Washington Post | November 3, 1999 | by Rick Weiss
Genetically engineered corn plants appear to pose only a modest and perhaps insignificant threat to monarch butterflies, according to several new studies described at a scientific symposium Nov. 2.
The mixed but mostly reassuring findings come five months after Cornell University researchers triggered widespread concern by suggesting that pollen from gene-altered corn plants may be killing the popular insects.
In the aftermath of the Cornell report, a consortium of biotechnology and pesticide companies quickly funded several studies to quantify the risk posed by corn containing a bacterial gene called Bt. The meeting on Nov. 2 was sponsored in Chicago by that consortium, the Agricultural Biotechnology Stewardship Working Group, and included early results from academic researchers and others, many of whom were funded by the industry group.
"One thing that came out pretty clearly today is that the worst-case image that may have gotten out there of a toxic cloud of pollen engulfing the Corn Belt and wiping out all the [butterflies] is clearly not the case," said Stuart Weiss, a Stanford University expert in ecological modeling, who presented data at the meeting.
Other researchers tracked how far corn pollen blows beyond corn fields. Mark Sears of the University of Guelph in Ontario found that 90 percent of pollen grains travel less than five yards from the field, and virtually all land within 10 yards. Sears also found that it takes at least 500 grains of pollen on a square centimeter of milkweed leaf to sicken monarch caterpillars - a concentration he found was barely attained on nearby milkweed leaves after three days of accumulation during pollination season.
Based on those findings, he said, "I'm assuming the risk of the hazard to monarch larvae is very minimal."
John Foster, a University of Nebraska entomologist, said he believes corn pollen poses an insignificant threat to the monarch, compared with the regular mowing of milkweed-rich meadows and rights-of-way in the United States and habitat destruction in Mexico, where the butterflies reside during the winter.
Asked whether the industry's funding of his research might bias his views, Foster said: "They don't give me enough money to buy my opinions."
