Insecticide Susceptibility and KDR Mutations in Aedes Albopictus Collected from Seven Districts of Guangyuan city, Northern Sichuan, China.

The Asian tiger mosquito, Aedes albopictus, is an important vector of chikungunya, dengue, yellow fever, and Zika viruses. Vector control remains an important means for the prevention and control of vector-borne diseases. The development of insecticide resistance has become a serious threat to the efficacy of insecticide-based control programs. To understand the resistance status and the underlying genetic mechanism in mosquitoes in Guangyuan City of Sichuan Province, China, we investigated the susceptibility of Ae. albopictus to four commonly used insecticides. We found that all the examined populations were susceptible to malathion and propoxur. However, Ae. albopictus populations in Guangyuan showed a possible resistance to the two tested pyrethroids (beta-cypermethrin and deltamethrin). Notably, phenotypic resistance to deltamethrin was detected in 2 of the 7 populations. The potential of resistance to pyrethroids was confirmed by the presence of knockdown resistance (kdr) related mutations in the voltage-gated sodium channel. Four kdr mutations (V1016G, I1532T, F1534L, and F1534S) were identified to be present alone or in combination, and their distribution displayed significant spatial heterogeneity. These findings are helpful for making evidence-based mosquito control strategies and highlight the need to regularly monitor the dynamics of pyrethroid resistance in this city.