Comparaison de l'efficacité de quatre modèles de pièges lumineux pour la collecte de Culicoides piqueurs en Allemagne

Résumé

Biting midges of the genus Culicoides are vectors of bluetongue disease, an OIE-listed animal disease which has recently led to severe economic losses in susceptible livestock species in Europe. Therefore, several affected countries conduct monitor­ing programmes for Culicoides spp. To compare the number and species composition of Culicoides obtained, the efficacy of various traps used to collect biting midges needs to be assessed. Four aspiration black light traps were thus compared: the Onderstepoort, John W. Hock, Riebt, and Biogents. One of the traps was operated from the 1st of April 2009 to determine the onset of increased Culicoides activity and thus the best time to start the study. The comparison was carried out from May 16th until September 26th. The traps were set up at four different sites on pastures of the Friedrich-Loeffler-Institut where cattle, sheep and goats were present. The comparison was carried out according to the Medreonet protocol in a 4×4 randomized Latin square design with one night of activity for each trap at each site. The highest number of Culicoides specimens was captured by the Onderstepoort (1245), followed by the Biogents (365), the Hock (30) and the Riebt (4) traps. The majority of midges caught was classified as belonging to the Obsoletus complex (1399), including C. obsoletus s.s., C. scoticus and C. chiopterus. Other encountered species were C. punctatus s.s. (87), C. albicans (78) and C. riethi (50). Most biting midges were collected in May (594) and June (575). In September only one Culicoides speci­men was caught. The results show that the trap model has a great impact on the number of Culicoides caught. Culicoides monitor­ing programmes should be harmonised by using the same type of trap everywhere or by adjusting the numbers of collected biting midges using a trap factor. The trap model should be taken into consideration in the decision to declare the seasonally-determined vector-free periods.