LED streetlights reduce insect populations by 50%, according to researchers at the University of Newcastle.
The negative impact that light pollution has on insects is well known. However, this is the first investigation to reveal the negative impacts of ‘eco-friendly’ LED lights.
The researchers found that the abundance of moths and caterpillars in hedgerows under LED street lamps was 52% lower than in nearby unlit areas.
This compared to a 41% lower abundance in hedgerows lit by sodium lighting.
Douglas Boyes from Newcastle University, who led the study, spent more than 400 hours sampling for caterpillars along roadsides at a total of 55 lit and unlit sites in the Thames Valley over the past three years.
He said: ‘The effects observed – on local abundance, development and feeding behaviour – were more pronounced for white LEDs compared to traditional yellow sodium lamps.
‘The rapidly increasing prevalence of LED lights, which are often much brighter as they are so energy-efficient and cheap to run, is likely to increase the negative impacts of light pollution on insects.
‘This is expected to have knock-on effects on other species, including predatory insects, hedgehogs, and songbirds, which need to find hundreds of caterpillars a day to feed themselves and their young.’
Previous research on light pollution has focused on adult insects, but studying caterpillars, which are a lot less mobile, has enabled the researchers to get more precise estimates of the impacts of street lighting on local populations.
Professor Darren Evans of Newcastle University’s School of Natural and Environmental Sciences, a co-author of the study, added: ‘Light pollution is one of the few causes of biodiversity loss that has easy solutions. Ultimately, we need a balance between protecting both public safety and wildlife, by ensuring that lighting is well-designed, away from important habitats and switched on for limited times.’
Photo by Jonas Verstuyft