Investigating ungulate site use as a driver of Culicoides (Diptera: Ceratopogonidae) emergence from larval habitats.

Culicoides (Diptera: Ceratopogonidae) Latreille biting midges are the vectors of several viruses of veterinary significance. The larvae of some biting midge species develop in semiaquatic habitats that are affected by the activity of vertebrates. However, the importance of vertebrate animal activity in biting midge density has not been satisfactorily quantified. The goal of this study was to investigate the impact that three different hooved animals representing agricultural (cattle), wild (cervids), and intermediate (bison) animal populations have on the density and emergence of Culicoides from larval habitats. Trail cameras recorded vertebrate activity at eight sites at the Konza Prairie Biological Station with cattle, cervids, and/or bison, which was paired with larval substrate sampling to investigate midge density. The total time spent by all 3 target animals over the previous month and the average time spent by bison were significantly positively correlated with overall biting midge emergence. Species-specific analyses revealed significant positive associations of C. crepuscularis Malloch with several cattle variables including number of cattle days and events and average number of cattle, while more bison variables were found to be significant for C. haematopotus Malloch (bison days and bison events, negative associations) and C. variipennis Coquillett (negative associations for bison days and average number of bison; positive relationship with average bison time). Significant results for cervids included negative associations of C. crepuscularis with average cervid time and C. variipennis with cervid days. These results show that different ungulates impact midge abundance and emergence in different ways, improving our understanding of midge population drivers.