Trypanosome infection rate of Glossina pallidipes during wet and dry seasons in Somalia.

Using biconical traps the distribution, population composition, insemination rate, pregnancy, age structure and trypanosome infection rate of G. pallidipes were studied during the wet season 1982 and the dry season 1983 at Mareerrey Somalia. Flies restricted to the riverine gallery forest in the dry season become dispersed into approximately 1 km of the Acacia thickets in the wet season. There was no significant variation in population components of G. pallidipes between wet and dry seasons. The male:female ratio remained at 0.5:1 in both seasons. The insemination rate of females was significantly high during the wet season. Pregnancy stages were not statistically different between the two study periods. A significantly greater proportion of females that were below age category 4 were found in the wet season. The trypanosome infection rate was 2.6% and 1.5% in the wet and dry seasons respectively. Flies were found infected with only the vivax and congolense group trypanosomes. A linear positive correlation existed between the trypanosome infection rate and the physiological age of females.