Permethrin Resistance in Aedes aegypti Affects Aspects of Vectorial Capacity

SIMPLE SUMMARY: Pyrethroids have been applied as a major type of insecticide targeted at mosquitoes, many of which are key vectors in the transmission of several flaviviruses. Resistance to pyrethroids has emerged and become a worldwide threat to mosquito control. Pyrethroid resistance is usually accompanied by knockdown resistance (kdr) where the voltage gated sodium channel gene is mutated. We selected a permethrin resistant (p-s) Aedes aegypti population from Florida and, along with its parental population, examined two mutation sites, V1016I and F1534C. The data showed the p-s population had the most homozygous mutations which correlated to the permethrin resistance level. To assess the risk of disease transmission, two parameters affecting vectorial capacity were checked. The p-s population showed the longer survival time and higher dissemination rate for dengue compared to its parental population. The results showed that the potential threat of vector-borne diseases was increased in areas with resistant mosquitoes. ABSTRACT: Aedes aegypti, as one of the vectors transmitting several arboviruses, is the main target in mosquito control programs. Permethrin is used to control mosquitoes and Aedes aegypti get exposed due to its overuse and are now resistant. The increasing percentage of permethrin resistant Aedes aegypti has become an important issue around the world and the potential influence on vectorial capacity needs to be studied. Here we selected a permethrin resistant (p-s) Aedes aegypti population from a wild Florida population and confirmed the resistance ratio to its parental population. We used allele-specific PCR genotyping of the V1016I and F1534C sites in the sodium channel gene to map mutations responsible for the resistance. Two important factors, survival rate and vector competence, that impact vectorial capacity were checked. Results indicated the p-s population had 20 times more resistance to permethrin based on LD50 compared to the parental population. In the genotyping study, the p-s population had more homozygous mutations in both mutant sites of the sodium channel gene. The p-s adults survived longer and had a higher dissemination rate for dengue virus than the parental population. These results suggest that highly permethrin resistant Aedes aegypti populations might affect the vectorial capacity, moreover, resistance increased the survival time and vector competence, which should be of concern in areas where permethrin is applied.