Investigation showed that Aedes albopictus (Skuse, 1894) of Chidambaram-Town, Annamalai-Nagar and Muthiah-Nagar of Tamil Nadu are still susceptible to the insecticide organophosphorus temephos with 98–100 mortality percentages. The resistance ratios of all the three sentinel sites are negligible. LC50 value was 0.002 - 0.003 ppm with high significance. It was the first temephos bioassay case study conducted on DENV vector Ae. albopictus in the selected sentinel sites and estimated lethal concentrations.

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Background: Morphological identification is the gold standard method for identifying species based on their external features. However, at times, this could lead to incomplete identification and faulty results when key features such as scales and bristles are damaged or when encountered mosquitoes with identical characteristics. Therefore, in the incumbent study, Aedes albopictus of Chidambaram strain was taken as a species model. Objectives: To identify the DENV vector morphologically and genetically, creating a Genbank ID for the variant strain, and mapping the trait of the species via phylogenetic tree construction. Methods: The specimen larvae were collected from Annamalai Nagar, DENV infected area. First, the specimen was morphologically identified using taxonomy key features, and subsequently, molecular identification was carried out using the Sanger Dideoxy sequencing method on the M1 cytochrome c oxidase subunit (COX1) gene, partial CDs; mitochondria. The sequenced nucleotides were analysed using the BLAST platform, and the evolutionary tree was inferred using the Neighbor-Joining method. Result: The vector species model was confirmed and identified as Aedes albopictus morphologically as well as genetically. The sequenced gene length was 517bp and submitted to NCBI under gene bank ID: OP002091.1. The sequenced data has shown 100% similarity of the COI gene with that of different geographically located Aedes albopictus species. Phylogenetic tree analysis reveals its common origin with species of MZ5001505.1; MF148287.1 and MN080757.1 accession numbers. Conclusion: Confirmation of Aedes albopictus in the present study is an immense asset in vector control planning and management in the region where vector borne disease are endemic. Also, the evolutionary history of the species recorded would enable better understanding of vector biology and its evolution navigation.