Knockdown times in a simple assay determination of insecticide resistance in malaria vectors.

ABSTRACT

BACKGROUND: Determining the insecticide resistance status of malaria vectors, particularly to insecticides used on mosquito nets, is important but is limited to a relatively small number of locations. We describe a simple assay that enables this information to be obtained over a much wider area. METHODS: The time to knockdown of mosquitoes in an insecticide-treated netting-covered metal frame cage were recorded. The shape of the curve of the proportion of knocked down mosquitoes provides information on resistance status. RESULTS: Resistant Anopheles funestus took significantly longer for knockdown than did susceptible Anopheles arabiensis. CONCLUSIONS: This simple technique will enable a wide range of locations to be sampled, enhancing our understanding of the spread of resistance to pyrethroids.