Host Associations of Culicoides Biting Midges in Northeastern Kansas, USA

Simple Summary Culicoides biting midges are small biting flies that can spread diseases to livestock. Understanding which animal species midges feed on in nature is important for assessing the risk of disease spread. In this study, we used molecular methods to determine host associations for five midge species. Midges were found to feed heavily on either birds or mammals, with a small degree of crossover for all species. The size of the bloodmeal was found to make a bigger difference in successfully detecting the host than did the digestion stage. These results indicate that species that were found to feed heavily on birds are unlikely to be vectors of mammalian diseases and provide further evidence of the vector status of the mammalian-feeding midge species. Culicoides biting midges (Diptera: Ceratopogonidae) are hematophagous flies that transmit several viruses of veterinary concern to livestock. Understanding blood feeding behaviors is integral towards identification of putative vector species and preventing the transmission of these pathogens. PCR-based blood meal analysis was conducted on 440 blood-engorged Culicoides midges collected in northeastern Kansas, with 316 (71.8%) returning non-human vertebrate identifications at the & GE;95% identity match level. Broadly, Culicoides sonorensis, Culicoides stellifer, and Culicoides variipennis were found to feed heavily on mammalian hosts, while Culicoides crepuscularis and Culicoides haematopotus fed on avian hosts. The blood meals in all specimens were graded prior to DNA extraction to determine whether blood meal size or digestion status significantly impacted the likelihood of a quality host match. Size had a significant impact on the likelihood of a quality match at grades 3-5, whereas digestion only significantly impacted outcomes at the most extreme grade. These vector-host dynamics have not previously been studied in Culicoides collected in Kansas, which represents a unique tallgrass prairie biome within the United States that is heavily interspersed with livestock operations. Based on these data, the highly abundant species C. crepuscularis and C. haematopotus are unlikely to be major vectors of mammalian viruses.

Automated summary

This study investigated host associations of five Culicoides biting midge species using molecular methods. It was found that these midges heavily fed on either birds or mammals, with some crossover. The size of the bloodmeal had a greater impact on detecting the host than the digestion stage. These findings provide insights into the vector status of these midge species.