Effects of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) sex Pheromone on behaviour of males in field and laboratory

Abstract

AbstractMore adult males of Glossina morsitans morsitans Westw. were caught with hand nets in Tanzania from a man-carried dark screen baited with surrogate female decoys impregnated with synthetic 15,19,23-trimethyl-heptatriacontane (the G. m. morsitans sex pheromone) than from a screen bearing unimpregnated decoys or from a screen alone. A similar pattern was obtained with G. pallidipes Aust., but the variations in numbers of both species caught within and between fly-round sectors were large. Although many G. m. morsitans males attracted to the screens visually were seen to engage in copulatory activity with pheromone-impregnated decoys, none of the G. pallidipes so attracted was seen to do so. It is therefore concluded that catches of G. m. morsitans were not improved by the presence of pheromone-baited decoys on visually attractive screens. Copulatory behaviour was frequently interrupted by other flies and/or the flies flew off as soon as the screen ceased to move. Of the G. m. morsitans males attracted to a baited screen on the back of a slowly moving vehicle, 51% were seen to have alighted on the impregnated decoys and 42% were engaged in copulatory behaviour with the decoys immediately after the vehicle stopped. Copulatory responses of wild male G. m. morsitans to pheromone-impregnated decoys in glass tubes approximated those of laboratory-reared males only after confinement for several hours at low light intensity. Contamination of laboratory-reared male G. m. morsitans with synthetic pheromone elicited prolonged male:male copulatory behaviour. Prospects for the use of the G. m. morsitans sex pheromone in population studies or control programmes are discussed.