Susceptibility status of Anopheles arabiensis (Diptera: Culicidae) commonly used as biological materials for evaluations of malaria vector control tools in Madagascar

BACKGROUND: Madagascar is a malaria-endemic country with an increase in cases in recent years. In vector control using insecticide, a susceptible strain is necessary to evaluate insecticide efficacy, either for spraying or on nets. The susceptibility of Anopheles arabiensis from Antananarivo, Madagascar to two organophosphate, three pyrethroid, two carbamate, and one organochlorine insecticides was investigated. Since 2010, An. arabiensis strain has been maintained away from insecticide source during 110 generations with optimal insectarium conditions. METHODS: Bioassay were performed on adult mosquitoes to assess the susceptibility of An. arabiensis to insecticide-impregnated papers (malathion 5 %, fenitrothion 1 %, deltamethrin 0.05 %, permethrin 0.75 %, alphacypermethrin 0.05 %, bendiocarb 0.1 %, propoxur 0.01 %, and DDT 4 %) following World Health Organization Pesticide Evaluation Scheme guidelines. Bioassay using Center for Disease Control bottle tests were also used to detect mortality. Molecular assay were carried out to detect the presence of knock down resistance (kdr) mutation using PCR techniques. RESULTS: Anopheles arabiensis is fully susceptible with 100 % mortality to malathion, fenitrothion, deltamethrin, permethrin, alphacypermethrin, bendiocarb, propoxur, and DDT. No kdr gene was detected using PCR method. CONCLUSION: The strain An. arabiensis maintained in the insectarium of Institut Pasteur de Madagascar is a fully susceptible strain and can be used for insecticide evaluation.