Detection of arboviruses in Culicoides (Diptera: Ceratopogonidae) collected from animal farms in the border areas of Yunnan Province, China

Biting midges of the genus Culicoides (order Diptera, family Ceratopogonidae) are potential biological vectors for the transmission of certain arboviruses among humans, livestock, and wild animals. This study collected a total of 405 Culicoides individuals from seven animal farms located in five counties in the border areas of Yunnan Province, China, and examined the Culicoides species composition and the major arboviruses carried by the Culicoides species. The collected Culicoides were classified into seven species with variable abundances: Culicoides arakawae (5.43%, 22/405), Culicoides homotomus (1.23%, 5/405), Culicoides obsoletus (19.75%, 80/405), Culicoides orientalis (17.28%, 70/405), Culicoides oxystoma (29.38%, 119/405), Culicoides peregrinus (5.68%, 23/405), and Culicoides nipponensis (21.23%, 86/405). Among the seven species, C. oxystoma and C. nipponensis were distributed in all the five counties with abundances of 13.33-44.87% and 10.00-46.83%, respectively, suggesting that these were the dominant species of Culicoides widespread on animal farms in the border areas. PCR was used to detect major arboviruses in the collected Culicoides specimens, including bluetongue virus (BTV), Japanese encephalitis virus, Dengue virus, Zika virus, African swine fever virus, and African horse sickness virus. Among the tested viruses, only BTV serotype 1 was tested positive in C. oxystoma specimens collected from a buffalo farm. Culicoides oxystoma was the dominant species on animal farms in the sampled areas, but it has not previously been documented as positive for BTV in China. The current results thus suggest that C. oxystoma could be an important vector for BTV transmission in these border areas, which, however, needs to be confirmed by further comprehensive experiments. Overall, the present study provides the first profile of Culicoides species on animal farms in the China, Vietnam, and Myanmar border areas, establishes the prevalence of arboviruses carried by these Culicoides species, and suggests the vector potential of C. oxystoma species for the transmission of BTV.