THE DISTRIBUTION OF THE TSETSE-FLIES GLOSSINA-MORSITANS-SUBMORSITANS AND G-PALPALIS-GAMBIENSIS (DIPTERA, GLOSSINIDAE) IN THE GAMBIA AND THEAPPLICATION OF SURVEY RESULTS TO TSETSE AND TRYPANOSOMIASIS CONTROL

A country-wide survey of the distribution of tsetse flies Glossina mor sitans submorsitans Newstead and G. palpalis gambiensis Vanderplank wa s carried out in The Gambia, during 1989-1990, using box traps at 1654 sites over an area of 10,000 km2. The general distribution of tsetse had changed little during the last 45 years. G. m. submorsitans was pr esent in dry, canopied woodland throughout most of the country, but wa s absent from an area south of the River Gambia stretching from the co ast to some 100 km inland. G. p. gambiensis occurred in evergreen fore st and woodland near the coast, and in riparian habitats along the len gth of the River Gambia and its major tributaries. Nowhere in the coun try was more than 20 km from tsetse-infested areas. Five major foci of G. m. submorsitans infestation were identified. Demographic, climatic and environmental factors affect tsetse populations in The Gambia, bu t it is expected that these foci of infestation will persist for at le ast the next 5-10 years. The numbers of tsetse trapped, expressed as r elative densities, were used to assess the extent and severity of loss es from trypanosomiasis to different categories of livestock. Survey r esults such as these could be used to assess whether control measures to reduce tsetse challenge are likely to be economically viable by usi ng techniques such as insecticide-impregnated targets, pour-ons or che motherapy.