FLYING TO FEED OR FLYING TO MATE - GENDER DIFFERENCES IN THE FLIGHT ACTIVITY OF TSETSE (GLOSSINA-PALPALIS)

To test the prediction that female and male tsetse should differ in th eir behaviour and the partitioning of their energy budgets to maximize their respective reproductive outputs, we investigated experimentally the relationship between blood intake, fat content and flight activit y in virgin and mated female flies, following the same procedure as in a previous study on males. Those flies whose fat content was raised t o higher levels by being fed more frequently performed more flight act ivity, but all females showed very little activity until day 4 after t heir last blood meal, thereby using only a small fraction of their fat reserves. This contrasted markedly with the large amount of flight pe rformed by males on day 3, resulting in the depletion of their fat res erves. The difference is interpreted with respect to females flying on ly to find food approximately once every 3 days (and larviposition sit es approximately once every 9 days), compared with males flying to fin d as many mates as possible during the earlier part of the feeding cyc le when their energy reserves are high and feeding is a low priority.