How street lighting changed ecology of ground-dwelling invertebrates and bugs

A new research suggests the presence of street lights substantially changes the ecology of ground-dwelling invertebrates and bugs.

Scientists trapped nearly 1,200 of the animals in areas under and between street lights in Helston in Cornwall, UK.

They report in Biology Letters that invertebrate predators and scavengers were more common near the lights, even during the day.

That suggests street lights influence ecology more than previously thought.

Much work in recent years has gone into addressing the effects that street lights can have on local, transient populations of bugs – particularly those that can fly and have significant ranges of exploration.

But the effects of street lights on the vast communities of invertebrates on the ground remained unaddressed.

Thomas Davies of the University of Exeter and his colleagues set 28 traps in Helston, some just under street lights, and some in dark regions midway between them, over a three-night period.

The team found in general that a higher number of animals were trapped near the lights.

But the relative proportions of scavengers such as beetles and predators such as harvestmen and wolf spiders were significantly different, with a higher proportion being found near the lights – even during the day.

“This study now seems to be indicating that those transient, nocturnal effects on the behavior of the animals are actually being translated into the habitat preferences of the animals in the daytime as well,” Dr. Thomas Davies said.

“It’s amazing how long we’ve been using street lighting and artificial lighting, and how little research has been done on the impact of those lights on the environment,” he said.

Dr. Thomas Davies stressed that the study was small and its findings preliminary, but that it invited future study into much wider-ranging environmental effects.

“Invertebrates in the UK at least are undergoing a bit of a biodiversity crisis and have been for some time now, and they’re very important for a number of ecosystem services such as pollination and the breakdown of organic matter,” he explained.

“So the impact of street lights on invertebrate communities could be very, very important, could be problematic, but we simply don’t know at the moment – we need to do the research.”