CIRCADIAN ACTIVITY PATTERNS IN 3 SPECIES OF TSETSE-FLY - GLOSSINA-PALPALIS, AUSTENI AND MORSITANS

ABSTRACT. Observations on the nature and control of spontaneous flight activity in tsetse flies have so far been made only on G. m. morsitans Westw. This paper reports preliminary observations of the same kind on two other species: G. p. palpalis (R.‐D.) and G. austeni Newst. The flight pattern of all three species consisted of short bursts of activity (usually lasting <1 min) separated by long intervals of rest, changes in activity level occurring exclusively as changes in the frequency of these flight bursts. In constant conditions in LD 12:12, G. palpalis and G. austeni were almost totally diurnal, with strongly predominant afternoon activity peaks, but a slight tendency to decrease activity around noon as occurs to a much greater extent in G. morsitans. This rhythm persisted in constant darkness (DD), but whereas in most G. morsitans only the morning peak was retained in DD, in G. palpalis and G. austeni it was only the afternoon peak. The loss of the afternoon peak in G. morsitans may be due to the very low activity levels in DD. Food deprivation led to increased activity in all three species, most markedly so in G. palpalis and G. austeni, in which the amount of activity per day increased c. ten‐fold over three days' post‐emergence starvation. Copyright © 1979, Wiley Blackwell. All rights reserved