UV traps to catch mosquitoes? Yes, it is possible to see some success, but it comes down to the species being targeted.
The success of light traps are based on the premise that insects are generally attracted to UV light. Although mosquitoes aren’t the main target for light traps, as carbon dioxide, heat and visual cues are key drivers in host location behaviour, they may still be useful in attracting them, although this only appears to be the case in certain species and only at specific times of the day.
Mosquitoes have evolved strong circadian rhythms – behaviours and physiological processes driven by an internal ‘body clock’ which follow a 24-hour cycle, and are typically set in response to light/dark patterns of day length. For example, Aedes mosquito species are primarily day biting mosquitoes and Anopheles mosquitoes are primarily night biting mosquitoes.
Researchers from the University of California investigated whether day biting mosquitoes (Aedes aegypti) and night biting mosquitoes (Anopheles coluzzi) responded differently to UV light.1 They created a split arena in which during the day, half the arena was exposed to a light source of specific wavelength and half the arena was kept dark, with mosquitoes able to freely move between the two areas.
During the night period, both halves of the arena were dark. Their results demonstrated that the day biting mosquito (Aedes aegypti) was strongly attracted to a wide range of light spectra during the day, whereas the night biting Anopheles coluzzi were strongly photophobic. Interestingly, the Aedes aegypti mosquitoes remained in the previously lit area during the dark period, but Anopheles coluzzi moved to the previously lit area once the lights went out. The level of attraction/avoidance was stronger in female mosquitoes than in male mosquitoes.
Although this study focused on the response of mosquitoes to UV light during the day, it did not assess how night biting mosquitoes respond to UV light during the night time, when their circadian rhythms drive their feeding activity. Indeed, studies on the night biting malarial mosquito, Anopheles arabiensis, suggest that light traps can deliver the same capture rates to human baits.2
The take away is that although light traps should never be a standalone treatment for mosquito control, to maximise catch it is important to understand whether day and/or night time biting mosquitoes are prevalent in the area and then make sure the traps are active at the appropriate time to maximise catch rates.
1 Baik, L.S et al (2020). Circadian Regulation of Light-Evoked Attraction and Avoidance Behaviors in Daytime versus Nighttime Biting Mosquitoes. Current Biology, 30:16, P3252-3259
2 Mwanga, E.P et al (2019). Evaluation of an ultraviolet LED trap for catching Anopheles and Culex mosquitoes in south-eastern Tanzania. Parasites & Vectors, 12: 418.