Integration of insect sterility and insecticides for control of <i>Glossina morsitans morsitans</i> Westwood (Diptera: Glossinidae) in Tanzania. V. The impact of sequential releases of sterilised tsetse flies

Abstract

Abstract A field trial of the sterile insect technique was conducted in Tanzania using males of Glossina morsitans morsitans Westw. that were reared, irradiated and packaged at Tanga. The experimental site was a 195–km 2 area 110 km to the south. Following two applications of endosulfan as an aerosol at an interval of 28 days, irradiated puparia of G. m. morsitans were released twice weekly at stations distributed throughout the experimental site. Each of the 120 release stations was serviced every 14 days with puparia which produced sterile adults synchronously within 30 min after placement. Over the 15–month experimental period, an average of 81% control of G. m. morsitans was obtained, whereas G. pallidipes Aust., against which no releases were carried out, recovered to prespray levels within five months. The released sterile insects were found to be highly competitive and to survive well in the field. Immigration of indigenous flies from outside the perimeter barrier surrounding the experimental plot provided a continuous influx of fertile flies that provided the nucleus of the 19% residual population. Under operational conditions, the prevention of migration should result in the elimination of an indigenous G. m. morsitans population subjected to the combined stress of population reduction by two applications of endosulfan aerosols and sequential releases of sterile males.