'Evolution in real time': silent crickets still singing for a mate

Scientists are fascinated that Hawaiian crickets still perform their vigorous mating call, despite having evolved to lose their song to avoid a deadly new parasite

Male field crickets traditionally attract a mate by “singing” – creating a sound by rhythmically scraping their wings back and forth.

In Hawaii, however, their song attracts a less welcome female: parasitic flies, whose larvae devour and kill the crickets from the inside out.

To survive, some smart field crickets have rapidly evolved to remove the sound-producing structures on their wings, meaning their vigorous “song” no longer endangers them, as it is completely silent.

These mutations were first identified on the island of Kauai and by photographing and recording these insects under lab conditions, scientists have now discovered that the singing continues, even though it appears to be an intensive use of energy for no purpose.

Writing in the journal Biology Letters, researchers from the University of St Andrews and the University of Cambridge reveal how they photographed and recorded the crickets under laboratory conditions to document this silent song.

Currently about 95% of males on Kauai and half the males on the neighbouring island of Oahu display the “flatwing” phenotype, which means they are incapable of producing song by rhythmically opening and closing their forewings.

These crickets have shown markedly higher success at evading the attentions of the parasitic flies. But there’s one major flaw: how can they attract a mate without song?

“It appears that they hang around singing males and intercept females that come in,” said co-author Dr Nathan Bailey of the University of St Andrews. “In effect, they parasitise the songs of the singing males. It’s a bit sneaky.”

But on islands where there are very few singing males left, the populations are enduring, suggesting that non-singing males are finding another way to attract a mate.

The field crickets fascinate evolutionary biologists because a popular hypothesis is that organisms can adapt to stresses such as new pathogens or predators by changing their behaviour. In this case, the rapid adaptation to silent singing is not a behavioural change but a morphological one – the crickets are still going through the motions of “singing”.

Bailey says he and his research group would like to examine whether the crickets now begin to save their energy by rubbing their non-singing wings less. They would also like to observe whether the soundless “singing” – a vestigial trait with no obvious function – could acquire a different function or already serves another undetected function.

“It’s evolution in real time,” said Bailey. “We can observe it happening as it unfolds.”


Patrick Barkham

The GuardianTramp

Related Content

Article image
Treat artificial light like other forms of pollution, say scientists
Impact of human illumination has grown to point of systemic disruption, researchers find

Jonathan Watts Global environment editor

02, Nov, 2020 @5:59 PM

Article image
Climate change threatens rare British orchid that tricks bees into mating
Researchers find that warmer temperatures are upsetting the seasonal relationship between the early spider orchid and pollinating bees

Patrick Barkham

05, Apr, 2018 @11:37 AM

Article image
Bad taste in the moth: study reveals insect's chemical defence
Unsavoury flavour may explain why certain species do not flee from predators, scientist says

Aaron Walawalkar

16, Dec, 2019 @5:00 AM

Article image
Sniffer dog Toby takes lead role in bumblebee conservation

Spaniel trained to find nests in £112,000 study as university team seeks answers to species decline

Kirsty Scott

29, Aug, 2008 @11:01 PM

Article image
Dracula ant's killer jaws are nature's fastest mover at 200mph
Tropical insect uses lethal speed of its spring-loaded mandibles to stun or kill prey

Hannah Devlin Science correspondent

12, Dec, 2018 @12:15 AM

Article image
Climate crisis causing male dragonflies to lose wing ‘bling’, study finds
Black patterns used to attract mates can cause the insects to overheat in hotter climates

Sofia Quaglia

05, Jul, 2021 @10:10 PM

Article image
Velvet ants share warning signals with the neighbours | @GrrlScientist
GrrlScientist: North American velvet ants are one of the world’s largest complexes of mimics. Although these beautiful insects produce an intensely painful venom, neighbouring species still mimic each other’s many warning signals, a trait that effectively protects them all from predators


17, Aug, 2015 @4:00 PM

Article image
Orange cave crocodiles may be 'mutating' into new species
In 2008 an archaeologist discovered crocodiles living in remote caves in Gabon. Now, genetics hint that these weird cave crocodilians may be in the process of evolving into a new species.

Jeremy Hance

29, Jan, 2018 @8:50 AM

Article image
RSPCA gives orphaned baby birds singing lessons

RSPCA play orphaned fledglings recordings of birdsong to hone twittering skills before they're released in to the wild

Ian Sample, science correspondent

15, Jun, 2008 @11:01 PM

Article image
Roll up … the first animal that curled into a ball to take cover
How 500m-year-old trilobite pioneered one of the most successful defences of life on Earth

Ian Sample, science correspondent

24, Sep, 2013 @11:01 PM