Status and Genes Involved in Insecticide Resistance in Anopheles gambiae Sibling Species in Lomé, (Togo), West Africa

Abstract

Malaria vector control relies on mosquito susceptibility to insecticides. Nowadays, the phenomenon of mosquitoes’ resistance to insecticides is growing wider and wider, including all chemical families of insecticides. In order to update data on the insecticides susceptibility, the species’ distribution and genes involved in insecticide resistance in Anopheles in the capital of Togo, we tested local strains of An. gambiae s.l. from three study sites in Lome, with five insecticides namely DDT, Permethrin, Deltamethrin, Bendiocarb, and Fenitrothion. The tests had been performed with the WHO kits from 2013 to 2015. The results of the tests showed mortality rates of 16.0% with 4% DDT, 28.0% with 0.75% Permethrin, 33.0% with 0.05% Deltamethin, 44.0% with 0.1% Bendiocarb and 98.8% with 1% Fenitrothion. The major malaria vectors were shown, across all sites, to be resistant to all of the classes of insecticides used in the experiments except Fenitrothion. PCR analyses for the species’ identification showed, proportions of 81% of An. gambiae s.s. and 19% of An. coluzzii in the city. For the Kdr gene, PCR analyses showed proportions of 57.94% RR, 33.33% RS and 8.73% of SS, revealing a high prevalence of kdr resistance in the Anopheles population in Lome. However, analyses showed mosquitos without Ace1R gene. The multiple resistance to various insecticides is a major concern for the control of malaria and other vector-borne diseases in Lome, as well as in Togo.