Kawada, Kazuo

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THE DEVELOPMENT OF WINGED FORMS IN THE CABBAGE APmD， BREVlCORYNE BRASSICA.E LINNAEUS 1. The Influence of Population Density， Photoperiod and Temperature Kazuo KAWADA It has been suggested by many previous investigators that the wing development in aphids is related with such enviromental factors as temperature， photoperiod， population density， and the moisture as well as the chemical composition or constituent of their host plants. Noda (1954) found that the population density is one of the powerful factors for the wing development in the apple grain aphid， Rho，μlos争'humprunifoliae Fitch. Temperature is another factor which has been investigatated by a number of workers. But the results published do not agree. The present experiment was conducted in order to study the e~ects of population density， photoperiod and temperature on the wing development in the cabbage aphid， Brevicoryne brassicae Linnaeus. MATERIALS AND METHODS All materials used in these experiments were the descendants originated by parthenogenesis from one unwinged viviparous female of Brevicoryne brassicae Linnaeus; and the host plant adopted was kale leaves， Brassica oleracea L. var. acephala DC. The first instar larvae born within two hours before the test were used. A definite number of young larvae were placed in a cage on the kale leaf; and their density in the cage varied as shown in Fig. 1 and 2， (viz.， 20， 40， and 60 individuals per 0.36 cm2). Japa-nese pharmacopoeia No. 0 capsule was used as the cage. The larvae were reared up to fourth instar; then， their thoracic structure was examined for their wing buds， which could be easily recognized by the naked eyes at that stage. The experiments were carried out in double-walled glass cabinets， in which both temperature and photoperiod were co任trolled. The t臼emp戸era削tωur陀ewa前sr問eg肝ul加a剖te吋d Fi氾1[.1. D附 a細mma副凶蹴t“批i比C'D町'Dro刈fi自仙of恥 伺叫叫b悩in附e悦t a剖t20σ。and250C， within a variation of - for r~ムari凶nga叩phid190 Berichte d. Ohara Institu. (Bd. 12， Ht. 2， | 容器--問内噂5p-|lbu!i!V-1-制|a c b Fig. 2. Rearing cage and aphid larvae on the surface of the kale leaf. a. Rearing cage coverd with fine-mesh ;nylon cloth. (x 4) b. Larvae， just after treatment. (x 4) c. Larvae， four days after treatment. (x 4)" 士O.5"C. A fluorescent lamp (Toshiba FL-20W)， operated by time switches， gave the daily photoperiod of 8 and 16 hours; and the light intensity on the surface of host plants was 800-1000 Lux. The water in the vial was supplied every day， the leaves having been cut from the stem in water to avoid their wilting. RESULTS E.fect of Potulation Density The results of the rearing experiments are shown in Tables 1 and 2. As shown clearly in these tables， most of 20 individuals on the given area (0.36 cm2) grew up to the unwinged forms at the constant temperatures of 200 and 2SoC， and under both“long" (16 hours) and “short" (8 hours) photoperiods. 1n this lot， the percentage of winged forms was the highest being 2.97 %， when the temperature was at 250C， and the photoperiod was 8 hours. 1n the 40 individuals placed in the same area， the percentage varied from the highest 10.76% to the lowest 8.37%， and was 9.48% on the average; and in the 60 individuals， the percentage was stilllarger， namely， 22.74% on the average. As it has been stated already， the higher the density is， the higher the percentage of winged form is in every combination of temperatures and 1964J Kawada : The development of winged forms in the cabbage aphid 191 photoperiods. To show this relationship more clearly， the writer prepared Table 3 and Fig. 3. ln this table it is clearly seen that the difference between TABLE 1 Influence of population density on the production of winged form in long (16 hours) and sMrt (8 hours) photoperiods atお℃Phptoperiod Density Tota1 Number of winged Percent of winged 20 窃 5 2.14 16 hr. 40 240 19 8.37 60 240 54 23.79 20 240 7 2.97 8 hr. 40 240 24 10.76 60 240 45 21. 84 TABLE 2 Death 6 13 13 4 17 34 Influence of population density on the production of winged form in longα6 hours) and幼例(8houn) photoperiods at却℃Photoperiod Density Tota1 Number of winged Percent of winged 20 240 4 1. 74 16 hr. 40 240 20 8.93 60 240 46 22.12 20 240 6 2.59 8 hr. 40 240 21 9.86 60 240 48 23.19 TABLE 3 The di任erenceof percentage of winged forms among three lots of different densities When density increased Temperature Photoperi吋 from 20 to 40 from 40 toω l6hr. 6.23 15.42 25・c8hr. 7.97 11.