Some effects of constant temperature and photoperiod on the diapause response of the flesh fly, Sarcophaga argyrostoma

Abstract

ABSTRACT. The sensitive period for the induction of pupal diapause in Sarcophaga argyrostoma (R.‐D.) (Diptera, Sarcophagidae) extends from the intra‐uterine embryos to puparium formation, although the degree of ‘sensitivity’ declines during that period. Embryos and larvae ‘add up’ both long and short nights to a threshold. The incidence of diapause may also be influenced by the photoperiodic manipulation of female flies containing ovarian eggs. High temperatures eliminate or override the diapause response, whilst lower temperatures enhance it. Still lower temperatures (10–12°C) bring about a high larval and pupal mortality and a failure to pupate which is more marked in long than in short nights. The results are discussed in terms of the external coincidence model and the concept of the ‘photoperiodic counter’.