Susceptibility of Aedes aegypti mosquitoes to pyrethroid insecticides and characterization of breeding habitats in selected districts of Mwanza, Tanzania

Abstract Background Tanzania has experienced outbreaks of dengue fever in major cities. The main vectors of the dengue virus in Tanzania are Aedes aegypti mosquitoes. The control of this mosquito vector is based on insecticide, and yet, the insecticide susceptibility of this species is not well known in many places in Tanzania. Conversely, the breeding habitats mostly preferred by this species are not well documented in the study area. Therefore, the present study aimed to determine the pyrethroid insecticide susceptibility status and breeding habitats preference of Ae. aegypti mosquito in the three sites from three districts in Mwanza, Tanzania. The assessment of Ae. aegypti mosquito 24-h percentage mortality was based on WHO criteria. Results A total of 850 Ae. aegypti were exposed to three pyrethroid insecticides. In Bwiru site, 100% mortality was observed for all three pyrethroids, indicating full susceptibility. At Igekemaja and Mwagagala villages, Ae. aegypti were resistant to all the three pyrethroid insecticides tested. In Igekemaja, there were variations in Ae. aegypti mortality rates induced by different insecticides, with mortality rates ranging from 72% for alphacypermethrin to 86% for deltamethrin. Although the mortality rates were lower than in Bwiru site, they were still substantial and statistically significant. The mortality rates in Mwagagala were lowest across the three insecticides, with mortality rates ranging from 60% for deltamethrin to 86% for alphacypermethrin. In Mwagagala, the Ae. aegypti mosquitoes were less susceptible to the insecticides tested. Aedes aegypti mosquito prefer breeding in abandoned old tires in urban area and in small containers and uncovered water storage containers in rural settings. Conclusion The study has revealed pyrethroid insecticide susceptibility status and breeding habitats of Ae. aegypti in the rural and urban settings in Mwanza, Tanzania. The study findings imply the need for public health interventions with focus on community education on mosquito control.