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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 o f Zoology. Ve accept t h i s thesis as conforming to the standard required from candidates f o r the degree of MASTER OF ARTS. Members of the Department of THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1955. I ABSTRACT Investigations were carried out to determine the effect of ecological factors on the induction of diapause i n the spruce budworm. Experimental rearings were conducted at elevations of 2500, 4200 and 4750 feet. The foliage 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 cycle conditions were used as experimental insects. A trend was observed i n emergence from hibernation with the one-year type leading, followed by the two-year and f i n a l l y the Ontario type • It was shown that the one-year type larvae may adopt the two-year habit. The main factor influencing t h i s i s a prolonged develop-ment period f o r the parents. The larvae reared at the higher elevations showed a greater proportion 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 alpine f i r . The increased percentage of larvae i n diapause i n 1952 i s attributed to a longer development period f o r t h e i r parents and to a sharp drop i n temperature occurring about 12 days p r i o r to diapause. The Ontario material may adopt the two-year habit. The factors contributing to t h i s have not been c l e a r l y shown as the rearing resul t s are inconclusive. There were no d e f i n i t e differences shown i n the time f o r development among the three foods. The insects at the lowest station i developed i n approximately three weeks less time than at the highest. The difference between the upper stations was s l i g h t . The i m p r a c t i c a b i l i t y of converting a one-year l i f e cycle population to a two-year cycle by forest management i s noted. I l l The diapause theories of Wiggles-worth and Andrewartha are commented on. A possible course of evolution leading 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) Autointoxication 7 (b) Diapause fa c t o r or hormone. 8 B Termination of diapause 11 Conditions a f f e c t i n g inception 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 larvae (B) ......41 One-year larvae .42 Two-year larvae ... ....44 Comparison of stations. 44 Diapause ....••••••••••••.«••••....••46 Ontario-Bolean type (B & Bi)....51 One-year types ...52 T r i n i t y Valley 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 •. •. • ......... • ... .66 Conclusions ... • ••••• 68 Acknowledgments .71 Literature cited 72 Appendic A Weather records 1951 «76 B Weather records 1952 82 VI INDEX TO TABLES TABLE I Dates f o r "beginning of emergence from hibernation 1951 29 TABLE I I Dates f o r beginning of emergence from hibernation 1952 .. 29 TABLE I I I Summary of rearing r e s u l t s , Station I - 2500 feet 1951 35 TABLE IV Summary of rearing r e s u l t s , Station I I - 4200 feet 1951 36 T A B L E V Summary of rearing r e s u l t s , Station I I I - 4750 feet 1951 37 TABLE VI Mean days from emergence from hibernation to adulthood 1951... 38 TABLE VII Station I - Tabulation of one-year and Ontario results...1952. 39 TABLE V I I I Station I I I - Tabulation of one-year and Ontario r e s u l t s 1952... 40 TABLE IX Total number i n diapause or sur-v i v i n g to pupation and the percentage i n diapause i n 1951.. 47 TABLE X Total number i n diapause or sur-v i v i n g to pupation and the percentage i n diapause i n 1952.. 48 TABLE XI Rearing resul 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 INTRODUCTION Diapause i s defined "by Wiggles-worth (1950) as a spontaneous arrest of development which, supervenes irrespective of the environmental conditions. 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 rule r i g i d l y f i x e d . In d i f f e r e n t insect species i t exerts i t s effect under various circumstances "but usually once the in d i v i d u a l has entered diapause i t has to remain i n that state for a certain period, regardless of the conditions of the environment. Insects i n diapause are characterized by a low metabolic rate, greatly diminished act-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 to survive unfavourable environments. They do not respond immediately to any ordinary amelioration of the external -2 conditions, as do insects 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 to certain required conditions, such as. cold, f o r a given period. Diapause plays a major role 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 north almost to the l i m i t of timber. I t extends down the Appala-? chian Mountains to V i r g i n i a i n the Eastern 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 entire range of i t s food plants. Spruce and balsam are the preferred food plants over the greater part of the range of the spruce budworm. In north-western Ontario and the Lake States a form that prefers 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 hosts. In Eastern America, the adults 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 within two to f i v e days. The eggs hatch i n nine to twelve days. The young larvae f i n d a sheltered niche, spin a cocoon or hlbernaculum, molt to the second i n s t a r and overwinter i n diapause. The following spring the larvae emerge from t h e i r hibernacula, coincident with or a few days "before the balsam buds open. This i s generally i n l a t e A p r i l or early Jiay. A large percentage of the young larvae form mines i n the old needles i n spring before attacking the new buds. Afte 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 period of about ten days, emerge as adults. 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 outlined f o r the eastern insects. The dates vary con-siderably due to l o c a l differences i n climate but i n general, the period of a c t i v i t y i s May, June and July* On the other hand, i n the spruce-balsam forests on the high plateaux of central and southern B r i t i s h Columbia, and extending into the north-western States and i n the spruce-balsam forests of the Rocky Mountains,, the spruce budworm has a two-year l i f e cycle. This was noted and studied f i r s t by Mathers {1922) i n the B a r k e r v i l l e d i s t r i c t . In t h i s case the larvae emerge from hibernation about the middle of June and develop slowly u n t i l the middle or l a t t e r part of July when, s t i l l i n the t h i r d i n s t a r , they spin hibernacula, molt to the fourth i n s t a r and enter diapause and overwinter again. The following spring, feeding i s resumed about the middle of June and adulthood reached by the l a t t e r part of J u l y . The pupal period i s approximately three weeks and the incubation period i s about the same length of time. Because of the synchronization of the development of the population there are small, inconspicuous larvae one year while the next year the larvae are large and feeding voraciously. The two-year l i f e cycle, with heavy feeding only i n alternate years, renders the insect much l e s s destructive than i t i s i n a one-year cycle area. It i s apparent that, i f by forest management or other means, the one-year cycle could be changed to a two-year cycle the depredations of t h i s insect would be greatly reduced. The crux of the problem l i e s i n the diapause intervening at the close of the t h i r d and the beginning of the fourth i n s t a r i n the two-year cycle. The determination of the factors 6 -causing this diapause is a necessary pre-liminary step "before any practical measure may be undertaken. By observation i t is known that the one-year type is 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 insects i s extensive. 