Evaluation of Insecticide Resistance in Aedes albopictus Population from Algiers, Algeria

Since its first detection in 2010, Aedes albopictus has spread across northern Algeria, where vector control relies on the use of chemical insecticides. This study aimed to evaluate the susceptibility of Ae. albopictus populations from Algiers to commonly used larvicides and adulticides, as well as to characterize the underlying resistance mechanisms. Eggs were collected from three sites in Algiers. The susceptibility of larvae to temephos and Bacillus thuringiensis israelensis (Bti), as well as that of adults to permethrin, deltamethrin, malathion, and bendiocarb was evaluated using WHO bioassays. Genotyping of knockdown resistance (kdr) mutations was performed via PCR and sequencing. Metabolic resistance mechanisms were investigated using CDC bottle bioassays. The larvae were found to be susceptible to temephos and Bti. Bioassays on adults demonstrated susceptibility to deltamethrin, suspected resistance to permethrin, and resistance to malathion and bendiocarb. Genotyping revealed low frequencies of heterozygous kdr mutations (V1016G, I1532T, F1534C/S). Synergist assays highlighted the key role of esterases in malathion resistance, a minimal involvement of glutathione S-transferases and an unexpected antagonistic effect of cytochrome P450 monooxygenases. Although larvicides remain effective, resistance to organophosphates, carbamates, as well as suspected resistance to permethrin, has been detected. Esterase-mediated metabolic resistance and kdr mutations may contribute to this profile. These findings highlight the need for resistance monitoring and integrated vector control to ensure sustainable control of Ae. albopictus.