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Even more worrisome are ecological concerns. In 1999 Cornell University entomologist John Losey performed a provocative, "seat-of-the-pants" laboratory experiment. He dusted Bt corn pollen on plants populated by monarch-butterfly caterpillars. Many of the caterpillars died. Could what happened in Losey's laboratory happen in cornfields across the Midwest? Were these lovely butterflies, already under pressure owing to human encroachment on their Mexican wintering grounds, about to face a new threat from high-tech farmers in the north?
The upshot: despite studies pro and con--and countless save-the-monarch protests acted out by children dressed in butterfly costumes--a conclusive answer to this question has yet to come. Losey himself is not yet convinced that Bt corn poses a grave danger to North America's monarch-butterfly population, but he does think the issue deserves attention. And others agree. "I'm not anti biotechnology per se," says biologist Rebecca Goldberg, a senior scientist with the Environmental Defense Fund, "but I would like to have a tougher regulatory regime. These crops should be subject to more careful screening before they are released."
Are there more potential pitfalls? There are. Among other things, there is the possibility that as transgenes in pollen drift, they will fertilize wild plants, and weeds will emerge that are hardier and even more difficult to control. No one knows how common the exchange of genes between domestic plants and their wild relatives really is, but Margaret Mellon, director of the Union of Concerned Scientists' agriculture and biotechnology program, is certainly not alone in thinking that it's high time we find out. Says she: "People should be responding to these concerns with experiments, not assurances."
And that is beginning to happen, although--contrary to expectations--the reports coming in are not necessarily that scary. For three years now, University of Arizona entomologist Bruce Tabashnik has been monitoring fields of Bt cotton that farmers have planted in his state. And in this instance at least, he says, "the environmental risks seem minimal, and the benefits seem great." First of all, cotton is self-pollinated rather than wind-pollinated, so that the spread of the Bt gene is of less concern. And because the Bt gene is so effective, he notes, Arizona farmers have reduced their use of chemical insecticides 75%. So far, the pink bollworm population has not rebounded, indicating that the feared resistance to Bt has not yet developed.
ASSESSING THE PROMISE
Are the critics of agricultural biotechnology right? Is biotech's promise nothing more than overblown corporate hype? The papaya growers in Hawaii's Puna district clamor to disagree. In 1992 a wildfire epidemic of papaya ringspot virus threatened to destroy the state's papaya industry; by 1994, nearly half the state's papaya acreage had been infected, their owners forced to seek outside employment. But then help arrived, in the form of a virus-resistant transgenic papaya developed by Cornell University plant pathologist Dennis Gonsalves.