3Por comprehensive bibliographies the reader i s referred to Uvarov (1931), Prebble (1941), Bonnemaison (1945), Dickson (1949), Wigglesworth (1950) and Andrewartha (1952). The write 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 basis of the suggested mechanisms, and the ecological conditions a f f e c t i n g d i a -pause. Suggested Mechanisms: A Inception of diapause -(a) Autointoxication - the theory of autointoxication was developed by Roubaud (1922) f working with L u c i l i a s e r i c a t a Meig., who postulated that autointoxication i s caused by the accumulation of metabolic wastes which b u i l d -8-up faster than they can he eliminated during active growth, so that a period of rest i s needed to allow elimination to catch up. This work has "been discredited 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 factor 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 factor (X factor) present i n the diapause type egg of that species at the time the eggs are l a i d . I f these eggs are held at comparatively high temperatures, the amount or potency of the d i a -pause factor increases u n t i l i t passes a threshold at the "three-weeks" stage and stops embryonic development. The diapause factor i s gradually dissipated a f t e r t h i s point and eventually allows development to resume. Exposure to low temperature at any time, either before or a f t e r the "three-weeks" stage, rapidly destroys the diapause f a c t o r , and development i -9-resumes as soon as the temperature i s r a i s e d . This theory was extended "by Salt (1947) working with the wheat stem sawfly Ceuhus cinctus Ebrt. He speculated that diapause i n t h i s species i s controlled not only "by an X factor as defined by Bodine, but also by a Y fa c t o r , which breaks down more slowly than does the X factor but at a constant rate, regardless of temperature. He was able to reinstate diapause by exposure to r e l a t i v e l y high temperatures (35°C) at any time before the Y factor was eliminated. Wigglesworth (1948) believes that diapause i s due to the absence of a growth-promoting hoimone which controls molting, secreted by the neuro-secretory c e l l s of the brain. He speculates that the raw materials for the hoimone i n Rhodnius may be vitamins produced by the symbiotic bacterium Actinomyces  rhodnii harboured i n the gut of the insect. •10. Way and Hopkins (1950) consider i t probable that 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 rather than the presence of an i n h i b i t i n g hormone. This 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 interruption of the normal processes of develop-ment by a f a i l u r e of the brain to supply a non-species-specific factor necessary f o r adult d i f f e r e n t i a t i o n . The causal agent f o r the i n h i b i t i o n of the hormone secretion has been postulated by Andrewartha (1952) to be a n accumulation of an intractable food reserve occurring i n the egg-yolk or, i n post-embryonic stages, i n the fat body, which may not be immediately broken down i n preparation for the next stage i n morphogenesis. -11 This intractable food reserve may be due to an unbalance i n the metabolism such that the building-up processes go on normally but the breaking-down processes are reduced to a minimum. Whether t h i s unbalance i s to be attributed to 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 physiological studies. B. Termination Recent experiments (Williams. 1946, 1947, 1948 and Williams and Sanborn 1948, Pappenheimer and Williams 1952) have shown the brain to be the organ of primary control over diapause i n pupae of Platysamia cecropia. I t was found, by implantation techniques, that the termination of diapause requires the action of a minimum of two factors, one a r i s i n g from the brain and the other from the prothoracic glands (Lee 1948). The brain factor i s necessary -12-for the a c t i v a t i o n of the prothoracic 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 period when development i s dependent on the prothoracic glands, the concentration of cytochrome c increases from less than 1 to more than 50 gamma per l i v e weight. S i m i l a r l y during the period of the "brain's secretory a c t i v i t y , the t i t r e of cyto-chrome oxidase increases from approximately 40 to nearly 700 u n i t s . As a result of the combined functions of both the brain and pro-thoracic glands, the tissues of the dormant pupa, for the f i r s t time, come into possession of a complete cytochrome system. Conditions affecting inception of diapause A Environment. The environmental factors 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 subjecting the l a s t l a r v a l stadium to declining 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 tempera-tures favours entry into diapause as f u l l - f e d larvae. (b) Food and water. Food and water are closely related i n insect dietary as most of the water taken by insects occurs in the food. The condition of the food has been found to influence the induc-t i o n of diapause. Squire (1940) reported that diapause of the f u l l - f e d larvae of the pink bollworm, Pectinophora gossypiella (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 effect 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 controlled by temperature and d a i l y exposure to l i g h t during the l a r v a l feeding period. 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 increases, reach-ing 100 per cent with about twelve hours of l i g h t . As the photoperiod i s increased to more than thirteen hours per day, the percentage of diapause drops suddenly to p r a c t i c a l l y zero. Way and Hopkins (1950) showed that the induction of diapause i n the pupa of -15 -Diataraxia oleracea L. i s influenced by temperature and photoperiod during the l a r v a l stage, with low temperatures and short photoperiods tending to induce d i a -pause while high temperatures and long photoperiods tend to 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 insect species which have but one generation per year, with a con-siderable part of each year spent i n diapause. This behaviour pattern may w e l l be gene t i c a l l y f i x e d . The diapause occurring i n second in s t a r larvae of the spruce budworm f a l l s i n t h i s category. In discussing the effect of inheritance on diapause, Dickson (1949) reviews two notable -16 cases as follows: "A few insect species are known i n which there are both single-genera-t i o n strains (univoltine) and mult i p l e -generation strains ( 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 univo 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. M u l t i v o l t i n e strains have two to several 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 inheritance of voltinism i n the silkworm i s somewhat complex, there being some evidence for somatic inheritance from the mother. I t i s reported by Uyema (1926) that i f the ovaries from an in d i v i d u a l of one race are transplanted to an in 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 voltinism of the moth i n which they are grown rather than that of t h e i r true ancestors. -17 -The l i k e l i h o o d that a given hatch of eggs w i l l enter diapause i s also influenced by the temperature at which the eggs and larvae of the preceding generation were held." 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 larvae, i t i s well known that some areas are occupied by one-generation s t r a i n s and others by two-generation s t r a i n s . Babcock (1924) reported that when specimens of the one-generation s t r a i n were transferred to an area occupied by the two-generation s t r a i n , and v i c e versa, they persisted i n retaining 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 for multiple generations, while i n Ohio i t i s mixed, containing factors f o r both single and multiple generations. He was able to -18 -is o l a t e a homozygous single-generation:strain from the Ohio population, and found that the genetic factors responsible f o r the single generation are recessive. O'Kane and Lowry (1927), working with t h i s insect i n New Hamp-shire , showed that although the population was homozygous for multiple generations, only a part of them actually went through two generations per year, the rest 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 that hatched after a certain date, usually about July 20 to 25, entered diapause and so had only one annual generation. Apparently, environmental factors are involved i n the i n -duction of diapause i n t h i s species, at least i n the multiple-generation 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 different strains within the species, with respect to the inherent tend-ency towards diapause or continued development. The population in the southern areas has two or more annual generations while the population in northern areas i s composed of a strain having one annual generation, diapause inter-vening after a single generation even under favourable environmental conditions. -20-PROCEDURE The present investigation was primarily designed to determine the effects of environmental conditions and food on diapause and secondarily to ascertain the effects of these factors on development of the hudwoim. Preliminary work on t h i s project was started at L i l l o o e t , B.