Temperature Determines Diapause Termination in Papilio troilus (Lepidoptera: Papilionidae).

Diapausing pupae of the spicebush swallowtail butterfly, Papilio troilus Linnaeus, were individually set up in screened cages under one of 4 temperature and 2 photoperiod treatments (14°,18°,22°, or 26°; in 18:6 or 12:12 photo/scotophase). The breaking of diapause and eclosion of adult butterflies was significantly faster at 26°C (13-24 days) than 22°C (18-36 days) and 18°C (36-69 days) regardless of the photoperiod conditions. As of 88 days, none of the pupae eclosed as adults in either 14°C chamber (18:6 or 12:12). While diapause induction for these Ohio populations was known to be determined in the larval stages by a critical photoperiod of less than 15 hours, it did not matter whether the photophase was 12h or 18h for termination of diapause and eclosion of adults. In every treatment (n = 6), the majority of the first 10 individuals eclosed were males, suggesting that protandry is likely In the field.