Lights Out: Fireflies Face Extinction From Human-Caused Threats

(CN) – Fireflies around the world are at risk of extinction due in part to habitat loss, pesticides and shockingly, artificial sources of light, according to new research released Monday.

A study published in the journal Bioscience by a Tufts University-led team asked firefly experts to determine what factors predominantly threaten extinction of one of Earth’s most unique insects. Sara Lewis, biology professor at Tufts said the loss of habitat brought about by human development is the most pressing threat.

A female glow-worm (Lampyris noctiluca) will shine for hours to attract her mate, yet brightening skies will dim her prospects. (Photo courtesy of Jason Steele)

“Lots of wildlife species are declining because their habitat is shrinking, so it wasn’t a huge surprise that habitat loss was considered the biggest threat,” Lewis said in a statement. “Some fireflies get hit especially hard when their habitat disappears because they need special conditions to complete their life cycle.”

Lewis pointed to a Malaysian firefly species called Pteroptyx tener that survives off of mangrove trees. She said the species’ population is in “drastic declines” following the destruction of mangrove trees for aquaculture and palm oil farms.

While habitat loss has been a known factor affecting firefly populations, co-author Avalon Owens said the researchers were surprised to find that artificial light was considered the second highest threat.

“In addition to disrupting natural biorhythms – including our own – light pollution really messes up firefly mating rituals,” Owens said.

Fireflies use their bioluminescence in searching for a mate, an activity that can be interfered with if there is too much surrounding light pollution. Even as more people switch to brighter LED bulbs, Owens said the switch isn’t helping.

“Brighter isn’t necessarily better,” she said.

The biologists also discovered pesticides may be the third most dangerous threat to fireflies. Exposure to the chemicals most often occurs when the insects are in their larval stages when they are at their most vulnerable.

The scientists said more research needs to be done on firefly populations in order to understand just how much the threats to their existence have already affected their numbers.

“Our goal is to make this knowledge available for land managers, policy makers, and firefly fans everywhere,” says co-author Sonny Wong of the Malaysian Nature Society. “We want to keep fireflies lighting up our nights for a long, long time.”

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