-C, i n 1949. The "basic plan was to introduce two-year type larvae into a one-year area with rearings made at d i f f e r e n t elevations. From t h i s i t was hoped to determine the approximate conditions under which diapause occurred. As there were no laboratory-reared insects available, reliance was placed on f i e l d -collected larvae. Due to delays the l o c a l one-year larvae were well advanced before rearing could be begun. Larvae of the two-year form were collected at Bolean Lake, near Falkland, B^ C , by Mr. V. . G. Mathers, and at Castle Mountain, Alberta, by Dr. E. Graham on June 21 and sent to -21 L i l l o o e t . These larvae entered diapause between June 28 and July 5 although very hot weather prevailed at that time. This indicated that the factors producing the diapause were operative early i n the l a r v a l stage, i f not i n the preceding generation. In 195G, studies were carried out from a camp at Bolean Lake, situated at an elevation of 4750 feet i n the alpine f i r -Engelmann spruce forest type. There i s a high endemic population of two-year spruce budworm i n t h i s l o c a l i t y . Three rearing stations were used, located as follows: Station I (2500 feet) i n a t y p i c a l Douglas f i r - y e l l o w pine forest type. Station I I (4200 feet) i n a t r a n s i t i o n zone with a mixture of Douglas f i r , Engelmann spruce and alpine f i r . Station I I I (4750 feet) i n a t y p i c a l Engelmamn spruce-alpine f i r forest type. One-year stock, progeny of adults mated at L i l l o o e t , two-year material which had -22-entered diapause at 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 Station I , spruce and alpine f i r at Station I I I and on a l l three hosts at Station I I , and i n v i a l s on the same foods at Station, I I I . Prom these studies i t was found that food i s not a major factor i n the i n i t i a t i o n of diapause. Some individuals of the one-year type entered diapause i n the v i a l s . Also on the basis of one specimen i t was seen that Ontario one-year material may be induced to take two years to develop. Following the findings of Uyema (1926) and the indications 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 effect on the diapause of the progeny. I t was arranged i n 1950 to hare matings made of one-year adults at the T r i n i t y Valley P i e l d Station (2100 feet elevation). The -23-moths were from forest 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 series provided larvae whose parents had matured under one-year conditions. Matings were also made at Bole an Lake (4750 feet elevation), of two-year, Ontario and one-year stock from the material reared there. This series provided larvae whose parents had matured under two-year conditions. The r e s u l t i n g larvae, from both breeding s e r i e s , were overwintered i n v i a l s at T r i n i t y Valley. Thus i n 1951, the following types of larvae were on hand. Each type was given a code l e t t e r f o r convenience i n record-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 cycle from B. C. (F) progeny of f i e l d - c o l l e c t e d larvae reared at T r i n i t y V a l l e y . One-year l i f e cycle from Ontario (B) progeny of "budworm reared at Bole an Lake. V i a l s containing the overwintering larvae were d i s t r i b u t e d among the three stations •...on Hay 18, so that at each st a t i o n there was a supply of each type of l a r v a . As the larvae became active they were transferred to s i x -ounce j e l l y j a r s , with taped-on tops. Ten larvae, i n the majority of cases, were placed i n each j a r with s u f f i c i e n t foliage to support the feeding of that number. A series of four or fiv e jars of each type of la r v a was reared on each of the three hosts, spruce (Picea Engelmanni Parry.), Douglas f i r (Pseudotsuga t a x i f o l i a (Poir.) B r i t t e n ) , and alpine f i r (Abies l a s i o -carpa (Hook.) Nutt). As a means of reducing possible v a r i a t i o n due to food source foli a g e was taken from Stati. on I I to feed the insects at Stations I and I I I . -25-feed the insects at Stations I and I I I . Breeding was carried out again as the insects reached maturity i n 1951. D i f f i c u l t y was experienced i n obtaining hibernating larvae of the Ontario type at Stations I I and I I I so that none was available f o r rearing 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 Station I I I but s u f f i c i e n t numbers were obtained from Station I I . The second in s t a r larvae from the breeding program, and those larvae i n the fourth i n s t a r diapause were overwintered at T r i n i t y Valley. Thus, the experimental larvae on hand f o r the 1952 season consisted of the following, coded as indicated. Two-year cycle from B. C. (s) progeny of budworm reared at Bolean Lake (4750 feet) i n 1950, overwintering i n the fourth i n s t a r from 1951. -26-One-year cycle from B.C. (D) progeny of budworm reared at Bole an Lake (4750 feet) i n 1950 and overwintering i n the fourth i n s t a r from 1951. One-year cycle from B. G. (F) progeny of f i e l d -collected larvae reared at T r i n i t y Valley (2150 feet) i n 1950 and overwintering i n the fourth i n s t a r from 1951. One-year cycle from B• C. (Pi) progeny of F material reared and bred at Station I (2500 feet) i n 1951. One-year cycle from B. 0. (.F^) progeny of F material reared at Station I I (4200 feet) i n 1951. One-year cycle from Ont. (B) progeny of budworm reared at Bolean Lake (4750 feet) i n 1950 and overwintering i n the fourth i n s t a r from 1951. One-year cycle from Ont. (B^) progeny of B material reared and bred at Station I (2500 feet) i n 1951. As the analysis of the 1951 res u l t s showed that Station I I was almost a duplicate of Station I I I , i t was decided to eliminate Station I I from the 1952 program. The o r i g i n a l designa-tions f o r Stations I and I I I were retained. The -27-second year larvae from Station I I were placed at Station I I I to complete t h e i r development. The rearing technique used was the same as i n 1951 except that when the larvae were available s i x jars were used for each series. -28-RESULTS Emergence. The overwintering larvae were placed i n the f i e l d on May 18 i n 1951 and on May 19 i n 1952. The following tables (I and II) give the dates for the f i r s t emergence f o r each type at each station f or the two years. The date f o r the f i r s t emergence i s used as the great majority of the one-year larvae emerged on that day. The emergence of the second instar two-year type was extended over approximately f i v e days. In Table I i n two instances tvro dates are given and explained below. The coding i s as given above. -29-TABLE I Dates f o r beginning of emergence from hibernation 1951. 1 yx.B.C. l y r . B.C. 2 yr.B.C 1 yr.Ont. Station reared at reared at reared at reared at TV. Sta. I l l S t a . I l l Sta. I l l E D S B I May 20 May 20 May 22 May 22 I I May 22 May 22 May 26 June 4 I I I May 22 & 26 May 26 May 31 May June 22 & 4 TABLE I I Dates for beginning of emergence from hibernation 1952. Second instar • Fourth i n s t a r Station F , B, :E D • B S 1 l x j l 1 : I May 20 May 21 May 24 :May 26 May 26 — May : 22 I I I May 22 May 22 May 30 :May 29 May May May : 28 29 26 -30-In Table I i t i s seen that the one-year cycle larvae came out together at the three stations. The two-year larvae were l a t e r i n each case, appearing at the same date as the Ontario-Bole an material at Station I. At Station I I the Ontario-Bolean material was l a t e r than the two-year larvae. At Station I I I a few Ontario-Bolean larvae came out on May 22, hut the onset of a period of cold weather delayed the main emergence u n t i l June 4. The same thing happened to the one-year T r i n i t y Valley type, hut i n t h i s case emergence was resumed on May 26. In 1952 (Table II) there was very l i t t l e difference between the dates f o r Stations I and I I I . This was due probably to the insects being on the verge of emergence when they were removed from storage. The Ontario type larvae, 31-as i n 1951, were the l a s t to emerge of the second i n s t a r larvae at "both stations. The fourth i n s t a r one-year type larvae were appreciably l a t e r than the second i n s t a r at both stations. 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 with the one-year material leading, followed by two-year and f i n a l l y the Ontario stock. Feeding. The larvae re a d i l y accepted the three foods offered. Atwood (1944), i n Ontario, 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 Biology 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 larvae on the same host at Heart Lake i n 1951 by -32-J . Grant. In t h i s experiment, individuals of a l l stocks mined needles of the three hosts at a l l stations i n 1951 and 1952. Development. The results of the rearing are summarised and tabulated by Stations and year (Tables I I I , IV, V, VI f o r 1951; Tables V I I , VIII f o r 1952). In these tables the f i r s t column gives the type and food. The code for types i s as given on pages 23 to 24 and 25 to 26 while the foods are coded as follows: spruce — s, Douglas f i r -- df, alpine f i r — a. The second column "emerged" shows the number of larvae 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 to feed successfully. "Unestablished" are those that f a i l e d to feed successfully and died. The "died" column gives the number of 33-larvae that died after establishment. "Killed** gives those that were accidentally k i l l e d while the food was being changed i n the j a r . "Unaccounted" includes those larvae that disappeared: many of these were i n the early in s t a r s and probably represented dead larvae 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 of specimens of each sex, and the mean number of days from the time of emergence to pupation are found. Under "adults" the number of each sex