Seasonal dynamics of biting midges (Diptera: Ceratopogonidae, Culicoides spp.) on dairy farms of Central Germany during the 2007/2008 epidemic of bluetongue.

The unforeseen outbreak of bluetongue in north-western Europe in August 2006 raised the question, which Culicoides spp. were involved in the transmission of bluetongue virus (BTV). Based on the decision 2007/20/EU of December 2006, a large-scale entomological surveillance programme was initiated in the five affected EU member states including Germany. This paper reports on the entomological findings obtained from March/April 2007 to May 2008 at 15 sampling sites in the federal states of Lower Saxony (eastern region), Mecklenburg-Western Pomerania, Brandenburg and Saxony-Anhalt: The number of captured biting midges in one trap varied from none or few Culicoides during winter (December 2007 to April 2008) to up to more than 12,500 individuals during summer and autumn. Catches of the C. obsoletus group were consistently higher than those of the C. pulicaris group. C. imicola, the principal afro-asiatic vector of BTV, was not detected. High numbers of midges were caught inside the cattle sheds. Eleven pools of biting midges were RT-PCR-positive to BTV-8 including pools of non-engorged midges of the C. obsoletus and of the C. pulicaris groups. The first BTV-genome positive pool of midges was detected in August 2007; the remaining genome-positive pools were detected during October and November 2007.