3 new ways to kill mosquitoes

We can use a mosquito's own instincts against her. At TEDxMaastricht speaker Bart Knols demos the imaginative solutions his team is developing to fight malaria -- including limburger cheese and a deadly pill.
(Filmed at TEDxMaastricht.)

(Mosquito buzzing)

(Swat)

Gotcha.

Mosquitos. I hate them.

Don't you?

That awful buzzing sound at night around your ears

that drives you absolutely crazy?

Knowing that she wants to stick a needle in your skin

and suck out your blood? That's awful, right?

In fact, there's only one good thing I can think of

when it gets to mosquitos.

When they fly into our bedroom at night,

they prefer to bite my wife.

But that's fascinating, right?

Why does she receive more bites than I do?

And the answer is smell, the smell of her body.

And since we all smell different and produce chemicals

on our skin that either attract or repel mosquitos,

some of us are just more attractive than others.

So my wife smells nicer than I do, or I just

stink more than she does.

Either way, mosquitos find us in the dark

by sniffing us out. They smell us.

And during my Ph.D, I wanted to know exactly

what chemicals from our skin mosquitos used,

African malarial mosquitos use to track us down at night.

And there's a whole range of compounds that they do use.

And this was not going to be an easy task.

And therefore, we set up various experiments.

Why did we set up these experiments?

Because half the world's population runs the risk

of contracting a killer disease like malaria

through a simple mosquito bite.

Every 30 seconds, somewhere on this planet,

a child dies of malaria, and Paul Levy this morning,

he was talking about the metaphor of the 727 crashing into the United States.

Well, in Africa, we have the equivalent of seven jumbo 747s

crashing every day.

But perhaps if we can attract these mosquitos to traps,

bait it with our smell, we may be able to stop transmission

of disease.

Now solving this puzzle was not an easy thing,

because we produce hundreds of different chemicals on the skin,

but we undertook some remarkable experiments

that managed us to resolve this puzzle very quickly indeed.

First, we observed that not all mosquito species

bite on the same part of the body. Strange.

So we set up an experiment

whereby we put a naked volunteer in a large cage,

and in that cage we released mosquitos

to see where they were biting on the body of that person.

And we found some remarkable differences.

On the left here you see the bites

by the Dutch malarial mosquito on this person.

They had a very strong preference for biting on the face.

In contrast, the African malarial mosquito

had a very strong preference for biting the ankles and feet of this person,

and that of course we should have known all along

because they're called mosqui-toes, you see? (Laughter)

That's right. (Applause)

And so we started focusing on the smell of feet,

on the smell of human feet,

until we came across a remarkable statement in the literature

that said that cheese smells after feet

rather than the reverse. Think of it.

And this triggered us to do a remarkable experiment.

We tried, with a tiny little piece of Limburger cheese,

which smells badly after feet,

to attract African malaria mosquitos.

And you know what? It worked.

In fact, it worked so well that now we have a synthetic mixture

of the aroma of Limburger cheese that we're using in Tanzania

and has been shown there to be two to three times

more attractive to mosquitos than humans.

Limburg, be proud of your cheese,

as it is now used in the fight against malaria.

(Applause)

That's the cheese, just to show you.

My second story is remarkable as well.

It's about man's best friend. It's about dogs.

And I will show you

how we can use dogs in the fight against malaria.

One of the best ways of killing mosquitos

is not to wait until they fly around like adults

and bite people and transmit disease.

It's to kill them when they're still in the water as larvae.

Why? Because they are just like the CIA.

In that pool of water, these larvae are concentrated.

They're all together there. They are immobile.

They can't escape from that water. They can't fly.

And they're accessible. You can actually walk up

to that pool and you can kill them there, right?

So the problem that we face with this is that,

throughout the landscape, all these pools of water

with the larvae, they are scattered all over the place,

which makes it very hard for an inspector like this

to actually find all these breeding sites and treat them with insecticides.

And last year we thought very, very hard,

how can we resolve this problem? Until we realized

that just like us, we have a unique smell,

that mosquito larvae also have a very unique smell.

And so we set up another crazy experiment,

because we collected the smell of these larvae,

put it on pieces of cloth, and then did something very remarkable.

Here we have a bar with four holes,

and we put the smell of these larvae in the left hole.

Ooh, that was very quick.

And then you see the dog. It's called Tweed. It's a border collie.

He's examining these holes, and now he's got it already.

He's going back to check the control holes again,

but he's coming back to the first one,

and now he's locking into that smell,

which means that now we can use dogs

with these inspectors to much better find

the breeding sites of mosquitos in the field,

and therefore have a much bigger impact on malaria.

This lady is Ellen van der Zweep. She's one of the best dog-trainers in the world,

and she believes that we can do a lot more.

Since we also know that people that carry malaria parasites

smell different compared to people that are uninfected,

she's convinced that we can train dogs

to find people that carry the parasite.

That means that in a population where malaria

has gone down all the way, and there's few people remaining with parasites,

that the dogs can find these people,

we can treat them with anti-malarial drugs, and give the final blow to malaria.

Man's best friend in the fight against malaria.

My third story is perhaps even more remarkable,

and, I should say, has never been shown to the public until today.

Yeah.

It's a crazy story, but I believe it's perhaps the best

and ultimate revenge against mosquitos ever.

In fact, people have told me that now they will enjoy

being bitten by mosquitos.

And the question of course is, what would make someone

enjoy being bitten by mosquitos?

And the answer

I have right here in my pocket,

if I get it.

It's a tablet, a simple tablet,

and when I take it with water,

it does miracles.

Thank you.

(Drinking)

Now let me show you how this works.

Here in this box I have a cage

with several hundred hungry

female mosquitos

that I'm just about to release. (Laughter)

Just kidding, just kidding.

What I'm going to show you is I'm gonna stick my arm into it

and I will show you how quickly they will bite.

Here we go.

Don't worry, I do this all the time in the lab.

There we go. Okay.

Now, on the video, on the video here,

I'm going to show you exactly the same thing,

except that what I'm showing you on the video

happened one hour after I took the tablet.

Have a look. That doesn't work. Okay. Sorry about that.

I'm sticking in my arm, I'm giving them a big juicy

blood meal, I'm shaking them off, and we follow them through time

to see these mosquitos get very, very sick indeed,

here shown in fast motion,

and three hours later what we see at the bottom

of the cage is dead mosquitos,

very dead mosquitos, and I'm going to say, ladies and gentlemen,

we have swapped the cards with mosquitos.

They don't kill us. We kill them.

(Applause)

Now — (Laughter) —

Maastricht, be prepared.

Now think of what we can do with this.

We can actually use this to contain outbreaks

of mosquito-born diseases, of epidemics, right?

And better still, imagine what would happen if,

in a very large area, everyone would take these drugs,

this drug, for just three weeks.

That would give us an opportunity to actually eliminate

malaria as a disease.

So cheese, dogs and a pill to kill mosquitos.

That's the kind of out-of-the-box science that I love doing,

for the betterment of mankind,

but especially for her, so that she can grow up

in a world without malaria. Thank you. (Applause)