and the mean number of days from pupation to adulthood are given. In Tables VII and VIII the t o t a l mean days for development from emergence to maturity i s given. These figures are given i n Table VI -34-for the 1951 r e s u l t s . This mean development period i s f o r the individuals 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 m ft w CD o a t ) CD P. CD H> hr) hrj he) P Pi CO Hi Type and Food if* if* Ui O O M -a -o l — 1 cn cn o UI if* Ol O CO CO if* Ol UI cD O H Emerged w.w ^3 cn 01 to cn cn H cn •f* rf* cd UI O CO if* rf* W Ol <0 O Established M CO if* Ol CD l -1 H O O M O) 1—1 UI CD rf* M if* 1—1 rf* line sta b l i shed > < W tO CO rf* Oi u « CO W CO Died > CO W CO CO M W M CO H CO CO Killed . h-1 CO rf* CO O CO if* W Ol if* Unaccounted ui cn to W if* CA U U (J) Diapause CP W O rf* H W if* Ol Died h-1 M rf* CO CO i — * 1—' 1—* CO CO O M H H CO W CO No. Male' tF* CJ1 ^ o> o • • H O Co ui a i if* O O cD • • • CO CO CO 48.4 48.5 49.0 Mean No, Days a Ol if* if* to M HJ M M M W 3^ cn cn No. Female if* if* Ol UI CO CP if* ui UI Ol Ol CO rf* H Ol Ul Ol W W CO Mean No. CD c n . O ai O ) W if> O W to Days h-1 H W CO to 1—• 1—• 1—' co cn o tO h-1 1—1 I—1 03 CO No. Male 1—1 1—1 1—' O O O • • • Ol Ol o 11.1 10.8 10.5 12.1 11.6 Mean No.. Days > cj t-l H ^ W H if* CO H 1—1 H CD CO H i e H Ol M H No. Female t-3 CQ I D ( D t O ' o O O CD 1—* 1——" 1—• O O M Mean No. W -<i CO o O CO ^ • . • cn W if* Days -32-CjJ GO CG CG W O W hrj hrj hij P< CO P J CO CD Pi CO ( B p . TO H> H> H> H j Type and Food w ui cn cn <£> cn w u i o i Cn O O O c n O O to M O Emerged H ; if> « co if» -a tf* w « ^  ' CD U 1 0 1 0 5 £». -<J 3^ U i O H Established H M H M H H ' M CO CJIOI-O H H c n W t D Unestablished > H I-1 H to (-* 01 H UI c n c n W CO -^H- ' Died <i > w J—1 M W H 05 K i l l e d if* cnCJI-o H o l c o H ^ 3 - J Unaccounted CJI M ^ a o i ^ t o c o oi i—• Diapause M CJI CJI (r^ t - 1 to Died PUPAE W h-1 if* tP* to O H Ho. Male PUPAE 64.0 65.9 64.-2 63.5 64,2 64.0 62.0 Mean No. Days PUPAE if* H O if* CO to rf* 1—' No. Female PUPAE 63 ;0 66;2 66. 6 67.5 67.9 66.4 57.0 56.2 Mean N o . Days PUPAE to M tO t O tO tO lO CJI No. Male .ADULTS 20.2 21.1 18 .-5 ' 18.1 17.7 22.5 Mean No. Days .ADULTS if* • M -O I—1 -O if>' No. Female .ADULTS 21.0 33.8 18.8 18.4 14.0 21.7 Mean No. Days .ADULTS 92 cd Cd tx) CO CQ CQ CO p. CD p3 p. CO W O O kr) hrj hrj fD Pi CD CB P> CD H> H> rf* rf* to if* cn ui a w 01 o> Q I m O ID 00 » O H iD UI O H-> if* O OJ 03 H rf* CO CO W M W ^ Ol « CO H Oi O M UI 03 if* UI CO O -O if* co co to Co cn criH-'oi to rf* OJ M CO Ol H-1 rf* Ol CO I—' M rf* H-1 OJ Oi to CO • rf* 01 cn cn rf* Ol M H OJ CO CO H-1 H-" 0-N3-3 CO O CO UI H « H-'M CO rf* H-1 OJ co -o cn UI H « Ol H M H cn Oi if* Ui cn rf* M Ol CD • • • O O 03 cn Cn 01 H -<3 -3 • • • H-1 O rf* en cn -<J rf* -O H-1 . . . CO CO cn CD rf* CO H-" ^  CO rf* Ol H-1 H Oi CO CO UI o> on OJ CD O S en cn <3 Ol • • • O cn to cn - O oi CO O -3 M rf* Ol W H U OJ O CO CD f 1 - 1 I - 1 if* cn co • • • O O OJ H-1 ~0 co Ol co to to O H K l OJ O OJ o cO rf* CO CD rf* rf* | _ _ J | I OJ co co H M H -<] to -o Ol Ol Ol H CO CO co cn cn CO CO to M H O Ol Ol UI Oi Ol O Type and Food emergence Established Unestablished Died Kil l e d Unaccounted Diapause Died No. Male Mean No. Days No. Female Mean No. Days No. Male Mean No. Days No. Female Mean No. Days is-O c! tr 1 02 CQ CO Hi << O H> <+ g" |X> CD 03 H -ti H CW cO Ol ft) H-" CD CD i= H-1 c+ CD CQ c+ 05 c+ O H HH rf* -<J Ol o H> CD CD c+ cd -L2-TABLE VI Mean Days of Development from Emergence from Hibernation to Adulthood 1951 S P R U C E B U D ? 0 R M T Y P E A N D 0 R I G I N One-year Trinity T&lley One-year Bolean Ontario -Bolean Two-year Bolean Male Female Male Female Male Female Male Female Food No. Days No. Days No. Days No. Days No. Days No. Days No. Days No. Days Stat ion I Sprue e 12 60. 6' 11 62.4 10 60.3 12 61.1 2 60.5 4 62.2 D. f i r 13 60.1 22 63.2 16 61.7 9 64.4 12 56.5 11 59.3 2 55.5 Abi es 21 60.5 15 62.8 12 61.1 10 62.9 13 54.7 3 55.6 Station II Sprue e 2 82.0 D. f i r 15 85.1 4 87.5 21 82.1 12 85.1 2 82.0 4 78.2 Abies 9 85. 6 12 86.4 9 80.7 7 85.4 1 71.0 Station III Spruce 8 97.6 3 87.5 3 92. 6' 4 91.5 3 60.6 2 68,0 D.' f i r 18 89.5 13 91.8 4 94.0 1 81.0 4 90.7 Abies 10 84.9 13 90.3 11 "78.2 8 82.5 3 66.0 8 72.8 Cd ^ ^ fcrj h=f taj H Ml-' H H H H « H H H J» 0 CO ^ H H H >"j > « CO "3 Type and Food •<] Cn Cn CJ> 01 <T> ->3 O O O O O O O Emerged LARVAE rf* cn cn cn ui rf* cn cn Cfl rf* O B cn O Established LARVAE CP H H H rf* ui cn o co if* o Unestablished LARVAE H CO 63 H U tD Cf> ^ 3 ->3 • H H H Died LARVAE OJ CO H rf* H K i l l e d LARVAE H -H H I—1 H <o <T> Ul UD co Unaccounted LARVAE H rf* CO H H H Male Diapause LARVAE rf* CO <J H 1 H Female Diapause LARVAE H H H H CO CO Diapause LARVAE H H H 03 CO H (P- Died PUPAE H H H H H H Cfl U (Jl U rf* rf*- CO- No. Male PUPAE 51.2 58; 7 51.9 54.3 58.8 50.5 53; 5 Days PUPAE Ul cn -a co CO rf*> No'. Female PUPAE 64,2 61.8 56.1 54.0 58.4 53.5 55.0 Days PUPAE H H H CO CO CJ1 ( D © I D No. Male ADULTS I—' H H M H H cn cn rf* rf* Cfl tp> •- . . . •• • O CO cn Ol H O Days ADULTS Ul Cn <3 CO Ul rf* CP No. Female ADULTS 11.0 11.7 14.2 15.0 12.8 14.3 11.4 Days ADULTS 72.3 72.1 67.1 0 70.2 64.7 67.1 Total Mean Days MALE 73.6 75.4 70.4 69.0 71,2 67.8 66.4 Total Mean Days FEMALE co % O P i-3 55 cr P H P c+ H-o p o H H> CO U l O CO P CO I *<1 CD CO CO P Pi O p d-05 >-l H-o 4 CD CO P H c+ CO <! H H -62 cd H € bj Hxj hx) H H P t—* 1—* }—" H H P Jo O CO *j ^  m M M M Jt> O CO hg Type and Food Ol co if* if* 03 O O Ol cn cn cn O O O Emerged if* CJl to N M •o ro oi Ol to if* tO N I H Established M H H tO 03 CO O 03 M CO 03 tO Unestablis hed > Cn M if* M M CO CO w Died O M H CO M K i l l e d > M co H Oi Cd 03 -<1 Unaccounted H O 03 if* M cn Male to if* 03 Female apau 03 H cn if* 01 M -3 03 ? CO CD CO Ol to W Died H O cn M if* M CO No. Male 54.8 71 P. 75.0 81.0 71.7 Days a H if* if* M CO 03 cn No. Female fed 70.4 CQ A oo. u 79.5 83.0 73.1 Days i — 1 o Ol M 03 No. Male • 22.5 H cn 20.1 Days > ci CT> if* CO to Ol No. Female t-" t-3 CO to cn ., cn 16,7 tO 03 CO M O "<3 » »• . 03 Ol if* Days 90.3 89.5 tO CO O o M Total Mean Days MALE 98.5 88.2 104.4 110.0 94.2 Total Mean Days FEMALE CO C+ co c + H * o p M M i-3 03 P M CO ct I- 1-O P o M H> tO Ol o CO p CD I <<i CD CD 4 03 P P> O P c+ (B 4 O 4 CD CO p M ct • CO 0 cd <1 H M H - 0 7 --41 Ontario-Bolean Larvae (B). The data f o r the development period of the Ontario-Bolean type are inadequate f o r d e f i n i t e analysis, notably at Stations I I and I I I i n 1951, and due to the low number available for rearing i n 1952. However, Table VI shows that at Station I the food apparently had some effect on the time f o r development with alpine f i r being the most favourable, followed by Douglas f i r , with spruce the least favourable. On spruce the number of days taken was approxi-mately the same as that f o r the one-year stock. On Douglas f i r and alpine f i r the time was roughly f i v e days l e s s . In 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 alpine f i r . Comparing the time i n 1951 f o r the two female adults recovered from the two-year larvae, with the Ontario material on alpine f i r and Douglas f i r , shows that these are some-what s i m i l a r . -42-One-yeax larvae Again, Table VI shows that at Station I the differences i n days f o r development "between foods and between types were s l i g h t . An analysis of variance of the mean days f o r development for the two types was made, based on f i v e rearing j a r s on each of three foods f o r both sexes of the two types. The mean f o r four jars was used as a f i f t h i n the case of the male T r i n i t y Valley type on spruce, and for a female on Douglas f i r i n the Bolean type. The mean f o r three ja r s was substituted for the missing two i n the Bolean type on alpine f i r . The analysis showed that the differences 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 difference f o r sex was s i g n i f i c a n t at 1 per cent. A further analysis was done of the days for development of the two types at the three stations 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 adults, necessitating substitution of means i n only three cases. The analysis showed that the differences due to sex were highly s i g n i f i c a n t and those due to st 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 interactions of type and station were s i g n i f i c a n t at the 5 per cent l e v e l . The differences due to type were not s i g n i f i c a n t . The results f o r the other foods are e r r a t i c and somewhat contradictory. This may be due to the small numbers of individuals i n some cases and to the fact 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 data f o r 1952 are not adequate f o r analysis but inspection of the days f o r develop-ment as given i n Tables VII and V I I I suggest that the P - j ^ type developed more quickly than the F^. I t i s suggested that a diet of alpine f i r favoured more rapid development. -44-Two-year