Sub-Lethal Pyrethroid Exposure at the Larval or Adult Life Stage and Selection for Resistance in the Major African Malaria VectorAnopheles funestus(Diptera: Culicidae)

Abstract

Malaria vector control by indoor residual spraying (IRS) in South Africa currently relies on the use of DDT to control pyrethroid-resistant populations of the major malaria vector Anopheles funestus. Pyrethroid resistance in An. funestus in South Africa and Mozambique is primarily based on the over-production of monooxygenase P450 genes. Preliminary evidence suggests that the pyrethroid-resistant phenotype is primarily expressed in adults, raising questions as to how resistance was selected for in the field given that there was no malaria control targeting adults in southern Mozambique when this resistant phenotype was first discovered there. The aim of this study therefore was to select for pyrethroid resistance at the larval or adult stages in southern African An. funestus and then assay the pyrethroid susceptibility of subsequent life stages using samples of progeny from the pyrethroid-resistant selections. There was no significant variation between the lethal permethrin concentrations inducing 50% mor...