Field comparison of broad-spectrum white LED-baited traps with narrow-spectrum green LED-baited traps in the capture of Anopheles mosquitoes (Diptera: Culicidae).

Light-Emitting Diodes (LEDs) have been effective light sources in attracting Anopheles mosquitoes, but the broad-spectrum white light, even with a wide-ranging application in lighting, have not been evaluated yet. In this study, the white light was field evaluated against the green one in the light trapping of anopheline mosquitoes by using two non-suction Silva traps and two CDC-type suction light traps. Anopheline mosquitoes were captured for two 21-night periods of collecting (2022 and 2023). In the first period, two LEDs were used per Silva trap, but three were used in the second one to increase the luminance/illuminance at traps. A CDC-type suction light trap equipped with an incandescent lamp was used in 2022 and a CDC-type suction light trap equipped with a 6 V-white light (higher luminance/illuminance) in 2023. A total of eight species and 3,289 specimens were captured in both periods. The most frequent species were Anopheles triannulatus s.l., An. goeldii, An. evansae and An. argyritarsis. In 2022, white LEDs were less attractive to anopheline mosquitoes than the other light sources, but without statistical difference among treatments (F = 2.703; P = 0.0752; df = 2). In 2023, even with an increased luminance/illuminance at traps, no statistical difference was found between the two LED-baited Silva traps (F = 6.690; P = 0.0024; df = 2), but rather between the 6 V-white-baited CDC-type suction light trap and green-baited Silva traps. Due to some drawbacks and the lower abundance of individuals caught by using white LEDs, the narrow-banded green LEDs is preferable to white ones for attracting anophelines.

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.