Scientists warn of a dark future for fireflies and the common glow-worm, as multiple species of insects are added to the IUCN’s Red List of Threatened Species.
An international team of scientists has warned of a dark future for the world’s fireflies, with four Southeast Asian firefly species entered into the IUCN’s (International Union for Conservation of Nature) Red List of Threatened Species for the first time.
The main threats include habitat loss and degradation, climate change and light pollution.
Over 2,200 firefly species have been described globally, with Southeast Asia and the Indo-Pacific home to at least 400 of the Lampyridae beetles, who use bioluminescence to communicate. In Southeast Asia, the most spectacular displays of glowing, flashing and flickering come from fireflies from the Pteroptyx genus, known as ‘congregating fireflies’, which occur in large numbers on trees and shrubs along the tidal rivers of mangrove swamps.
The IUCN Firefly Specialist Group assessed four congregating firefly species across Malaysia, Indonesia, Cambodia, Thailand, Singapore and Brunei, and found that all four are threatened with extinction. Once abundant and widespread, the Comtesse’s firefly (Pteroptyx bearni), Synchronous bent-wing firefly (Pteroptyx malaccae), Perfect synchronous flashing firefly (Pteroptyx tener), and Non-synchronous bent-winged firefly (Pteroptyx valida) are all now listed as Vulnerable.
“The findings of this study are deeply concerning,” says Dr Wan Faridah Akmal Jusoh, IUCN SSC Firefly Specialist Group Co-chair and Senior Lecturer at Monash University Malaysia.
“Without significant improvements in the factors affecting their survival and reproduction, these species are at risk of disappearing. What’s particularly worrying is the absence of a comprehensive conservation plan of action at a national and global level.”
Why are fireflies important?
Fireflies require moist habitats and can be found in freshwater swamps, grasslands and forests. Like many insects, they are vital to ecosystem health.
“Fireflies are crucial for maintaining the food web balance, as they serve as both predators and prey,” Jusoh explains. “Their larvae feed on soft-bodied invertebrates, like snails, slugs and earthworms, making them beneficial for gardens and farms.”
One of the world’s most captivating natural wonders, the stark news should serve as a ‘wake-up call’.
“Fireflies’ beauty makes them a noticeable indicator species for a wider trend seen around the world,” says Sérgio Henriques, Invertebrates Conservation Coordinator for the Global Center for Species Survival at Indianapolis Zoo, USA.
“Many people may not notice the decline in a keystone species of butterfly, or the loss of ecosystem engineers, like spiders, but they might notice if they haven’t seen a firefly since childhood.
“These findings on the decline of fireflies are an indicator of broader insect decline, sometimes called the ‘insect apocalypse’ or Insectageddon, and that should be very concerning for everyone, as all ecosystems and all species, including ourselves, rely on insect and invertebrates for crucial ecological roles.”
Why are so many firefly species threatened?
Expanding urban development and intensive agriculture in Southeast Asia have accelerated the loss of fireflies’ natural environments, especially the draining of swamps and destruction of mangrove vegetation and riverbanks.
Scientists are also concerned that rising sea levels, due to climate change, will result in further losses of mangroves.
Light pollution from human cities, towns and villages, which is increasing by as much as 10% annually, is also impacting firefly populations.
“Fireflies attract their mates at night and have evolved to flash and glow brightly against natural darkness,” says Jusoh. “Studies have shown that artificial lights confuse male fireflies, making it harder for them to find mates and decreasing their reproductive success.”
Eco-tourism projects for people to witness firefly displays have helped protect some areas. But they’re a double-edged sword. “Fireflies are a major attraction for tourists in Malaysia and Thailand, but tourism has caused habitat degradation,” Jusoh explains. “For instance, speedboats used to access firefly display trees erode river banks and threaten fireflies’ habitat. While firefly ecotourism is generally good for local economies, care must be taken to protect firefly habitats at these heavily trafficked sites.”
The fact that only 1% of the known firefly species in Southeast Asia have been assessed but all of them are at risk of extinction in the near future suggests a much wider problem. “It’s highly likely many other firefly species are also to be at risk,” says Jusoh.
The scientists behind the study stress that it isn’t yet too late to reverse course. Dr Jusoh wants to see an “extensive and coordinated conservation effort to ensure the long-term survival of these firefly species,” including local, state, and national conservation organizations coming up with conservation action plans to create, restore, and protect fireflies’ habitats, as well as more surveying and monitoring work to understand threats.
Europe’s glow-worms and fireflies
There is grim news from Europe too. A new analysis of the state of Europe’s glowworms and fireflies shows shrinking populations, with similar threats – habitat loss (including grasslands, woodlands, and riverbanks), climate change (including floods and droughts), and increased light pollution – again to blame. Chemicals used in agriculture and gardening have also been found to not only kill fireflies but also their food sources, such as slugs, snails and worms.
Around 65 Lampyridae species are found in Europe. Researchers from the IUCN Firefly Specialist Group assessed ten European species and found half of them to be threatened with extinction. Two species, Lampyris pallida and Luciola novaki, are Endangered, while three are deemed Vulnerable. The common glow-worm (Lampyris noctiluca), the most widespread Lampyridae species, is categorised as Near Threatened.
“The humble British glow-worm was added to the global Red List, and it’s future is uncertain, as the species was classified as Near Threatened, meaning it may also be pushed to extinction in the near future,” says Henriques. “However, this should also bring us hope and opportunity, as that means that we still have time to save it if we act now.”
The findings add to global calls for action on light pollution (which is known to impact insects and other wildlife species), chemical pollution (such as pesticides), and other threats to fireflies, glow-worms and other insects.
“It’s startling to learn that as many as one fifth of the world’s fireflies could be facing extinction,” says Dr Sara Lewis, IUCN SSC Firefly Specialist Group Co-Chair, from Tuft University in Boston, USA. “But the good news is that we already know enough about their ecology, behaviour and threats to protect these dazzling insects. What we need now is strong policies to protect firefly habitat and reduce chemical and light pollution.”
Main image credit: Banthoon Pankaew
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