Species Diversity and Molecular Screening of Pyrethroid Resistance Mediated by the Voltage-Gated Sodium Channel in Ixodid Ticks from Puducherry, India

Ticks are major ectoparasites of livestock in India, causing substantial economic losses and transmitting a wide range of pathogens. Control strategies rely heavily on synthetic pyrethroid acaricides; however, resistance associated with mutations in the voltage-gated sodium channel (VGSC) gene has been widely reported. Information on tick species diversity and molecular resistance status in Puducherry remains limited. This study investigated tick diversity, host-associated infestation patterns, and the presence of key VGSC knockdown resistance (kdr) mutations (C190A and G215T). A cross-sectional survey was conducted across 15 villages in Puducherry, where ticks were collected from cattle, goats, and dogs and identified using standard morpho-taxonomic keys. A total of 3779 ticks representing eight ixodid species were identified, showing clear host-associated infestation patterns. Individual ticks were selected from stratified pools (based on village, host, tick species, and sex) and processed individually for genomic DNA extraction. A fragment of the VGSC gene was amplified by PCR and analysed using Sanger sequencing. Molecular analysis of 62 high-quality VGSC sequences representing all eight species across the surveyed villages revealed no mutations at the investigated loci (C190A and G215T) in the analysed samples. All sequences exhibited the wild-type genotype at these positions. These findings provide baseline molecular information on the screened VGSC loci in ixodid ticks from Puducherry and highlight the importance of continued surveillance, phenotypic validation, and integrated tick management strategies.