Chilling period for effective survival of diapausing pupae of the flesh fly, Boettcherisca peregrina, collected from Tokyo

Abstract

Diapausing pupae of the flesh fly, Boettcherisca peregrina (Robineau-Desvoidy) (Diptera : Sarcophagidae) were held two months at 20℃ and then chilled at 4℃ for between 0 and 48 weeks before transfer to diapause-terminating conditions (27℃). 70-89% adult emergence occurred in unchilled pupae and pupae chilled for 3-15 weeks, with the highest rate observed in those chilled for 12 weeks. Pupae chilled for 12 weeks emerged over the shortest interval (10 days) from day 14 to day 23 after being transferred to 27℃. The interval of adult emergence was longest (40 days) from day 20 to day 59 for unchilled pupae. A low percentage of adult emergence occurred in pupae chilled either 2-3 or ≥20 weeks. All pupae that failed to emerge were dead. These results show that length of the hypothermic phase during diapause is one of the important factors determining the timing of adult eclosion in diapausing individuals of B. peregrina. The results further indicate that long hypothermic phases lower the survival rate, and this may limit the northern distribution of this species.