ielts_trainer_2_academic_six_practice_tests

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LISTENING PART 4
10
Exam Practice
You will hear a student giving a presentation about the way that different
insect species are being threatened.
Now listen carefully and answer questions 31 to 40.
Student: So today I’m going to be talking about the way that different
insect species are being threatened. In other words, the reasons why
some insect populations are declining – and might even become extinct
in the 21 st century. I’ll also talk about the consequences – if extinction
occurs – and some possible ways to prevent that.
Let’s start with the reasons. First of all, when we look at what’s going on
in Europe, we can see a huge decline in certain species of insect. This is
partly because farmers no longer allow certain plants to grow in their
fields. But farmers are not entirely to blame. The gardens that people
have nowadays don’t always contain the kind of plant that insects need.
So perhaps we need to rethink what we’re putting there. In more tropical
regions of the world, for example, the Amazon rainforest, scientists have
noticed that the number of beetle and butterfly species also appears
to be diminishing. They put this down to climate change, rather than
say, the fragmentation of habitat – but more research has to be done.
And then, there’s the use of pesticide, and of course, this happens
everywhere in the world. Pesticide is designed to kill a range of insects
that farmers don’t like, but it also kills bees, which they need. Pesticide
might not kill bees directly, but we know that it impacts on their spatial
skills – meaning they cannot make sense of what they see around them –
and also their memory. This means that they cannot remember how to
get back to their hive.
So why worry about whether insects become extinct? Well, the
consequences would obviously be terrible not just for them, but for us.
Pretty much everywhere on the planet, with the exception of Antarctica,
insects are at the bottom of the food chain. They’re absolutely vital,
because if there were no insects, there would also be no birds or lizards
or mammals. Then there’s the role that insects play in crop production.
We use them to pollinate our fruit and vegetables, and it would be
impossible to manage without them. It’s also worth remembering that
scientists are now studying plants to find out whether they might be a
source of medicine in the future. If these plants disappear because of
insect extinction, that would be another lost opportunity.
So, there’s some possible ways we could prevent insect extinction, some
more controversial than others. I think it’s a given that governments have
to do something about the sale of pesticides; in fact, some countries
have already passed laws to ban certain products. That’s a good move
forward. But ordinary people can also make a difference. If we cut down
on how much meat we ate, some of the land now used for grazing could
be turned back into insect-friendly environments.
I’d like to finish with a positive story. There’s a place in California called
the Antioch Dunes. In the 1900s, people looked at the dunes and the
sand that formed them and thought ‘that sand is a great raw material’.
And because they needed to build houses, they removed tons and tons
of the sand and turned it into bricks. It wasn’t really until the 1960s that
biologists suddenly realised that the Antioch Dunes had actually been
home to some unique species of plant and insect. But by this time, there
was only one species of butterfly left. The metalmark butterfly. And a
major problem for the metalmark was that it required a certain plant
to survive –something called the naked-stem buckwheat. It was on this
plant that it laid its eggs, so yes, you can see why the buckwheat was
important. Well, in the end, the only way that the biologists could get the
buckwheat to start growing properly was to replace the sand. That was a
great first step, but the metalmark butterfly is still endangered.
In the last decade, a significant number of butterflies and plants have
been destroyed in the Antioch Dunes by fire. So now, the biologists are
limiting the number of visitors who can wander around the dunes. That’s
fair enough, I think. All right, the final point I want to make about the
project to restore the Antioch Dunes area is to do with how much land
is required: when we think about the concept of conservation we often
assume we need to set aside a large amount of it. And that might be true
for some large species. But in this case, relatively little land was required.
But the important thing is to leave it undisturbed. OK...
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IELTS Trainer 2 Tests 1–6 audioscripts © Cambridge University Press and UCLES 2019 5