Insecticide Susceptibility status of An. gambiae s.l. (Culicidae: Giles) from selected in-land and coastal agricultural areas of Ghana

Abstract

Malaria, a mosquito-borne disease is preventable and treatable, provided the right steps are taken to control it; it is regarded as today’s biggest killer of children in Africa. In Ghana, A. gambiae s.l. plays an important role in the transmission of this disease. This study investigates the insecticide resistance status of A. gambiae s.l. collected from two different agricultural areas: Coastal and In-land in Ghana. Samples of Anopheles larvae were collected and reared to adults, after which susceptibility tests were performed on F1 female A. gambiae s.l. using standard WHO insecticide testing procedures by exposing the mosquitoes to Bendiocarb 0.1%, DDT 4.0%, Alphacypermethrin 0.5% and Pirimiphos methyl 5.0% at diagnostic doses [1]. Knock down and mortality counts at different time intervals were further carried out on the samples. Both populations of An. gambiae s.l. from Inland and coastal areas were resistant to all tested insecticides. However, the Coastal, Korle-Bu population was more resistant to Alphacypermethrin (12.2% mortality) and DDT (71.1% mortality) than the coastal, Okyereko population, 50% and 10% for the same insecticides respectively. Mortality (245hr) was higher in Korle-Bu than in Okyereko. With the exception of Pirimiphos methyl and Bendiocarb, resistance of A. gambiae s.l. from the inland areas to all the insecticides was significantly higher than the coastal areas although vegetable growing is practiced in both areas. Information on the resistance mechanisms and species composition underlying the pattern of resistance in both areas is recommended.