The Circadian Rhythm of Flight Activity in the Mosquito Aedes Aegypti (L.): The Phase-Setting Effects of Light-On and Light-Off

Abstract

1. The circadian flight-activity of individual, sugar-fed Aedes aegypti females has been studied, using the flight-sound as an indicator of activity. 2. The activity appears to be controlled by an endogenous rhythm with a period of 22-24 hr. in constant dark and about 26 hr. in constant light. 3. Both light-on and light-off have phase-setting effects. Under favourable conditions, peaks of activity occur 13-14 hr. after light-on and 22-23 hr. after light-off. Both these peaks persist in constant dark following an LD 4:20 regime. 4. The total amount of flight-activity is correlated with the duration of light (70 lux) in the 24 hr. period.