Larval growth and the effect of temperature on head capsule size in Atrophaneura alcinous (Lepidoptera: Papilionidae)

Abstract

The size of head capsule is one of the most important factors for identifying developmental stage. In order to understand the developmental characteristics of the butterfly Atrophaneura alcinous, we examined fluctuations in larval head capsule size under three different temperature conditions (20, 25, and 30°C) and 60% humidity. As a result, larvae developed to the fifth instar at all three temperatures. The head capsule size of larvae tended to be larger at the lowest temperature and smaller at the highest temperature. The development rate showed a regular change, consistent with Dyar’s rule regarding head capsule size development. Furthermore, the development of head capsule size was found to correspond to a second degree polynomial regression better than to a linear regression. On the basis of these results, it would appear to be possible to perform an accurate assessment of instar status during the development of A. alcinous.