Light Pollution And Moth Behavior

As a result of increasing urbanization and electrification, light pollution has become a global concern. While, though other forms of pollution—like noise pollution and plastic pollution—have been studied in detail to determine how they may impact the environment and ecosystems, light pollution has received relatively little attention.

Nonetheless, the potential ecological risks could be substantial: light pollution interferes with animals’ experiences of the natural cycle of day and night. This, in turn, may affect wild animals’ hunting and foraging behaviors, and such changes in behavior could have far-reaching impacts on mating and reproduction. Additionally, some studies have noted that animals in highly light-polluted areas can die at a faster rate than those in dark-sky regions.

This 2016 study explored whether and how exposure to light pollution affected the behavior and reproduction of small ermine moths. Moths and many other animals, including birds, can be attracted to artificial light sources. The study aimed to determine whether this flight-to-light behavior varied between moths from dark-sky areas and moths from light-polluted areas.

Moth larvae were collected from ten independent populations across France and Switzerland, and all of these moths were raised in a uniform environment. Once they reached adulthood, over 1000 moths were tested to compare their flight-to-light behaviors. The researchers found that moths from highly light-polluted areas were significantly less attracted to lights compared to those from dark-sky areas. This suggests that moth populations do adapt, and that they become less inclined to fly toward lights if they are from an area with a lot of light pollution.

Many questions remain about how light pollution may affect wild animals, but this study tentatively suggests that moth behavior may adjust over time due to light pollution. On one hand, this means that they might not die at as high of rates as expected given the threats posed by light pollution: decreased flight-to-light behavior means that moths might have a lowered chance of being attacked by predators or flying into light traps.

On the other hand, it is possible that this change in behavior is accompanied by changes in physiology, like smaller or less sensitive eyes, or a lowered ability to travel. Crucially, these kinds of changes could make it harder for moths to pollinate plants widely, or to adjust to habitat destruction. Further study will be important in discovering how light pollution impacts ecosystems, but it seems clear that it poses a real risk and that humans should be careful about allowing light pollution to increase unabated.