「神奈川県産」アカボシゴマダラにおける幼虫の発育と休眠に対する光周期と温度の影響

抄録

Larval development and diapause of the alien nymphalid butterfly Hestina assimilis assimilis, which was accidentally introduced into Kanagawa Prefecture, central Japan were investigated under various photoperiodic conditions at 20℃ or 25℃. The larval diapause, which was linked with the formation of a short horn head, was frequently induced at the 4th-instar by a short photoperiod of 12L-12D or less, and averted by a long photoperiod of 14L-10D or more at 20℃. The critical photoperiod was around at 13L-1 ID. At 25℃, although larval diapause was induced by short photoperiods, its ratio was about 50% and some short horn individuals did not enter diapause. This is in contrast with the cases of many temperate native Japanese butterfly species where diapause is completely induced under such conditions, suggesting that this population may have come from warm temperate or nearly subtropical regions located at a rather low latitude. In addition, development during middle larval life was greatly retarded under an intermediate photoperiod such as 13L-11D. This retardation may be important in synchronizing their life cycle with seasonal changes in air temperature and day-length, but it remains unclear whether this functions fully in the climatic conditions of central Japan, which are unfamiliar to this butterfly.