Insect pest control by genetically-modified crops can raise
yields and profits from non-GM varieties grown nearby, a study
from the US indicates. Researchers looked at maize grown in five
US states, where plants are affected by the European corn borer.
They found fewer borers - and higher profits - in GM fields, and
in neighbouring non-GM fields. Writing in the journal Science,
they say this is the first time that a wider impact on profits
has been shown. Maize (known as corn in the US) can be
genetically modified with a gene taken from a bacterium,
Bacillus thuringiensis (Bt). The introduced gene makes a toxin
that kills corn borers - in principle rendering the plants
immune to its attack, and increasing yields. Bt varieties now
make up about two thirds of the US maize crop. But regulations
require farmers to plant conventional varieties as well, which
is intended to stop the borers becoming resistant. Previous
research has shown that Bt plants can curb insect damage in
neighbouring non-GM fields, because th