From forests to fields: investigating Culicoides (Diptera: Ceratopogonidae) abundance and diversity in cattle pastures and adjacent woodlands

Culicoides Latreille (Diptera: Ceratopogonidae) biting midges are hematophagous flies that feed on wild and domestic ruminants, and transmit many arboviruses, including bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) circulating in the United States (US). They occupy a range of aquatic and semiaquatic habitats, and disperse short distances from their development sites. In the southeastern US there are limited studies on the abundance and diversity of Culicoides in wooded and adjacent livestock pasture habitats. In thus study, we characterized Culicoides diversity and abundance within these distinct habitat types by setting BG-Sentinel and CDC miniature suction traps baited with CO2 or UV-light in wooded and pasture habitats at two locations on a university beef farm in Savoy, AR. Traps were set once per week for nine weeks in August-October of 2021-2022. Fifteen species were collected during this study. The two most abundant species were Culicoides haematopotus Malloch and Culicoides stellifer Coquillett. There was a significant effect of site and location on C. haematopotus collections, and a significant effect and interaction of site and trap on C. stellifer collections. In the woods, significantly more C. stellifer were collected from the CDC-UV trap, while in the pasture, significantly more were collected in the CDC-CO2 trap. These data suggest that C. stellifer, a putative vector of BTV and EHDV in the southeast, may be traveling into the pasture to host-seek, while C. haematopotus remains primarily in the woods. This study reveals community differences between these habitat types and implications for Culicoides control.