Standardization of DNA Barcoding Techniques to Identify Culicoides Species in Europe

Abstract

The design of efficient control strategies for Culicoides midges lies in correct species identification. From the approximately 1340 described Culicoides species, only 30 have been incriminated as vectors of bluetongue disease virus. However, the actual number of vector species could be different considering that relatively few species have been studied. In Europe, the most important vec­tor was assumed to be Culicoides imicola, an Afro-Asian vector. However, during the last two years other species such as C. puli­caris (Pulicaris complex), C. dewulfi, C. chiopterus and species of the Obsoletus complex have increased in importance, as their populations have been found abundant in outbreak areas, outside the geographical range of C. imicola. Whereas C. imicola is the most easily identified, C. obsoletus sensu stricto and C. scoticus, from the Obsoletus complex, are extremely difficult to identify by using traditional methods such as morphological examina­tion. The deoxyribonucleic acid (DNA)-barcoding regions is located in the cytochrome oxidase 1 gene (CO1). Recent stud­ies have shown that this region is valuable in the identification of Culicoides species; however, the CO1 fragment to be used must be selected with great care. We propose to standardize the methodology and the selection of the fragment to be amplified to homogenize results obtained by different groups.