August 22, 2000
New Study Links Biotech Corn to Butterfly Deaths
By CAROL KAESUK YOON
New York Times
Ever since scientists reported last year that pollen from genetically
engineered corn could kill monarch butterfly caterpillars in the
laboratory, scientists, industry representatives and activists opposed to
genetic engineering have been battling over one central question: Are these
butterflies being harmed by the millions of acres of biotech corn being
planted across the country?
Now, in the first study published on the subject since the debate began,
scientists from Iowa State University say plants growing in and near the
corn fields are being dusted with enough toxic pollen to kill monarch
caterpillars that feed on them. The genetically modified corn produces the
insecticide Bt in its tissues, including its windblown pollen.
Scientists say it is the first published data showing the potential for
genetically engineered pollen in the wild to harm monarchs, but leaves open
the crucial question of what impact the corn actually has on the butterfly
population. Critics of the original study, published by researchers at
Cornell University, said caterpillars in the study could have died because
they were fed levels of toxic pollen that were much higher than those found
"This is telling us that with naturally deposited pollen there's a good
probability you'll get some mortality," said Dr. John Obrycki, who along
with Laura Hansen wrote the article published Saturday in the journal
In their study, the researchers gathered leaves from plants growing in and
around corn fields and onto which pollen had blown. The leaves were then
fed to caterpillars in the laboratory. Twenty percent of the caterpillars
eating leaves bearing genetically engineered pollen died, while all
caterpillars eating leaves with regular corn pollen survived.
"This is a big deal," said Dr. John Losey, one of the authors on the
original Cornell study.
"It's an important next step."
But the new study seems to have only fueled the battle for public opinion
inspired by the monarch butterfly, which has become a symbol to many of
fragile nature threatened by genetic engineering.
"This study should dispel any doubts about whether or not the effect
observed in the Cornell study is a real one in the field," said Dr. Rebecca
Goldburg, a scientist at the Environmental Defense Fund, a group that has
been critical of the biotechnology industry and its regulators. "The
Environmental Protection Agency should take some steps to ensure that
butterflies in this coming planting season are protected."
Industry representatives say the new study did not accurately reflect what
is happening in nature.
"I don't see how this can be construed as a field study," said Lisa Dry,
spokeswoman for the Biotechnology Industry Organization, referring to the
fact that leaves from the field were brought back to the lab to be fed to
caterpillars. Ms. Dry said she believed that rain, wind and sun would
degrade the pollen to the point that caterpillars' chances of contacting
toxic pollen in nature was "remote." Ms. Dry said she knew of 20 other
studies that would disagree with the new research, though none had yet been
"We're confident that the Bt has minimal, if any, impact," she added.
Scientists interviewed agreed that the ultimate effect on monarchs was
So far the Environmental Protection Agency has requested but not required
farmers to alter plantings to reduce the flow of genetically engineered
pollen out of their fields.
The agency has announced that the registrations that allow the widespread
planting of Bt corn would be extended until September 2001.
2nd Study Links Gene-Altered Corn, Butterfly Deaths
By Marc Kaufman
Washington Post Staff Writer
Tuesday, August 22, 2000; Page A02
A second study has found that pollen from genetically engineered corn
plants can harm monarch butterflies.
About 20 percent of monarch larvae died after being exposed to pollen from
corn genetically engineered to produce a pesticide that had blown onto
nearby plants that the monarch caterpillars eat, the study found.
The finding reignites a heated scientific and regulatory debate over
whether biotech crops in general, and the engineered corn in particular,
pose heightened risks for the environment, and whether federal authorities
have appropriately addressed those risks.
"This takes the monarch research a step further," said John Obrycki of Iowa
State University, who conducted the new study. "We had lab research showing
the effect, and now we have a modified field study that shows an effect as
But both the biotech industry and the federal Environmental Protection
Agency cautioned against making conclusions based on the study, which
looked at the effects of corn modified to produce a pesticide called
Bacillus thuringiensis (Bt). Opponents of the corn have been concerned that
pollen from the plants containing the pesticide could blow onto nearby
plants where the monarch caterpillars feed.
According to Stephen Johnson, deputy assistant administrator for the EPA,
tests monitoring the engineered corn in fields have not shown any negative
consequences of the Bt-producing corn on monarchs. "There may be a
potential hazard, but research shows there is unlikely to be any
significant exposure to Bt toxin by the monarchs," Johnson said.
Val Giddings, vice president for food and agriculture of the Biotechnology
Industry Organization, also said that the theoretical risk of Bt pollen on
monarchs has not been found in the field.
"Dr. Obrycki's research stands in the shadow of more than 20 independent
studies by widely recognized scientific experts who have found that
Bacillus thuringiensis corn does not pose a significant risk to the monarch
butterfly," he said. "This report considers only one small area of this
complex topic and the conclusions put forward by the authors stand in stark
contrast to those of the broader scientific community's research."
Obrycki agreed that the potential harm from Bt corn remained unclear. To be
harmed, monarch larvae would have to appear at the same time that the corn
pollen was flowering, and the overlap of the two events was necessarily
limited, he said. Growing conditions in different areas and planting times,
he continued, would determine where the danger might lie.
Nonetheless, he and co-author Linda Hansen concluded in their paper,
published in the journal Oecologia, that "the ecological effects of
(genetically engineered crops) need to be evaluated more fully before they
are planted over extensive areas."
Bt corn has been planted since 1996, and now accounts for about one-third
of all corn planting. The Bt in the corn protects against corn-boring
caterpillars, which cause an estimated $1 billion in yearly crop damage.
Much of the nation's corn is grown in the Midwest, which is on the
migration path of monarchs.
The butterflies feed exclusively on milkweed plants, which commonly grow in
or near cornfields. The pollen from the corn can blow onto the milkweed.
The issue of Bt corn's potential impact on monarchs was first raised last
year, when Cornell University researcher John E. Losey published results
showing Bt corn pollen could harm monarch larvae in the laboratory. The
research was attacked by some other scientists, who said the lab findings
had no relation to real field conditions.
The new Iowa research attempted to respond to those criticisms. The
researchers placed milkweed plants in and around a corn field to see how
much pollen the plants would collect. Leaves from the milkweed plants were
then collected and placed in dishes with monarch larvae. About 20 percent
of the larvae exposed to leaves from plants growing within about 10 feet of
the engineered corn died, the researchers found.
The potential effects of Bt corn and cotton on plants and animals are also
being reconsidered by the EPA. Earlier this month, the agency announced
that it would extend until next year the licenses it issued five years ago
for both Bt corn and cotton, but would review the entire regulatory
oversight of that technology. The agency's first assessment will be made
public next month, and public hearings and possible new regulations may
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