Placeholder Image

Subtitles section Play video

  • I would like to introduce you to my favorite parasite.

  • There are millions that I could choose from

  • and this is it:

  • it's called the jewel wasp.

  • You can find it in parts of Africa and Asia.

  • It's a little under an inch long,

  • and it is a beautiful looking parasite.

  • Now, you may be saying to yourself,

  • "This is not a parasite.

  • It's not a tapeworm,

  • it's not a virus,

  • how could a wasp be a parasite?"

  • You are probably thinking about regular wasps,

  • you know, the ones that build paper nests as their house.

  • Well, the thing is that the jewel wasp

  • makes its house inside a living cockroach.

  • Here's how it happens.

  • A jewel wasp is flying around, looking for a cockroach.

  • When it sees one, it lands and bites on its wing.

  • So, I'll be the cockroach.

  • Be-wha! Bewha!

  • And the cockroach starts shaking it off,

  • "Get away from me!"

  • The wasp very quickly starts stinging the cockroach.

  • All of a sudden, the cockroach can't move,

  • for about a minute.

  • And then it recovers

  • and stands up.

  • It could run away now,

  • but it doesn't.

  • It just doesn't want to.

  • It just stays there.

  • It's become a zombie slave.

  • Again, I'm not making this up.

  • The wasp goes off,

  • it walks away and finds a hole

  • and digs it out, makes it into a burrow.

  • It walks back.

  • This can take up to half an hour.

  • The cockroach is still there.

  • What do we do now?

  • The wasps grabs onto one of the antenna,

  • bites down on it,

  • of the cockroach,

  • and pulls the cockroach.

  • And the cockroach says, "Alright,"

  • and walks like a dog on a leash.

  • The wasp takes it all the way down into the burrow.

  • The cockroach says, "Nice place."

  • The wasp takes care of some business

  • and then goes and leaves the burrow

  • and seals it shut,

  • leaving the cockroach entombed in darkness, still alive.

  • The cockroach says, "Alright, I'll stay here if you want."

  • Now, I mentioned that the cockroach took care,

  • ah, the wasp took care of a little business

  • before it left the burrow.

  • The business was laying an egg

  • on the underside of the cockroach.

  • The egg hatches.

  • Out comes a wasp larva.

  • It looks kind of like a maggot with big, nasty jaws.

  • It chews a hole into the cockroach

  • and starts to feed from the outside.

  • It gets bigger, like you can see over here.

  • And then when it gets big enough,

  • it decides to crawl into the hole,

  • into the cockroach.

  • So now it's inside the still-living cockroach

  • and the cockroach doesn't mind much.

  • This goes on for about a month.

  • The larva grows and grows and grows,

  • then makes a pupa, kind of like a cocoon.

  • Inside there it grows eyes,

  • it grows wings,

  • it grows legs,

  • the cockroach is still alive, still waiting.

  • Finally the wasp is ready to leave,

  • and that's when the cockroach finally dies

  • because the fullly-formed adult wasp

  • crawls out of the cockroach's dying body.

  • The wasp shakes itself off,

  • climbs out of the burrow,

  • goes and finds another wasp to mate with

  • to start this whole, crazy cycle again.

  • So, this is not science fiction,

  • this happens every day, all over the world.

  • And scientists are totally fascinated by this.

  • They're just starting to figure out how all this happens.

  • And, when you really start to look at the science of it,

  • you start to kind of respect this very creepy wasp.

  • You see, the thing is that when it attacks the cockroach,

  • it's not just stinging wildly,

  • it delivers two precise stings.

  • It knows this cockroach's nervous system

  • like you know the back of your hand.

  • The first sting goes to that spot there,

  • called the "walking rhythm generators,"

  • and, as you can guess,

  • those are the neurons that send signals

  • to the legs to move.

  • It blocks the channels that the neurons use

  • to send these signals.

  • So the cockroach wants to go, it wants to run away,

  • but it can't because it can't move its legs.

  • And that lasted for about a minute.

  • This is really sophisticated pharmacology.

  • We actually use the same method,

  • a drug called Ivermectin,

  • to cure river blindness,

  • which is called by a parasitic worm

  • that gets into your eye.

  • If you take Ivermectin, you paralyze the worm

  • using the same strategy.

  • Now, we discovered this in the 1970s,

  • the wasp has been doing this for millions of years.

  • Then comes the second sting.

  • Now the second sting actually hits two places along the way.

  • And to try to imagine how this can happen,

  • I want you to picture yourself with a friend

  • who's got a very long, very, very scary looking needle.

  • And your friend,

  • or at least you thought he was your friend,

  • sticks it in your neck,

  • goes into your skull,

  • stops off at one part of your brain

  • and injects some drugs,

  • then keeps going in your brain

  • and injects some more.

  • These are two particular spots,

  • marked here, "SEG",

  • and you can see the tip of it in the brain, marked "Br".

  • Now, we can do this, but it's really hard for us.

  • It's called stereotactic drug delivery.

  • You have to put a patient in a big metal frame

  • to hold them still,

  • you need CAT Scans to know where you're going,

  • so you look at the picture and say,

  • "Are we going the right way?"

  • The jewel wasp has sensors on its stinger

  • and scientists think that it can actually feel its way

  • through the cockroach's brain until it gets

  • to the exact, right place,

  • and then penetrates an individual neuron

  • and then delivers the goods.

  • So, this is quite amazing stuff,

  • and what seems to happen then

  • is that the wasp is taking away the control

  • that the cockroach has over its own body.

  • It's taking away the cockroach's free will.

  • We didn't really appreciate that cockroaches

  • have free will until this wasp showed us.

  • And, we have no idea how it's doing this,

  • we don't know yet what the venom has in it

  • and we don't know which circuits

  • it's hitting in the cockroach's brain,

  • and I think that's why this is,

  • most of all, my favorite parasite

  • because we have so much left to learn from it.

  • Thank you very much.

I would like to introduce you to my favorite parasite.

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B2 TED-Ed cockroach wasp parasite burrow jewel

【TED-Ed】Parasite tales: The jewel wasp's zombie slave - Carl Zimmer

  • 412 34
    wikiHuang posted on 2014/01/11
Video vocabulary