laryae. Because of the very few adults recovered from t h i s type, no conclusions regarding the period of development can he drawn. The s i g n i f i c a n t fact i s established that some individuals 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. No note-worthy data were obtained on t h e i r development as i t proved impossible to trace the development of individuals as emergence was spread over several days i n the spring. The main object i n rearing t h i s type i n 1952 was to obtain progeny for use i n 1953. Comparison of Stations. In comparing the entire r e s u l t s from the three stations, i t i s evident that develop-ment was markedly f a s t e r at Station I than at -45-Stations I I and I I I "but the l a t t e r two showed very l i t t l e difference. In an attempt to evaluate these differences the means f o r the sexes at each station were calculated, combining the data for the four stations. The following means were obtained, Kale Female Station I 59.5 days 60.9 days 1951 I I 82.9 days 84.5 days I I I 81.3 days 85.4 days Station I 68.9 days 70.5 days 1952 I I I 90.2 days 99.0 days Thus development at Station I was faster by about 23 days i n 1951 and 25 days i n 1952 than at Station I I I . Stations 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 larvae surviving i n diapause or to pupation and the number and percentage of these entering diapause i s given by type, food, and sta t i o n i n Table IX for 1951 and i n Table X for. 1952. Table XI presents the data given i n Tables I I I , IV and V and Table XII presents the data i n Tables VII and V I I I i n condensed form showing the t o t a l number of larvae reared and t h e i r fate expressed i n percentages. TABLE DC Total number in diapause or surviving to pupation and the percentage in diapause in 1951. Picea Pseudotsuga Abies Sngelmanni ta x i f o l i a lasiocarpa • Type No. of Survivors — — No. in 'Diapause fa in Diapause No. of Survivors No. in Diapause % in Diapause No. Of Survivors-CO OJ • H cd PH • . . cd O - H % in Diapause Station I F 29 1 3.4 39 0 •0 39 0 0 D 26 6 23.1 32 3 9.3 36 13 36.1 S 43 43 100.0 65 63 96.9 59 59 100.0 B 6 0 0 26 0 0 19 0 0 Station II F 3 1 33.3 25 5 20; 0 21 0 0 D 24 18 75.0 57 19 33.3 25 4 8.0 S 10 10 100.0 17 17 100.0 32 31 96.8 B 12 5 41.6 Station III F 16 0 0 37 1 2.7 32 0 0 D • 23 13 56.5 16 11 68.7 28 5 17.8 S 22 22 100.0 20 20 100.0 39 39 100.0 B 12 7 58.3 22 17 77.2 33 20 60.6 TABLE X Total number in diapause or surviving to pupation and the per-centage i n diapause for one-year and Ontario types in 1952. Picea Pseudotsuga Abies Engelmanni taxi f o l i a lasiocarpa Type No. of Survivors No. in Diapause fo. in Diapause No. of Survivors No. in Diapause f 0 in Diapause • No. of Survivors No. in Diapause fo in Diapause Station I F l 20 4 20.0 23 2 8.7 25 3 12.0 F l l l 7 2 28.5 38 16 42.1 26 7 26.9 B l 23 5 21.7 Station I I I *1 20 12 60 12 8 66. 6 35 9 25.7 F l l l 8 S 100 14 14 100 25 16 64.0-B l 27 3 11.1 TABLE XL Rearing Results Condensed and Expressed as Percentage 1951 Fate of Larvae Established Failed to Establish Died After Es-tablished Diapaused Pupated Rearing Rearing History of Environment Parents Total No. No. % No. No, As $ Of Total As % Of . Larvae Establ. No. i Of Total Station I 2,500' 1 yr. B.C. Stock Reared at T.V. 150 19 12.65 24 18.3 1 .33 .76 106 70.7 1 yr. B.C. Stock Reared at Sta. I l l 151 . 28 18.55 26 20.8 22 14 .-6 17.6 75 49.0 2 yr, B.C. & Alta. Reared at Sta. I l l 207 33 15.9 7 4.0 165 79.7 95.0 2 .96 1 yr. Ont. Reared at Sta. I l l 131 48 36.6 32 38.5 0 0 0 51 39.0 Station II 4,200' 1 yr. B.C. Reared at T.V. 141 28 19.9 64 56.5 6 4.2 5.3 43 30.4 1 .yr. B.C. Reared at Sta. I l l 206 37 18.0 63 37.2 41 19.9 24.3 65 31.5 2 yr. B.C. Reared at Sta. I l l 150 47 31.-4 44 42.7 58 38.6 56.3 1 .53 1 yr. Ont. Reared at Sta. I l l 36 18 50.0 6 33.3 5 13.8 27.7 7 19.4 Station III 4,750' 1 yr. B.C. Reared at T.V. 175 39 22.3 50 36,5 2 1.1 1.46 85 48.5 1 yr. B.C. Reared at Sta. I l l 124 32 25.8 25. .27.2 29 12.0 31.-5 38 30,6 .2 yr. B.C. Reared at Sta. I l l 153 66 43.0 6 6.9 81 52.2 93.1 - 0 0 1 yr. Ont. Reared at Sta. I l l 117 34 29.0 16 19.3 44. 37.6 53.0 23 19.6 TABLE XII Rearing Results, Condensed and Expressed as Percentages 195B Fate of Larvae Established Failed to . Establish Died After Es-tablished Diapaused Pupated Rearing Rearing History of Environment Parents Total No. No. No. lo No. As % Of Total As % Of Larvae Establ. No. % Of Total Station I 1 yr. B;C. Reared at Sta-, I 190 32 16.8 91 57.6 9 4.7 5.6 59 21; 0 1 yr. B.C. Reared at Sta. I l l 180 21 11.3 88 55; 3 " 25 • 13.8 27.1 46 25.5 1 yr. Ont. Reared at Sta. I 70 24 34.2 23 50.0 5 7.1 • 10.8 6 8.5 Station III 1 yr. B.C. Reared at Sta. I 180 60 33.3 53 44.1 29 16.1 24.1 38 21.1 1 yr. B.C. Reared at Sta. I l l 115 51 44.3 17 26.5 38 33.0 59.3 9 7.8 1 yr-. Ont. Reared at Sta. I 58 13 22.4 18 40.0 3 5.1 6.6 24 41.7 - 5 1 Ontario-Bolean type (B and B^). The diapause reaction of the Ontario-Bolean 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 Station I I I the majority of these insects entered diapause. As can be seen i n Table IX food appeared to be an influence, Douglas f i r "being more favourable to diapause than alpine f i r or spruce. Unfortunately, the data f o r Station I I are incomplete but from those a v a i l -able i t i s seen that approximately 41 per cent went into diapause. At Station I none of the larvae entered diapause* Because of the paucity of material i t was not feasible to use three foods i n 1952. The behaviour of the insects reared was con-tr a d i c t o r y to that of 1951 i n that a higher per-centage (Table X I I ) entered diapause at Station I than at Station I I I . Ho explanation of t h i s anomaly i s offered other than to stress the small number of larvae involved. The result was -52-unexpected as i t was thought that "being the progeny of parents reared under one-year conditions very few of the larvae would enter diapause. One-year types* T r i n i t y Valley type (F and I^) Of the individually-reared larvae at Station I I I i n 1950, f i v e of the one-year larvae went into diapause. In 1951, at the three stations, a t o t a l of eight one-year T r i n i t y Valley larvae entered diapause. In 1952 a t o t a l of 44 larvae entered diapause, 15 at Station I and 29 at Station I I I . The r e s u l t s f o r Station I I I (Table X ) , indicate that alpine f i r tended to reduce the percentage entering diapause. This was not apparent at Station I . The effect of the higher elevation i n increasing 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 -uals of the one-year Bolean type entered diapause - 5 3 -at a l l stations and on a l l foods i n 1951. An analysis of variance was made to determine the effect of foods and stations and t h e i r i n teractions. The means of f i v e j a r s were used. At Station I I , with s i x j a r s available on spruce and alpine f i r , one was discarded from each. In "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 available f o r Douglas f i r . In t h i s case the odd numbered ones were used. The calculations were based on the percentage of larvae not going into diapause. This device was used to reduce the number of zeroes. I t was shown that the differences between the means f o r Stations 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 for stations and food are given below. The mean difference required f o r significance was calculated and i s shown below. -54-STATIOHS I 80.08^ I I 61.24% I I I 51.22% FOODS alpine " f i r 76.50^ Douglas f i r 63.23$ spxuce 46.81% MEAN DIFFERENCE at 5 per cent at 1 per cent Thus i n the case of stations the difference between I and I I i s s i g n i f i c a n t at 5 per cent, hut the difference between I I and I I I i s not s i g n i f i c a n t . The difference between I and I I I i s s i g n i f i c a n t at 1 per 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 alpine f i r and Douglas f i r did not d i f f e r s i g n i f i c a n t l y neither did Douglas f i r and spruce. The fact that alpine f i r markedly reduced the 18.75$ 25.30$ -55-percentage of diapausing larvae i s somewhat anomalous, as i t i s one of the foods on which the two-year cycle larvae normally feed. Douglas f i r , the host commonly supporting a one-year cycle population showed a higher per-centage of diapausing larvae than did spruce, hut the difference was not s i g n i f i c a n t . Due to the uneven su r v i v a l i n the rearing 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 with a higher percentage of larvae entering diapause at the higher eleva/tion and a diet of alpine f i r reducing the number i n diapause at both stations. Comparison of the one-year types Referring to Tables IX and X i t i s apparent that the larvae (D and Fixi) whose -56-parents had "been reared at Station I I I i n 1950 and Station I I i n 1951 went into diapause i n considerably greater numbers than did 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 over-wintered under the same conditions. In the rear-ing