STATION I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1951  DATE May  8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 June 1 2 3 4 5  MEAN DAILY TEMP.  MEAN DAILY R.H. DATE  56.04 55.1 57.5 54.8 42.5 47.1 54.3 55.3 58.0 50.5 47.6 49.1 54.8 57.0 62.8 56.3 46.8 50.3 51.6 52.3 41.3 41.0 41.5 47.6 48.6 52.3 47.6 50.8 47.8  54.64 June 55.0 46.5 52.3 83.0 63.0 52.6 53.0 47.0 55.6 56.6 48.8 44.3 46.0 39.5 46.5 47.1 35.0 44.1 35.3 66.1 66.6 53.8 44.6 41.6 54.1 J u l y 80.0 64.8 64.8  6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5  MEAN DAILY TEMP.  MEAN DAILY R.H.  43.8 51.6 56.1 56.3 56.3 57.1 58.5 58.3 62.5 58.0 53.8 55.3 50.0 53.0 48.8 50.1 55.1 53.0 55.3 57.3 59.5 54.5 59.0 61.6 61.6 57.8 62.6 66.1 56.8 56.0  75.1 65.1 48.8 47.3 52.8 54.1 55.0 55.6 50.1 34.8 45.3 53.3 77.1 49.3 65.3 63.5 62.3 71.6 52.3 48.3 31.3 40.1 39.8 36.1 62.3 75.0 53.0 43.0 64.3 61.1  4 Incomplete reoords  -77-  DATE 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Aag. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 July  MEAN DAILY TEMP. 52.0 51.1 54.6 59.0 58.1 62.6 69.6 68.6 65.1 68.3 69.5 69.6 69.1 60.1 55.8 61.5 66.3 70.5 67.5 69.6 66.6 69.3 70.1 68.8 67.1 66.1 66.1 71.0 70.5 68.5 60.0 61.0 60.3 64.1 64.6 67.0 61.1 57.0 57.6 51.OA 71.14  MEAH DAILY R.H.  MEAH DAILY TEMP.  MEAll DALLY R.H.  66.6 Aug.16 62.8 63.3 17 62.3 67.6 18 62.1 54.6 19 63.3 36.0 20 63.0 41.6 21 68.5 33.0 22 58.3 45.0 23 53.1 50.1 24 55.0 43.8 25 61.0 42.1 26 59.6 44.0 52.6 27 38.5 28 41.1 49.6 29 47.5 61.6 51.3 30 52.3 54.6 31 49.3 Sept. 1 55.3 32.6 2 55.8 43.6 55.3 3 43.5 56.8 4 43.6 5 57.8 27.3 59.8 6 30.8 7 60.0 4i.6 8 59.8 30.1 9 57.5 40.3 52.0 10 43.5 11 37.64 37.6 12 33.8 13 41.0 14 42.3 15 43.0 16 44.8 73.34 17 46.6 62.0 18 47.5 19 54.5 49.3 52.1 20 63.0 21 56.5 66.5 22 56.8 58.5 23 48.1 72.1 46.6 24 63.7 25 43.04 4 Incomplete records  63.1 60.0 38.0 38.0 37.0 35.04  DATE  29.54 35.5 41.3 48.5 85.1 81.0 78.8 68.6 64.3 67.04 74.24 30.34 50.8 47.8 55.1 47.5 52.5 46.8 78.14 mmmm-mwm  _  ~mm mm  mmmm**  —  25.34 39.8 48.3 44.0 46.3 68.5 87.1 85.34  -78-  STATION I I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1951  DATE May  8 9 10 11 12 13 14 15 16 17 18 19 20 21 82 23 24 25 26 27 28 29 30 31  June 1 2 3 4 5 6 7 8 9 10 11 12  MEAN DAILY TEMP.  MEAN DAILY R.H.  DATE  46*34 50.3 55.1 57.0 35.8 40.6 47.3 50.5 51.5 46.0 41.1 45.1 49.6 55.1 60.0 51.0 40.6 42.8 45.6 46.6 35.3 34.8 38*3 44.1 47.8 48.6 42.6 45.6 45.3 39.1 44.3 49.3 50.6 53.1 53.0 52.0  79*04 69.1 60.5 64.5 89.3 81.8 72.5 63.6 66.6 68.6 74.1 65.1 60.1 56.8 52.0 64.5 68*0 61.6 62.5 55.3 80.0 82.0 66.0 56.3 55.0 63.8 86.1 76.0 66.3 82.0 83.6 70.3 66.6 66.8 70.6 74.6  J u n e  4  July  13  14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30  1  2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17  MEAN DAILY TEMP.  