TED Talks · Neuroscience

Mosquitoes buzz

We've all heard the annoying sound of a mosquito in our ear, and we will stop at nothing to make it go away.

Level: B1 · 88 sentences

Transcript

1. We've all heard the annoying sound of a mosquito in our ear,
2. and we will stop at nothing to make it go away.
3. Now, while this sound may be maddening to us,
4. perhaps it's music to a mosquito's ears.
5. Mosquito's nervous system has almost as many sensory auditory cells as we do.
6. But why would they have so many in such a small body?
7. And why would they need to be so sensitive to sounds?
8. The answer is love.
9. As humans, we do a lot to attract each other.
10. Some are conscious.
11. We put on makeup and make sure we smell nice.
12. And some are unconscious.
13. You may unconsciously point your body or even sit closer to someone you like.
14. These are courtship behaviors, and a lot of animals have them.
15. And mosquitoes are no different.
16. So Haley's been spending her summer bravely listening to mosquitoes,
17. and what she observed may surprise you.
18. So we want to investigate how the mosquitoes make their song.
19. So Haley, we want to record their wing beats.
20. How are we going to do that?
21. We need to tether them.
22. And the way to do that is to first anesthetize them in a fridge or a bed of ice.
23. And then I transfer them to this petri dish of ice just to get them even more anesthetized.
24. Next, I take an insect pin.
25. And what I do is put a tiny little dab of super glue on this pin.
26. I want to make sure that I get it on his thorax.
27. above his wings so that when he is suspended, his wings are still free to move.
28. So here's one down.
29. It's really hard to catch male mosquitoes in the wild because females are the only mosquitoes that are attracted to humans.
30. They feed on human blood.
31. And now... We can try to get some recordings from them.
32. So this is the stand that I use to hold them.
33. I like to place it right over the microphone so that I can get a recording of the buzzing that you hear.
34. That sound is generated by how fast they're beating their wings.
35. This is a male.
36. The males have very bushy antenna.
37. They look kind of feathery, and they are also much smaller.
38. So he's flying around 600 hertz.
39. Yep. Let's try another mosquito.
40. Can we try a female mosquito?
41. Sure. There we go.
42. Wow. So this is a much lower frequency than the male.
43. Yeah, it sounds completely different than the other guy.
44. So is it just because they're two different mosquitoes?
45. Or is it because they're male and female?
46. It's because they're male and female.
47. Let's find out.
48. Let's verify that.
49. Can you bring in another female and see if she sounds like mosquito A or mosquito B?
50. Yeah. And again, she is much lower than the male.
51. Yeah, she sounds different.
52. And she's spot on 400.
53. She really is.
54. Yeah, that's a good one.
55. It's really bizarre.
56. The females were actually at a much lower pitch.
57. They were around 400 hertz.
58. I got you.
59. And all of the females were around that, too.
60. I noticed that they were much larger than the males.
61. So they didn't have to flap their wings as fast to stay in free flight.
62. So they have larger wings.
63. They're flapping slower.
64. And you notice that all the females have the same frequency,
65. roughly, and all the males have the same frequency.
66. That's kind of interesting.
67. Really cool, yeah.
68. So that must mean something.
69. All right, we'll see what happens when we put the male and the female together.
70. So when I put them into the same hearing range,
71. I noticed that they were kind of changing their tones.
72. It was kind of more dull almost.
73. And then when I put it back in my spectrogram to see their interaction,
74. they were meeting at the same tone.
75. Okay, pause. The males and females are singing a duet,
76. meaning that they adjust their wings to be able to produce a common tone.
77. You have the male singing up here at G.
78. You have the female singing down here at D.
79. And when they get together,
80. you're saying that they change the frequency of their wings such that they come together.
81. Yeah, exactly. They sort of sing a duet.
82. They're communicating with each other to let each other know that they've basically found a potential mate.
83. So in other words, the female tends to choose a male that best sings her duet.
84. And studies have found that if she's pregnant, she doesn't even bother.
85. So if we can understand the mosquito mating behavior,
86. we may be able to disrupt it in the wild and prevent diseases like malaria.
87. But for now, the next time you hear a mosquito buzzing, just pause and remember,
88. she may be in love and she may be singing her song and she may be looking for the perfect match.