We normally think of a mosquito’s buzz as being an overture for biting, but in fact it’s more like a lover’s aria. At least, if you’re another mosquito.
Writing in the journal Science, Lauren Cator, from Cornell University in the US, has found that male and female Aedes aegypti mosquitoes harmonise their buzzing just before mating, creating what must be the world’s most irritating duet.
The scientists carried out some very fiddly experiments involving mosquitoes tied to pins, moving one past the other to simulate courtship. Females beat their wings at a frequency of around 400 hertz (roughly a concert A, for any musicians listening), while males beat at a higher-pitched 600 hertz (that’s about a fourth higher). But just before they mate, they adjust the resonance of their thoraxes to produce a buzz of 1,200 hertz – a harmonic that’s about an octave and a half above the female mosquito’s pitch. And they could even get mosquitoes to harmonise with a simulated tone played through an earphone.
What’s interesting about these findings is that they overturn the conventional wisdom that male mosquitoes can’t hear anything above 800 hertz, and that female mosquitoes are completely deaf. They discovered this by taking careful electrical readings from the insects’ antennae and Johnston’s organs- the mosquito equivalent of our ears.
But there’s also something more important at stake. The mosquitoes that Cator and her team studied spread nasty – and even fatal – diseases like yellow fever and dengue fever. Dengue fever affects 50 million people around the world.
The researchers found that female mosquitoes who had just mated were much less likely to harmonise with male tones, suggesting they’re not really up for it again.
So the scientists suggest that releasing lots of sterile males into areas plagued by the mosquitoes might lead to female mosquitoes mating with them, which would not result in baby mosquitoes. And then the females would be less likely to go on to mate with fertile males. So it could help to control the population.