Pharyngula

Mosquito love songs

It’s July in Minnesota, and you know what that means: bugs. Clouds of bugs. Some people complain, but I generally rationalize a large population of fecund invertebrates as simply a sign of a healthy ecosystem, so yeah, we’ve got bugs, but it’s good for us.

Except for those mosquitoes. It’s hard to think charitably of some invertebrates when you’re lying in bed at night and you hear…that…high-pitched whine rising as the nearly invisible little blood-sucker buzzes by your exposed flesh. Now, in a discovery calculated to increase my irritation, I learn that the little bastards are singing a love song as they hover about, looking for an opportunity to stab me and suck my blood. “Come to me, come to me, mon chéri,” they sing, “after I gorge myself on ze fat, torpid hu-man (and daintily spit up a little backwash into his capillaries), we shall make sweet, sweet love in the moonlight and zen I shall lay a thousand eggs, and our progeny shall feast on his children!” (Sorry, but now whenever I hear them they’ve also got a silly Pepe LePew French accent.)

i-79a57264701682e63a0c88fe1e5d7dab-tethered_mosquito.jpg

Here’s how you figure this out. With a tiny drop of sticky beeswax, tether a mosquito to a thin steel wire, and lift it into the air. When its feet have left the ground, it will spontaneously start flapping its wings, making its usual whine (you can stop them just by bringing a piece of paper into contact with the legs, so that it is fooled into thinking it has landed.) In the photo to the right, you’ll see a small, blocky microphone mounted within a few centimeters of the beast. Easy—now you can make a mosquito buzz at will, and get high quality recordings.

Now the interesting part: the mosquito whine is variable, and they can change the pitch by modulating the wingbeat frequency. How do you get them to change the pitch? By playing musical tones at them. It’s true: in a perverse variant of the closing scene of Close Encounters of the Third Kind, scientists are talking with mosquitos by playing tones at them, and the mosquitos are talking back by changing the tone of their whine. No word is yet available on any translations, but I suspect it will be some variations on “blood” and “sex,” emphasis on the sex.

Another thing they can do with this rig is record the conversations between mosquitoes. In the recording below (tres creepy if mosquito whines make your skin crawl), a tethered female is singing along at about 370Hz, and after about 5 seconds, a tethered male is launched nearby. His “voice” is higher pitched than hers at 595Hz, but almost immediately you’ll hear him try to sound huskier, while she raises her pitch a little bit, so that soon enough they’re singing at almost the same frequency (not quite, though—you can also hear the beating as they aren’t quite in perfect tune.)

This only works well if the two mosquitos are of different sexes. Put two males in the air at the same time, for instance, and you get a recording like the one below.

The two males first converge on the same frequency, but then after a period of anarchic oscillations, they diverge. I found the sound files difficult to pick up on that behavior, so I think us visual animals can see it better in the graphs of frequency below (D is the spectrogram of this recording).

i-6898d6d1b0b15137a3f9ff8212b07dc9-mosquito_freq.gif
Frequency Convergence and Divergence of Flight Tones by Pairs of Tethered Tx brevipalpis. Spectrograms of the fundamental components of flight tones of opposite (A-C) and same (D-G) sex pairs of mosquitoes (male [?], blue; female
[?], red). Numbers alongside each spectrogram refer to the flight-tone frequency of flying mosquito at onset of record, peak frequency of second
mosquito at take off, and frequency of both mosquitoes at end of record.

Different sex pairs sing in harmony together, but same sex pairs don’t; something clues them in about the gender of their partner from their song, which is curious, since both sexes can converge to the same frequency. The authors speculate that the key difference is responsiveness. Males respond much more quickly, but not instantaneously, to the pitch of their partner; females are slower and are in no hurry to respond.

What this means is that when two males meet, they try to synchronize, but they react to what their partner was doing just a moment before. Their “voices” dart up and down, each trying to meet the other, but never quite doing it. Two females, on the other hand, will slowly harmonize, but when one drifts away from the common frequency, the other may take a few seconds to try and match up. Their “voices” wander away from other other in slow rhythms. The only stable convergence is to match up a fast male and a slow female, where the male can rapidly lock in to her frequency, and she isn’t reacting quickly to his frequency shifts.

Two mosquitoes don’t have to actually see each other, they just sing at each other…and if they find they can make beautiful music together, they know they’re sexually compatible and should hook up. I think that’s beautiful, but I’m still going to crush their blood-sucking insectile bodies between my hands if I can catch them.


