Circadian flight activity in four sibling species of the Anopheles gambiae complex (Diptera, Culicidae)

Circadian flight activity in the males and females of Anopheles gambiae Giles species A and B, A. melas (Theo.) and A. merus Don. has been investigated using the acoustic actograph technique. In each species the pattern and timing of activity in males and females is almost identical. Cyclical activity continues in constant dark; the period of the cycle is approximately half-an-hour shorter in A. gambiae species A and half-an-hour longer in A. merus than in the other two species. In alternating 12 h light: 12 h dark, both sexes are active during the dark period, with peaks of activity following light-off and light-on. After light-off, the species become active in the following order: A. gambiae species A, A. melas, A. gambiae species B, A. merus. A. merus is approximately 20 min later than species A.