MEAN DAILY  52.3 56.8 51.6 51.6 50.5 47.3 47.8 46.6 49.3 50.5 48.1 50.3 54.3 52.1 49.8 55.1 58.3 55.1 53.6 58.0 61.0 52.5 53.8 47.3 47.0 50.6 54.5 56.3 60.8 65.6 64.5 59.3 61.8 61*6 66.5  75.8 69.0 56.3 59.6 68.8 80.8 68.6 71.6 70.3 74.8 82.5 66.0 65.1 38.1 63.0 53.3 55.6 75.5 78.0 68.1 63.0 79.6 75.3 81.5 81.1 82.8 70.8 55.8 56.1 56.5 63.8 69.0 68.1 68.5 61.0  Incomplete records  R.H.  -79-  MEAN DAILY R.H.  H E O ,  DATE J u l y 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Aug. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21  DAILY TEMP.  61.8 67.3 74.8 69.1 62.6 50.8 62.0 66.5 63.8 48.5 54.0 65.0 64.8 69.6 58.6 54.1 57.5 63.0 70.5 67.5 67.0 69.6 70.8 70.0 76.5 78.0 79.3 77.1 70.5 62.8 60.5 58.5 59.6 55.3 51*6  60.5 53.0 49.5 54.6 61.5 64.3 63.0 62.6 60.8 62.1 63.1 60.8 61.1 61.0 62.6 66*0 63.6 61.0 52.5 54.1 56.5 59.0 58.6 62.0 58.0 52.3 51.6 50.54 54.64 64 .#4 57.4 57.6 59.0 60.5 66.5 4  DATE Aug.22 23 24 25 26 27 28 29 30 31 Sept. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25  MEAN DAILY TEMP.  MEAN DAILY R.H.  51.6 47.3 52.6 56.3 54.8 47.3 43.3 46.0 46.3 50.6 50.6 50.6 50.8 55.1 56.6 61.1 54.8 52.3 53.8 45.0 44*3 49.6 52.1 55.1 58.6 60.3 61*1 61.1 48.0 46.6 52.5 52.5 45.5 43.8 41*0  72.8 75.8 65.5 61.3 62.3 72.3 86.3 85.0 82.8 81.5 79.0 69.6 66.1 62.8 62.3 59.6 68*6 74.3 65.3 72.6 70.0 70.8 63.8 64.3 62.0 63.6 59*1 55.1 62.3 68.8 61.1 72.0 77*0 88*1 82*6  Incomplete records  -80 STATION I I I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1951  DATE May 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Jane 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17  MEAN DAILY TEMP. 51.04  44.5 40.5 40.6  47.0  42.5 46.0 49.6 43.8 37.1 39.3 41.3 42.3 32.8 32.8 35.8 39.1 41.6 43.0 40.3 42.3 40.3 37.0 42.1 46.5 46.1 41.3 46.8 50.1 49.5 53.3 49.6 47.8 48.1 4  MEAN DAILY R.H. 64.6 55.6 62.0 58.3 56.8 52.0 50.6 46.5 52.0  48.1 46.1 42.6 56.6 70.1 56.0  47.0 45.5 53.8 66.0 61.5 52.6 55.0 63.1 56.6 45.5 45.1 46.1 50.3 56.5 51.1 36.1 40.1 64.8  DATE  MEAN DAILY TEMP.  June 18 44.6 19 45.8 20 43.5 21 45.8 22 48.5 23 46.5 24 48.8 25 51.0 26 49.5 27 48.3 28 51.0 29 53.6 30 53.0 July 1 51.0 2 55.0 3 57.5 4 51.1 5 51.5 .6 45.8 7 45.1 8 49.3 9 51.5 10 52.1 11 57.5 12 61.6 13 61.6 14 57.5 15 59.1 16 58.8 17 62.1 18 58.8 19 53.0 20 47.3 21 51.0  Inoomplete records  MEAN DAILY R.H. 84.5 59.1 69.0 65.6 68.0 77.5 50.6 57.1 46.6 45.8 48.1 45.3 76.5 82.3 68.6 59.8 76.1 74.1 80.3 76.8 79.6 66.3 47.1 48.3 52.0 53.6 64.3 61.1 61.0 55.8 53.0 67.3 71.8 69.1  -81-  DATE  MEAN DAILY TEMP.  MEAN DAILY R.H.  J u l y 22 23 24 25 26 27 28 29 30 31 Aug. