Urban light pollution can disrupt the winter dormancy period of mosquitoes, thus promoting bites and, by domino effect, the transmission of diseases such as the West Nile virus.
- Light pollution disrupts the circadian clock of mosquitoes.
- This leads mosquitoes not to go into diapause. They are thus active over longer periods and can bite humans for longer.
- However, this disruption could also lead to greater mosquito mortality in winter.
Street lamps, neon lights, shop window lighting… urban light pollution does not just prevent you from seeing the stars clearly at night. It also disrupts the rhythm of humans and nocturnal animals. Researchers at Ohio State University have shown that bright light in cities disrupts mosquito activity. Their winter sleep is shorter. This can, among other things, support the transmission of diseases of which they are vectors, such as the West Nile virus.
Mosquitoes bite longer due to artificial light
The winter diapause (pause in the development and activity of animals, Editor’s note) of mosquitoes Culex pipiens is mainly triggered by the reduction in day length and temperatures. But by studying this phenomenon, the researchers discovered that females exposed to light at night did not go into diapause and became reproductively active, even if the days were still short. Thus, the light pollution of cities promotes the extension of the duration of activity of mosquitoes, and therefore the period when humans can be bitten.
“We see the highest levels of West Nile virus transmission in late summer and early fall in Ohio. If you have mosquitoes that delay their diapause and continue to be active more long in the year, that’s when they’re most likely to get infected with West Nile virus, so people might be at higher risk of getting it as well.”explained Megan Meuti, lead author of the study, in a communicated.
Mosquitoes: nocturnal pollution could lead to greater mortality in winter
Changing mosquito behavior due to light pollution has another repercussion, even this time for their species. Beasts affected by light tend to store less sugar glycogen. However, they transform this element into fat when temperatures drop. This lack of reserve could thus lead to greater insect mortality during the cold season, according to the researchers.
For Matthew Wolkoff, also author of the study published in insects, these observations suggest that light pollution causes mosquitoes to avoid diapause and scrambles their circadian clock signals.
“It could be bad for mammals in the short term, because mosquitoes might bite us later in the season, but it could also be bad for mosquitoes in the long term, because they might not fully engage in the preparatory activities they need to survive winter during diapause, and this could reduce their survival rate”he adds.
Scientists plan to conduct field studies to see if these lab results hold true in nature.