An eclosion timing mechanism in the mosquito Anopheles gambiae

Abstract

ABSTRACTThe circadian control of adult emergence was studied in Anopheles gambiae. In contrast to the situation reported for other mosquitoes, the timing of adult eclosion can be modified by the light regime. Comparison of the timing of pupal—adult ecdysis in groups of individuals pupating at the same time and then kept either in 12 h light alternating with 12 h dark (LD 12:12) or constant light, at temperatures from 22 to 34·5°C, showed that the timing can be modified by the light regime. In LD, eclosion due to take place during the middle and later part of the light phase was delayed, giving a peak near light‐off; the maximum delay was of the order of 4–5 h at both 22 and 34·5°C. This effect appears to be mediated by a temperature‐compensated timing mechanism. Experiments with different light regimes indicated that the time cue is a previous change from light to dark. When this was given to late fourth stage larvae it affected the timing of adult eclosion without affecting the time of pupation.