Genetically Engineered Bt Corn Harms Insects
Lab-Designed Corn May Harm Insects
May 19, 1999 Filed at 4:03 p.m. EDT
By The Associated Press
Scientists have discovered a disturbing unintended consequence
of genetic engineering: Pollen from a widely planted,
laboratory-designed strain of corn can kill monarch butterflies.
Monarch caterpillars eating milkweed leaves dusted with pollen
from the altered corn plants ate less, grew more slowly and died more
quickly. After four days, 44 percent of them had died vs. none of the
caterpillars that didn't feed on the pollen.
Monarchs are not an endangered species. But environmentalists
fear that if the genetically engineered corn is killing the
orange-and-black butterflies, it may be killing other insects and doing other
unseen damage to the food chain.
The strain is called Bt corn and is manufactured by
agricultural giants Novartis AG, Pioneer Hi-Bred International Inc. and Monsanto
Co. The corn is genetically engineered to produce a natural pesticide
that kills the corn-destroying European corn borer.
It was approved by the Food and Drug Administration and hit
the market in 1996. It accounted for more than 25 percent of the 80
million acres of corn planted in the United States in 1998.
Bt corn has been touted by the industry as a way to fight a
major pest without using chemicals.
The study was led by Cornell University entomologist John
Losey and published in Thursday's issue of the journal Nature.
``It's very disturbing,'' said Jeremy Rifkin, whose
Washington-based Foundation on Economic Trends is pushing for a moratorium on
genetically engineered crops until their environment effects
can be more thoroughly studied. ``It's a smoking gun. This now is a red
flag everyone is going to have to look at.''
Losey, however, said that while he thinks the crop's harm to
other insects deserves more research, studies have shown that the corn does
not harm humans or other mammals. He added: ``I still think the proven
benefits of Bt corn outweigh the potential risks.''
Monsanto spokesman Randy Krotz said the finding is not very
important. Many monarch butterflies would not be exposed to the toxic
pollen, he said, since most milkweed does not grow near corn fields.
And Val Giddings, vice president for the Biotechnology
Industry Organization, said: ``Whatever the threat to monarch
butterflies that is posed by Bt corn pollen, we know it's less than the threat of
drifting pesticide sprays.''
Industry officials said they were not surprised by the
finding, because the larvae of monarch butterflies are similar to the corn borer.
They also called the study sloppy because the researchers didn't
precisely measure the amount of pollen ladled onto the milkweed leaves.
For 20 years, biotech laboratories have been altering the
genetics of vegetables to make them taste better or resistant to pests,
raising fears among environmentalists of ``Frankenstein foods.''
This is not the first time scientists found possible
unintended consequences of genetic engineering.
A Swiss study last year showed an indirect effect of Bt corn
on the food chain: Insects called lacewings died more quickly if they fed
on corn borers reared on Bt corn.
A University of Chicago study published in September found
that a weed altered by scientists to resist an herbicide developed a far
greater ability to pollinate other plants and pass on its traits. The findings
raised fears that genetic engineering could lead to the rise of
``superweeds'' impervious to weedkillers.
In Scotland, a toxicologist who added insect-resistant genes
and proteins to potatoes and fed them to rats reported that the animals
suffered damaged immune systems, growth problems and shrunken brains.
But his findings were sharply disputed by other scientists.