Effect of different doses of ivermectin on the survival and fecundity of Glossina palpalis gambiensis Vanderplank 1949 fed on treated cattle

Background Tsetse flies, (Glossina spp), are the main vectors of trypanosome parasites responsible for the the Human African Trypanosomiasis (HAT) and the African Animal Trypanosomosis (AAT), both of which remain significant obstacles to the socio-economic development of affected regions in sub-Saharan Africa. Several control strategies have been developed, among which, vector control plays a central role. To achieve the elimination of HAT and AAT, additional and integrated complementary control strategies, such as the ivermectin treatments of animals, need to be explored. Methods To assess the systemic insecticidal efficacy of ivermectin on the survival and fecundity of Glossina palpalis gambiensis , batches of tsetse flies were fed on 6 calves that were treated with three different doses of the drug: therapeutic dose (TD) of 0.2 mg/kg, two-fold TD, and four-fold TD. Two untreated calves were used as the control group. Results The TD and 2TD induced significant mortality of the tsetse flies up to 1 days post injection (DPI), with mortality rates varying from 59.82% to 90.43%. The 4TD caused a significant decrease of 55.09% of the survival of the tsetse flies up to 15 DPI (Z = -4.37; P < 0.001 ). The cattle treatments with ivermectin also resulted in a decrease of the number of pupae produced by tsetse flies, of 43.57% with the TD, and 92.47% with the 4TD. A delay from 9 to 13 days has also been observed in the deposit of the first larva, with the doses 2TD and 4TD at 1DPI and to 10 days with the dose 4TD at 8DPI. Conclusions The ivermectin treatments to animals against the common parasitosis have an additional effect against insect vectors like tsetse flies. Thus, mass treatments of farmed animals with ivermectin, may be considered in order to improve both human and animal health.