Elucidation of population structure of Culicoides oxystoma a vector of BTV in India and its genetic variability within conspecifics.

Deciphering the population structure and variations of vector species is indispensable for effective disease management programs. The population genetic structure of a species is an attribute of its vector competence. In India, Culicoides oxystoma Kieffer, 1910 (Diptera: Ceratopogonidae) has recently been implicated in the transmission of BTV-1. We studied the genetic structure of C. oxystoma obtained from various physiographic regions of India and evaluated it based on cytochrome c oxidase subunit-1 (COX-1). Genetic similarity was assessed through median-joining networks based on haplotypes and FST analysis. Major findings reveal that the geographic clustering is aligned with the Palearctic-Indomalayan-Australian cluster which is distinct from the Senegal haplotypes. Pairwise FST showed significant genetic differentiation among the haplotypes of the Palearctic, Indomalayan, Australian and African regions except between China and Japan. Tests of neutrality illustrated an expanding population within the Indian subcontinent. Calculated values of coefficient of difference of morphological parameters across various physiographic regions suggest an absence of subspecies, which, however, requires further validation. In summary, our study indicates there is presence of gene flow in C. oxystoma across various physiographic regions of India. However, homogeneity in the population structure of this vector species, C. oxystoma, indicates that it poses a significant risk of outbreaks in multiple localities in a conducive environment. [ABSTRACT FROM AUTHOR]