Night lights hamper firefly courtship

WASHINGTON • Fireflies are under threat globally, with familiar hazards such as habitat loss and pesticides compounded by another peril – humanity’s ubiquitous night-time artificial light which plays havoc with their balletic nocturnal courtship, scientists said.

In the most comprehensive worldwide assessment to date of dangers facing these flying beetles, researchers concluded that some of the 2,000-plus firefly species may face extinction threats while others are doing fine.

Using assessments from 350 experts on fireflies from around the world, the researchers determined the top threat was habitat loss and fragmentation caused by factors such as urbanisation, industrialisation and agricultural intensification.

The second-leading threat was light pollution. Fireflies boast specialised light-emitting organs, typically on their lower abdomen, called lanterns.

Fireflies flash to communicate as a part of courtship and reproduction.

“Light pollution affects lots of nocturnal creatures, but fireflies are especially susceptible to this particular threat,” said biology professor Sara Lewis of Tufts University in Massachusetts, who led the research published last week in the journal Bioscience.

“That’s because many – though not all – fireflies rely on bioluminescent courtship signals to find their mates. When their night-time environment is too bright, it’s difficult for them to see one another’s signals, so they never get to hook up,” Prof Lewis added.

Satellite data has shown night-time light pollution from the incessant flow of electric lights expanding on a global scale.

The third-leading threat was widespread agricultural use of pesticides.

Most exposure occurs during the fireflies’ larval stages because juveniles spend up to two years living below ground or under water.

The researchers said that while there is scant data on long-term population trends for most species, there is evidence that these insects have vanished from many places where they formerly were abundant.


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