The Circadian Rhythm of Flight Activity in the Mosquito <i>Aedes Aegypti</i> (L.): The Phase-Setting Effects of Light-on and Light-Off

Abstract

ABSTRACT The circadian flight-activity of individual, sugar-fed Aedes aegypti females has been studied, using the flight-sound as an indicator of activity. 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. 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. The total amount of flight-activity is correlated with the duration of light (70 lux) in the 24 hr. period.