Comparative effectiveness of UV-LED light and CO2 using a 3D-printed suction trap for Culicoides surveillance and bluetongue virus detection in central Thailand.

This study aimed to (i) compare the effectiveness of three attractants (UV-LED light, CO2-only, and UV-LED light + CO2) using a 3D-printed suction trap for Culicoides surveillance, and (ii) determine the presence and circulating serotypes of bluetongue virus (BTV) in Culicoides species in central Thailand. A total of 12474 Culicoides specimens representing 21 species were collected over nine nights. Overall, UV-LED light and UV-LED light + CO2 traps yielded comparable abundance and species diversity, and both outperformed the CO2-only trap (P < 0.001). The five most abundant species were C. oxystoma, C. imicola, C. guttifer, C. peregrinus, and C. huffi. All five species, except C. guttifer, were also more abundant in UV-LED light-based traps than in the CO2-only trap (P < 0.001), and this pattern was consistent for nulliparous and parous females (P < 0.05). Only C. imicola showed a higher parity rate in UV-LED light traps than in the CO2-only trap (P < 0.05). Of 154 pools tested, 53 (34.4%) were BTV-positive; 27 from C. imicola, 20 from C. oxystoma, 5 from C. peregrinus, and 1 from C. huffi. One pool of C. imicola exhibited a relatively high virus titer (Ct value = 25.7). Five serotypes (BTV-2, BTV-4, BTV-7, BTV-12, and BTV-15) were identified, with BTV-15 newly reported. In conclusion, a 3D-printed suction trap baited with UV-LED light alone effectively collected Culicoides spp. without reducing abundance or species diversity, while the co-circulation of multiple BTV serotypes highlights the need to strengthen bluetongue control measures in the country.