The Second Pupal Diapause in the Univoltine Papilionid, Luehdorfia japonica (Lepidoptera : Papilionidae) and Its Terminating Factor

Pupal Diapause in the univoltine papilionid, Luehdorfia japonica, is terminated by a short day (less than about 15 hr) and a moderate temperature (14 to 25°C). However, adult eclosion rarely occurs in individuals kept under a short day at 20°C. To elucidate the factor inducing adult emergence, pupae of this papilionid were subjected to a humidity change, an increase in photoperiod or a low temperature after termination of the 'first' diapause. Adult emergence was observed in most individuals experiencing a low temperature of 4 or 10°C for 90 days after being kept under a 20°C-12L-12D condition for 30, 60 or 90 days following pupation. Irrespective of the duration of the pre-chilling period, the chilled insects underwent adult eclosion about 2 weeks after transfer to a 20°C condition. A short (30-day) chilling, in contrast, retarded adult emergence. The results demonstrate that the pupae of this papilionid enter a second (winter) diapause after termination of the first diapause.