Maturation of the tsetse fly Glossina pallidipes (Diptera: Glossinidae) in relation to trap‐orientated behaviour

Abstract

ABSTRACT The fat free dry weight or residual dry weight of the thorax (Trdw) increased linearly for the first 10 days of adult life in both sexes of G.pallidipes in the laboratory as their flight muscles developed. Using ovarian dissection to estimate the ages of nulliparous adult females of G.pallidipes, the Trdw was also found to increase linearly for at least 14 days in the field. Significant increases in pteridine fluorescence with age were measured in both laboratory‐reared males and females of known chronological age and in wild‐caught nulliparous females whose ages were estimated by ovarian dissection. A linear relationship existed between pteridine fluorescence and wing fray category for a wide range of ages of field‐caught flies of both sexes. A stationary trap baited with ox odour was selective in that only the hungrier portion of the flies attracted to it actually entered. However, it was not selective in terms of the mean ages of flies caught. Comparisons were made of the age compositions of catches of both sexes of G.pallidipes attracted to a stationary trap baited with synthetic odours or to a mobile electrified net by plotting Trdw values against pteridine fluorescence. Nulliparous females were not attracted to the stationary trap, but were attracted to the mobile bait. Males of all ages appeared to be equally attracted to both. It is concluded that nulliparous females do not respond to host odour stimuli until they are ready to mate, perhaps relying on the energy‐conserving strategy of watching for a moving host animal before attempting to feed. Alternatively, synthetic odours may differ from natural host odours in terms of their attractiveness to young females. Males, however, probably exhibit dual sexual and feeding behaviour by responding to an odour‐baited stationary trap even when young.