experiments they were treated 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 Valley (p) type were made from July 13 to 26, 1950, while those f o r the Bolean (D) type were made from August 31 to September 5, 1950. These l a t t e r averaged 75.1 days for males and 76.2 days f o r females f o r develop-ment from emergence to adulthood. The one-year type reared i n cages at Station I i n 1950 took 52.5 and 52.8 days f o r development for males and females: these matured from July 12 to 21. Thus the dates of eclosion f o r the T r i n i t y V alley (p) type and those reared at Station 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 period 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 Valley (F) type. The parents of the ^ type averaged 60.4 days f o r males and 62.8 days f o r females at Station 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 Station II. Thus the development period f o r the parents was 24 and 25 days longer than that of the j F - ^ parents. This shows that prolonging the develop-ment period of the parents by about 24 days has a profound effect on the a b i l i t y of the larvae to enter diapause. Comparison of 1951 and 1952 results of one-year types. The percentage of larvae entering diapause i n 1952 was higher than that found i n 1951. One factor contributing to t h i s difference may be the -58-longer development period of the parents of the 1952 larvae than of the 1951 material. This difference i s about 8 days, the period being approximately 52 days i n 1950 and 60 days i n 1951 at T r i n i t y Valley and Station I respectively, and 75 days i n 1950 and 84 days i n 1951 at Stations I I I and I I respectively. There was a further increase i n 1952 with a mean f o r Station I of 70 days and f o r Station I I I of 95 days. Another factor may be the weather conditions occurring p r i o r to the larvae entering diapause. An examination of the d a i l y mean temperatures (Appendix B) shows that at Station I i n 1952, the mean d a i l y temperature f e l l from 59.6°F on June 9 to 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 period. The larvae at Station I entered diapause from June 24 to July 14 approxi-mately. Thus there was a drop, within three days -59-of 18° I? i n the mean temperature roughly 12 days before the appearance of diapause. A second depression, from July 5 to 5 from 6 1 . 6 0 ] ? to 45.2° I 1, i n 1952, corresponds to one i n 1951 of 10° F difference between 66.1° F f o r Ju l y 3 and 56.8° F f o r July 4. At Station I I I i n 1952 from July 3 to 5, the mean f e l l from 55.89 F to 38.00F, or 17.8° F i n two days. The s i m i l a r decline i n 1951 was from 57.5° F f o r July 3 to 45.1° F on July 7, or a drop of 12° F over a period of 5 days. The larvae at Station I I I entered diapause from approximately July 16 to 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 fact that at both stations 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 factor i n causing some larvae to enter diapause that would have developed i n one year i n the absence of t h i s stimulus. -60-DISCUSSIOl One objective of t h i s project 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 highly destruc-t i v e one-year cycle to the less destructive two-year cycle by changing the forest 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 to reduce diapause inception, indicate that i t would not be possible to effect t h i s change. Some int e r e s t i n g observations may be made regarding diapause and the theories put f o r t h to explain i t s inception on the basis of the l i f e cycle of the budworm. One theory, postulated by V. B. Wigglesworth (1948), i s that diapause i s due to the absence of a growth-promoting hormone, which controls molting, secreted by neuro-secretory c e l l s i n the b r a i n . -61-This theory i s substantiated "by the observa-t i o n that diapause occurs at the close of a l a r v a l i n s t a r or i n the pupa, never interrupting a stage of active 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 contradictions to t h i s theory i n i t s habit of molting, from f i r s t to second, and t h i r d to fourth i n s t a r . While i t i s d i f f i c u l t to determine exactly 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 con-struction of a hibernaculum are behaviour patterns d e f i n i t e l y associated with diapause. The molt i n the hibernaculum, following t h i s bahaviour pattern strongly suggests that diapause can not be due to the absence of the hormone that controls molting. I f we ignore the associated behaviour pattern and assume that diapause begins a f t e r the -62-molt, then i t might he due to the absence of the hormone and t h i s i s due i n turn to complete u t i l i z a t i o n of the hormone i n the molting process. However, i f t h i s were true, then i t would be l o g i c a l to expect diapause after each molt i n the l i f e of the la r v a due to depletion of the hormone. Andrewartha (1952) has postulated that diapause i s caused by the accumulation of a reserve of intractable food i n the fat-body or egg yolk. That the food supply i s not available for metabolism may be due to the quality of the food reserve, to the absence of a necessary enzyme system, or to both, i s l e f t open f o r physiological determination. The intractable food supply, i t i s suggested, f a i l s to stimulate the neuro-secretory c e l l s to produce the molting hormone, whose absence i n turn causes diapause. The writer has no information on the quality or quantity of the food reserves of the budworm l a r v a . These - 6 3 -reserves could play a part i n the diapause reaction 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 effect on the i n -cidence of diapause i n the progeny which must he due to some substance carried i n the cyto-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 to cause diapause, or as a stimulus to a tissue which i n turn secretes a hormone which causes diapause. I t i s simpler to think of the intractable food supply as part of the diapause reaction rather than as a causal l i n k i n the chain of events leading to diapause. The two-year l i f e cycle, occurring i n regions with 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 to regularly complete i t s l i f e cycle. The development of the larvae i s arrested p r i o r to the advent of cold weather by the intervention -64-of diapause and thus the danger of f r o s t -k i l l i n g i s greatly reduced. The following spring the larvae are small enough to f i n d the developing "buds of the host trees a sa t i s f a c t o r y food source, yet are able to complete t h e i r development i n time f o r the new generation of larvae to enter diapause before being endangered by f r o s t . The evolutionary process leading to the e s t a b l i s h -ment of two types of population of the insect, each adapted to 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 following explanation may be given: Consider a mountain slope with Douglas f i r growing at the lower elevations, and the upper slope l e v e l i n g off into a plateau with spruce and alpine f i r . The budworm population on the Douglas f i r has a one-year cycle. As t h i s population reaches the l i m i t of i t s range at the -65-upper elevations, the retarded development of one generation w i l l cause some of the next to adopt a two-year cycle. This cycle permits the migration of the insect onto the plateau where the conditions are such that only the two-year cycle can survive due to the l a t e spring and early autumn f r o s t s . A cold, wet summer may now i n t e r -vene and eliminate the one-year type from the t r a n s i t i o n zone. Thus the two-year type i s isolate d on the higher regions. The individuals 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 desiccation and predation, as they w i l l be i n t h e i r hibernacula from mid-July onwards and w i l l thus have to withstand some of the hottest weather of the season, and also w i l l be available to the s t i l l active predators f o r at least two and possibly three months. As the populations remain separate, selection w i l l favour those individuals whose genetic constitution predisposes them to the appropriate l i f e cycle. -66-SIMMARY Investigations were carried out to determine the effect of ecological factors on the induction of diapause and development i n the spruce "budworm. Experimental rearings were conducted at elevations of 2500, 4200 and 4750 feet i n 1951 and at 2500 and 4750 feet i n 1952. The fol i a g e of spruce, Douglas f i r and alpine f i r was used as food. Progeny of Ontario, two-year and one-year types reared under one-year and two-year conditions, was used. Conclusions are drawn as to the effects of the treatment of the parents, food, a l t i t u d e and weather on diapause i n the budworm larvae and the effects of food and a l t i t u d e on develop-ment. The growth-promoting hormone theory of diapause by Wigglesworth and the intractable 