Conclusion
This study identified a 4.3kb transposon-containing structural variant on chromosome 2 within a cluster of cytochrome P450 genes in Ugandan and Cameroonian populations of Anopheles funestus and showed it to be: associated with pyrethroid resistance, associated with enhanced expression of nearby P450 genes; rapidly evolving under strong selection in Cameroon and is spreading westward in Africa. This study shows how genetic variation, such as transposable elements, can contribute to adaptive changes and be rapidly selected in the mosquitoes carrying them. The molecular assay designed here will facilitate the detection and tracking of the spread of this transposon-based resistance and help assess its impact on control intervention and malaria transmission.