Multiple insecticide resistance and first evidence of V410L kdr mutation in Aedes aegypti from Burkina Faso

Hyacinthe K. TOE, Soumanaba Zongo, Moussa W. Guelbeogo, Basile Kamgang, Hilary Ranson, Philip J. McCall

Introduction: Burkina Faso responded to major dengue outbreaks in 2013 and 2016 with insecticide-based vector control targeting Aedes aegypti. We investigated the susceptibility profile, and underlying mechanisms, for the main insecticide classes in Aedes aegypti populations from urban and peri-urban areas from 2019 to 2020.

Methods: Immature stages were collected from July to October in Ouagadougou and Banfora. Adult F0 or F1 females were exposed to insecticides in WHO susceptibility tests (including pre-exposure to piperonyl butoxide (PBO) and quantitative bioassays). Real time melting curve qPCR analyses were performed to genotype the F1534C V1016I V410L Aedes kdr mutations in unexposed and in live and dead mosquitoes, 4h post-exposure to 0.03% deltamethrin.

Results: Aedes aegypti from both cities showed moderate resistance to 0.1% bendiocarb (80-100%), 0.8% Malathion (60-100%) and 0.21% pirimiphos-methyl (75-97%), and high resistance to 0.03% deltamethrin (5-70% mortality). Mortality was 75% and 92% following exposure to 0.25% and 0.5% deltamethrin respectively. Mortality was below 50% following 4h exposure to 0.3% deltamethrin. Pre-exposure to PBO significantly increased mortality to 0.03% deltamethrin and 0.03% alpha-cypermethrin (p<0.0001) suggesting the involvement of cytochrome p450s monooxygenases. Genotyping detected the presence of F1534C and V1016I at frequencies of 0.45-0.92 and 0.1-0.32 respectively. The V410L mutation was detected for the first time in Burkina Faso at frequencies of 0.1-0.32 depending on location. High frequencies also occurred in mosquitoes surviving 4h exposure to 0.03% deltamethrin, but the difference was significant only for the 1534C mutation (0.70 vs. 0.96, p<0.0001).

Conclusion: Burkina Faso populations of Aedes aegypti are resistant to multiple classes of insecticide with multiple mechanisms involved. This highlights the urgent need for a nationwide monitoring programme to manage insecticide resistance and ensure effective control in future outbreaks of dengue or other arboviruses transmitted by Aedes aegypti.

Keyword: Aedes aegypti, insecticide resistance, kdr mutations, Burkina Faso