While Washington is up in arms about human cloning and stem-cell manipulation -- technologies that exist mostly in theory -- it pays virtually no attention to the more immediate matter of genetically engineered insects and microbes already being created. These designer critters could be an enormous boon for public health and crop production -- but could also pose great environmental risks.
One of the most advanced projects involves the glassy-winged sharpshooter, a native of the Southeast U.S. that first turned up in California vineyards in 1990. It has already destroyed some $14 billion worth of grapes and other crops in the state by passing on a disease that prevents plants from absorbing water. A team of scientists, led by entomology professor Tom Miller at the University of California at Riverside, hopes to outgun this pest with a genetically modified microbe that could be ready to test in vineyards this summer.
Miller's team is focusing on a bacterium called Xylella fastidiosa that resides in the mouth of the sharpshooter. When the insect feeds on plants, it passes the bug along, causing a blight called Pierce's disease that makes leaves and fruit wither and die.
The blight, which can't be treated, spreads quickly as the sharpshooter darts from plant to plant. The bug displays uncanny skill in staying ahead of pesticide spraying. Worse, it's a prodigious eater, feeding on a variety of plants including oleanders, alfalfa, and almond trees. Recently, new strains of X. fastidiosa have caused Pierce's in these crops.THE BUG STOPS HERE. Rather than modifying the insect, Miller's team decided to develop an insect "symbiont" -- a bacterium closely associated with X. fastidiosa that takes up residence on a plant. In lab experiments, when the insect feeds, it ingests the designer microbe, which neutralizes X. fastidiosa. The new microbe only survives for a few weeks, so it doesn't present a continuing environmental threat. Nor does it pass into the stem or fruit of the grapevine -- which would matter to growers, and to the public. "They won't accept a genetically modified plant," Miller says.
Public acceptance matters. But first, Miller's team has to negotiate a chaotic regulatory system. There's no clear framework for regulating a bioengineered insect or bacterium. Right now the scientists are seeking approvals from the Environmental Protection Agency, which oversees pesticides. But the U.S. Agriculture Dept. may also have jurisdiction, because it has the authority to act against the spread of plant pests.
The nonprofit Pew Initiative on Food & Biotechnology addressed this confusion in January with a report titled Bugs in the System. "The regulatory system is lagging well behind the science," says Pew Executive Director Michael L. Rodemeyer. Although designer insects and pathogens could prove safer for the environment than pesticides, Rodemeyer complains that regulators have done a poor job of making that determination. "Can we get these bugs to do what we want?" he asks. The answer may well be obvious before Washington gets around to addressing the issue. By Catherine Arnst in New York