The study was executed from November 2019 to December 2020 in the different districts of the cotton zone (Kandi, Bantè, Dassa and Savè) of North Benin. All sites in this zone are characterized by heavy use of insecticides (carbamates, organophosphates and pyrethroids) against cotton pests. With the "Dipping" method, larvae of An. gambiae s.l. were collected. The efficacy of seven different types of LLINs incorporated with pyrethroids was evaluated on populations of susceptible Kisumu and wild mosquitoes.

After exposure of the kisumu strain to different types of conventional nets (Olyset-Net, Permanet 2.0, Yorkool, Dawa Net and Aspirational), a knock-down effect greater than 95% is induced after just fifteen (15min) minutes of observation or with the different strains in the field, a decrease in the kd and mortality rate is observed in all districts. Unlike conventional nets, new generation nets significantly increase the kd effect and mortality rate on field strains. These results show that detoxification enzymes through mixed function oxidases are strongly implicated in the resistance of An. gambiae s.l. to pyrethroids in these sites.

From these results, we can say that the new generation nets (Olyset-Net plus and Permanet 3.0) are a solution for the NMCP in its fight against An. gambiae s.l. in these districts.