Scientists already know that the annoying buzz of a mosquito is the sound of love. But now, a new study has shown that males and females flap their wings and change their tune to create a harmonic duet just before mating.
For the study, Cornell University researchers recorded mosquito sound to study how they use it in mating.
They found that male and female mosquitoes (Aedes aegypti), which can spread such diseases as yellow and dengue fevers, 'interact acoustically with each other when the two are within earshot - a few centimetres of each other.'
"The frequency at which males and females converge is a harmonic or multiple of their wing-beat frequencies, which is approximately 400 hertz [vibrations per second] for the female and 600 hertz for the male," said Ron Hoy, professor of neurobiology and behaviour.
The mating duet, generated just before the couple mates on the fly, settles at around 1,200 hertz -- roughly an octave and a half above concert A (the pitch to which instruments are tuned -- the A that has a frequency of 440 hertz and is above middle C).
That is significantly higher than what was previously thought to be mosquitoes' upper hearing limit," he added.
Interestingly, the mosquitoes adjust the harmonic resonance of their thoracic box to produce a harmonic frequency that converges at a frequency that is the female's third harmonic (three times her fundamental frequency) and the male's second harmonic (two times his fundamental frequency).
To study mosquito-mating calls, the researchers tethered mosquitoes and flew them past each other while recording the flight tones with a special microphone.
Co-first author Benjamin Arthur, a postdoctoral researcher in Hoy's laboratory, placed electrodes in the mosquitoes' auditory organ in their antennae during playback to measure physiological responses of the mosquitoes to the sounds of potential mates.
According to the researchers, their study will offer new ways to better control of mosquito populations in places where yellow and dengue fevers are significant problems.
"By studying these flight tone signals, we may be able to determine what kind of information males and females consider important when choosing a mate. This will allow us to release 'sexy' transgenic or sterilized males that will be able to successfully compete with wild populations," said co-first author Lauren Cator, a Cornell graduate student.
The study will be published in a February issue of Science.