Susceptibility status of Anopheles gambiae s.s. and An. coluzzii to Organophosphates and Carbamates in the Agricultural Exploitation Zones of oil Palm at Mouila, Gabon

Abstract

This study was conducted during the rainy season of 2017 in the agricultural areas at Mouila, with the aim to assess the determination of susceptibility of Anopheles gambiae complex to insecticides and the detection of Ace 1R mutation. Mosquito larvae were collected by using the dipping method and nursed to adult stage. The susceptibility of adult Anopheles gambiae s.l. populations to organophosphates and carbamates was assessed using the standard WHO susceptibility test protocol. The tested mosquitoes species were identified by PCR. These tested mosquitoes were used to search for the Ace 1R mutation. The insecticides used were pirimiphos-methyl 0.25% and 1.25%, fenitrothion 1%, malathion 5%, propoxur 0.1%, bendiocarb 0.1%, 0.5% and 1%. In the prospected areas, An. gambiae s.l. included An. gambiae s.s. and An. coluzzii sympatric in their larval habitats. However, An. gambiae s.s. was predominant in all studied areas (99.1%) comparatively to An. coluzzii Moreover, the susceptibility tests of Anopheles to organophosphates and carbamates revealed mortality rates of 100% regardless of the origin of the mosquitoes. PCR diagnosis of Ace 1R mutation showed that none tested mosquito (An. gambiae s.s. and An. coluzzii) from prospected areas harbored the Ace 1R gene in all prospected areas. The lack of Ace 1R mutation in An. gambiae s.l. reveals the current effectiveness of organophosphates and carbamates for the control of these mosquitoes. Bboth these classes of insecticides could be used for the anopheline populations control in the agricultural spaces at Mouila.