Assessment of Level of Susceptibility of Anopheles gambiae S.L to Public Health Insecticides in a Malaria Vector Sentinel Site, Rivers State, Nigeria

Abstract

Aims: To investigate the status of susceptibility of Anopheles gambiae sensu lato (Diptera: Culicidae) mosquitoes to the WHO-approved insecticides for indoor residual spraying  in field collected samples in a malaria vector sentinel site in Nigeria and Ts to provide an update on the current status of resistance to the major insecticide classes in wild populations of Anopheles gambiae sensu lato Study Design: Field and laboratory –experimental design was used in this study. Place and Duration of the Study: The study was carried out at a malaria surveillance site, established by the National Malaria Elimination Programme at Oduoha-Emohua in Rivers State, between April to September, 2015.  Methodology: Anopheles larvae were collected from stagnant pools around the malaria surveillance site. The mosquitoes were reared to adulthood in the insectary and identified using morphological keys. Two- to three-day old adult female mosquitoes were exposed to standard diagnostic doses of Deltamethrin, Lambdacyhalothrin, Alphacympermethrin, Permethrin, Bendiocarb, Propoxur, DDT and   Premiphos-Methyl using standard WHO protocols, insecticide susceptibility test kits and treated papers. Knockdown every 10 min and mortality 24 h post exposure was noted. All Anopheles mosquitoes tested belonged to the Anopheles gambiae-complex. Results: Mortality results indicated that the vectors were susceptible to Bendiocarb and Alphacympermethrin with mortality rates of 100% and 98% respectively. There was complete resistance to Deltamethrin, Lambdacyhalothrin, Permethrin, Propoxur, DDT and Premiphos-Methyl with mortality ranges of 25%-65%. Conclusion: The present study shows the effectiveness of Bendiocarb and Alphacympermethrin in malaria control with indoor residual spraying. It also provides baseline information for monitoring the status of insecticide resistance in Rivers State.