Light Pollution Transforms Insect Communities

Streetlights have substantially transformed the ecology of ground-dwelling insects and other invertebrates, according to a new study from the University of Exeter.

Artificial lighting, which is believed to be increasing by 6 percent per year globally, is already known to affect individual organisms, but this is the first time that its impact on whole communities has been investigated.

In the study, based in the market town of Helston in West Cornwall, the researchers discovered that groups of invertebrates living near artificial light include more predators and scavengers. This could impact the survival rate of several different species, and could also affect birds and mammals that rely on these bugs for food. Entire ecosystems and even humans could experience the impact.

To gather information, the team placed pitfall traps directly under and between street lamps that were 35 m apart for a number of days and nights. They compared results for day and night, as well as differences between areas under and away from artificial lighting.

They gathered 1194 individuals covering 60 species and discovered that total numbers were more abundant under streetlights. Here they found more predatory and scavenging species such as ground beetles and harvestmen. Similar findings occurred during the day, suggesting that the effect on communities is ongoing.

“Our study shows that light pollution could be having a dramatic effect on wildlife in our towns and cities,” said Dr. Tom Davies of the university’s Cornwall Campus. “We need to be aware of how the increase in artificial lighting is impacting on the delicate ecosystems on which we all rely.”

The scientists will now examine light pollution’s impact on other communities and how this may affect important ecosystem services, to determine whether to change how we light urban spaces.

The study appeared in Biology Letters.

For more information, visit: www.exeter.ac.uk