Two Years of Culicoides Trap Comparison in the Balearic Islands

Abstract

Several types of light traps are being used in different European countries to help determine the potential vector species of blue­tongue virus (BTV). The four traps compared in this study were: i) the Onderstepoort trap – black light trap, with 8 W ultraviolet light tube used in the United Kingdom and Italy; ii) mini-CDC – black light, model 912, with 4 W UV light tube, used in Spain and Portugal; iii) Rieb trap, white light model, with 4 W UV light tube, used from 2000 to 2006 in France; iv) UK trap, with 4 W standard white incandescent bulb, used in the past in the UK and other European countries for African horse sickness surveillance. All traps included a downdraught suction fan. Tests were conducted from 18 Oct. to 19 Nov. 2007, from 18 Feb. to 4 June 2008, and from 1 Oct. to 28 Nov. 2008. During at least nine non-consecutive nights the traps were placed following a randomized block design in four different positions on a cattle farm located on the island of Mallorca (Balearic Islands, Spain). In 2008, only three traps (Onderstepoort, UK and mini-CDC) were tested. Results showed major differences in collecting Culicoides. The Onderstepoort trap showed the best performance in terms of total number of Culicoides captured in autumn both in 2007 and 2008. The UK trap, and especially the Rieb trap showed the lowest efficacy in terms of captures. In autumn 2008, the Onderstepoort trap cap­tured on average 90 Culicoides per night, whereas the mini-CDC captured on average 27. During spring 2008, however, the mini- CDC performed better as it captured on average 180 Culicoides per night, against 84 captured by the Onderstepoort. However, Fisher’s least significant difference test showed no statistically sig­nificant differences between the traps (P < 0.05). No remarkable difference was observed between the four traps as they all cap­tured a similar range of species. Captures of Culicoides newsteadi were greater during the autumn, and those of C. obsoletus in the spring. Finally, the Onderstepoort trap showed a higher sensitiv­ity in catching Culicoides midges in low population levels of the vector, especially during the winter season.