Bioassay and molecular study for detection of insecticide resistance dengue causing mosquito vectors.

Nowadays, dengue infection creates a major problem across the country. The vector species carrying dengue infection has progressively started to developed resistance against most of the currently used insecticides. Hence, a study was carried out in dengue-endemic areas of Assam and Arunachal Pradesh to find the current situation of insecticide susceptibility status of dengue vectors. Based on the previous history of dengue incidence, Aedes mosquitoes were collected from Dibrugarh, Kamrup, Sivasagar, Tezpur and Tinsukia districts in Assam and Pasighat district in Arunachal Pradesh to test the insecticide resistance status through bioassay and molecular methods. The WHO standard bioassay test kits were used to detect insecticide susceptibility status among dengue vectors. In molecular study, allele-specific polymerase chain reaction (PCR) method was done for the detection of mutations in paratype voltage-gated sodium channel gene of Aedes aegypti and Aedes albopictus mosquitoes. In bioassay method, 100% A. aegypti mosquitoes were found to be resistant towards dichlorodiphenyltrichloroethane (DDT), 8% towards pyrethroid and 4% towards malathion. Similarly, 92% A. albopictus mosquitoes have shown resistance competency towards DDT, 12% towards pyrethroid and 8% towards malathion. In allele-specific PCR methods, V1016G heterozygous mutations were detected from the field collected A. aegypti and A. albopictus mosquitoes of Tinsukia, Dibrugarh and Sivasagar district. Similarly, F1534C heterozygous mutations were observed from A. aegypti mosquitoes of Tezpur, Tinsukia and Sivasagar district and A. albopictus mosquitoes of Tinsukia, Dibrugarh and Sivasagar district. From the study, it was concluded that the Aedes mosquitoes have progressively started to developed resistance towards commonly used insecticides.