The not-so-deadly Bt corn

[Paul Cherubini]

Monday August 27 7:08 PM ET 

Study: Biotech Corn OK for Monarchs

By MAURA KELLY, Associated Press Writer 

CHICAGO (AP) - A new study found that pollen from genetically 
altered corn poses little risk to monarch butterfly larvae, contradicting 
previous findings that led to calls to curb the spread of bio-engineered crops. 

The larvae digest the pollen when they eat milkweed. A 1999 lab study 
at Cornell University showing that pollen from the corn could poison larvae
caused a public outcry in Europe and rallied environmentalists to demand
limits on the crops. 

But the latest study, which will be discussed Wednesday at a meeting
of the American Chemical Society, found that the larvae usually do not
eat enough pollen for it to harm them. 

 ``It's a negligible risk at best. They must consume considerable amounts 
of pollen to show an effect, and that amount of pollen rarely exists in nature,'' 
said Mark K. Sears, chairman of the Department of Environmental
Biology at the University of Guelph in Canada. 

Sears and a team of scientists looked at how far pollen traveled in a 
cornfield, if monarch larvae were exposed to it and how much of it 
the larvae typically ate. The research, funded mostly by the Canadian 
government, took place on corn fields in Canada, Iowa, Maryland and 
Minnesota between 1999 and 2000. 

The scientists saw no adverse effects except when larvae ate 
about 4,000 pollen grains. At that point, they began to eat and gain weight 
more slowly than larvae that ate corn pollen that was not genetically altered. 

The symptoms suggested that their stomach linings were breaking
down, Sears said. 

However, because there is an average of only 120 pollen grains per square 
centimeter of a milkweed leaf, ``it's highly unlikely that larvae are going to 
be exposed to that much pollen to cause a measurable effect,'' Sears said.

 
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