The effect of light and temperature on the rhythm of pupal ecdysis in the Queensland Fruit-fly, Dacus (Strumeta) Tryoni (Frogg.)

Abstract

Adults of the Queensland fruit-fly, Dacus (Strumeta) tryoni, show a pronounced diurnal rhythm in pupal ecdysis. Experiments are described which show that the rhythm can be induced and oriented by alternation of light and darkness during the larval stage or the adult stage of the previous generation. The alternation of light and darkness during the pupal stage had no direct effect on the rhythm of pupal ecdysis. When pupae were exposed to a small daily fluctuation in temperature, the rhythm of ecdysis was more pronounced - i.e. ecdyses were spread over fewer hours of the day. Most of the flies emerged within a few hours after the initial increase in temperature.