Spatial Distribution and Ecological Determinants of Tsetse Flies in Trypanosomiasis-endemic Regions of Mali

Abstract

Tsetse flies are harmful to humans and animals through their bites and infestations. Their distribution depends on the presence of vegetation and forest patches, etc. Visiting resting places, hunting grounds, or breeding grounds is a means of contact between human, animal, and insect populations. It encourages host–vector encounters and thus pathogen exchanges among humans, wildlife, and the environment. Controlling these insects considerably reduces their nuisance and breaks the pathogen transmission chain. Knowledge of the diversity of tsetse species and the main determinants of their geographical distribution is necessary to effectively combat this scourge. This study was initiated to determine the distribution of tsetse flies and identify the main species currently present in Mali. The 4 regions endemic for trypanosomiasis in Mali (Kayes, Koulikoro, Sikasso and Ségou) were selected for capture. In each region, 10 captures sites were randomly selected. The captures occurred from March to December 2020. The traps were placed on the banks of watercourses, in galleries, and in the Savannah. They were installed for 48 h and renewed every 24 h. A total of 1353 tsetse flies were captured, including 270 in Kayes, 527 in Koulikoro, 554 in Sikasso, and 4 in Ségou (p = 0.009). Two riparian species were identified, and no Savannah species were recorded. Tsetse flies were heterogeneously distributed. All sites in the Sikasso region recorded the presence of at least one tsetse fly (100%), while distribution was 80, 40 and 30%, respectively, in the Koulikoro, Kayes, and Ségou regions. These results show that tsetse flies are still present in these regions, albeit with an uneven distribution. A positive correlation was established between diversity and environmental parameters (<0.05).