The most annoying love song ever written: this one's for the mosquitoes

Feb 25 2009 Published by under Natural Sciences

Actually, I would like to dedicate this post to the lovely Stephanie Zvan of Almost Diamonds. This is because Stephanie recently sent Sci her blogging muse: an entire box of dark chocolate Moose Munch!!!!!! Moose Munch is indeed Sci's muse, and could not have come at a better time. Stephanie Zvan is awesome for any number of reasons (I particularly recommend her short stories) , but sending food in the mail definitely adds a little extra.
Unfortunately, this means that last night was spent suffering the effects of a Moose Munch overdose. But today Sci is back up and rolling...literally. And to you, Stephanie, the bringer of my mental muse, I give you...a love song. In major fifths. At 600 and 400 Hz. Cator et al. "Harmonic convergence in the love songs of the dengue vector mosquito" Science, 2009.
This post brought to you by Stephanie Zvan. And moose munch. Also kilts, rum, and sugar highs.
I'm sure we all know about mosquitoes. I know I cringe at the very sound of that high-pitched whine. If you're delicious (like Sci), then you KNOW that every time you hear those nasty ear-splitting notes of horror, you can give up, because bug spray or not, you're going to be scratching for days. But to a lady mosquito, what sounds to us like a teeth-gritting shrill is the hottest love song on the planet.

But we all know that mosquitoes are not just song and itchy bites. They spread many diseases which are endemic in countries around the world, things like malaria, yellow fever, and dengue. These diseases have to have a mosquito as their vector, and so a lot of research has focused on mosquitoes as vectors and how to prevent them getting access to humans (mosquito nets and things).
But for all the research and all the hype we hear about preventing mosquito bites when we go to certain countries, we don't actually know a lot ABOUT mosquitoes. Ok, we know they come in male and female. Most of the time the female is the one who drinks the blood (though there are some "vegetarian" mosquitoes). We know the females need still water in which to lay their eggs. And...well...yeah. So this paper today is a big deal, not just because it implies a new way in which to possibly fight mosquitoes, but also because it tells us a whole boatload of stuff about them that we never knew before.
So we know they make that high-pitched whine. This is not because mosquitoes are vocally talented, the whine comes from the frequency of wing beats. For males, this is around 600Hz, and for females it's around 400. This is actually about a fifth apart on the traditional musical scale. The 600 Hz tone is the higher one, which I think might be because the males are smaller, but I'm just guessing there.

One of the things I love about this study was how they did it. First, take a mosquito and tether it to a pin (I would kill to know how they did they, but I'm imagining a very frustrated grad student with very swollen fingers). Leave it free so it can flap its wings. Record the sound into a microphone. Then, hold the boy mosquito near a tethered girl mosquito for a few seconds, moving slowly in and out of range for a few fly-bys. Record the sounds and see what happens.
And what happened? Instead of the male mosquito and female mosquito continuing at 600 and 400 Hz, they made beautiful music together, matching their wing beats to a tone of 1200 Hz. This is a pretty high tone, as you might imagine. Not only that, they could get the bugs to match a mating tone (at 1200 Hz) played artificially, so they could be fooled with a fake. Interestingly, females tended to match a tone only if they were virgins (mosquitoes only make once), and lost interest once they had mated.
So what does this tell us about mosquitoes? Quite a lot. Most scientists believed that mosquitoes could only hear between 300 and 800 Hz, and this tone shattered all the records. Not only that, many researchers believed that only male mosquitoes could hear, and that females were deaf. So males would be able to find females, and females may never know what was coming. But this experiment proves that females can hear, and react to what they hear.
Secondly this experiment could provide a lot of information about how to keep mosquito populations down in heavily populated areas. For example, some people have thought of releasing sterile males into the wild. The males would mate with the female, who would then complete their life cycle and die without ever giving birth. This could significantly reduce the female mosquito population. This experiment backs up this idea, as females are more susceptible to males when they are virgins, so they'd be more likely to mate with the sterile males than if they could just mate loads of times.
The idea that occurred to me was this: bug zappers. Bug zappers make noise, right? It's not very loud, but all that electricity produces a hum. How much would it hurt to turn it up to 1200 Hz? If the horny mosquitoes can be fooled by a tone, this could encourage them to draw closer and bring some flowers and make dinner reservations, and then...ZAP! Kill them before they mate, and you've stopped a major disease vector.
L. J. Cator, B. J. Arthur, L. C. Harrington, R. R. Hoy (2009). Harmonic Convergence in the Love Songs of the Dengue Vector Mosquito Science, 323 (5917), 1077-1079 DOI: 10.1126/science.1166541

9 responses so far

  • Cuttlefish says:

    They need your blood, they need their song,
    And so it's plain to see--
    Should someone want mosquitos bred
    They need both whine and thee.

  • Stephanie Z says:

    Aw, thanks, Sci. Ben was happy to hear you mentioned kilts, too.
    As far as bug zappers go, though, I want something that will get the recently mated females as well. Speaking as another delicious individual (if it bites, it will bite me), I say zap the nasty little things before they can lay those eggs.

  • Erin says:

    Beginning this post with Moose Munch rendered me unable to concentrate on anything you said afterwards...just to let you know...

  • arvind says:

    Why doesn't it surprise me that the default assumption was that the female would be passive?
    The following is inspired by a combination of your suggestion and seeing Cuttlefish on this thread:
    Anopheles, a young lass from the delta
    Felt a feeling she never before felta
    Thought she found a mate
    But cruel was her fate
    What she found really made her melta

  • Becca says:

    I listened to the science podcast for this issue and they talked about this paper.
    From what I gathered:
    1) very frustrated grad student with very swollen fingers is dead on
    2) 1200Hz is apparently one of the most incredibly universally agreed upon annoying sounds to the human ear ever. Evolutionary adaptation?

  • nanoAl says:

    Bug zappers buzz at 60 Hz because thats the frequency of your mains power. If they were going to make the 1200Hz tone they would need speakers. and they would be super annoying. Very cool stuff though.

  • lauren says:

    Hello I'm Lauren Cator (the grad student)
    No swollen fingers here. However, there was a case in which a male got off of the pin covered in glue and made a bull's eye into MY eye.

  • Scicurious says:

    Lauren! Thanks so much for commenting! It's absolutely the coolest when I get the paper authors on the blog. This paper is fantastic, btw.
    I did have a couple of questions for you. I'm very glad you didn't have swollen fingers (though sorry hear about the bug in your eye!), but how DID you get the bug on the glue-covered pin?
    My other question is this: 400 and 600 Hz is about a 5th apart on the musical scale, but I've looked around, and I don't know what musical notes they would correspond to. Do you know? I'm just curious.
    Thanks again for commenting! And if there's anything I missed, please let me know.

  • gradstdentsteve says:

    I'd have to look up it up america, those aren't notes, but in Europe they are. In America, the standard defining tone is A-442 (if you ever get a tonal tuner, ie, one that plays a set tone that you match, then this is what is plays), so that a mid-range A is 442 Hz. It's 440 in Europe (or vice versa...I can never remember any more which is which, but it doesn't matter since the human ear cannot differentiate any sound less than 5 'cents', to use the musical term, [1 cent = 1 Hz] in either direction). so, some quick math...if a 5 is 200 Hz, then it's 40 Hz per note, as that the male is playing a G while the female is playing an E above that.

Leave a Reply