Combining Piperonyl Butoxide and Dinotefuran Restores the Efficacy of Deltamethrin Mosquito Nets Against Resistant Anopheles gambiae (Diptera: Culicidae)

One strategy suggested for the management of mosquito insecticide resistance consists of combining a pyrethroid with an insecticide that has a different mode of action. To restore the efficacy of deltamethrin (pyrethroid) against pyrethroid-resistant strain of Anopheles gambiae Giles (VKPR: homozygous Kdr), deltamethrin was combined with the neonicotinoid insecticide dinotefuran and piperonyl butoxide (PBO). Bednets impregnated with deltamethrin, dinotefuran, and PBO alone and in combination were tested in the laboratory. Knockdown (KD) and mortality were measured using WHO cone tests on susceptible and pyrethroid-resistant adult mosquitoes. The combination of deltamethrin and PBO was synergistic against resistant female An. gambiae (58.2% mortality). Both mortality and knockdown time (KDt(50/95) values) of the tricomponent mixture on the VKPR strain were similar to the insecticidal activity of deltamethrin on the pyrethroid-susceptible KIS strain (98.8 and 100% mortality, respectively). The three-compound mixture of deltamethrin + PBO + dinotefuran showed an insecticidal efficacy greater than the deltamethrin + PBO mixture to the extent of completely restoring the efficacy of deltamethrin on pyrethroid-resistant An. gambiae.