Dengue is the most rapidly spreading vector-borne disease with an estimated 100–400 million cases each year. Control of Dengue vectors largely depends upon synthetic pyrethroids. Development of insecticide resistance in Aedes mosquitoes however, poses severe threat to insecticide-based vector management programme. Mutations in the Voltage Gated Sodium Channel gene (vgsc) serve as the primary machinery behind this resistance development. In Aedes albopictus, at least four such kdr (knock down resistance) mutations had already been documented. Here, we describe the occurrence of F1534C kdr mutation in wild population of Ae. albopictus from northern part of West Bengal, India including a novel T1520I mutation. Four populations of Ae. albopictus from the studied region were found resistant against DDT and synthetic pyrethroids, among them only one population possessed F1534C kdr mutation. A total of 200 successful amplification followed by partial sequencing of vgsc gene further revealed the presence of F1534C kdr mutation in both phenotypically susceptible and resistant mosquito specimen. Studied populations were found 81% homozygote susceptible (1534F/F), 12.5% heterozygote (1534F/C) and 6% homozygote resistant (1534C/C) for F1534C kdr mutation. The findings of the current study will help to uncover the mechanisms underlying insecticide resistance and hence to reduce errors in vector control measurements.

West Bengal is a dengue endemic state of India with several dengue outbreaks in the recent years. Synthetic pyrethroids are the major arsenal used for the control of these vectors. The emergence of pyrethroid resistance in mosquitoes has recently been described from many parts of the world due to kdr (knock down resistance) mutations in the voltage gated sodium channel gene (vgsc). In Aedes albopictus, at least four such mutations had already been found. In this study, wild populations of Ae. albopictus were sampled from different locations of northern part of West Bengal, India. World Health Organization, 2016 recommended adult bioassay was followed throughout the experiment in order to determine susceptibility status. A total of 200 Ae. albopictus specimens including both phenotypically resistant and susceptible individuals were successfully amplified for F1534C kdr genotyping. Among them, 81% were homozygote susceptible,12.5% were heterozygote and 6.5% were homozygote resistant. Presence of F1534C mutation in pyrethroid resistant Ae. albopictus mosquitoes is the first report from India. Moreover, another novel mutation T1520I was also found to be coexisting with F1534C mutation in Ae. albopictus. This study will aid in identifying insecticide resistance mechanism and therefore, will reduce errors in vector control measures.