Identification of Culicoides obsoletus (Diptera: Ceratopogonidae) as a vector of bluetongue virus in central Italy.

In 2001 and 2002, 235 outbreaks of bluetongue were observed in the Lazio and Tuscany regions of central Italy. During entomological surveillance Culicoides imicola, the main vector of bluetongue virus in the Mediterranean region, was detected in only 14 of 28 municipalities affected by outbreaks; Culicoides obsoletus was the most abundant species, contributing 83 per cent of individuals in catches, whereas C. imicola contributed only 2 per cent. In affected municipalities the maximum catch of C. obsoletus was 18,000 specimens, compared with 54 of C. imicola. In October 2002 bluetongue virus serotype 2 was isolated from a single pool of wild-caught, non-blood-engorged parous C. obsoletus inoculated on to BHK-21 cells. Its identity was confirmed by reverse transcriptase-PCR.