Prospects for autosterilisation of tsetse flies, Glossina spp. (Diptera: Glossinidae), using sex pheromone and bisazir in the field

Abstract

In the presence of the odour of carbon dioxide and acetone, an electrified net adjacent to a stationary cylindrical black model in the Zambezi Valley, Zimbabwe, in the hot dry season caught more adults of Glossina morsitans morsitans Westw. and G. pallidipes Aust. than in the absence of odour. In the absence of odour, a moving model attracted more G. m. morsitans males than did a stationary model. Between 20 and 50% of males of G. m. morsitans but only 0 to 12% of males of G. pallidipes near a model were caught by electrified decoys (surrogate females) on the model. Hidden observers recorded the numbers of flies copulating with decoys baited with pheromone or pheromone plus bisazir (P, P-bis(1-aziridinyl)-N-methylphosphinothioic amide) on a stationary model with odour between 16.00 and 19.00 h daily. Males of G. m. morsitans contacted the decoys with much greater frequency than did males of G. pallidipes although the latter species was the more abundant. The numbers of copulatory attempts by G. m. morsitans males during each 10 min suggested that changes were a function of the total numbers of flies attracted to the model. At all times of the day, the average duration of copulation was 37–40 s. However, approximately 50% of responses were of 10 s duration or less and fewer than 10% endured for longer than 3 min. The presence of bisazir on the decoys did not influence the response duration or the total numbers of flies responding. A comparison with laboratory data suggested that further refinement of technique will allow pheromone-baited decoys to be used in the autosterilisation of G. m. morsitans males with bisazir in the field.