Nighttime Light Pollution May Be Cause of Insect Population Decline

An analysis of the effects of artificial light at night on insects shows that there is strong evidence to suggest a link between nighttime light pollution and declines in insect populations.

Scientists from the Light Pollution and Ecophysiology research group at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) summarize recent evidence of impacts of artificial light at night (ALAN) on insects and discuss how these impacts can drive declines in insect populations in light-polluted areas.

Counting insects is part of the job. Courtesy of Gabriel Singer/IGB.

For example, flying insects attracted by artificial lights are removed from other ecosystems and die from exhaustion or as easy prey. Rows of light prevent flying insects from spreading, reducing genetic exchange within fragmented insect populations.

“Half of all insect species are nocturnal,” said researcher Maja Grubisic. "As such, they depend on darkness and natural light from the moon and stars for orientation and movement or to escape from predators, and to go about their nightly tasks of seeking food and reproducing. An artificially lit night disturbs this natural behavior — and has a negative impact on their chances of survival."

A decline in insect populations in agricultural areas, which make up 11 percent of land use worldwide, could jeopardize important ecosystem services, such as plant pollination. Changes in the occurrence and behavior of pests, such as aphids (or their enemies, such as beetles and spiders) can disturb the balance of the ecosystem. ALAN could also have a direct impact on the growth and flowering time of plants, and therefore on yield.

“Our overview study shows that artificial light at night is widely present and can have complex impacts in agricultural areas, with unknown consequences for biodiversity and crop production,” said researcher Franz Hölker. "Thus, light pollution should be generally considered as a potential ecosystem disturbance in future studies to identify ways in which practical steps can be taken to reduce environmental concerns."

The research was published in Annals of Applied Biology (doi: 10.1111/aab.12440).