Aedes aegypti. Credit: Marcos Teixeira de Freitas
As far as bloodthirsty insects go, the mosquito Aedes aegypti might be slightly less disagreeable than most. For starters, it was the second mosquito to have its genome sequenced (the first was Anopheles gambiae), providing us with useful genetic markers to help combat the spread of disease. And despite carrying several of these diseases itself (dengue fever, yellow fever, and malaria), it boasts a contemporary black and white coat that would satisfy just about any designer’s palate.
But a recent study suggests that Aedes aegypti is more than just tolerable. When Laura Harrington, Ronald Hoy, and colleagues at Cornell University tethered Aedes aegypti to the end of a pin, they discovered that males and females perform a wing-flapping musical duet that harmonically converges at 1,200 hertz. This is twice the normal wing-flap rate of males, and three times the normal wing-flap rate of females. What we hear as an irritating buzzing is actually a deliberate and synchronized harmony that is profoundly, ahem, romantic.
Hoy says that upon investigating the way in which mosquitoes interact during courtship, they made an unlikely discovery: “During the interaction, when they are very close to each other,” he says, “they are singing a duet.” But this is no ordinary tune. It is highly nuanced, with each frequency an integer multiple of an overall, fundamental frequency.
“The male and female are actually adjusting their flight tones,” Hoy says, “so that there is a matching, and hence we call our paper ‘harmonic convergence.’ It’s basically a conversation between the sexes.”
The finding comes as a double surprise because male mosquitoes were thought to be deaf to frequencies greater than 800 hertz. Female mosquitoes were thought to be deaf altogether.
Harrington says that scientists have more or less ignored this area of study for decades. “There really hasn’t been much work done on the mating behavior — and especially the biology — of male mosquitoes, because they don’t take a blood meal,” she says. “So they haven’t been considered important.”
By shedding light on the dynamics of mosquito courtship, this finding could directly aid in the development of novel strategies to control mosquito populations. Releasing sterile males into the wild is an effective method of population control, but sterile males are not the fittest males — and their acoustics might reflect that, diminishing their sex appeal. A useful application of this study might be to get sterile males to modulate the tones of fit males, restoring their status as Casanovas and diminishing the spread of mosquito-borne disease in the process.
Harmonic Convergence in the Love Songs of the Dengue Vector Mosquito
Science February 20, 2009
