Bt Corn Poses
No Significant Risk to Monarchs
By Kim Kaplan
February 6, 2002
A consortium of federal, university
and industry scientists led by the Agricultural Research Service has completed
two years of research to answer the question: Does Bt corn pose a threat to
monarch butterflies? The answer, supported by science, is that there is no
The results are discussed at length in a feature story that appears in the
February issue of Agricultural Research magazine. ARS, the
U.S. Department of Agricultures
primary scientific research agency, also has a web site about the Bt
corn-monarch butterfly issue at:
Bt corn is corn to which genes from the bacterium Bacillus thuringiensis
have been added so the plant naturally produces proteins that protect it
from insect pests such as the European corn borer.
The research found that Bt corn pollen levels usually had to be more than
1,000 grains per square centimeter to have any negative impact on monarch
caterpillars, let alone mortality. Scientists have concluded that less than 1
percent of the time are monarch caterpillars in the environment exposed to
levels that even come close to that magnitude.
ARS entomologist Richard Hellmich is already planning the next round of
investigations. He hopes to extend the consortiums work this summer with
new collaborative studies, especially field studies, to look at whether there
are any effects on monarch caterpillars from long-term or chronic exposure to
Bt corn pollen.
While the data already accumulated show Bt corn pollen does not pose a
threat to monarch populations, these new studies should indicate if any minor
effects are possible and the nature of those effects if they occur.
ARS entomologist Leslie C. Lewis is planning to extend the work to look at
whether Bt corn has any impact on non-target ground insects such as beetles.
Hellmich and Lewis are both with the ARS Corn Insects and Crop Genetics
Laboratory in Ames, Iowa.
You can read more about this in the
February issue of
Agricultural Research magazine, available on the World Wide Web.