The effects of deltamethrin 'pour on' control technique on glossina pallidipes austen population structure and incidence of trypanosomiasis in cattle

Abstract

A field trial was carried out in Galana ranch to assess the use of deltamethrin 'pour on' technique for the control of Glossina pallidipes. In Dakabuku (experimental area) 1167 Orma Boran steers were kept and treated with the insecticide (deltamethrin) every two weeks. Fly suppression was monitored using biconlcal traps baited with acetone and phenols. Incidence of trypanosomiasis in cattle was monitored every week by haematocrit centrifugation technique and Buffy Coat Examination (Murray et a/1977). The Packed Cell Volume (PCV) of cattle were measured and the infecting trypanosome species Identified by their morphology and mortility. In Kapangani (control area) which is 10 Km away, 100 Boran steers were kept and the trypanosomiasis incidence in cattle and tsetse population density were monitored in a similar way. In Dakabuku, fly population density declined from a mean of 350 fly/trap/day (f/t/d) to less than 10 f/t/d by the end of the study period. The berenil index in cattle in Dakabuku was also low (less than 2% and sometimes 0 by the end of the study period) compared to that of cattle in Kapangani which was high throughout the study period (between 4% and 12%). However, trypanosome infection rates in tsetse in the -two areas were not significantly different (2.50% and 2.70% in Dakabuku and Kapangani respectively). In Dakabuku the average age of <.: female tsetse was higher than in Kapangani for mostof the study period; which may explain the lack of a significant difference In the trypanosome infe~ction rates. By the end of the study period tsetse challenge in Dakabuku was much lower than in Kapanganl as a result of low population density of tsetse. This led to a low trypanosome transmission rate in cattle in that area (Dakabuku) and hence the low incidence of trypanosomiasis in cattle.