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23  58.0 62.0 58.1 59.0 57.5 59.3 60.3 59.1 58.0 57.3 58.3 61.3 59.8 57.6 48.8 50.6 52.3 54.8 54.3 56.3 54.3 49.0 49.1 50.5 61.5 53.1 50.8 52.3 53.6 53.6 59.0 49.1 44.6  61.6 45.24 60.1 60.6 57.3 38.3 44.0 56.8 46.0 52.0 60.0 50.6 48.6 58.3 69.8 63.6 63.6 66.0 64.0 68.3 79.0 80.0 89.7 81.2 68.0 57.5 58.6 61.3 56.0 59.0 50.3 75.3 80.8  DATE  MEAN DAILY TEMP.  MEAN DAILY R.H.  Aug.24 25 26 27 28 29 30 31 Sept. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25  47.3 51.6 51.6 43.6 42.3 43.1 44.3 47.3 47.3 45.5 46.5 47.6 49.0 50.5 50.6 47*6 47.1 41.6 39.6 46.1 45.3 46.0 49.6 52.3 53.5 54.0 46.8 41.8 46.5 45.8 41.0 41.3 37.24  60.6 60.6 63.1 74.8 81.8 86.0 86.1 81.5 83.0 75.3 74.0 69.0 66.0 64.6 70.3 77.6 69.5 76.2 71.1 70.3 68.3 68.3 63.6 65.0 64.0 60.0 49.0 68.0 63.3 69.8 86.1 92.5 90.04  Incomplete records  -82  APPENDIX B Weather  Records  STATION I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1952  DATE May  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31  June 1 2 3 4 5 6 7  MEAN DAILY TEMP.  MEAN DAILY• R.H. DATE  46.5 49.5 53.8 55.0 52.5 52.3 46.3 46.3 52.1 45.6ft  41.0 36.6 48.8 52.0 68.6 54.8 81.1 70.5 60.6 77.04  —  —  -  June  _  6 2 . 3S 72.44 54.8 48.6 46.8 47.8 40.0 38.5 61.1 62.1 50.6 50.5 62.8 67.0 45.3 50.6 66.5 47.6 38.0 36.0  56.34 48.54 51.3 51.6 52.1 56.3 57.8 55.6 56.0 50.6 45.6 46.5 48.3 51.0 54.5 53.3 54.5 56.1  59.8  53.3  4  July  8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7  8 9  MEAN DAILY TEMP.  MEAN DAILY R.H.  55.3 59.6 51.0 45.6 41.8 46.3 50.6 52.5 45.8 48.3 53.5 59.3 56.3 49.3 45.6 51.0 57.5 59.3 56.3 58.0 56.0 53.3 52.5 53.1 54.5 61.6 60.6 45.3 49.6 58.6 65.5 69.1  42.6 43.5 68.0 70.6 84.3 52.8 49.1 40.5 74.5 66.5 60.0 39.8 54.6 59.1 81.0 68.6 59.6 64.3 70.6 71.8 81.3 74.3 70j5 55.8 55.1 53.6  Incomplete records  50.8  70.6 60.3 49.8 48.8 44.3  -83  DATS  MEAN DAILY TEMP.  MEAN DAILY R.H.  J u l y 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Aug. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19  69.0 67.3 63.3 66.6 72.3 69.6 60.8 59.1 57.5 60.5 55.1 51.8 50.8 61.6 51.8 58.3 63.6 67.6 65.1 68.6 69.6 71.3 69.6 66.8 68.5 70.5 73.3 69.1 65.0 65.5 71.3 71.8 68.0 69.5 73.6 68.5 61.6 57.6 59.6 62.0 58.5  Aug. 20 61.1 35.6 41.6 21 60.3 36.5 22 54.5 44.6 23 56.8 48.2* 24 50.1 28.74 25 49.0 49.8 26 51.3 61.3 27 51.0 66.5 28 52.3 55.0 29 50*3 56.6 30 49.8 65.0 31 54.0 67.1 Sept. 1 57.1 85.5 2 60.1 75.5 3 63.3 56.3 4 52.5 60.3 5 54.1 37.0 6 58.6 47.6 7 49.5 44.8 8 50.8 36.3 9 50.3 30.6 10 51.1 36.3 11 50.1 37.1 12 48.0 44.1 13 47.3 43.3 14 49.3 15 55.5 22.34 43.8 16 53.3 59.1 17 60.3 58.3 18 58.8 44.6 19 57.3 42.3 20 53.1 46.5 21 57.6 41.5 22 59.0 39.5 23 60.0 41.5 24 60.6 25 63.3 50.5 55.5 26 61.0 56.1 27 55.1 39.5 28 52.3 52.3 29 57.0  DATE  MEAN DAILY TEMP. :  £ Incomplete re cords  MEAN DAILY R.H. 48.6 48.1 79.3 42.3 64.8 79.5 60.1 55.0 55.8 55.8 55.1 53.6 44.1 50.1 33.8 42.5 43.0 42.6 42.6 45.8 62.8 59.0 56.1 66.6 50.5 49.8 45.8 50.1 49.8 64.1 52.6 52.6 51.8 50.6 47.5 38.0 36.5 40.8 47.6 64.3 51.6  -84-  DATE  MEAN£ DAILY TEMP.  