<i>Anopheles gambiae s.l.</i> insecticide susceptibility status in Umudike, Ikwuano LGA, Abia State, Nigeria

This study was conducted in order to determine the insecticide susceptibility status of Anopheles gambiae in Umudike, Abia State, Nigeria. Larval and pupal stages of An. gambiae mosquitoes were collected from different points within Umudike, and reared to adult stage in the laboratory. The adults that emerged were tested on four types of WHO bioassay test papers impregnated with recommended diagnostic concentrations of 4% DDT (Organochlorines); 0.1% bendiocarb (Carbamates); 0.25% Primiphos-methyl (Organophosphates); and 0.05% Deltamethrin (Pyrethroids) procured from National Abovirus and Vector Research Institute Enugu. Twenty 10% sugar solution fed female Anopheles gambiae mosquitoes aged 3-5days were used for the bioassay which was replicated four times with two control of same population without insecticide treatment. Knockdown was recorded at five minutes post-exposure, and then at 10 minutes interval for 1 hour and then maintained for 24 hours post-exposure on 10% sugar solution, after which a final mortality was recorded. The Knockdown Times (KDT50 and KDT90) were determined by Probit analysis. An. gambiae was resistant to DDT, primiphos-methyl and Deltamethrin with 24 hours post exposure percentage mortalities of 4.65, 11.85, and 24.83 respectively.In contrary the mosquitoes were susceptible to bendiocarb which killed 98.88% of the mosquitoes 24 hours after exposure. Bendiocarb is hence recommended as the most effective insecticide for the control of Anopheles gambiae in Umudike, while there were need for the investigation of the mechanism behind the resistance displayed by this mosquito. Furthermore, routine surveillance of insecticide susceptibility/resistance in mosquito population is advocated in line with integrated vector control strategy. Keywords: Insecticide; susceptibility; Anopheles gambiae; Umudike; Abia State; Nigeria