The hosts and trypanosome infection rates of Glossina pallidipes in the Lambwe and Roo valleys

Abstract

Several thousand Glossina pallidipes flies were dissected to determine trypanosome infection rates in the Lambwe Valley and to collect information on the hosts of this tsetse. A total of 1 450 (19.3%) flies had mature trypanosome infections but the rate varied between 9.6% and 30.9% in the Lambwe Valley. In the Roo Valley the rate was 19.7-28.6%. Blood-meal squashes from tsetse collected in the Roo Valley and Obaluanda areas and in the Ruma, Otuok, and Rari thickets showed that the important hosts were bushbuck and bushpig. Analyses showed that T. brucei subgroup infection rates in the Roo Valley near two small dams (3.7% and 4.0%) were higher than might have been expected; in another part of the Roo Valley the rate was only 0.8%. To account for such a large difference it is concluded that the dissecting techniques were probably at fault, leading to an overestimation of T. brucei subgroup infection rates in the Roo Valley tsetse. In the main Lambwe Valley there was a tendency for the tsetse trypanosome infection rates to increase towards the southern part of the valley where game animals were numerous and readily available to tsetse in the favourable thicket habitats.