The night-walkers of Uganda

3 Comprehension check
 
1. c
2. e
3. a
4. g
5. b
6. h
7. f
8. d
4 Vocabulary: Collocations / Word pairs
difficult times
toilet paper
wheat harvest
tobacco production
shopping trip
lose control
shrinking economy
hidden market
call centres
property developer
128

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Shock of the new
Scientists hope to release GM mosquitoes 
into the wild to try and destroy malaria. They 
should be very careful, says James Randerson 
- introducing new species can be dangerous.
 
March 21, 2007
 
It is an exciting scientific project that could 
offer hope to 300 million people with malaria 
worldwide. The plan is to genetically modify the 
mosquitoes in countries with malaria, so that the 
insects can no longer carry the malaria parasite 
– and so can’t pass it to people. Without the right 
mosquitoes, the disease would soon die out. 
Using genetically modified insects is not a new 
idea but this week, scientists at Johns Hopkins 
University in Maryland gave it new importance. 
The scientists there cannot be sure what the 
results would be but their lab studies suggest that 
the GM mosquitoes might soon be stronger than 
normal ones.
Many human lives might be saved. But what 
would happen if millions of GM-insects were 
released into the wild? When the mosquitoes 
are in their natural habitat, would the gene they 
carry jump into other species? GM animals have 
never been released in large numbers, so these 
questions are hard to answer. 
But in the past, when non-native species have 
been moved into new environments, on purpose 
or by accident, there have been big problems, so 
scientists need to be very careful. 
“If new species get out of their habitat and are 
not kept under control by other processes, they 
start to cause trouble,” says Deborah Long 
at Plantlife Scotland. New species may have 
no natural predators, or may meet prey that 
cannot defend themselves against their hunting 
methods. New species can also affect local 
plants and animals by bringing in diseases they 
have not met before.
“This is a particular problem for islands in the 
southern hemisphere,” says Andre Farrar, an 
expert on birds. In the past, small islands in the 
southern hemisphere didn’t usually have any 
land-based predators because mammals simply 
couldn’t get there, and many bird species nested 
on the ground. So when European explorers 
took rats, dogs, pigs and cats to the islands, the 
birds’ eggs were easy prey. When the brown 
tree snake (native to Australia) was accidentally 
taken to Guam in the western Pacific in the 
1950s, for example, it nearly destroyed local bird 
populations. 
When Portuguese sailors brought animals to 
Mauritius, they probably caused the extinction of 
the dodo. 
There are many examples of disasters. When 
rabbits were taken to Australia, they quickly 
multiplied and destroyed native species. They 
are still a big problem. The African honeybee 
was taken to Brazil in the 1950s and multiplied, 
replacing the European honeybees that came 
to South America with the first Europeans. It 
is much more aggressive than native species, 
attacking people and animals. In Africa, the 
water hyacinth plant was introduced from South 
America in the 19th century. Now boats cannot 
move down the rivers. 
Even in this country, some foreign plants are 
a big problem. The worst one is Japanese 
knotweed, which grows well in gardens. Dr Long 
says it is bad for home owners, because it can 
grow through walls and concrete, as well as 
taking over gardens. 
Another problem plant is rhododendron 
ponticum, which is taking over the so-called 
‘Celtic rainforest’ woodlands of the west coast 
of Scotland and Wales. It damages the special 
plants there, which need exact amounts of light 
and water. The rhododendrons, which were 
introduced by Victorian gardeners, take light 
away from native plants. 
The destructive cane toad of Australia was 
brought in to control sugar-cane pests in 1935. 
But it soon began eating – and destroying 
– native species. It now occupies much of the