Molecular differentiation and species composition of genus Culicoides biting midges (Diptera: Ceratopogonidae) in different habitats in southern China

Culicoides biting midges (Diptera:Ceratopogonidae) cause a significant biting nuisance to humans, livestock, which are the biological vectors of a range of risky pathogens. Accurate illustration of vector play a key role in arthropod borne diseases surveillance. However, few studies have focused on the Culicoides, which caused bluetongue disease in 29 provinces of China since 1979. In this study, we assessed cytochrome oxidase subunit I (COI) mtDNA molecular marker for identification of ten major vector species and analyzed the Culicoides species community and diversity in different habitats. A total of 20,795 Culicoides samples collected from 11 sample sites were identified as 23 species belonging to 7 subgenera. Sequences of COI gene worked well as barcodes for identifying all the determined specimen in this study and were comparable with the existing sequence data from GenBank. We first reported COI barcode sequences of C. morisitai, C. insignipennis and C. homotomus. Morphological identification of Culicoides spp. samples within southern China appears relatively robust and some unidentified species were required further study. Our study shows that the COI sequence data can be used as a tool to identify species of Culicoides in Jiangxi Province. In our sampled area, the most abundant species was C. arakawae (61.89%), followed by C. oxystoma (13.77%), C. punctatus (10.10%), C. nipponensis (8.82%), C. homotomus (3.19%) and C.morisitai (1.17%) in this study. C. punctatus was the dominant species of Park habitat (62.22%), C. arakawae was the predominant species of Chicken habitat (96.66%), Vegetable plot habitat (92.0%), and Peasant household habitat (83.21%), respectively. C. oxystoma was the abundant species of Residential area habitat (40.11%), Hospital habitat (56.65%), and Pig & Cow habitat (48.77%), respectively. Results also show that the potential Bluetongue virus vectors belong to the Obsoletus and Pulicaris groups, are also included and relatively abundant, notably: Culicoides punctatus. These findings expand the current knowledge of Culicoides population composition in the southern part of China.