- Researchers at New York University have shown that BT
corn, the genetically modified seed variety which is resistant to corn
borer pests, releases an insecticide through its roots into the soil. The
powerful toxin remains in the soil as it is not easily broken down. It
retains its insecticide properties which could help to control pests or
promote insects resistant to the pesticide - the scientists aren't sure
which.
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- "Further investigations will be necessary to shed
light on what might happen underground," Dr Guenther Stotzky and
his colleagues said in a report published this week in the science journal
Nature.
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- Their work is the first to show that the toxin from BT
corn can seep into the soil. The researchers describe their findings as
"surprising and unexpected", raising fresh fears about the environmental
impact of such crops. The concern is that beneficial soil organisms might
be killed and that insects living in the soil might become resistant to
the poisons.
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- Several crops, from maize to corn and potatoes, have
been genetically modified to kill insect pests using a gene derived from
a bacterium called Bacillus thuringiensis (BT). Concerns about the impact
of such crops on the environment were triggered earlier this year when
it was found that monarch butterflies had died after feeding on milkweed
dusted with pollen from GM corn.
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- Professor Stozky of New York University's laboratory
of microbial ecology, who has led the research, says that the monarch
research showed that the toxin was released from the pollen. "Now
we have found it is also continuously released from the roots into the
soil. The fact that the toxin is released from the roots was unexpected,"
he says. Because the roots are constantly leaking the toxin, there is
also the risk that pests in the soil might rapidly become immune to the
poison triggering new, resistant strains.
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