Integration of insect sterility and insecticides for control of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) in Tanzania. III. Test site characteristics and the natural distribution of tsetse flies

Abstract

Detailed data from a preselected release site in Tanzania were collected preparatory to testing the insect sterility concept against Glossina morsitans morsitans Westw. The site was at Mkwaja Ranch, a north-eastern coastal cattle-ranching enterprise, in which about 195 km 2 was encompassed by a 1-km-wide fly barrier constructed at an average cost of $37/ha. Weekly surveys of flyround transects spaced 1 km apart were conducted over a 14-month period. The estimated male density of G. m. morsitans in the release site was about 630/km 2 and for G. pallidipes Aust., 255/km 2 . The only other species of tsetse found was G. brevipalpis Newst., which was restricted to drainage areas during periods of low rainfall.

Integration of insect sterility and insecticides for control of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) in Tanzania. IV. Application of endosulfan as an aerosol prior to release of sterile males

“…The overall effect of the combined use of aerosols of endosulfan and sterile insect releases is presented in the last report of this series (Williamson et al, 1983). The high level of efficiency achieved by insecticides with dense populations effectively complements the high level of efficiency expected of sterile insects when the population is low.…”

“…The characteristics of the Mkwaja Ranch test site with regard to the present study were described by Gates et al (1983). Ford & Blaser (1971) discussed this cattle ranching operation and the impact of animal trypanosomiasis, although they were not aware of the presence of G. m. morsitans at that time.…”

“…Ten representative flyround transects (totalling about 58 km) were monitored once before and once after each spray application by three-man teams equipped with a conventional black cloth screen. This procedure had been in use for more than a year previous to the control operation (Gates et al, 1983). An adjacent control area was also surveyed, although it was not encompassed by a fly barrier as was the test site.…”

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

“…The ranch maintained about 12 000 cattle in an area populated by numerous game animals. A full description of the experimental and control areas is reported in Gates et al, 1983. The experimental area consisted of about 195 km 2 of ranch land bordered by a sheer-cleared 1-km-wide barrier clearing, designed to inhibit fly migration.…”

“…The dynamics of the two main tsetse species were monitored for 14 months prior to the initiation of the experiment; the apparent density (based on the total number of teneral and non-teneral males collected per 10 km) was determined weekly during this period, and the distribution of the flies throughout the ranch was ascertained (Gates et al, 1983). In November 1977, the first of two aerial sprays of endosulfan at 20 g/ha as an aerosol was applied (Williamson et al, 1983c), setting the stage for sterile male releases and an assessment of SIT.…”