Preparatory entomological surveys for full-scale tsetse-fly control, assisted with a geographic information system: PATTEC case in Burkina Faso

Abstract

A geographic information system is a helpful tool for the defi­nition of a control plan against tsetse. Its practical application in entomological data collection for the planning and future evaluation of tsetse control was carried out in Western Burkina Faso from December 2007 to November 2008. The sampling area was selected according to the main rivers basins and the limits of Glossina palpalis gambiensis and G. tachinoides dis­tributions. The study area was gridded in 100-kilometer-square cells. In each cell a maximum of 13 potential trapping sites were selected, then spotted in the field by using a global posi­tioning system. The entomological survey was carried out with biconical Challier-Laveissière traps collected 72 hours after their installation. The data analysis was performed with binomial mixed random and Poisson distribution models. Mapping was carried out with Arc GIS 9.3 to help to deter­mine the Northern limit (12° 45’ N) of tsetse distribution in the target area. The proportions of infested sites were 89.6 and 76.4% on the ascending and descending sections of Mou­houn River, respectively (the first flows northeastward from the spring, and the second southeastward, then southward from the confluence with Sourou River), and 16.7 and 10.3% on their tributaries, respectively. Between isohyets 700–800 and 800–900 m no significant differences were observed in tsetse apparent density per trap or in the infested sites. Both trapped species were however distributed unevenly depending on the sections of Mouhoun River. On the ascending branch G. p. gambiensis represented 79.5% of tsetse catches, and on the descending branch G. tachinoides represented 96.0% of them. Catches of mechanical vectors were relatively few. Their distri­butions were similar to that of tsetse but with higher densities on some tributaries.