| Abstrakt: |
Background: Resistance to insecticides is spreading among populations of Aedes aegypti, the primary vector of important human arboviruses. The escalating insecticide resistance poses a significant threat to dengue vector control, with an expanding number of countries affected by the disease. To gain a deeper insight into the evolution of insecticide resistance, it is essential to have longitudinal surveillance results, which are currently lacking, particularly from African Ae. aegypti populations. Here we report on three-years of surveillance of Ae. aegypti susceptibility to insecticide resistance phenotypes and associated kdr mutations in Burkina Faso, a country with regular dengue outbreaks. Methods: Ae. aegypti susceptibility to insecticides and the V410L, V1016I, and F1534C kdr target site mutations linked to pyrethroid insecticide resistance were monitored in Ouagadougou from 2016 to 2018. Larvae were collected from artificial containers at two sites and reared to adulthood in an insectary. Bioassays were conducted on female adults, along with a laboratory-susceptible strain, following standard WHO protocols. Allele-specific PCR genotyping assays were utilized to identify the V410L, V1016I, and F1534C kdr pyrethroid target site mutations. Results: Bioassays revealed a high level of resistance to permethrin and deltamethrin that progressively increased over the three-year period in both localities. The 1534C mutation was nearly fixed throughout the three years at each locality, and while the closely-related 410L and 1016I mutations did not vary between localities, their frequency notably increased from 2016 to 2018. Interestingly, Ae. aegypti populations in both areas remained susceptible to bendiocarb, fenitrothion, and malathion. Modelling the mortality data further confirmed the escalating resistance trend over the years and emphasized the significant role played by the three kdr mutations in conferring resistance to pyrethroids. Conclusion: Mortality rates indicate that Ae. aegypti populations from Ouagadougou are becoming increasingly resistant to pyrethroid insecticides, likely due to an increase in the frequencies of the 410L and 1016I kdr mutations. Organophosphate insecticides are likely to be better alternative options for control. Author summary: Aedes aegypti transmits diseases including dengue, chikungunya, and Zika. This vector has developed resistance to several insecticides used in vector control interventions. Resistance data for Ae. aegypti in Africa remain sparse, and the evolution of insecticide resistance is still under-investigated. We undertook three-years of monitoring of insecticide resistance in Ae. aegypti and the associated kdr mutations in two localities of Burkina Faso. Larvae were collected from two different breeding sites, tyres and drums, from both localities. Insecticide bioassay susceptibility tests to commonly used insecticides were performed in the laboratory. The results revealed escalating resistance to pyrethroid insecticides, supported by increasing frequencies of the 1016I and 410L kdr mutations, while the 1534C mutation is fixed. Interestingly, Ae. aegypti populations in both areas remained susceptible to bendiocarb, fenitrothion, and malathion, providing a conservative option of organophosphates for Ae. aegypti control in Burkina Faso. These data provide important results to support decisions on dengue vector control. [ABSTRACT FROM AUTHOR] |
