Faunistic inventory of the genus Culicoides (Diptera: Ceratopogonidae) in Mauritius Island, Indian Ocean: Diversity and spatial distribution of species of veterinary interest

Viruses transmitted by biting midge species of the genus Culicoides (Diptera: Ceratopogonidae) affect and threaten human or animal health worldwide. In Mauritius, the risk of virus introduction through imported livestock or travellers is high, while serological evidence has demonstrated the circulation of two Culicoides-borne viruses in domestic ruminants and native deer, namely, bluetongue (BTV) and epizootic haemorrhagic disease (EHDV) viruses. To this day, no data at the main island scale have been published on the diversity and distribution of Culicoides species present in Mauritius. A spatial survey across Mauritius was conducted using black light suction traps (OVI traps) from 10 to 20 April 2023. Nineteen farms were selected to cover a diversity of hosts and environments. The traps were operational from dusk to dawn, with a single night capture per site. While the presence of Culicoides imicola Kieffer and Culicoides enderleini Cornet and Brunhes in Mauritius was confirmed, two additional species were detected, Culicoides kibatiensis Goetgheguer and Culicoides bolitinos Meiswinkel. All species were distributed all over the island. Overall abundance ranged from 4 to 19,764 females, with a mean and median abundance of 2,010 and 352 individuals/night/site. The total number of individuals collected during the study was highest for C. imicola (21,065) and lowest for C. bolitinos (313). All four species are Afrotropical and are suspected or historically known to be involved in BTV and EHDV transmission. While intra-specific morphological variations were detected, genetic analyses did not reveal any cryptic diversity. This work has updated the faunistic inventory of the genus Culicoides of veterinary interest in Mauritius and established a list of 4 Afrotropical species known to be vectors and distributed on the island. The abundance of Culicoides was relatively low as compared to mainland Africa but in the range of other islands in the south-west Indian Ocean region. Further work will investigate the temporal dynamics of the four species to identify high-risk seasons.