Artificial lights are disrupting firefly mating, putting them on the road to extinction – Salon

On a summer evening in the Smoky Mountains, photographerRadim Schreiber, is standing in a forest. Wind is rustling the leaves.As dusk sets in, he looks through the trees and sees amazing flying specks of light a wild, fairy glow.

He's looking at fireflies, also known aslightning bugs. Butfireflies may be in trouble because of, ironically,light itself.

According to a2019 study, artificial light impacts fireflies in a big way. Fireflies find mates through a courtship process that involves flashing their "lights." And not just any light: the courting process involves a series of flashes,which areunique to each male and female. Femaleswill choose their matebased on their unique flashing patterns. The females, in turn, will start a flashing "dialogue"with the mate of their choosing. It's an amazingsight to see.

So how does this courtship process clash with the lights we keep on at night? Fireflies rely on light to communicate, which hasled scientists to wonderif light pollution impacts them in some way. Prior studies by the researchers confirmed this, as well as asubstantial bodyof research. So the next logical question, and the one that the researchers tackled, was how this lighting impacts fireflies at the most basic level: courtship.

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To measure and investigate how attracted fireflies were to artificial light, Ariel Firebaugh and Kyle Haynes, two scientists based at the University of Virginia, set up 15 pairs of white tarps outside at the Blandy Experimental Farm. One tarp in each pair was illuminated by an LED light, while the other, located 10m (~32 ft) away, was left in the dark.

The researchers then watched the courtship "flashings" of stationary females and free-flying males inPhoturis(predator) andPhotinus(prey) fireflies. In the wild, females sit stationary on a plant while the males fly around and flash their lights. To replicate this while disturbing the process as little as possible, a nylon-mesh container is placed on top of females as they perch on grasses.

Finally, to look more closely at how lights affected mating success, Firebaugh and Haynes used mesocosms (an experimental tool where natural conditions are replicated in a controlled environment) consisting of mesh sided canopies.These mesocosm canopies looked much like apop-upcanopy tent, but with mesh screen sides. To find mating behavior, the fireflies are marked with a fluorescent powder. After the trial was over, they are collected and observed for signs of mating: male-colored powder on female reproductive organs.

In these lighted zones, the fireflies were less likely to engage in courtship flashes, and mating success was reduced. The researchers also investigated whether light pollution affected predator-prey relationships, but no significant impact was found.

Outdoor LED lighting spaces, like the one used in this study, canalso act as demographic traps, say the researchers. That means that immigration (or the amount of firefliescoming intothe area) far exceeds emigration (the amount of firefliesleavingthe area) meaning that fireflies, barring other circumstances, will stay in the lit areas. While the fireflies may be loving the bright LED lights, the lighting affects courtship behaviors, which are significantly reduced, and also likely reduces mating success.

Fireflies are attracted to light but this light "sucks" them in. It's like how a warm, cozy house is where you want to be on a cold winter day.It attracts you and you don't want to leave. In the same way, fireflies are attracted to our bright LEDs and don't want to leave the light.More fireflies enter the area, and then leave. They are attracted to it like a trap.But, like how it's not healthy for us to stay home all the time, it's not healthy for fireflies to stay attracted to this light. Fireflies rely onambientlight cuesto know when to start courtship flashing, but when the environment is always lit, there is a problem. Courtship behaviors go down and breeding success is also likely to go down.

ForSchreiber, a photographer specializing in fireflies, their significance transcends the food chain into that of cultural importance:"Often people have very joyful memories [about fireflies] from childhood, and when these experiences are being shared across people from different nations, they may feel that these experiences are more important than other differences we may have."

Schreiber is now on a mission to capture the beauty of fireflies before they disappear forever.He said, via email, that "There are unique and beautiful species of fireflies that live in very small areas, and when they lose their habitat, we may not see these fireflies ever again. I have been recording some of these species on camera with the idea of preserving them at least on video."

This is a huge problem light pollution is one of thefastest growing typesof environmental degradation,andmore than99 percentof people living in America and Europe don't experience a "natural" night sky.

As urban areas continue to grow, this problem will only get worse. In early February,researchers atTufts University released a studypegging light pollution as the second most serious threat to fireflies, according to a survey of 49 experts across the world. Only habitat loss is more dangerous.

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Artificial lights are disrupting firefly mating, putting them on the road to extinction - Salon