TITLE:
Resistance Status of Various Populations of Anopheles gambiae s.l. to Insecticides and Resistance Mechanisms Involved in Different Crop Zones of Benin (West Africa)
AUTHORS:
Serge Akpodji, Arsène Fassinou, Clement Agbangla, Zinsou Come Koukpo, André Sominahouin, Esdras Odjo, Olivier Oussou, Germain Gil Padonou, Martin Akogbéto
KEYWORDS:
Anopheles gambiae s.l., Benin, Resistance, Insecticide, Growing Areas, Gene
JOURNAL NAME:
Advances in Infectious Diseases,
Vol.15 No.2,
April
25,
2025
ABSTRACT: The resistance of An. gambiae s.l. to pyrethroids remains a major concern. The development and use of alternative insecticides seems to be the solution. At the same time, monitoring of the susceptibility of these mosquitoes to insecticides needs to be stepped up. The aim of the present study is to investigate the resistance status of various Anopheles gambiae s.l. populations to insecticides and the resistance mechanisms involved. Ten localities, divided into four growing zones, were studied in Benin. Larval surveys were carried out during the 2021-2023 rainy seasons. Larvae were reared at the insectarium of the Centre de Recherche Entomologique in Cotonou. Adult females aged 2 - 5 days were morphologically identified and subjected to 4 insecticides including pirimiphos-methyl 0.5%, bendiocarb 0.01%, deltamethrin 0.05% and alphacypermethrin 0.05%; and the impact of pre-exposure to PBO measured in accordance with WHO protocols. L1014F and G119S mutations in the Kdr and Ace1 genes were determined by PCR. Pyrethroid mortality rates ranged from 2.88% to 39.19% for An. gambiae s.l. populations in all growing areas. Pre-exposure to PBO increased pyrethroid mortality. The results also show phenotypic resistance to bendiocarb in the lagoon zone and suspected resistance in the cereal, cotton and rice-growing zones. As for pirimiphos methyl, we noted sensitivity in the cotton zone, suspected resistance in the rice zone and resistance in the cereal and lagoon zones of the different Anopheles gambiae s.l. populations. A significant difference was observed in the distribution of L1014F, which ranged from 76.58% to 82.33% in our crop zones, while no significant difference was observed in the distribution of G119S, which ranged from 3.52% to 4.86%. The resistance of An. gambiae s.l. to pirimiphos-methyl, bendiocarb, deltamethrin and alphacypermethrin, as well as the relatively high frequency of the kdr mutation, call for the development and implementation of measures for effective insecticide resistance management.