Interaction of food and photoperiod in the termination of larval diapause in Chaoborus americanus (Diptera: Culicidae).

Abstract

The role of food in the termination of diapause is probably without significance in the many diapausing insects which are inactive and which seldom, if ever, feed. There are, however, certain nematocerous Diptera which overwinter as larvae and are capable of both movement and feeding. Indeed, studies concerning the photo periodic induction of development in diapausing larvae of the chironomids Metrioc nemus (Paris and Jenner, 1959) and Chironomus (Engelmann and Shappirio, 1965) or of the culicids Anopheles barberi (Baker, 1935), Anopheles bifurcatus (Vinogradova, 1964), Anopheles plumbeus (Vinogradova, 1962), Aedes triseriatus (Love and Whelchel, 1955), and Tozorhinchites rutilus (McCrary and Jenner, 1965) involved the effects of photoperiod on fed animals only. Studies concerning the overwintering larvae of the culicid Chaoborus americanus (Bradshaw, 1969) considered the effects of photoperiod on both fed and starved animals. The assess ment of the contribution of food is difficult, if not impossible, in filter feeders or detritus eaters like the chironomids or the culicine and anopheline mosquitoes. Chaoborine and toxorhinchitine mosquitoes, on the other hand, are carnivores. In Chaoborus, food and photoperioci have been shown to interact synergistically to effect the termination of larval diapause (Bradshaw, 1969). Furthermore, develop ment in Chaoborus is proportional to the number of long days with food. Chao borus, therefore, is conveniently adapted for the study of the food component in the termination of diapause.