Ecol. aspects of transgenic crops summary (fwd)

Paul Cherubini cherubini at
Wed Apr 19 21:14:51 EDT 2000

Chris J. Durden wrote:

> The whole area that was not investigated is on the consumption end. How
> does GM crops used as food, affect the ecology of the consumer? 

The Bt bacterium produces a protein that is easily digested by
people and animals--but not by some insects, and it degrades in sunlight.
Therefore, there is no concern about it being placed in food. There are
also significant human health benefits as those outlined in the article 
below by the American Phytopathological Society

Threats To Human Health Reduced With Bt Corn Hybrids 

St. Paul, MN (October 18, 1999) -- The recent approval and commercial
release of geneticallymodified, insect-resistant corn hybrids (Bt corn) represents
the culmination of decades of research.This innovative technology has a distinct 
health benefit of discouraging the build up of mycotoxins in corn, potentially
dangerous human and animal toxins produced by fungi that cause plant disease.

Mycotoxin build up is directly related to certain fungal plant diseases,
which can be increased by insect damage in crops. Insect larvae chew on stalks 
and kernels, creating wounds where fungal spores can enter the plant. Once
established, these fungi often produce mycotoxins. Some mycotoxins such as
fumonisin, can be fatal to horses and pigs, and are probable human carcinogens.
"Lower mycotoxin concentrations in Bt corn hybrids clearly represent a benefit to
consumers," says Gary Munkvold, plant pathologist at Iowa State University 
and American Phytopathological Society member. "Studies show Bt corn 
hybrids that control European corn borer damage to kernels usually have very little
Fusarium ear rot, and consequently, lower fumonisin concentrations." 

Bt corn hybrids control feeding by the European corn borer and to some 
extent closely related insects such as the corn earworm, common stalk borer,
armyworm, and Southwestern corn borer. All of which cause mechanical damage 
to the corn which influences the development of several
crop damaging diseases including ear rots, kernel rots and stalk rots. 

Kernel rot caused by the fungus Aspergillus is also associated with insect 
damage to ears. Several species of this fungus produce the most notorious 
mycotoxins found in corn, the aflatoxins. "The economic impact of aflatoxins
has been greater than that of other mycotoxins in corn because aflatoxins can be 
passed into milk if dairy cows consume contaminated grain," says Munkvold. 

Bt corn hybrids can be an important tool in the integrated management 
of corn ear and stalk rots and a boon to the environment as well. "Using 
genetically modified hybrids to control insects and diseases offers an 
alternative that is much more effective, consistent, economic and environmentally
sound than foliar insecticides. For example, non-Bt hybrid sweet corn 
can require 12 or more insecticide applications in a single season for the
production of sweetcorn for fresh market sales."

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