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Abstract: Culicoides obsoletus (Diptera: Ceratopogondae) is considered as the probable main vector of Bluetongue virus (BTV) in northern Europe. Its breeding sites are poorly documented at the present time. We report numerous emergences of C. obsoletus s. str. from soil samples collected in two holdings between August and September 2010. Specimens were collected regularly in the laboratory during 80days. In one holding, 1584 C. obsoletus midges emerged from used litter collected inside a dairy cow building and 211 C. obsoletus midges emerged from manure left outside the farm buildings. In the second holding, the number of emergences observed was much lower, especially for indoor samples. We discuss the impact of the farming practices on the abundance of emergence between both holdings on one side and between indoor and outdoor breeding sites on the other side. The observation of a peak in emergence and high emergence rates recorded in the laboratory for indoor samples let us assume that these breeding sites are of great importance, especially when it comes to understand the biology of this widespread species and its role in the transmission of BTV. [Copyright &y& Elsevier]

Knowledge on host-feeding pattern of blood-sucking insects helps to understand the epidemiology of a vector-born disease. We determined blood meal origin from blood-fed Culicoides thanks to molecular techniques. A set of primers was used to selectively amplify segment of vertebrates' prepronociceptin gene from abdomen of engorged Culicoides (Diptera: Ceratopogonidae). Vertebrate DNA was successfully amplified in 91% of blood-fed Culicoides assayed. Direct sequencing and comparison of resultant sequences with sequences in GenBank, using BLAST, lead to the specific identification of the host in 100% of the cases. A total of 157 blood-fed females belonging to 13 different Culicoides' species were captured thanks to light traps in different areas of France between 2008 and 2009. Blood meal origin was determined for 143 blood-fed midges: 59 Culicoides obsoletus, 18 Culicoides dewulfi, 16 Culicoides scoticus, 11 Culicoides chiopterus, 10 Culicoides lupicaris, 1 Culicoides pulicaris, 8 Culicoides punctatus, 10 Culicoides pallidicornis, 3 Culicoides achrayi, 2 Culicoides furcillatus, 3 Culicoides brunnicans, 1 Culicoides picturatus and 1 Culicoides poperinghensis. The predominant species in our study belong to the C. obsoletus complex; they are considered as putative vectors of Bluetongue virus in the north of Europe. C. chiopterus sampled fed only on cattle, while blood meal origin of C. dewulfi, C. obsoletus and C. scoticus was diversified. In our sampling, we found that midges were fed mainly on cattle (54%), rabbits (20%), horses (17%), sheep (4%), pigs or wild boars (4%) and human (1%). Cattle DNA was found in at least 11 different species of Culicoides assayed. [ABSTRACT FROM AUTHOR]

Bluetongue virus (BTV) is a Culicoides-borne pathogen infecting both domestic and wild ruminants. In Europe, the Red Deer (Cervus elaphus) (RD) is considered a potential BTV reservoir, but persistent sylvatic cycle has not yet been demonstrated. In this paper, we explored the dynamics of BTV1 and BTV8 serotypes in the RD in France, and the potential role of that species in the re-emergence of BTV8 in livestock by 2015 (i.e., 5 years after the former last domestic cases). We performed 8 years of longitudinal monitoring (2008–2015) among 15 RD populations and 3065 individuals. We compared Culicoides communities and feeding habits within domestic and wild animal environments (51,380 samples). Culicoides diversity (>30 species) varied between them, but bridge-species able to feed on both wild and domestic hosts were abundant in both situations. Despite the presence of competent vectors in natural environments, BTV1 and BTV8 strains never spread in RD along the green corridors out of the domestic outbreak range. Decreasing antibody trends with no PCR results two years after the last domestic outbreak suggests that seropositive young RD were not recently infected but carried maternal antibodies. We conclude that RD did not play a role in spreading or maintaining BTV in France. [ABSTRACT FROM AUTHOR]