日本生態学会誌
Online ISSN : 2424-127X
Print ISSN : 0021-5007
ISSN-L : 0021-5007
ヨツモンマメゾウムシに見られた相に似た二型, 第4報
内田 俊郎
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ジャーナル フリー

1965 年 15 巻 5 号 p. 193-199

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UTIDA, Syunro (Entom. Lab. Kyoto U., Kyoto) "Phase" dimorphism observed in the laboratory population of the cowpea weevil, callosobruchus maculatus, IV. The mechanism of induction of the flight form. Jap. J. Ecol. 15,193-199 (1965). In the population of the southern cowpea weevil, Callosobruchus maculatus, the existence of two distinctly different forms was observed by the writer (UTIDA, 1954) and CASWELL (1956). One is very active in its behavior and can fly while the other which is of rather dark body color can not fly. Distinction between both forms is not only morphological but also physiological and behavioristic (UTIDA 1956 ; Utida & TAKAHASHI 1958 ; CASWELL, 1960). It was observed that the active one appears when the density of the weevil population is high (UTIDA 1954). Therefore, the experiments were made to prove the soundness of this observation. It was found that with the increase of the percentage of emergence of the flight form increases in both sexes the density of the larval population in a bean from 1 to 6 (Fig. 1). The temperature in a small heap of beans (20 gr. or 40 gr.) rises to 6° to 8° above the air temperature of the environment (30℃), when the larval density in a bean is so high as to produce the flight form in high percentage (Fig. 2). This seems to be a mechanism due to the density effect, thus determining the emergence of the flight form. This condition was proved by the simple experiment that the high percentage of emergence of the flight form is seen even in the uncrowded population, when the rearing temperature rises from 30° to 36° at a certain stage of larval life. The stage most susceptible to high temperature is the third instar. The following course is assumed for the operation of the density effect : crowding of larvae of the older stage→heating of the heap of bean→induction of rather young larvae to flight form.

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© 1965 一般社団法人 日本生態学会
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