Altered Corn’s No Threat to Butterfly, Researchers Say

Facing protests around the world against genetically modified foods, the biotech industry is responding by presenting new evidence that such crops are not harmful to the environment.

Researchers meeting in Chicago today are saying that the monarch butterfly, a symbol for the environmental dangers of genetically modified crops, is unlikely to be threatened by pollen from widely used varieties of genetically engineered corn.

The issue is extremely important to seed industry giants like Monsanto, Novartis and Pioneer Hi-Bred, which were hit by a backlash in Europe against genetically engineered varieties of corn, soybean and cotton. The industry is concerned that the opposition movement will spread to the U.S., where environmental groups have filed suit in an effort to recall crops that have already received federal regulatory approval.

In addition to the possibility of risks to beneficial insects like the monarch, critics worry about creation of super-bugs resistant to natural pesticides and super-weeds that no longer respond to common weedkillers.

There is also concern about unexpected health consequences from plants transformed by genes from other species. Some worry that engineered crops could trigger allergic reactions, spread antibiotic resistance and introduce new toxins into common food crops.

But in the five years since the introduction of the first genetically modified crops, there is no evidence of any untoward effects.

Today’s scientific conference is a response to a report last May by Cornell University researchers, who found a high death rate among monarch larvae that were fed on milkweed that had been dusted with pollen from genetically modified corn.

The report was criticized by the biotech industry, which argued that exposure was unlike anything typically seen under normal field conditions.

But the possible threat to the monarch was immediately seized upon by environmentalists opposed to genetically engineered crops. They said it was an example of how little was known about the potential impact of these new varieties of corn, which contain genes for toxins from a common soil bacterium, Bacillus thuringiensis, or Bt.

Bt varieties represent more than 30% of the corn grown in the U.S. this year. The Bt protein is effective against the European corn borer, and for decades, organic growers have sprayed the bacterium itself on plants as an alternative to chemical pesticides.

The industry responded to attacks by forming the Agricultural Biotechnology Stewardship Working Group and provided funding for a number of studies of the impact of Bt corn on the monarch during this summer’s growing season. The group is hosting today’s meeting of 20 scientists to discuss their early results.

Describing their results at an advance press briefing Monday, several of the scientists said the amount of insecticide-laced pollen that is blown from cornfields drops off sharply within a few yards of the plantings and probably does not represent much of a risk to the sensitive larvae of the orange-and-black butterflies.

However, the scientists acknowledge that exposure to the pollen will vary from region to region and could be significant in undisturbed areas near cornfields, where the monarch larvae’s natural food, milkweed, is likely to grow in relative abundance.

Some of the scientists said Monday that their findings are reassuring.

“There’s not a thimbleful of soil on God’s earth that does not have one form of Bt or another on it, from the tropics to the dry deserts,” said John Foster, a professor at the University of Nebraska.

Foster and his team found that by late July, corn pollination in Nebraska was already 95% complete before the first monarch eggs were hatched--suggesting little if any threat to the butterfly.

Similarly, professor Galen Dively of the University of Maryland found no larvae during corn pollination in the mid-Atlantic region. He did see adult butterflies, but the adults feed on plant nectar and are not expected to be affected by the toxin-containing pollen.

Other studies measured the movement of corn pollen out of the fields and plotted pollen deposits on nearby milkweed.

Mark Sears, an environmental biologist from the University of Guelph in Ontario, Canada, said he found that 90% of Bt corn pollen is deposited within 15 feet of the edge of a cornfield. He noted that his counts of corn pollen grains near the fields were high enough to have a small impact on early-stage monarch larvae, but that the amount of pollen falls off sharply farther away.

John Losey, the Cornell University professor who did the first, controversial study of the impact of Bt pollen on the butterflies, said that his field tests showed that monarchs avoid laying eggs on milkweed planted near corn--minimizing the impact of the pollen on larvae.

But he and others also noted that milkweed grows best in undisturbed areas, and he speculated that the edges of cornfields could be very important to the monarch’s survival. “It’s too early to be reassured or more alarmed,” Losey said.

Greenpeace activist Charles Margulis said he was not surprised that some of the research being reported in Chicago was favorable to biotech crops. “These guys are funded by the industry,” he said.

Libby Mikesell, a representative of the Biotechnology Industry Organization, a member of the industry working group, said that not all of the 20 researchers at today’s conference were sponsored by industry.

And those who were insist that they remain objective.

“Industry has supported me over the years,” said University of Nebraska’s Foster. “The reason they come to me is to give an honest answer. . . . They don’t give me enough money to buy my opinion.”