Sex recognition pheromone in tsetse fly Glossina morsitans

Abstract

ATTEMPTS to identify a sex attractant substance in tsetse flies have failed because there seems to be no olfactory agent for sex recognition^1,2. Males are apparently sexually activated only by movement of the female, but the adverse effects of naturally occurring low population densities³ on mating frequency is overcome as both sexes encounter one another at relatively high density around host animals¹. Experience in the laboratory confirms that sexual arousal in male tsetse flies, Glossina morsitans morsitans (Westwood), is initiated by movement of other individuals. Thus, mature adult males will initiate sexual behaviour in the absence of females and the level of activity is increased if the flies are disturbed. This behaviour ceases, however, as soon as physical contact is made with the target male. It seems unlikely that a sexually aggressive male would rely on rejection or acceptance by its target in order to distinguish females of its own species, and in view of the discovery of a short range sex pheromone in the housefly Musca domestica L.^4–7, an attempt has been made to demonstrate the existence of a positive sex recognition pheromone in G. morsitans.