Susceptibility status of the malaria vector, Anopheles arabiensis to insecticides used in vector-borne diseases control in areas with heterogeneous sources of pollutants in South-East Tanzania

Abstract In malaria-endemic countries, monitoring of insecticide resistance in malaria vectors in areas contaminated with different sources of pollutants is still lacking. This study investigated insecticide resistance and its mechanisms in Anopheles arabiensis across four villages in Southeast Tanzania. Mosquitoes were collected from breeding habitats and tested against permethrin, deltamethrin, lambda-cyhalothrin, pirimiphos-methyl, and bendiocarb. Mechanisms of resistance [P450s enzymes and knockdown resistance (kdr)] were investigated. Comparison of mosquito mortality between sites was performed through one-way analysis of variance (ANOVA) and Tukey–Kramer tests. Anopheles arabiensis was highly resistant to pyrethroid and fully susceptible to bendiocarb and pirimiphos-methyl with mortality ranges of 29%−57%; 37%−65%; 34%−53%; 98%−100%; and 100% in permethrin, deltamethrin, lambda-cyhalothrin, pirimiphos-methyl, and bendiocarb respectively. Anopheles arabiensis mortality, particularly, in permethrin and deltamethrin was significantly higher in less polluted areas (Mofu and Namwawala) p < 0.001 as compared to areas with agrochemicals (Minepa) and domestic pollutants (Ifakara town) (p < 0.01). Moreover, significant involvement of P450s enzymes in pyrethroid resistance was observed while kdr mutations were not detected. The present study shows that pollution of mosquito breeding habitats might accelerate insecticide resistance which could impede the control of malaria vectors.