Identification of the knockdown resistance (Kdr) mutations in Anopheles gambiae s.l. in the Mouila area, Southwest Gabon

In Gabon, members of the Anopheles gambiae complex are the reference vectors of Plasmodium falciparum. In Libreville and Port-Gentil, anopheles found resistant to organochlorines and pyrethroids. This resistance was related to the presence of the Kdr-east and Kdr-west genes. Otherwise, mechanisms of resistance in mosquitoes are still poorly known in Gabon. This study reports the situation of insecticide resistance and underlying mechanisms in An. gambiae s.l. populations from palm oil plantations from Mouila. All the anopheline populations tested showed resistance to almost all insecticides except organophosphates and carbamates families, which remain the only lethal molecules. Molecular identification of specimens revealed the presence of An. gambiae s.s. An. gambiae s.s. (93.14%) and An. coluzzii (6.86%). Kdr genotyping showed the presence of the L1014F mutation (kdr-West) as well as L1014S (kdr-East). This L1014F mutation was found at very high frequencies (0.99) in almost all sites surveyed, and in association with the L1014S (0.20). Results showed the mechanisms, which confer pyrethroids and organochlorines resistance to An. gambiae s.l. from Mouila area. These data, although preliminary, stress the need for monitoring of An. gambiae s.l. populations of these agricultural zones for a suitable insecticide resistance management system and vector control.