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Subject: =?iso-8859-1?Q?GMW:_Transgenic_Corn_Found_to_Damage_Stream_Ecosystems?=
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Date: Fri, 12 Oct 2007 13:41:33 +0100
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Transgenic Corn Found to Damage Stream Ecosystems=20
Environmental News  Service, October 11 2007
http://www.ens-newswire.com/ens/oct2007/2007-10-11-096.asp

BLOOMINGTON, Indiana, October 11, 2007 (ENS) - A widely planted variety of g=
enetically engineered corn has the potential to harm aquatic ecosystems, fin=
ds a new study by an Indiana University professor of environmental science a=
nd his colleagues.=20

Pollen and other plant parts containing toxins from genetically engineered B=
t corn are washing into streams near cornfields and harming a type of fly th=
at is eaten by fish and amphibians, the study demonstrates.=20

Bt corn is engineered to include a gene from the micro-organism Bacillus thu=
ringiensis, Bt, which produces a toxin that protects the crop from pests, es=
pecially the European corn borer.=20

The research team led by Todd Royer, an assistant professor in the Indiana U=
niversity School of Public and Environmental Affairs, found that consumption=
 of Bt corn pollen, leaves and cobs increased mortality and reduced growth i=
n caddisflies, aquatic insects related to the pests targeted by the toxin in=
 Bt corn.=20

"Caddisflies," Royer said, "are a food resource for higher organisms like fi=
sh and amphibians. And, if our goal is to have healthy, functioning ecosyste=
ms, we need to protect all the parts."=20

Caddisfly larvae are an important part of stream ecosystems, where they help=
 control algae populations and provide food for fish and other creatures.  I=
n healthy streams, caddisflies are very common and their cases are found by=20=
the hundreds under rocks and logs.

Bt corn was licensed for use in 1996 and quickly gained popularity. By 2006,=
 around 35 percent of corn acreage planted in the United States was genetica=
lly modified, the study says, citing U.S. Department of Agriculture data.=20

Before licensing Bt corn, the U.S. Environmental Protection Agency conducted=
 trials to test its impact on water biota. But it used Daphnia, a crustacean=
 often used for toxicity tests, and not insects that are more closely relate=
d to the target pests, Royer said.=20

"Every new technology comes with some benefits and some risks," he said. "I=20=
think probably the risks associated with widespread planting of Bt corn were=
 not fully assessed."=20

If there are unintended consequences of planting genetically engineered crop=
s, Royer says farmers should not be held responsible. In a competitive agric=
ultural economy, producers have to use the best technologies they can get, h=
e said.=20

Funded by the National Science Foundation, the study is published this week=20=
by the journal "Proceedings of the National Academies of Science, PNAS."=20

There was a public outcry over the use of Bt corn in 1999, when a report ind=
icated it might harm monarch butterflies. But studies coordinated by the fed=
eral Agricultural Research Service and published in PNAS concluded Bt corn w=
as not a significant threat to monarchs.=20

Around that time, Royer said, he and his colleagues wondered whether the tox=
in from Bt corn was getting into streams near cornfields, and, if so, whethe=
r it could have an harmful impact on aquatic insects.=20

Their research, conducted in 2005 and 2006 in an intensely farmed region of=20=
northern Indiana, measured inputs of Bt corn pollen, leaves and cobs in 12 h=
eadwater streams, using litter traps to collect the materials. They also fou=
nd corn pollen in the guts of caddisflies, showing they were feeding on corn=
 pollen.=20

In laboratory trials, the researchers found caddisflies that were fed leaves=
 from Bt corn had growth rates that were less than half those of caddisflies=
 fed non-Bt corn litter. They also found that a different type of caddisfly=20=
had significantly increased mortality rates when exposed to Bt corn pollen a=
t concentrations between two and three times the maximum found in the test s=
ites.=20

Royer said there was considerable variation in the amount of corn pollen and=
 byproducts found at study locations and there is geographical variation. Fa=
rmers in Iowa and Illinois, for instance, are planting more Bt corn than tho=
se in Indiana. The level of Bt corn pollen associated with increased mortali=
ty in caddisflies, he said, "could potentially represent conditions in strea=
ms of the western Corn Belt."=20

There are four bands of Bt corn seed available commercially - YieldGard from=
 Northrup King (Novartis); YieldGard2 from Monsanto; YieldGard Rootworm from=
 Monsanto; and Herculex from Pioneer DowAgra-Sciences.=20

Other crops such as potatoes and cotton also make use of Bt technology. By 1=
999, 29 million acres of Bt corn, potato and cotton were grown globally.=20

When proponents of Bt technology list the benefits, they often say the Bt pr=
oteins in the crops will not kill beneficial insects. Royer and his team sho=
wed that claim is not accurate in the case of caddisflies.=20

Other principal investigators for the study, titled "Toxins in transgenic cr=
op byproducts may affect headwater stream ecosystems," were Emma Rosi-Marsha=
ll of Loyola University Chicago, Jennifer Tank of the University of Notre Da=
me, and Matt Whiles of Southern Illinois University.=20



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