The changing distribution of two riverine tsetse flies over 15 years in an increasingly cultivated area of Burkina Faso

Changes in the distribution of two riverine tsetse flies, Glossina tachinoides Westwood and Glossina palpalis gambiensis Vanderplank are described in an agropastoral area of Burkina Faso subject to increasing human population pressure and land use change. Two similar entomological surveys (one trap every 100 m, 120 km of river) were conducted in 1981 and 1996. Changes in tsetse distribution were compared to land use changes through high resolution remote sensing imagery (LANDSAT, SPOT). There was a close relationship between proximity of crops relative to riverine forest and the density of Glossina. Where fields encroached on riverine vegetation, tsetse populations declined. Where the geomorphological structure was not well suited to agricultural activity, riverine vegetation and tsetse fly populations were relatively unaffected, even with intense agricultural activity nearby. In contrast, increased human activity and higher cattle densities in the surrounding savannah areas were associated with increased tsetse numbers. The results demonstrated a wide diversity of tsetse distribution and habitat within a few kilometres in an agro-pastoral landscape in West Africa.