Spatial ecology of Culicoides biting midges in sylvatic and agricultural habitats

Culicoides are important vectors of bluetongue (BTV) and epizootic hemorrhagic disease viruses (EHDV), which infect wild and domestic ruminants. The movement of Culicoides between habitat types is poorly understood, and it is possible that Culicoides movement onto farms from the surrounding woodlands could increase the risk of disease transmission. To address whether livestock are at risk of BTV/EHDV transmission from sylvatic Culicoides species, BG-Sentinel-2 traps baited with CO2 (dry ice) and Centers for Disease Control (CDC) miniature light traps baited with either CO2 or UV-LED were set in two forest habitats and two adjacent pastures on a working beef farm in Washington County, Arkansas. Traps were set once a week for 9 weeks from August to October 2021. We collected a total of 601male (n=13) and female (n=588) Culicoides, from 14 different species. The two most common species were C. haematopotus (n= 485) and C. stellifer (n= 70). CDC-UV traps set in the woods caught significantly more Culicoides than the other trap types, and BG traps were ineffective for Culicoides collection. Significantly more C. haematopotus were collected from CDC-UV traps set in the woods versus in the pasture, but both C haematopotus and C. stellifer were frequently collected in both habitats, suggesting that they will move into pastures to host-seek. Culicoides stellifer is a putative BTV and EHDV vector in the southeast, and our results suggest that livestock on silvopasture may be at risk of transmission from this species. Future work will assess Culicoides movement between these habitat types.