天蚕蛹の夏眠
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概要
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Antheraea yamamai is an univoltine insect, the life cycle of which is as follows : In the fall the egg enters into hibernation, when every organ of the embryo has developed in appearance almost to the full. Owing to the warm spells from March to April, it gradually completes its developement, until at last it hatches in May. After Ecdysis four times, the hatched larva becomes perfectly mature and begins to cocoon-in the Matsumoto district it takes usually 45〜50 days from hatching to cocooning. Four to five days are required to complete cocooning which is followed by pupation three to four days thence forth. As regards emergence, it commences 20〜25 days after pupation and continues as long as four months viz. from July to October as is exemplified in table I. Needless to say, silkworms are reared in a house where the air is to some extent conditioned, so that they keep step with each other in ecdysis, cocooning, pupation and emergence, viz. every metamorphic phase occurs rather simultaneously. Antheraea yamamai, on the contrary, being reared outdoors, the enviromental condition is not equal everywhere in the Quercus trees, that is there are wide differences between the upper layer of the tree crown and the lower one, not only microclimatically but in the quantity of the fodder as well. Therefore even though the worms hatch simultaneously they do not keep step in ecdysis, cocooning, pupation, and emergence but sometimes differ by several days in the same metamorphic phase. However, the emergence of A. yamamai is extremely protracted even if the above-mentioned irregularities are considered. Moreover the daily fluctuation of emergence shows that the emergence does not occur evenly during the period but that there are two peaks, viz. the minor one is from late July to early August and the major one in late September. In order to reveal the cause of this noteworthy phenomenon, the writers observed the pupae analytically just before the beginning of emergence, with the result that, concerning the imago differentiation, there are three kinds of pupae, that is, the one is those that have already completed their imago differentiations, the second is those that show no trace of imago differentiation but enter into aestimation-this aestivation cannot be broken even if they are put under a temperature favorable for emergence such as for instance, 25℃-and the third is the intermediate ones who do not enter into aestimation but the imago differentiations of which are sluggish.
- 日本生態学会の論文
- 1956-06-30