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 cycle population of budworm to a two-year cycle i s shown. Speculation i s made as to the probable cause of evolution leading to the establishment of a two-year cycle population. •68-COUCLUSIONS A trend was noted i n emergence from hibernation with the one-year material leading, followed by the two-year and f i n a l l y the Ontario stock. The three types of larvae can adopt the habit of mining needles i n the second i n s t a r . There was no s i g n i f i c a n t difference i n the time f o r development of the one-year types on the three foods at Station I i n 1951. However, i t i s suggested by the data f o r 1951 and 1952 that alpine f i r favoured more rapid development i n the one-year and Ontario types than did spruce or Douglas f i r . Females took s i g n i f i c a n t l y longer than males to develop. The difference i n time f o r develop-ment between Station I I and I I I i n 19531 was not marked but these two d i f f e r e d from Station I. 69-Development at Station I was faster by 23 days i n 1951 and by 25 days i n 1952 than at Station I I I . On the basis of three individuals 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 two-year habit. The elevation of the rearing s i t e i s a fact 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 to diapause than one of alpine 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 to a two-year cycle by forest management i s indicated. Prolonged development of the parents i s a major factor i n causing the one-year type to adopt the two-year habit. -70-The higher percentage of larvae entering diapause i n 1952 may he attributed to a longer development period of the parents of the 1952 larvae or to 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 to a combina-t i o n of these two fac t o r s . The growth-promoting hormone theory of diapause, as postulated by Wigglesworth, i s untenable for the budworm. I t i s suggested that an enzyme, carried over i n the cytoplasm of the egg, i s more probable as a causal agent than i s the intractable food supply suggested by Andrewartha. -71-ACIOJ0¥JbEDGS£EinT S Indebtedness i s expressed to the Unit of Forest Zoology o f the Forest Biology Division.of the Science Service of the Canada Department of Agriculture, f o r the p r i v i l e g e of conducting the research. Thanks are extended to Mr. ¥. G. Mathers of Vernon f o r advice and encouragement throughout the work. Acknowledgment i s made to Dr. 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 analysis; 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 studies. Grateful appreciation i s expressed by the author to Dr. ¥. A. Clemens, Professor G.J. Spencer and Dr. Kenneth Graham of the Department of Zoology, University of B r i t i s h Columbia, f o r t h e i r help and encouragement and for t h e i r valuable 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. Strains 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 habits of young spruce budworm larvae. Can. Ent. 76: 64-66 Babcock, K. ¥. 1924. Environmental studies 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 certain Orthoptera. I I I . Diapause—a theory of i t s mechanism. .Physiol. Zool. 5: 549-554. Bonnemaison, L. 1945. Arrets de development et diapauses. Ann. des Epiphyties (n.s.) 11: 19-56. Brown, A. W. A., and M. M• HcKay. 1943. The jack pine budworm and the spruce budworm Cacoecia fumiferana Can. Ent. 75: 207-211. Cousin, G. 1932. Etude experimental de l a diapause des insects. B u i . B i o l , de l a Prance et Belg. 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, (felea polyphemus Cramer). Jour. E x p t l . Zool. 59V 87 -132 ' . -73-Dickson, R. C. 1949. Factors governing the induction of diapause i n the o r i e n t a l f r u i t moth. Ann. Ent. Soc.Amer. 42: 511-537. F i f e , L. G. 1949. Studies of the diapause i n the pink bollworm i n Puerto Rico. XJ. S. Dept. Agr. Tech. B u i . 977: 1-26. Graham, S. A. 1935. The spruce budworm- on Michigan' pine. Univ. of Mich. School of For. and Cons. B u l l . Ho. 6. Lee, H. T. 1948. A comparative morphological study of the prothoracic glandular bands of some Lepidopterous larvae with special reference to t h e i r innervation. Ann.Ent. Soc. Amer. 41: 200-2G5. Lees, A.D . 1950. Diapause and photoperi odism i n the f r u i t tree red spider mite (M et at et rany chu s ulmi Koch) Nature 166: 874-5. Mathers, W.G. 1932. The spruce budworm i n B r i t i s h Columbia. For. Chron. 8: 157-160. M i l l e r , L.W. 1950. Factors influencing diapause i n the European red mite (Paratetrany-chu3 pilosus ) Nature 166: 875. O'Kane, W. G., and P. R. Lowry. 1927. The European corn borer: L i f e h i s t o r y i n New Hampshire, 1923-1926. New Hampshire Exp. Sta. Tech. B u i . 33: 1-39. Pappenheimer, A.M. and C.M. Williams. 1952. The effects of d i p t h e r i a toxin on the cecropia silkworm. Jour. Gen. P h y s i o l . 35: 727-740. -74-Prebble, M. L., 1941. The diapause and related phenomena i n G i l p i n i a polytoma (Hartig) Can. Jour. Res. D., 19:.295-322; 323-346; 350-362; 417-436; 437-454. Roubaud, E. 1922. Etudes sur l e sommiel d'hiver pre-imaginal des muscids. Bui. B i o l , de l a Prance et Belg. 56: 455-544. S a l t , R. V. 1947. Some effect of temperature on the production and elimination of diapause i n the wheat stem sawfly, Cephus cinctus ffort. Canad. Jour. Res. Sect. D, Zool. S c i . 25: 66-86. Squire, R.A. 1940. Observations on the l a r v a l diapause of the pink bollworm, Platvedra gossypiella Sound. B u i . Ent. Res. 30: 475-481. Uvarov, B. P. 1931. Insects and climate. Ent. Soc. London, Trans. 79: 1-247. Uyema, Y. 1926. Experiments of ovarian trans-plantation and blood transfusion i n silkworms, with special reference to the alternation of voltinism. Bui. S e r i c . Exp. Sta. Chosen Is 1-26. Way, M.J. and B • A. Hopkins. 1950. The influence of photoperiod and temperature on the induction of diapause i n Diataraxia oleracea L. (Lepidoptera). Jour. Exp. Biology 27: 365-374. Wigglesworth, V. B. 1948. The insect as a medium f o r the study of physiology. Proc. Roy. Soc. Series B. 135: 430-446. Wigglesworth, V. B. 1950. P r i n c i p l e s of insect physiology 4th ed. Methuen and Co. London. 75-Williams, C M . 1946. Physiology of insect diapause: the role of the brain i n the production and termination of pupal dormancy i n the giant silkworm Platysamia cercopia B i o l . B u l l . 90: 234-245. Williams, C M . 1947. Physiology of insect diapause: II Interaction between the pupal brain and prothoracic glands i n the metamorphosis of the giant s i l k -worm Platysamia cecropia B i o l . B u l l . 93: 89-98. Williams, C. M. 1948. Physiology of insect diapause: III The prothoracic glands i n the Cecropia silkworm, with s p e c i a l reference to t h e i r s i gnificance 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 to diapause and development i n the Cecropia silkworm Samia cecropia. B i o l . B u l l . 95: 282-283. -76-APPEWDIX A Wea ther Re cords STATION I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1951 MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. May 8 56.04 54.64 June 6 43.8 75.1 9 55.1 55.0 7 51.6 65.1 10 57.5 46.5 8 56.1 48.8 11 54.8 52.3 9 56.3 47.3 12 42.5 83.0 10 56.3 52.8 13 47.1 63.0 11 57.1 54.1 14 54.3 52.6 12 58.5 55.0 15 55.3 53.0 13 58.3 55.6 16 58.0 47.0 14 62.5 50.1 17 50.5 55.6 15 58.0 34.8 18 47.6 56.6 16 53.8 45.3 19 49.1 48.8 17 55.3 53.3 20 54.8 44.3 18 50.0 77.1 21 57.0 46.0 19 53.0 49.3 22 62.8 39.5 20 48.8 65.3 23 56.3 46.5 21 50.1 63.5 24 46.8 47.1 22 55.1 62.3 25 50.3 35.0 23 53.0 71.6 26 51.6 44.1 24 55.3 52.3 27 52.3 35.3 25 57.3 48.3 28 41.3 66.1 26 59.5 31.3 29 41.0 66.6 27 54.5 40.1 30 41.5 53.8 28 59.0 39.8 31 47.6 44.6 29 61.6 36.1 June 1 48.6 41.6 30 61.6 62.3 2 52.3 54.1 July 1 57.8 75.0 3 47.6 80.0 2 62.6 53.0 4 50.8 64.8 3 66.1 43.0 5 47.8 64.8 4 56.8 64.3 5 56.0 61.1 4 Incomplete reoords -77-MEAN MEAH MEAH ME All DAILY DAILY DAILY DALLY DATE TEMP. R.H. DATE TEMP. R.H. July 6 52.0 66.6 Aug.16 62.8 63.1 7 51.1 63.3 17 62.3 60.0 8 54.6 67.6 18 62.1 38.0 9 59.0 54.6 19 63.3 38.0 10 58.1 36.0 20 63.0 37.0 11 62.6 41.6 21 68.5 35.04 12 69.6 33.0 22 58.3 13 68.6 45.0 23 53.1 14 65.1 50.1 24 55.0 29.54 15 68.3 43.8 25 61.0 35.5 16 69.5 42.1 26 59.6 41.3 17 69.6 44.0 27 52.6 48.5 18 69.1 38.5 28 41.1 85.1 19 60.1 49.6 29 47.5 81.0 20 55.8 61.6 30 51.3 78.8 21 61.5 52.3 31 54.6 68.6 22 66.3 49.3 Sept. 1 55.3 64.3 23 70.5 32.6 2 55.8 67.04 24 67.5 43.6 3 55.3 74.24 25 69.6 43.5 4 56.8 30.34 26 66.6 43.6 5 57.8 50.8 27 69.3 27.3 6 59.8 47.8 28 70.1 30.8 7 60.0 55.1 29 68.8 4i.6 8 59.8 47.5 30 67.1 30.1 9 57.5 52.5 31 66.1 40.3 10 52.0 46.8 Aag. 1 66.1 43.5 11 37.64 78.14 2 71.0 37.6 12 3 70.5 33.8 13 mmmm-mwm 4 68.5 41.0 14 5 60.0 42.3 15 6 61.0 43.0 16 _ ~mm mm 7 60.3 44.8 17 73.34 mmmm** — 8 64.1 46.6 18 62.0 25.34 9 64.6 47.5 19 54.5 39.8 10 67.0 49.3 20 52.1 48.3 11 61.1 63.0 21 56.5 44.0 12 57.0 66.5 22 56.8 46.3 13 57.6 58.5 23 48.1 68.5 14 51.OA 72.1 24 46.6 87.1 15 71 . 