MEAN DAILY R.H.  Sept.30 Oct. 1 2 3 4 5 6  58.3 51.5 51.6 50.3 45.6 47.6 50.8  44.6 58.3 57.3 35.1 42.0 48.5 51.0  MEAN DAILY TEMP.  DATE Oot.  7 8 9  10 11 12 13  51.8 53.5 52.8 49.0 52.3 51.3 45.1  MEAN DAILY R.H. 45.1 43.6 49.5 58.0 51.8 59.3 46.8  -85APPENDIX B Weather  Records  STATION I I I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1952  DATE May 21 22 23 24 25 26 27 28 29 30 31 June 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21  \  MEAN DAILY TEMP.  MEAN DAILY R.H.  40.6 41.3  84.3 75.8 73.1 71.5 64.3 57.0 65.3 80.5 81.8 72.0 81.8 75.8 69.5 67.6 85.5 69.6 63.5 61.5 61.0 58.8 80.0 79.6 90.0 79.3 69.5 69.0 88.1 79.6 69.5 61.3 74.3 79.5  39.8  46.5 47.1 48.0 49.5 46.1 37.5 41.5 43.1 44.5 49.1 49.0 46.1 48.0 50.5 45.3 49.3 54.3 43.5 40.8 35.3 38.1 44.8 44.6 37.1 40.6 45.8 51.5 48.3 41.6  DATE  MEAN DAILY TEMP.  MEAN DAILY R.H.  June 22 23 24 25 26 27 28 29 30 July 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23  38.8 43.0 49.6 51.5 49.5 52.6 50.6 47.1 44.3 45.0 46.5 55.8 52.6 38.0 43.0 52.0 60.8 63.1 62.5 58.3 56.5 60.0 63.6 60.6 52.5 48.6 50.6 52.6 45.5 43.3 44.8 46.3  89.1 86.3 76.5 81.3 85.0 81.8 88.5 85.8 84.1 78.8 75.6 71.8 73.0 83.8 75.3 67.8 65.5 60.8 52.5 62.3 63.1 61.6 60.5 53.1 70.6 80.6 78.0 73.3 80.3 83.3 84.0 88.8  -86-  DATE  MEAN DAILY TEMP.  J u l y 24 25 26 27 28 29 30 31 Aug. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24  44.8 50.0 55.8 54.6 56.8 61.5 61.1 63.1 60.0 58.6 60.0 62.8 63.6 59.1 55.1 56.3 60.6 59.6 59.3 60.5 62.6 56.6 51.6 47.3 51.5 50.8 48.3 50.6 51.1 48.3 47.5 43.0  MEAN , DAILY R.H. DATE Aug. 25 87.3 73.5 26 61.0 27 69.1 28 70.6 29 63.3 30 60.8 31 65.0 Sept . 1 61.0 2 62.0 3 66.3 4 63.3 5 58.6 6 68.6 7 77.5 8 9 8o.i : 70.0 10 69.5 11 68.5 12 64.3 13 63.0 14 68.3 15 74.5 16 79.0 17 72.1 18 66.0 19 74.6 20 69.6 21 71.6 22 85.1 23 71.3 24 25 86.0  MEAN DAILY TEMP.  MEAN DAILY R.H.  41.6 43.6 44.5 46.3 40.8 43.6 45.0 48.5 51.5 53.6 42.0 45.5 47.5 38.5 40.5 43.1 41.3 42.0 39.3 38.6 42.1 47.1 46.5 48.6 51.8 46.6 46.0 49.3 50.5 53.3 52.8 57.5  87.3 83.0 79.3 74.3 83.3 78.6 77.5 74.3 73.5 62.6 71.6 66.0 73.3 72.1 78.0 80.5 81.8 81.1 80.0 70.6 75.1 69.0 73.8 71.0 80.1 76.5 78.1 73.8 73.6 68.1 66.3 58.5  -87  MEAN DAILY TEMP.  MEAN DAILY R.H.  DATE  Sept.86 53.1 27 45.5 28 44.3 29 48.5 30 48.0 Oct. 1 44.1 2.46.6 3 41.3 4 39.0  68.8 76.5 85.5 76.6 73.1 83.1 76.5 61.1 71.1  Oct. 5 42.6 6 45.6 7 50.6 8 48.5 9 47.0 10 40.6 11 44.1 12 43.0 13 39.0  DATE  MEAN DAILY BEMP.  MEAN DAILY R.H. 73.8 68.6 59.3 71.0 71.5 83.8 77.5 75.0 72.0  

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