Photoperiodic induction of diapause in normal and allatectomized precocious pupae of Papilio machaon

Abstract

Diapause in the swallowtail, Papilio machaon occurs at the pupal stage in response to short days during larval development. The precocious pupae obtained by allatectomy also entered diapause in response to short days. The photoperiodic induction of diapause in precocious pupae was very similar to that in normal pupae in spite of the abbreviation of the last-larval instar. The critical photoperiod for diapause in the precocious pupae was 14.5 h, being about the same as that in normal pupae. Occurrence of diapause in the swallowtail is closely associated with the pupal stage and the induction process may be triggered by the cessation of juvenile hormone secretion.