1 4 63.7 25 43.04 85.34 4 Incomplete records - 7 8 -STATION I I Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1951 MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. May 8 46*34 79*04 J u n e 13 52.3 75.8 9 50.3 69.1 14 56.8 69.0 10 55.1 60.5 15 51.6 56.3 11 57.0 64.5 16 51.6 59.6 12 35.8 89.3 17 50.5 68.8 13 40.6 81.8 18 47.3 80.8 14 47.3 72.5 19 47.8 68.6 15 50.5 63.6 20 46.6 71.6 16 51.5 66.6 21 49.3 70.3 17 46.0 68.6 22 50.5 74.8 18 41.1 74.1 23 48.1 82.5 19 45.1 65.1 24 50.3 66.0 20 49.6 60.1 25 54.3 65.1 21 55.1 56.8 26 52.1 38.1 82 60.0 52.0 27 49.8 63.0 23 51.0 64.5 28 55.1 53.3 24 40.6 68*0 29 58.3 55.6 25 42.8 61.6 30 55.1 75.5 26 45.6 62.5 July 1 53.6 78.0 27 46.6 55.3 2 58.0 68.1 28 35.3 80.0 3 61.0 63.0 29 34.8 82.0 4 52.5 79.6 30 38*3 66.0 5 53.8 75.3 31 44.1 56.3 6 47.3 81.5 June 1 47.8 55.0 7 47.0 81.1 2 48.6 63.8 8 50.6 82.8 3 42.6 86.1 9 54.5 70.8 4 45.6 76.0 10 56.3 55.8 5 45.3 66.3 11 60.8 56.1 6 39.1 82.0 12 65.6 56.5 7 44.3 83.6 13 64.5 63.8 8 49.3 70.3 14 59.3 69.0 9 50.6 66.6 15 61.8 68.1 10 53.1 66.8 16 61*6 68.5 11 53.0 70.6 17 66.5 61.0 12 52.0 74.6 4 Incomplete records -79-H E O , DAILY DATE TEMP. July 18 60.5 19 53.0 20 49.5 21 54.6 22 61.5 23 64.3 24 63.0 25 62.6 26 60.8 27 62.1 28 63.1 29 60.8 30 61.1 31 61.0 Aug. 1 62.6 2 66*0 3 63.6 4 61.0 5 52.5 6 54.1 7 56.5 8 59.0 9 58.6 10 62.0 11 58.0 12 52.3 13 51.6 14 50.54 15 54.64 16 64 .#4 17 57.4 18 57.6 19 59.0 20 60.5 21 66.5 MEAN DAILY R.H. DATE 61.8 Aug.22 67.3 23 74.8 24 69.1 25 62.6 26 50.8 27 62.0 28 66.5 29 63.8 30 48.5 31 54.0 Sept. 1 65.0 2 64.8 3 69.6 4 58.6 5 54.1 6 57.5 7 63.0 8 70.5 9 67.5 10 67.0 11 69.6 12 70.8 13 70.0 14 76.5 15 78.0 16 79.3 17 77.1 18 70.5 19 62.8 20 60.5 21 58.5 22 59.6 23 55.3 24 51*6 25 MEAN MEAN DAILY DAILY TEMP. R.H. 51.6 72.8 47.3 75.8 52.6 65.5 56.3 61.3 54.8 62.3 47.3 72.3 43.3 86.3 46.0 85.0 46.3 82.8 50.6 81.5 50.6 79.0 50.6 69.6 50.8 66.1 55.1 62.8 56.6 62.3 61.1 59.6 54.8 68*6 52.3 74.3 53.8 65.3 45.0 72.6 44*3 70.0 49.6 70.8 52.1 63.8 55.1 64.3 58.6 62.0 60.3 63.6 61*1 59*1 61.1 55.1 48.0 62.3 46.6 68.8 52.5 61.1 52.5 72.0 45.5 77*0 43.8 88*1 41*0 82*6 4 Incomplete records -80 STATION III Tabulated mean d a i l y temperatures and r e l a t i v e humidities 1951 MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. May 15 51 . 0 4 June 18 44.6 84.5 16 44.5 64.6 19 45.8 59.1 17 40.5 55.6 20 43.5 69.0 18 40.6 62.0 21 45.8 65.6 19 47 . 0 58.3 22 48.5 68.0 20 42.5 56.8 23 46.5 77.5 21 46.0 52.0 24 48.8 50.6 22 49.6 50.6 25 51.0 57.1 23 43.8 46.5 26 49.5 46.6 24 37.1 52 . 0 27 48.3 45.8 25 39.3 48.1 28 51.0 48.1 26 41.3 46.1 29 53.6 45.3 27 42.3 42.6 30 53.0 76.5 28 32.8 56.6 July 1 51.0 82.3 29 32.8 70.1 2 55.0 68.6 30 35.8 56 .0 3 57.5 59.8 31 39.1 47.0 4 51.1 76.1 Jane 1 41.6 45.5 5 51.5 74.1 2 43.0 53.8 .6 45.8 80.3 3 40.3 66.0 7 45.1 76.8 4 42.3 61.5 8 49.3 79.6 5 40.3 52.6 9 51.5 66.3 6 37.0 55.0 10 52.1 47.1 7 42.1 63.1 11 57.5 48.3 8 46.5 56.6 12 61.6 52.0 9 46.1 45.5 13 61.6 53.6 10 41.3 45.1 14 57.5 64.3 11 46.8 46.1 15 59.1 61.1 12 50.1 50.3 16 58.8 61.0 13 49.5 56.5 17 62.1 55.8 14 53.3 51.1 18 58.8 53.0 15 49.6 36.1 19 53.0 67.3 16 47.8 40.1 20 47.3 71.8 17 48.1 64.8 21 51.0 69.1 4 Inoomplete records -81-MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. July 22 58.0 61.6 Aug.24 47.3 60.6 23 62.0 45.24 25 51.6 60.6 24 58.1 60.1 26 51.6 63.1 25 59.0 60.6 27 43.6 74.8 26 57.5 57.3 28 42.3 81.8 27 59.3 38.3 29 43.1 86.0 28 60.3 44.0 30 44.3 86.1 29 59.1 56.8 31 47.3 81.5 30 58.0 46.0 Sept. 1 47.3 83.0 31 57.3 52.0 2 45.5 75.3 Aug. 1 58.3 60.0 3 46.5 74.0 2 61.3 50.6 4 47.6 69.0 3 59.8 48.6 5 49.0 66.0 4 57.6 58.3 6 50.5 64.6 5 48.8 69.8 7 50.6 70.3 6 50.6 63.6 8 47*6 77.6 7 52.3 63.6 9 47.1 69.5 8 54.8 66.0 10 41.6 76.2 9 54.3 64.0 11 39.6 71.1 10 56.3 68.3 12 46.1 70.3 11 54.3 79.0 13 45.3 68.3 12 49.0 80.0 14 46.0 68.3 13 49.1 89.7 15 49.6 63.6 14 50.5 81.2 16 52.3 65.0 15 61.5 68.0 17 53.5 64.0 16 53.1 57.5 18 54.0 60.0 17 50.8 58.6 19 46.8 49.0 18 52.3 61.3 20 41.8 68.0 19 53.6 56.0 21 46.5 63.3 20 53.6 59.0 22 45.8 69.8 21 59.0 50.3 23 41.0 86.1 22 49.1 75.3 24 41.3 92.5 23 44.6 80.8 25 37.24 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 MEAN MEAN MEAN MEAN DAILY DAILY• DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. May 7 4 6 . 5 4 1 . 0 June 8 5 5 . 3 4 2 . 6 8 4 9 . 5 3 6 . 6 9 5 9 . 6 4 3 . 5 9 53.8 4 8 . 8 10 51.0 6 8 . 0 10 5 5 . 0 5 2 . 0 11 4 5 . 6 7 0 . 6 11 52.5 6 8 . 6 12 4 1 . 8 8 4 . 3 12 5 2 . 3 5 4 . 8 13 4 6 . 3 52.8 13 4 6 . 3 8 1 . 1 14 5 0 . 6 4 9 . 1 14 4 6 . 3 7 0 . 5 15 5 2 . 5 4 0 . 5 15 5 2 . 1 6 0 . 6 16 4 5 . 8 74.5 16 45.6ft 7 7 . 0 4 17 4 8 . 3 6 6 . 5 17 — — - _ 18 5 3 . 5 6 0 . 0 18 19 5 9 . 3 3 9 . 8 19 5 6 . 3 4 62. 3S 20 5 6 . 3 54.6 20 4 8 . 5 4 7 2 . 4 4 21 4 9 . 3 5 9 . 1 21 51 .3 5 4 . 8 22 4 5 . 6 8 1 . 0 22 51.6 4 8 . 6 23 51 .0 6 8 . 6 23 5 2 . 1 4 6 . 8 24 57.5 5 9 . 6 24 5 6 . 3 4 7 . 8 25 5 9 . 3 6 4 . 3 25 57.8 4 0 . 0 26 5 6 . 3 70.6 26 55.6 3 8 . 5 27 5 8 . 0 71.8 27 5 6 . 0 61.1 28 5 6 . 0 8 1 . 3 28 5 0 . 6 6 2 . 1 29 5 3 . 3 74.3 29 4 5 . 6 5 0 . 6 30 5 2 . 5 70j5 30 4 6 . 5 5 0 . 5 July 1 5 3 . 1 55.8 31 4 8 . 3 6 2 . 8 2 5 4 . 5 5 5 . 1 June 1 51.0 6 7 . 0 3 61.6 5 3 . 6 2 5 4 . 5 4 5 . 3 4 6 0 . 6 50 .8 3 5 3 . 3 5 0 . 6 5 4 5 . 3 70.6 4 5 4 . 5 6 6 . 5 6 4 9 . 6 6 0 . 3 5 5 6 . 1 4 7 . 6 7 5 8 . 6 4 9 . 8 6 59 .8 3 8 . 0 8 6 5 . 5 4 8 . 8 7 5 3 . 3 3 6 . 0 9 6 9 . 1 4 4 . 3 4 Incomplete records -83 MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATS TEMP. R.H. DATE TEMP. R.H. July 10 69.0 35.6 Aug. 20 61.1 : 48.6 11 67.3 41.6 21 60.3 48.1 12 63.3 36.5 22 54.5 79.3 13 66.6 44.6 23 56.8 42.3 14 72.3 48.2* 24 50.1 64.8 15 69.6 28.74 25 49.0 79.5 16 60.8 49.8 26 51.3 60.1 17 59.1 61.3 27 51.0 55.0 18 57.5 66.5 28 52.3 55.8 19 60.5 55.0 29 50*3 55.8 20 55.1 56.6 30 49.8 55.1 21 51.8 65.0 31 54.0 53.6 22 50.8 67.1 Sept. 1 57.1 44.1 23 61.6 85.5 2 60.1 50.1 24 51.8 75.5 3 63.3 33.8 25 58.3 56.3 4 52.5 42.5 26 63.6 60.3 5 54.1 43.0 27 67.6 37.0 6 58.6 42.6 28 65.1 47.6 7 49.5 42.6 29 68.6 44.8 8 50.8 45.8 30 69.6 36.3 9 50.3 62.8 31 71.3 30.6 10 51.1 59.0 Aug. 1 69.6 36.3 11 50.1 56.1 2 66.8 37.1 12 48.0 66.6 3 68.5 44.1 13 47.3 50.5 4 70.5 43.3 14 49.3 49.8 5 73.3 22.34 15 55.5 45.8 6 69.1 43.8 16 53.3 50.1 7 65.0 59.1 17 60.3 49.8 8 65.5 58.3 18 58.8 64.1 9 71.3 44.6 19 57.3 52.6 10 71.8 42.3 20 53.1 52.6 11 68.0 46.5 21 57.6 51.8 12 69.5 41.5 22 59.0 50.6 13 73.6 39.5 23 60.0 47.5 14 68.5 41.5 24 60.6 38.0 15 61.6 50.5 25 63.3 36.5 16 57.6 55.5 26 61.0 40.8 17 59.6 56.1 27 55.1 47.6 18 62.0 39.5 28 52.3 64.3 19 58.5 52.3 29 57.0 51.6 £ Incomplete re cords -84-MEAN£ MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. Sept.30 58.3 44.6 Oot. 7 51.8 45.1 Oct. 1 51.5 58.3 8 53.5 43.6 2 51.6 57.3 9 52.8 49.5 3 50.3 35.1 10 49.0 58.0 4 45.6 42.0 11 52.3 51.8 5 47.6 48.5 12 51.3 59.3 6 50.8 51.0 13 45.1 46.8 -85-APPENDIX 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 MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. May 21 40.6 84.3 June 22 38.8 89.1 22 41.3 75.8 23 43.0 86.3 23 39.8 73.1 24 49.6 76.5 24 46.5 71.5 25 51.5 81.3 25 47.1 64.3 26 49.5 85.0 26 48.0 57.0 27 52.6 81.8 27 49.5 65.3 28 50.6 88.5 28 46.1 80.5 29 47.1 85.8 29 37.5 81.8 30 44.3 84.1 30 41.5 72.0 July 1 45.0 78.8 31 43.1 81.8 2 46.5 75.6 June 1 44.5 75.8 3 55.8 71.8 2 49.1 69.5 4 52.6 73.0 3 49.0 67.6 5 38.0 83.8 4 46.1 85.5 6 43.0 75.3 5 48.0 69.6 7 52.0 67.8 6 50.5 63.5 8 60.8 65.5 7 45.3 61.5 9 63.1 60.8 8 49.3 61.0 10 62.5 52.5 9 54.3 58.8 11 58.3 62.3 10 43.5 80.0 12 56.5 63.1 11 40.8 79.6 13 60.0 61.6 12 35.3 90.0 14 63.6 60.5 13 38.1 79.3 15 60.6 53.1 14 44.8 69.5 16 52.5 70.6 15 44.6 69.0 17 48.6 80.6 16 37.1 88.1 18 50.6 78.0 17 40.6 79.6 19 52.6 73.3 18 45.8 69.5 20 45.5 80.3 19 51.5 61.3 21 43.3 83.3 20 48.3 74.3 22 44.8 84.0 21 41.6 79.5 23 46.3 88.8 \ -86-MEAN MEAN MEAN MEAN DAILY , DAILY DAILY DAILY DATE TEMP. R.H. DATE TEMP. R.H. July 24 44.8 87.3 Aug. 25 41.6 87.3 25 50.0 73.5 26 43.6 83.0 26 55.8 61.0 27 44.5 79.3 27 54.6 69.1 28 46.3 74.3 28 56.8 70.6 29 40.8 83.3 29 61.5 63.3 30 43.6 78.6 30 61.1 60.8 31 45.0 77.5 31 63.1 65.0 Sept . 1 48.5 74.3 Aug. 1 60.0 61.0 2 51.5 73.5 2 58.6 62.0 3 53.6 62.6 3 60.0 66.3 4 42.0 71.6 4 62.8 63.3 5 45.5 66.0 5 63.6 58.6 6 47.5 73.3 6 59.1 68.6 7 38.5 72.1 7 55.1 77.5 8 40.5 78.0 8 56.3 8 o.i : 9 43.1 80.5 9 60.6 70.0 10 41.3 81.8 10 59.6 69.5 11 42.0 81.1 11 59.3 68.5 12 39.3 80.0 12 60.5 64.3 13 38.6 70.6 13 62.6 63.0 14 42.1 75.1 14 56.6 68.3 15 47.1 69.0 15 51.6 74.5 16 46.5 73.8 16 47.3 79.0 17 48.6 71.0 17 51.5 72.1 18 51.8 80.1 18 50.8 66.0 19 46.6 76.5 19 48.3 74.6 20 46.0 78.1 20 50.6 69.6 21 49.3 73.8 21 51.1 71.6 22 50.5 73.6 22 48.3 85.1 23 53.3 68.1 23 47.5 71.3 24 52.8 66.3 24 43.0 86.0 25 57.5 58.5 -87 MEAN MEAN MEAN MEAN DAILY DAILY DAILY DAILY DATE TEMP. R.H. DATE BEMP. R.H. Sept.86 53.1 68.8 Oct. 5 42.6 73.8 27 45.5 76.5 6 45.6 68.6 28 44.3 85.5 7 50.6 59.3 29 48.5 76.6 8 48.5 71.0 30 48.0 73.1 9 47.0 71.5 Oct. 1 44.1 83.1 10 40.6 83.8 2.46.6 76.5 11 44.1 77.5 3 41.3 61.1 12 43.0 75.0 4 39.0 71.1 13 39.0 72.0 

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