Action Alert: Gene-Altered Corn Pollen Threatens Monarchs
May 28, 1999
Entomologists at Cornell University in the U.S. have found significant
adverse effects in monarch butterfly caterpillars that were fed pollen
from genetically engineered corn. Since about half of the summer
monarch population migrates through the U.S. Corn Belt, where
millions of acres of genetically engineered insect-resistant Bt corn now
grow, the monarch butterfly may be imperiled.
Pesticide Action Network North America is calling on groups and
concerned individuals to write the U.S. Environmental Protection
Agency and demand that the agency:
-- Deny any further approvals and renewals of Bt corn.
-- Immediately institute a moratorium on further planting of Bt crops
until independent and comprehensive studies can be conducted on the
short and long-term ecological effects of large scale release of
organisms engineered to contain Bt toxins.
-- Convene a panel of respected independent ecologists, soil scientists,
butterfly specialists and others to begin developing a program to detect
and address ecological risks of engineered crops.
Bt corn produces a specific toxin, originally derived from a soil
microorganism, Bacillus thuringiensis. In its natural form, the Bt toxin is
activated when consumed by caterpillars of moths and butterflies and
kills them. Several agrochemical companies including Monsanto and
Novartis have engineered corn varieties to produce Bt toxin to kill
insects that feed on corn plants.
In many Bt-corn varieties, the Bt toxin is produced in most of the plant's
tissues, including its pollen. Toxic corn pollen is then blown by the wind
onto milkweed and other plants in the vicinity of Bt-corn fields. The
Cornell laboratory study, published this week in the journal Nature,
found that monarch caterpillars eating Bt-corn pollen had significantly
higher death rates and stunted growth compared with those eating
normal pollen. Nearly half the caterpillars that consumed the toxic
pollen died after four days; none of those eating normal pollen died.
In one field study, Iowa State University scientists have confirmed the
toxicity of Bt corn pollen to monarch caterpillars. Nearly 20% of the
caterpillars fed milkweed leaves taken from Bt corn fields and adjacent
areas died, compared to no deaths of those exposed to normal corn
pollen. In addition to monarchs, some of the 19 species of butterflies and
moths on the U.S. Endangered Species List may also be at risk from the
toxic pollen if they eat plants near Bt-corn fields.
Monsanto has stated that an important advantage of the crop is reduction
or elimination of spraying of broad-spectrum insecticides to control the
European corn borer. However, according to the Union of Concerned
Scientists and other experts, based on figures from the National
Agricultural Statistics Service, U.S. field corn is not often sprayed for
European corn borer or any other insect, especially in the heart of the
cornbelt. Therefore, little if any reduction in insecticide use can be
expected as a result of planting Bt-corn.
The Cornell study is not the only one to suggest that Bt crops are far
from benign. Swiss scientists last year showed detrimental effects on
beneficial insects that ate corn pests that had been fed Bt corn. Other
scientists have shown that Bt toxins accumulate in the soil and may
adversely affect soil ecosystems. And there is near universal scientific
consensus that widespread use of Bt corn and other Bt crops will
accelerate the evolution of resistance to Bt toxins in insect pests. Once
pests are resistant to Bt, organic growers and everyone else who relies
on Bt to control pests will lose an effective, natural biocontrol agent.
PANNA urges all those concerned to write Carol Browner, U.S. EPA
Administrator, and demand that EPA deny any further approvals and
renewals of Bt corn and institute a moratorium on further planting of Bt
crops until independent and comprehensive studies can be conducted on
the short and long-term ecological effects of large scale release of
organisms engineered to contain Bt toxins. Send letters to:
Carol Browner, U.S. EPA Administrator
Environmental Protection Agency (Mail code 1101)
401 M St., SW, Washington DC 20460
Fax (202) 260-0279; email browner.carol@epa.gov
Sources: Union of Concerned Scientists press release, May 20, 1999;
UCS Fact Sheet: Monarch Butterflies, Bt Corn and Toxic Pollen, May
19, 1999; Monsanto Statement on Bt Corn: Environment and a Recent
Report on the Monarch Butterfly, May 20, 1999; L. Hansen and J.
Obrycki, "Non-target effects of Bt corn pollen on the Monarch butterfly
(Lepidoptera: Danaidae)," abstract of a poster presented at the North
Central Branch meeting of the Entomological Society of America,
March 29, 1999, available at http://
www.ent.iastate.edu/entsoc/ncb99/prog/abs/d81.html
Contact: PANNA.
===========================================
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49 Powell St., Suite 500, San Francisco, CA 94102 USA
Phone: (415) 981-1771
Fax: (415) 981-1991
Email: panna@panna.org
Web: www.panna.org
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