Right across the ecosystem, our pollution has a deleterious effect on the reproductive behaviour of many species. This is also true for light pollution. Imagine you are in a crowded noisy room and trying to ask your partner whether they would marry you, but they can't hear you no matter how loudly you shout the words. Pardon? What?
New research published in Insect Conservation and Diversity indicates that artificial light at night is most likely now to be interfering with the courtship and mating of bioluminescent fireflies.
Fireflies, or glowworms, attract mates by flashing light. The female finds a plant stalk to climb. and then she bends her abdomen upwards showing her glowing organs to attract males.
For the study, investigators exposed courting pairs of fireflies to five colours of light at two intensities, and they recorded changes in the rate, brightness, and pattern of male advertisement flashes, as well as how often females responded.
All artificial light treatments significantly suppressed courtship activity, but bright amber light had the greatest impact on female receptivity. This suggests that artificial lights that are closest in colour to firefly bioluminescence may be the most disruptive to firefly courtship.
“It’s definitely concerning because many ecologically-minded people are pushing the use of amber lights to safely light up streets and parks. But we’re finding that no colour of light is safe for fireflies—they need the dark,” said co-author Avalon C.S. Owens, a PhD candidate at Tufts University.