Gibson G, Russell I (2006) Flying in Tune: Sexual Recognition in Mosquitoes. Curr Biol 16:1311-1316.

Comments

  1. #1 donsalva
    February 2, 2008

    I came accross this line of discussions hoping to find a way to protect my children from insect bites. As I write this comment, my son is in the hospital trying to recouperate from Dengue fever. Weighing all the valid information, is it possible then to harness the tone of the female to attract the male mosquitos to somekind of ecologically, safe trap, like say a bird or bat cage or a mat of beeswax? Let’s use the sexual activeness of male insects to destroy themselves just like what we are unoticeably doing to the human species. I have read all the comments highlighting the possibilities and problems. Can we now use our intelligence for the solution? What commercially available CD or music popchart hit song replicate the female frequency? Please name it and I will buy it and set up trap using the best surround sound system available laced with beeswax. Or come to think of it, I think I will go into recording myself under the artist name “Insect buster”, and make millions in sales of insect drawing CDs and beeswax adhesive paper.

  2. #2 donsalva
    February 2, 2008

    I came accross this line of discussions hoping to find a way to protect my children from insect bites. As I write this comment, my son is in the hospital trying to recouperate from Dengue fever. Weighing all the valid information, is it possible then to harness the tone of the female to attract the male mosquitos to somekind of ecologically, safe trap, like say a bird or bat cage or a mat of beeswax? Let’s use the sexual activeness of male insects to destroy themselves just like what we are unoticeably doing to the human species. I have read all the comments highlighting the possibilities and problems. Can we now use our intelligence for the solution? What commercially available CD or music popchart hit song replicate the female frequency? Please name it and I will buy it and set up trap using the best surround sound system available laced with beeswax. Or come to think of it, I think I will go into recording myself under the artist name “Insect buster”, and make millions in sales of insect drawing CDs and beeswax adhesive paper.

  3. #3 Dave
    May 23, 2008

    The noise in the ‘converging’ signals appears much smaller. Assuming this represents a compression of the Y axis in the data, the apparent divergence in the same-sex pair recordings could be misrepresentative. So based on the data shown, I am not convinced. The frequency difference should be quantified and statistically compared.

  4. #4 Amy
    August 3, 2008

    When you read this post, picture the little French skunk as the male mosquito, and the little French cat as, well, the victim. Of course, mosquitos still suck. Literally. But isn’t it more amusing doing it my way?

  5. #5 woodsong
    May 14, 2009

    On the question of what roles do skeeters play in the ecosystem, they are also pollinators of wildflowers, especially in forests. From Wikipedia: http://en.wikipedia.org/wiki/Mosquito

    “Males live for about a week, feeding on nectar and other sources of sugar. Females will also feed on sugar sources for energy but usually require a blood meal for the development of eggs. After obtaining a full blood meal, the female will rest for a few days while the blood is digested and eggs are developed. This process depends on the temperature but usually takes 2?3 days in tropical conditions. Once the eggs are fully developed, the female lays them and resumes host seeking.”

    Speaking of no-see-ums, here’s an amusing snippet (any chocolate fiends out there?) from http://pollinators.nbii.gov/portal/community/Communities/Ecological_Topics/Pollinators/Pollinator_Species/Invertebrates/Flies,_Mosquitoes,_and_Midges/

    “Chocolate lovers may be more impressed by another example of pollination by dipterans: biting midges (or “no-see-ums”) and gall midges in the Ceratopogonoidae and Cecidomyiidae families, respectively, are the only known pollinators of cacao trees, which produce the beans from which chocolate is made.”

    Whiles I like wildflowers (and bats!), I’m still tempted to put a speaker playing female-skeeter songs in a bug zapper…except that this would only attract the males, and it’s the females that bite. Sigh. I guess I’ll have to get some catnip oil! I like that idea, btw–I HATE most repellants (I think I find them more repellant that the bugs do, sometimes)!

  6. #6 woodsong
    May 14, 2009

    I guess the point I would make would be to echo some other posters: Don’t exterminate species lightly! Especially not an entire genus or family.

    Although, if biologists want to exterminate disease-causing agents, I’d request that they work on the malaria parasite first. Yes, skeeters carry many other diseases, but I think that’s the worst one.

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