Hawaiian crickets still try to call for females, despite having lost their ability to sing.
Male crickets woo females by “singing”, which they do by vigorously rubbing their wings together. Bumps and ridges on the wings scrape against each other, making a distinctive sound.
However, in the early 2000s researchers noticed that up to 95 per cent of male Hawaiian crickets () on the islands of Kauai and Oahu had lost their voices. Both sets of males independently evolved flat wings, making them effectively mute.
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This vastly reduced their romantic prospects, but it meant the crickets were protected from a fly called . This parasite homes in on a male cricket’s song and sprays maggots onto its back. These burrow into the male and devour it from the inside out.
“Silent males are protected from attacks by this fly, and so this mutation has spread very rapidly,” says at the University of St Andrews, UK.
*crickets*
Now Bailey and his colleagues have found that silent males still rub their wings against each other, as if to call females. Not only does the behaviour not work – the females can’t hear them – but the action uses up a lot of energy.
Just as some animals have vestigial organs that have lost all function, like the human appendix, the crickets seem to have a vestigial behaviour.
It may not last. “If there’s no advantage anymore to singing, you might expect over time that males would put less effort in,” says Bailey. “On the other hand, if there is another function to the behaviour we don’t know about, then it may continue.”
Unable to court females, the mute males are reduced to hanging around near the few remaining singing males, hoping to sneakily grab a mate. However, if these last singers die off, the species could die out.
Biology Letters
