Areas with LED streetlights have up to 50 per cent fewer moth caterpillars living in the immediate vicinity of the light, potentially having huge impacts on an area鈥檚 wildlife ecosystem.
鈥淲e don鈥檛 think of light pollution as big a driver of biodiversity [loss] as climate change,鈥� says at the UK Centre for Ecology & Hydrology. 鈥淏ut that doesn鈥檛 mean it鈥檚 not a significant factor.鈥�
Prior research about the impact of artificial light has looked at adult insects like moths, which are able to move around the landscape and could be double-counted. Moth caterpillars barely move more than a few metres in their lifetimes, meaning it is easier to be more precise in measuring light鈥檚 impact on them.
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Boyes and his colleagues used Google Maps and Google Street View to identify parts of Oxfordshire, Buckinghamshire and Berkshire in the UK where there were pairs of habitat areas that appeared identical, except that one had streetlights while the other didn鈥檛.
They then counted the number of caterpillars in each 14-metre-long habitat by beating the hedgerows and sweeping grass margins, finding about eight different species of moth caterpillars. The team also noted the type of streetlight 鈥� whether it was an LED light or an older, yellow, sodium lamp 鈥� and the intensity of light it produced.
Sites where street lighting was present had 47 per cent fewer caterpillars in the hedgerows and 33 per cent fewer caterpillars in the grass margins. LED lights had a more pronounced effect than sodium lamps.
Having a lower number of caterpillars is expected to have effects on future moth counts and on other wildlife nearby. Small birds, hedgehogs and predatory insects feed on the caterpillars, while larger birds and bats feed on adult moths.
鈥淸Moths] are also really important pollinators, so there could be knock-on effects,鈥� says Boyes.
at Harper Adams University in the UK says the paper is another helpful piece of the puzzle of insect declines. 鈥淲hat is really clear from the discussion is how much the different types of light are having an impact, with LEDs seeming to be worse for caterpillars,鈥� she says.
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