Moths & street lighting

STREET lights change the natural behaviour of moths and disrupt nocturnal pollination, new research by scientists of Newcastle University, U.K., has shown. The study was published in the journal Global Change Biology. It is only recently that the crucial role moths play in plant pollination has been appreciated fully as previous studies have focussed on daytime pollinators.

“Where there are street lights, our research indicates that the 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 which rely upon moths for pollination, and, of course, there could be negative effects on the moths themselves as well,” said Callum Macgregor, lead researcher. “There is a great deal of concern at the moment about falling pollinator populations and the knock-on effect on plant pollination. Our research suggests that it’s a process that is being damaged on two fronts, night and day, and together the impact could be significant,” pointed out Darren Evans, a co-author. Like the more well-known pollinators, bees and butterflies, the researchers say that pollution due to artificial lighting could be one potential cause for the long-term decline of moth populations. Capturing and counting moths in lit and unlit areas of farmland in Oxfordshire, the team found that moth abundance at ground level was halved in lit areas but flight activity at the height of the street light was nearly doubled. Species richness was also reduced at ground level, with 25 per cent fewer species in lit areas compared with unlit areas. Analysing the presence of pollen on the moths, the team found that one in four of the insects were carrying pollen, so the halving of moth activity at ground level at lit sites could be affecting nocturnal pollination.

“The role of artificial light in causing moth declines remains unclear, but this new research indicates effects not just on moths but on the whole ecosystem,” said Richard Fox, a team member. This study focussed on the high-pressure sodium street lamp found on most streets in Britain, but the researchers are now investigating the impact of replacing these with LED lights.