In a new study, researchers found that nighttime - versus day-biting species of mosquitoes have been behaviorally attracted and repelled by different colors of light at different times of day.

<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://som.uci.edu/news_releases/Mosquitoes-respond-differently-to-colors-of-light-time-of-day.asp">Mosquitoes are one of important disease vectors impacting animals and humans around the globe and also the findings have important implications for applying light to restrain them.</a></span>

At the University of California, Irvine School of Medicine-led team analyzed mosquito species that bite in the day (Aedes aegypti, aka the Yellow Fever mosquito) and the ones that snack at night (Anopheles coluzzi, also a member of the Anopheles gambiae household, the significant vector for malaria).

They found distinct answers to ultraviolet light and also different colors of light between both species. Researchers also found light preference is determined by the mosquito's sex and species, the period of day and the color of the lighting.

"Traditional wisdom has been that insects have been non-specifically attracted to ultraviolet light, thus the widespread use of ultraviolet lighting"bug zappers" for insect control.

We discover that day-biting mosquitoes are attracted to a vast array of light spectra during the day, whereas night-biting mosquitoes are ardently photophobic into short-wavelength light throughout the daytime," said principal investigator Todd C. Holmes, PhD, a professor in the Department of Physiology and Biophysics in the UCI School of Medicine.

Mosquitoes pose prevalent dangers to people and other creatures as infection vectors. It's estimated historically that infections spread by mosquitoes have contributed to the deaths of half of all people ever to have lived.
<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://som.uci.edu/news_releases/Mosquitoes-respond-differently-to-colors-of-light-time-of-day.asp">The new work demonstrates that day-biting mosquitoes, particularly females who need blood meals due to their fertilized eggs, are attracted to light during the day regardless of spectra. In contrast, night-biting mosquitoes especially avoid ultraviolet (UV) and blue light during the day.</a></span>

Past work from the Holmes laboratory using fruit flies (that can be related to mosquitoes) has ascertained that the light sensors and circadian molecular mechanisms for mild mediated attraction/avoidance behaviors.

Accordingly, molecular disturbance of the circadian clock severely interferes with light-evoked fascination and avoidance behaviours in mosquitoes. At the moment, light-based insect controllers do not take into account the day versus night behavioral profiles which alter with everyday light and dark cycles.

<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://som.uci.edu/news_releases/Mosquitoes-respond-differently-to-colors-of-light-time-of-day.asp">"Lighting is the principal regulator of circadian rhythms and elicits a broad assortment of time-of-day particular behaviors," said Holmes.</a></span>

"By getting an comprehension of how insects respond to short wavelength light at a species-specific fashion, we can develop newand environmentally friendly alternatives to controlling harmful insects more efficiently and reduce the need for environmentally harmful poisonous pesticides."

This research was financed in part by the National Institutes of Health, National Science Foundation along with the ARCS Foundation. This new study builds on the Holmes lab's previous studies in the UCI School of Medicine published over the Last Few decades at Science, Nature and Proceedings of the National Academy of Sciences.
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<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://som.uci.edu/news_releases/Mosquitoes-respond-differently-to-colors-of-light-time-of-day.asp" target="_blank" rel="noopener noreferrer">University of California - Irvine</a></span>

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Baik, L. S., <em>et al</em>. (2020) Circadian Regulation of Light-Evoked Attraction and Avoidance Behaviors in Daytime- versus NighttimeBiting Mosquitoes. <em>Current Biology</em>.<span style="color: #ff6600;"> <a style="color: #ff6600;" href="http://doi.org/10.1016/j.cub.2020.06.010" target="_blank" rel="noopener noreferrer">doi.org/10.1016/j.cub.2020.06.010</a></span>.

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