October 22, 2020

Increased light pollution may be making mosquitoes more bitey

Just when you though 2020 couldn't get any worse, La Niña is on its way bringing hot and humid conditions mosquitoes will thrive in ... and now we're hearing light pollution is making them bite more at night!

Artificial light abnormally increases mosquito biting behaviour at night in a species that typically prefers to bite people during the day, according to research from the University of Notre Dame that was published in The American Journal of Tropical Medicine and Hygiene.

Increased biting by Aedes aegypti mosquitoes, which normally fly and bite in the early morning and during the afternoon, highlights the concern that increasing levels of light pollution could impact transmission of diseases such as Dengue fever, Ross River virus, Barmah Forest virus and Zika.

"This is potentially a very valid problem that shouldn't be overlooked," said Giles Duffield, associate professor in the Department of Biological Sciences. Unlike other species that may emerge from the forest to feed on humans and animals, Aedes aegypti evolved with humans and prefers to feed on them.

"They live and breed in the vicinity of houses, so the chances of Aedes aegypti being exposed to light pollution are very likely," he added.

In a recent study, the female mosquitoes, the only ones that bite, were twice as likely to bite, or blood-feed, at night when they were exposed to artificial light.

The findings will help epidemiologists better understand the true risk of disease transmission by this species. The discovery could also lead to more recommendations for bed net use. Usually mosquito bed nets are used at night to ward off bites from a different genus of mosquitoes, Anopheles, but because Aedes aegypti were shown to be stimulated by artificial light, mosquito nets could also be used in areas with a likelihood of disease transmission even with limited Anopheles activity.

"The impact of this research could be huge, and it probably has been overlooked," Duffield said. "Epidemiologists may want to take light pollution into account when predicting infection rates."