佃l6hr. 7.19 13.19 20・c8hr. 7.27 13.33 Death 10 16 32 8 27 3 the percentage of winged forms of 20 individual-lot ~nd that of 40 individual-lot was about as half much as the difference between the 40 individual-lot and 60 individual-lot; viz.， the former was 7.12% and the latter 13.26% on the a verage. The rate of increa開 ofthe percentage of winged forms was compa-ratively lower in 40・lotand higher in 60・lot. Therefore， the curve which 192 25 a 与唱白、.]，15 ロ量、司。U 国s a u u 』U E匂5 。Berichte d. Ohara Instituts. (Bd. 12， Ht. 2， ーー -ー25・'C.8hr. ---25・C.16hr. 一一-20'1こ.8 h r. ーー ー 200C.16 h r.20 40 60 Number of individuals per 0.36cml Fig. 3. The relation between the population density and the percentage of winged forms. indicates the percentage of winged forms produced becomes concave upwards. It is apparent that significant difference at 5 percent level exists in the wing development among three lots of different densities. E.fect of Photoperiod The Table 4 was prepared to examine the inftuence of photoperiod under TABLE 4 The difference of percentage of winged forms between UJng (16 hours) and slwrt (8 hours) photoperiods Temperature Density Oifference between 16hr.-8hr. 250C 20・c????-0.83 -2.39 1. 95 -0.85 -0.93 -1.07 ????the泊 metemperature. This table indicates that， when temperature was 2500 the percentage of wing formation in long photoperiod was less than that in short photoperiod， excepting the result at the density of 60 individual-lot， while at the temperature of 20.0 the percentage of winged forms in long photoperiod was always less than that in short photoperiod. According to the result of 1節句 Kawada : The development of winged forms in the cabbage aphid 193 x2-test there is no significant difference in the wing formation between short and long photoperiods. E.fect of刀mteratureThe e町ectof temperature on wing formation ma y now be considered in detail. Table 5 was constructed from Tables 1 and 2. The difference is always TABLE 5 The difference of percentage of winged forms between 20・and25・cPhotoperiod Density Difference between 25・_2QOC8hr. ???????0.40 -0.56 1. 67 16hr. 0.38 0.90 -1.35 very litle， but the percentage of winged forms at 250C is somewhat larger than that at 200C excepting two cases observed at 200C. The result of x2・testdoes not show that the differences of percentage of winged forms between 200 and 250C is significant. DISCUSSION ln various investigations， ithas been noted that the number of winged forms tends to increase with the increase of population density on the host plant. Bonnemaison (1951)， studying on the cabbage aphid， Brevicoヮnebrassicae Lin-naeus， conc1uded that “crowding" (i. e.， high density) caused the number of winged forms to increase. The result of the present study indicated that population density was more important factor than either temperature or photoperiod， for the production of winged or unwinged form. Bonnemaison， indeed， suggested in his work that density acted directly， not through the plant， on the insect. But judging from his ex戸rimentaldesign， itis doubtful that there was no change at al in the physiological condition of the plant in the course of his experiment. Therefore， the conclusion that the influence of density alone acted on the aphid directly seems to be somewhat hasty according to the writers opinion. From the nature of the present experiment， itis impossible to determine which caused the increased number of winged forms， the density or the physiological change in the host plant resulting from a high population. To solve this problem， 1believe that more detailed studies must be 伺 rriedout. 194 Berichte d. Ohara Instituts. (Bd. 12. Ht. 2， Photoperiod is another factor which has been investigated by a number of workers， such as Marcovitch (1924)， Shull (1929)， and others. It has been shown that for some aphids the alternation of photoperiod might have caused proportional increase or decrease of winged forms. The results of the present experiment， however， indicated that photoperiods of 16 hours and 8 hours had nothing to do with the production of winged forms， under the temperature range of 200-250C. Temperature has been investigated by many workers as a causatic factor， whether positive or negative， which caused the development of winged forms. Ewing (1916) correlated the maximum wing production in Aphis avenae Fabricius with the temperature of 18.30C. The results of Call (1918)， investigating wing-inducing factors in Aphis maidis Fitch， indicated that the maximum number of winged forms was <?btained when temperature was in the range of 15.50-21.10C. More recently， White (1946) found in her work with Macros争honielasanborni Gillette that 120C and continuous light produced more winged forms than under other temperature and light condition. Kenten (1955)， studying Acythω砂'hon戸isumHarris， showed that wing formation in this aphid was brought about by low temperature of from 70 to 11 oC combined with 16 hours photo-period. Reinhard (1927) and Rivnay (1937) found that there was no e百'ectof temperature on the winged forms production in Aphis gosy戸iGlover and Toxoptera aurantii Fonscolombe. According to the writers' present investigation， the difference in wing development was not discernible， between 200 and 250C; so it is clear that temperature played litle or no part in the production of winged forms. the writer， however， did not avail of low temperature of 1500 in the present experiment; so the writer is not， asyet， able to show whether low temperature had any effect on the wing formation. SUMMARY The e町ectsof population density on the development of wings in the larvae of cabbage aphid， Brevicoワnebrassicae Linnaeus， were examined experi-mentally at the constant temperature of 200 and 250C， both in long (16 hours) and short (8 hours) photoperiods; and the following results were obtained. 1) The rate of occurrence of winged forms tended to increase with increase in the population density. 2) The maximum rate of occurrence of winged forms amounted to 23.799杉under the condition of 250C， 16 hours photoperiod， and population density of 60 individuals per 0.36 cm2• 3) The wing development does not seem to be correlated with the length of photoperiod under the constant temperature of 200 and 250C， asfar as the photoperiod is between 16 and 8 hours. 4) The increase in the rate of winged forms was not observed at the constant temperatures of 200 and 250C， unless accompanied by high population 19(4) Kawada : The development of winged forms in the cabbage aphid 195 density. Acknowledgement. The writer wishes to express sincere thanks to Dr. Y. Yasue for kindness in reading through the manuscript and also for kindly advice. LlTERA TURE CITED Bonnemaison， L.1951. Contribution a l'~tude d個 facteursprovopuant l'apparition d担 form四ailees et sexuees chez les Aphidinae. Ann. Inst. Rech. Agron. Ser. C. Ann. Epiphyt. 2: 1-3加.白 1，L. E. 1918. Climate and inju巾 usinsect investigation. Kansas Agr. Expt. Ann. Rept. 1917-1918: 20-21. Ewing， H. E. 1925. The f:司ctorsof inheritance and parentage as affecting the ratio of alate to apterous individuals in aphids. Amer. Nat. 59: 311-326. Kenten， J.1955. The effect of photoperiod and temperature on reproduction in Aりrthosithonpisum Harris and on the forms produced. Bu11. Ent. Res. 46: 599-624. Marcovitch， S. 1924. The migration of the Aphidae and the apperance of the sexual forms剖affected by the relative length of daily light exposure. Jour. Agr. Res. 27 : 513-522. Noda， I. 1954. The emergence of winged viviparous female in aphid. 1. The influence of f，国対，temperature， family line and population density. Mem. Ehime Univ. Sect. 2. Ser. B. 2: 61-70. Reinhard， H. J. 1927. The influence of parentage， nutrition， temperature， and crowding on wing production in Athis gossytii G1over. Tex. Agr. Expt. Sta. Bu11. 353: 5-19. Rivnay， E.1937. Moisture as the factor affecting wing development in the citrus aphid， Toxotlera aurantii Boy. Bu11. Ent. Res. 28: 173-179. Shull， A.F. 1929. The effect of intensity and duration of light and of duration of darkness， partly modified by temperature， upon wing production in aphids. Wilhelm Roux' Arch. Entwickl. Mech. Organ， 115 : 825-851. White， W. S.ω46. The enviromental conditions a汀ectingthe genetic mechanism of wing production in the chrysanthemum aphid. Amer. Nat.田:245-270. 

THE DEVELOPMENT OF WINGED FORMS IN THE CABBAGE APHID, BREVlCORYNE BRASSICAE LINNAEUS I. The Influence of Population Density, Photoperiod and Temperature

THE DEVELOPMENT OF WINGED FORMS IN THE CABBAGE APHID, BREVlCORYNE BRASSICAE LINNAEUS I. The Influence of Population Density, Photoperiod and Temperature

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