Searching for potential Culicoides vectors of four orbiviruses in Yunnan Province, China

Some species of Culicoides (Diptera, Ceratopogonidae) are major vectors for arboviruses, and Yunnan Province is a key area for arbovirus prevalence in China. Therefore, this study attempts to search for potential Culicoides vectors for the common orbiviruses bluetongue virus (BTV), epizootic hemorrhagic disease virus (EHDV), Palyam virus (PALV) and Tibet orbivirus (TIBOV) in Yunnan Province, China.

Culicoides specimens were collected from 16 counties in Yunnan Province, China, using UV traps and tested for BTV, EHDV, PALV and TIBOV through one-step reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A total of 543 conspecific pools of Culicoides containing 9895 specimens were tested.

A total of 46 species belonging to 8 subgenera and 2 groups were recognized. A total of 19 species and a Culicoides subgenus Trithecoides complex were tested using RT-qPCR. One pool of Culicoides shortti Smith & Swaminath and one pool of Culicoides orientalis Macfie tested positive for BTV, one pool of Culicoides oxystoma Kieffer tested positive for PALV, and four pools of Culicoides jacobsoni Macfie tested positive for TIBOV. All the tested samples were negative for EHDV, and all the tested C. subgenus Trithecoides midges were negative for any virus.

Culicoides shortti was identified as a potential BTV vector for the first time. Culicoides jacobsoni was confirmed as a potential TIBOV vector and C. orientalis as a potential BTV vector. Culicoides oxystoma was also shown to be a natural carrier of PALV using the RT-qPCR method.