The V410L knockdown resistance mutation occurs in island and continental populations of Aedes aegypti in West and Central Africa

Abstract

The extensive use of insecticides for vector control has led to the development of insecticide resistance in Aedes aegypti populations on a global scale, which has significantly compromised control actions. Insecticide resistance, and its underlying mechanisms, has been investigated in several countries, mostly in South American and Asian countries. In Africa, however, studies reporting insecticide resistance are rare and data on resistance mechanisms, notably knockdown resistance (kdr) mutations, is scarce. In this study, the recently described V410L kdr mutation is reported for the first time in old world Ae. aegypti populations, namely from Angola and Madeira island. Two additional kdr mutations, V1016I and F1534C, are also reported for the first time in populations from Angola and Cape Verde. Significant associations with the resistance phenotype were found for both V410L and V1016I individually as well as for tri-locus genotypes in the Angolan population. However, no association was found in Madeira island, probably due to the presence of a complex pattern of multiple insecticide resistance mechanisms in the local Ae. aegypti population. These results suggest that populations carrying the same kdr mutations may respond differently to the same insecticide, stressing the need for complementary studies when assessing the impact of kdr resistance mechanisms in the outcome of insecticide-based control strategies. One of the pillars for the prevention of Aedes-transmitted arboviral infections has been vector control, which is primarily based on the use of chemical insecticides. However, extensive use of insecticides has led to the development of insecticide resistance, undermining the sustainability of control programs. Mutations in the voltage-gated sodium channel gene have been associated with knockdown resistance in many insect species including Aedes aegypti. In Africa, in spite of the use of insecticides for vector control in many countries, data on insecticide resistance and its underlying mechanisms remain scarce. In this study, we report for the first time the occurrence of a recently described kdr mutation, V410L, in Old World Ae. aegypti from Angola and Madeira island. Two other kdr mutations, V1016I and F1534C, were also identified in populations from Angola and Cape Verde, extending our knowledge about the distribution of these mutations in Africa. We found significant associations between kdr genotypes and the resistance phenotype but only in the Angolan population. These results suggest that populations carrying the same kdr mutations may respond differently to the same insecticide, stressing the need for complementary studies when assessing the impact of kdr resistance in the outcome of insecticide-based vector control.