Researchers at Ohio University in the United States conducted a study showing that urban night lighting alters the bite season of mosquitoes. This light pollution, the excess artificial illumination at night, lengthens the period during which mosquitoes are active and capable of biting.
The work, published in Vermin, examines how artificial night lighting shifts the circadian rhythms and metabolic activity of the northern house mosquito, Culex pipiens. This mosquito is known to carry the West Nile Virus and can transmit fever to humans and horses after biting infected birds.
The level of artificial night light affects how mosquitoes accumulate nutrients and triggers diapause, the dormant stage they enter as winter nears. Diapause is a crucial survival phase for reproductive-age females when temperatures drop. During this phase, they seek sheltered places such as caves, sewers, and sheds, entering a period of reduced activity to survive the colder months.
As a result, diapause-activated females avoid blood meals and feed on nectar during the winter. The study notes that longer nights help these insects survive, which can lead to fewer bites during the deepest winter months but more activity in late fall and early spring as conditions fluctuate.
Active and longer feeding windows
The cycle of mosquito activity is naturally governed by light, the cue that helps regulate daily and seasonal biological processes. When artificial light is added, these processes shift, delaying the onset of diapause in Culex pipiens and keeping them potentially more active and biting for a longer portion of the year.
Experts emphasize that the heaviest West Nile virus transmission in Ohio tends to occur in late summer and early fall. If mosquitoes delay diapause and remain active later into the year, the chance of virus transmission to humans increases, raising public health concerns according to Megan Meuti, the study’s lead author and an entomology assistant professor at Ohio State University.
Beyond the risk of longer biting seasons and the consequent rise in fall transmission of West Nile virus in urban settings, researchers stress that this shift could threaten mosquito populations’ winter survival. The study notes that some mosquitoes raised under short daylight conditions show slightly higher daily activity when exposed to artificial light and greater variability in lipid stores, while those raised under longer daylight conditions exhibit reduced lipid accumulation of glycogen and water-soluble carbohydrates when exposed to artificial light.
This line of research aligns with prior findings that artificial lighting can promote the spread of certain mosquito species. Biologist Álex Richter-Boix, involved with the Mosquito Alert citizen science program, notes that effects vary among species. For instance, the yellow fever mosquito tends to bite more when lights are present at moderate brightness, while Culex pipiens may extend its seasonal activity and biting period in lit environments, increasing disease risk in cities.
Artificial lighting also reduces diapause by notable margins in some mosquito species such as the tiger mosquito and can extend their operational period. In contrast, the malaria vector Anopheles shows different responses, with ultraviolet light sometimes suppressing activity. The precise outcomes depend on species and light conditions.
These observations are summarized in work available through MDPI on the topic of light influence on mosquito biology and disease transmission. The study adds to a growing body of evidence that urban lighting patterns can shape mosquito behavior and public health risk in North American cities.
Further discussion of the topic is supported by data from environmental monitoring of light exposure and vector surveillance programs in different regions. Researchers emphasize that the findings underscore the need for urban lighting designs that minimize ecological disruption while maintaining safety and energy efficiency. The implications extend to vector control strategies, urban planning, and public health messaging as city environments continue to evolve with growing nighttime activity.
Notes: The cited work is part of ongoing research on how artificial light at night affects mosquito physiology and disease dynamics in temperate zones. The results highlight the importance of considering light pollution as a factor in vector-borne disease risk assessments and control planning.
Reference work: MDPI Entomology Journal, 2024 edition.
Mention: The study emphasizes the role of light exposure patterns in shaping mosquito behavior and potential disease transmission risks in urban landscapes.