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What's the worst bug on the planet?
You might vote for the horsefly or perhaps the wasp, but for many people, the worst offender is by far the mosquito.
The buzzing, the biting, the itching, the mosquito is one of the most commonly detested pests in the world.
In Alaska, swarms of mosquitoes can get so thick
that they actually asphyxiate caribou.
And mosquito-borne diseases kill
millions of people every year.
The scourge that is the mosquito isn't new.
Mosquitoes have been around
for over a hundred million years
and over that time have coevolved
with all sorts of species,
including our own.
There are actually thousands of species
of mosquitoes in the world,
but they all share one insidious quality:
they suck blood, and they're really, really good at sucking blood.
Here's how they do it.
After landing, a mosquito will slather
some saliva onto the victim's skin,
which works like an antiseptic,
numbing the spot so we don't notice their attack.
This is what causes the itchy, red bumps, by the way.
Then the bug will use its serrated mandibles
to carve a little hole in your skin,
allowing it to probe around
with its proboscis,
searching for a blood vessel.
When it hits one,
the lucky parasite can suck
two to three times its weight in blood.
Turns out we don't really like that too much.
In fact, humans hate mosquitoes so much
that we spend billions of dollars worldwide
to keep them away from us --
from citronella candles
to bug sprays
to heavy-duty agricultural pesticides.
But it's not just that mosquitoes are annoying,
they're also deadly.
Mosquitoes can transmit everything
from malaria
to yellow fever
to West Nile virus
to dengue.
Over a million people worldwide
die every year from mosquito-borne diseases,
and that's just people.
Horses, dogs, cats,
they can all get diseases from mosquitoes too.
So, if these bugs are so dastardly,
why don't we just get rid of them?
We are humans after all,
and we're pretty good at getting rid of species.
Well, it's not quite so simple.
Getting rid of the mosquito
removes a food source
for lots of organisms
like frogs and fish and birds.
Without them, plants would lose a pollinator.
But some scientists say
that mosquitoes aren't actually all that important.
If we got rid of them, they argue,
another species would simply take their place
and we'd probably have far fewer deaths from malaria.
The problem is
that nobody knows what would happen
if we killed off all the mosquitoes.
Something better might take their spot
or perhaps something even worse.
The question is,
are we willing to take that risk?
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B1 Intermediate US

【TED-Ed】The loathsome, lethal mosquito - Rose Eveleth

71661 Folder Collection
VoiceTube published on February 23, 2015

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