Reproductive diapause in univoltine phytophagous lady beetle, Epilachna admirabilis (Coleoptera: Coccinellidae) in Kanagawa prefecture, Japan

We clarified the effects of photoperiod on feeding and egg-deposition activity on the phytophagous univoltine lady beetle, Epilachna admirabilis. Emerged females were housed under 15.5h light: 8.5 h dark (15.5L-8.5D) and 13L-11D for varying lengths of time. Irrespective of the photoperiod condition experienced females showed decreased food consumption in June, which then recovered in July. Beetles transferred from the 15.5L-8.5D to 13L-11D condition showed higher feeding recovery than with other treatments. On the other hand there were remarkable differences in the number of eggs produced in different photoperiod treatments. Females are apparently sensitive to photoperiod changes; egg-laying was confirmed with transfer from 15.5L-8.5D to 13L-11D. We suggest that photoperiod-induced reproductive diapause provides E. admirabilis a chance to synchronize reproduction in favorable seasons such that larvae are able to reach the full-grown fourth instar before winter.