Street lights don’t just lure moths, they may be helping to impoverish suburban gardens by causing them to fly too high to pollinate flowers, researchers at Newcastle University report.
It could be at the cost of honeysuckle, ivy, the roadside wildflower white campion, and even buddleia, say the authors of a new study in the journal Global Change Biology.
The scientists have been looking not at the effect of change on either plants or on pollinators but on the interactions in an increasingly urban world.
“We all know that moths are attracted to light,” said Callum Macgregor, a PhD student at the university’s centre for ecology and hydrology and one of the authors.
“Where there are street lights, our research indicates that moths are being attracted upwards, away from the fields and hedgerows. This is likely to cause disruption of night-time pollination by moths, which could be serious for the flowers that rely on moths for pollination, and of course there could be negative effects on the moths themselves.”
Moth and butterfly populations are in long-term decline in both the UK and Europe, and artificial lighting could be one potential cause, they say. The researchers captured and counted moths – including hawkmoths – in lit and unlit farmland in Oxfordshire. Where there were street lights, moth abundance at ground level was halved, but doubled at lamp-post height.
The range of species was reduced: there were 25% fewer in lit areas, compared with places where there was no street lighting. The researchers also analysed the pollen on their captive moths. One in four carried pollen – from a minimum of 28 varieties of plant – so with only half the number of moths at ground level, nocturnal pollination must be affected.
“The species are what make up an ecosystem but the interactions are what glue it together,” said Macgregor. “Moths play, we think, quite an important role in ecosystems in the UK and abroad, not just as pollinators but also as food for bats and birds and as herbivores. So if something is affecting moths it could be affecting other things in all sorts of ways.”
