The Bedroom
Even as late as the end of October or early November, the buzz of gnats wakes me up at night. This buzz, caused by their rapidly up and down moving wings, plays an important part in the communication around the mating. Gnat couples are formed through hearing. With a good match, their buzzing sounds in unison: they fly in tune. The female may exert a degree of mate choice by changing her flight-tone to see how well the male follows her, or change frequencies if she wants to “lose” him, for example if she has already mated. (Warren, Gibson, and Russell 2009: 489)
In 2006, British biologists Gabriella Gibson and Ian Russell show, for the first time, interactive auditory behavior between male and female mosquitoes leading to sexual recognition. Individual males and females of the Toxorhynchites brevipalpis both respond to pure tones by altering wing-beat frequency. Each mosquito alters its wing-beat frequency in response to the flight tone of the other, so that within seconds their flight tone frequencies are closely matched, if not completely synchronized (Gibson and Russell 2006: 1311).
A female flies alone; after five seconds a male joins in. Within a second they produce the same tone
A male flies alone; after five seconds a female joins in. The male adapts his flight tone so as to sound almost perfectly in unison
“Deaf” mosquitoes – mosquitoes with cut antennae; they hear with an organ very sensitive to vibrations at the basis of their antennae – do not react to the other.
With Culex quinquefasciatus – this nighttime-active, opportunistic blood feeder – the wing-beat frequencies of males and females differ considerably. They converge not on the fundamental but on the nearest shared harmonic (usually female’s third and male’s second). (Warren, Gibson, and Russell 2009: 485)
While testing the flight tones of same-sex pairs, Gibson and Russell discovered that the gnats initially try to merge their wing-beat frequency but eventually diverge dramatically. (Gibson and Russell 2006: 131)
Initially two females produce almost the same buzz tone, but shift their frequencies after a few seconds to be more different
The significance of this research is primarily theoretical: these results show that sound plays an important part in recognition and in the willingness to copulate. A concrete application, a gnats-trap on the basis of sound, is not even a distant prospect. Gibson in a Dutch daily: “Female mosquitoes don’t fly towards sounds or from it. They only change their wing-beat frequency in reaction to certain sounds. That is why those devices with ultrasound don’t work against mosquitoes.” (Voormolen 2006: 8, my translation) Which means that the gnats’ buzz in my bedroom will sometimes be followed by a dry slap with a short attack and a short decay; a more animal friendly solution is to turn on a fan which drowns out the mosquito’s buzzing …