lunes, 27 de enero de 2014

The loathsome, lethal mosquito

The loathsome, lethal mosquito is a Ted Ed lesson by Rose Eveleth. This is the way Ted Ed introduces the lesson:

"Everyone hates mosquitos. Besides the annoying buzzing and biting, mosquito-borne diseases like malaria kill over a million people each year (plus horses, dogs and cats). And over the past 100 million years, they've gotten good at their job -- sucking up to three times their weight in blood, totally undetected. So shouldn't we just get rid of them?"

Self-study activity:
Watch this short video clip and answer the questions below about it.

The activity is suitable for intermediate 2 students.

1 What's the worst bug on the planet?

2 How long have mosquitoes been around?
3 What quality do all mosquito species share?
4 What does 'two or three times' refer to?
5 What two 'qualities' of mosquitoes are mentioned?
6 How many people die of mosquito-borne diseases every year?
7 Why don't we get rid of mosquitoes?

To check your answers, you can read the transcript below.

You can also drop by the Ted Ed lesson and keep to the standard procedure all the Ted Ed lessons follow: Watch the video, answer some listening comprehension questions, check additional resources to explore the topic (Dip Deeper) and talk about the questions in the Discuss section.

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 mosquitos 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 mosquitos 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 mosquitos 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 mosquitos are annoying, they're also deadly. Mosquitos 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 mosquitos 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 mosquitos. Something better might take their spot or perhaps something even worse. The question is, are we willing to take that risk?