Online Extra: Much Ado Over "Lethal Genes"

As scientists prepare genetically engineered bugs that could wipe out pest species, environmentalists raise the alarm about unforeseen consequences

The pink bollworm is only a half-inch long, but ever since it started wriggling its way through cotton fields in 1917, it has grown into one of agriculture's most detested pests. The slimy, pink-striped blob causes more than $32 million in losses every year. So far nothing has been able to eradicate it -- not insecticides, not sterilization techniques, not even biotech-enhanced cotton engineered to resist it.

The lowly fruit fly may provide a magic bullet. Scientists at the University of California in Riverside and the U.S. Agriculture Dept. have figured out how to breed bollworms that can't procreate. They do it by inserting into the pests a single piece of the fly's DNA -- known as a "lethal gene" -- that can be programmed to interfere with the development of the larvae, killing the next generation.

The bollworm is one of a swarm of genetically engineered insects on the horizon. Scientists at labs around the world are trying to develop mosquitoes with lethal genes, hoping that as the bugs mate with their malaria-spreading counterparts, the disease will die out.


 UC Riverside is altering bacteria in the glassy-winged sharpshooter, another species of crop pest, so it can't pass on a destructive disease that is threatening $3.2 billion worth of wine grapes in California. Similar techniques are being tried on mites and medflies, among other insects.

These solutions may seem like no-brainers, but in fact they have stirred up a whole hive of fears. Many genetically engineered insects are created using vectors known as "jumping genes," which transport the desired DNA into the chromosomes of the target species. The jumping genes have been known to leap around. Experts worry that the lethal "transgenes" they carry could travel, too, possibly into insects that are not targets for extinction.

Thomas Miller, the UC Riverside scientist who created the sterile pink bollworm, argues that the likelihood of its transgenes migrating into something else "is so remote it's funny." A more realistic risk is that, after the transgenic pests are released, their altered traits will fail to kick into action.


 Nonetheless, safety fears persist. And the ones swirling around engineered insects are more intense than concerns about other transgenic creatures. While it's true that scientists are experimenting with viral vectors to create humanized mammals and birds, they keep their animals under lock and key. Even if the critters escaped, they probably could be tracked down before ending up in the food supply or causing any other type of damage.

Transgenic insects, on the other hand, are designed to be set free. Once they're out, they can't be called back if something goes wrong. In the words of Michael Rodemeyer, executive director of the Pew Initiative on Food & Biotechnology in Washington: "The introduced organism could become a pest itself. There would be no mechanism to go back in and fix it."

The absence of a regulatory pathway is adding fuel to the controversy. Before they can do field trials, USDA scientists must obtain permits from their agency's Animal & Plant Health Inspection Service (APHIS). The Environmental Protection Agency and the Food & Drug Administration may get involved, too.


 But the interplay among the three is so tangled that it could hold back valuable research. Several agencies are reviewing the regulatory system for all transgenic animals, including insects, to see where improvements might be made.

Some watchdogs growl that much more research needs to be done before transgenic insects are let out of their lab cages. When the Center for Food Safety in Washington got wind that USDA scientists were planning to release transgenic bollworms in open-field trials, it demanded that studies be run to predict the environmental impact.

The agency has taken the first steps in that process. "It's important to do these studies," says John Turner, a director in the biotech division of APHIS. Meanwhile, the little pink terminator waits eagerly in the wings.

By Arlene Weintraub in New York

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