Comparative Genetic Analysis of Lesser‐Studied Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) Collected in Ireland and Related Populations Across Europe

Culicoides biting midges are ectoparasites that act as vectors of animal and human pathogens. While much research effort has focused on species that serve as vectors for important livestock pathogens (belonging to the then Obsoletus and Pulicaris groups in the Palearctic region), other, less common, species are understudied. This study aimed to shed light on the genetic diversity of this lesser‐studied subgroup. A total of 133 Culicoides midges collected in Onderstepoort light traps in 13 sites across Ireland (June 2022–December 2023) were identified as Culicoides achrayi , Culicoides fascipennis , Culicoides festivipennis , Culicoides kibunensis , Culicoides impunctatus , Culicoides nubeculosus, Culicoides pallidicornis, Culicoides pictipennis , Culicoides poperinghensis , Culicoides salinarius and Culicoides vexans based on their wing morphology. Identities were confirmed using a PCR targeting a 478 bp fragment of the mitochondrial cytochrome C oxidase subunit gene (COI), followed by Sanger sequencing. Resulting sequences were compared against records on GenBank and aligned with international sequences to create phylogenetic trees and networks to assess their genetic diversity and relationship. Overall, 93.5% of morphological identifications were confirmed by COI barcoding. While several haplotypes were only recorded in Ireland, their apparent uniqueness is possibly a reflection of the limited number of published sequences in the database. Overall, there was limited evidence to suggest that midges collected in Ireland are genetically isolated from their continental European counterparts, with many sequences closely resembling or identical to those found elsewhere. The results suggests frequent exchanges between Irish and continental European midge populations, reinforcing the need for continued surveillance. Understanding the genetic structure of less‐well studied Culicoides species provides insights into midge population dynamics and connectivity, and informs future surveillance of midge‐borne pathogens in Ireland.