Monitoring of biting midges (Diptera: Ceratopogonidae: Culicoides Latreille) on farms in Sweden during the emergence of the 2008 epidemic of bluetongue

In light of the emergence of bluetongue in northern Europe, populations of Culicoides species were monitored in 2007-2008 by means of Onderstepoort blacklight suction traps operating at livestock farms in Sweden. The location of the 22 sampling sites ranged from about latitude 55A degrees N to about 68A degrees N. A total of 61,669 male and female Culicoides were captured, of which, 52,319 were trapped outside the farms and 9,350 in byres or livestock sheds. Thirty-three Culicoides species were recorded, of which, 30 were new to Sweden. The species and their relative abundance and spatial distribution on sites are presented. Two species incriminated as vectors of bluetongue virus, viz. Culicoides obsoletus (about 38%) and Culicoides scoticus (about 36%), were predominant and common in the environment of livestock farms practically all over the Swedish mainland, penetrating far north to at least 65A degrees N. The two species were also recorded from the island of Gotland. Culicoides pulicaris, another potential vector species, accounted for about 9% of all Culicoides captured.