Evaluation of light emitting diode suction traps for the collection of livestock-associated Culicoides species in South Africa

Effect of ultraviolet LED and trap height on catches of host-seeking anopheline mosquitoes by using a low-cost passive light trap in northeast Brazil

Light traps have been widely used for monitoring malaria vectors, although drawbacks remain. In this context, new tools and attractants are always becoming available to perform monitoring tasks, like the Silva trap, a passive and low-cost LED-light trap for host-seeking anopheline mosquitoes. In this work, the effectiveness of the Silva trap by using UV-LED and at different heights as well as a comparison with the conventional CDC-type (HP) light trap was studied. A total of 9009 mosquitoes and nine species were caught, Anopheles triannulatus, An. argyritarsis, and An. goeldii being the most frequent species. The green (520 nm) and blue (470 nm) LEDs attracted almost equal numbers of anopheline mosquitoes, but UV LEDs (395 nm) attracted a significantly lower number of individuals (Kruskal-Wallis = 19.68, P = 0.0001). Even with the predominance of mosquitoes trapped at the height of 1.5 m, no significant statistical difference was found among the four heights tested (0.5 m; 1.0 m; 1.5 m; 2.0 m). Green-baited Silva traps collected significantly more individuals than incandescent-baited CDC-type traps (U = 60.5; P = 0.0303). LEDs have been useful as light sources for attracting insect vectors and together with a low-cost trap, as the Silva trap, a feasible alternative to conventional trap-based monitoring Anopheles mosquitoes that can be implemented in the field.

The Effects of Light Wavelength and Trapping Habitat on Surveillance of Culicoides Biting Midges (Diptera: Ceratopogonidae) in Alabama

In the southeastern United States, biting midges transmit agents of hemorrhagic diseases that are enzootic among white-tailed deer (Odocoileus virginianus (Zimmermann), Artiodactyla: Cervidae). Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae), the only confirmed vector of epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV) in the United States, is rarely collected in the Southeast, implying that other Culicoides Latreille species act as vectors. Despite multiple surveillance studies, the influence of trapping habitat and light wavelength on Culicoides sampling has yet to be investigated in Alabama. This study sampled Culicoides species at a deer research facility using CO2-baited CDC light traps with three distinct wavelengths. Traps were rotated within three habitats to examine impacts of habitat type and light wavelength on Culicoides abundance and parity status. For most species, midges were more abundant in a pine forest compared to a hardwood-forest riparian zone or a lightly wooded area adjacent to a seasonal pond. The pine forest generally had negative effects on parity status, suggesting that most females in this habitat were foraging for their first bloodmeal. Ultraviolet (UV) black-light (350 nm-360 nm) attracted more midges than incandescent light or UV LED light (385 nm-395 nm), but wavelength had less of an effect on parity than habitat. This study indicates that light wavelength and habitat significantly influence Culicoides sampling outcomes, and that when collecting parous females is desired (e.g., EHDV/BTV surveillance), targeting areas around oviposition sites may be a better strategy than trapping where midges are most abundant.

Comparison of the efficiency of the Onderstepoort- and Centres for Disease Control ultraviolet light traps for the collection of livestock associated Culicoides species in South Africa

Comparative monitoring of the abundance and distribution of Culicoides biting midges (Diptera: Ceratopogonidae), the biological vectors of the causative agents of several diseases of global veterinary importance, will be crucial in determining the risk of disease outbreak and spread. Ultraviolet (UV) suction traps have become the most frequent method used for the monitoring of Culicoides diversity and abundance. The current study compared the trapping efficiency of the two most used UV suction light traps, i.e., the Onderstepoort (OP)- and the Centres for Disease Control trap, for the collection of livestock associated Culicoides species in South Africa. The study confirmed the superiority of the OP trap and indicated a correlation in species composition and age grading results as determine with the two trap types. Substantial variations in the comparative trap efficiency, as found between areas and sites within an area, suggest that a universal conversion factor between the two trap types may not be advisable as it is unclear to what extent species composition and environmental factors may influence the conversion factor. Light traps, independent of trap model, can be considered acceptable for determining the serial comparison of population numbers for seasonal fluctuation and species abundance in distribution surveys.