First gene-engineered pesticide tested.

First gene-engineered pesticide tested

Researchers from the U.S. Department of Agriculture (USDA) last week oversaw the inoculation of corn plants with genetically engineered bacteria designed to protect the plants from a crop-damaging caterpillar. The bacteria, developed by Hanover, Md.-based Crop Genetics International, is the first gene-altered microbial pesticide to undergo outdoor tests in the United States. It was injected into young corn plants at a federal agricultural research station in Beltsville, Md.

The USDA and the Environmental Protection Agency recently approved the test. It is the fifth gene-altered microbe to gain U.S. government approval for small-scale testing in the environment (SN: 5/2/87, p.277; 2/20/88, p.117).

The pesticide is made of a bacterium that can live in corn plants; into that bacterium, a gene from another bacterium has been inserted. The gene codes for the production of a protein, called Bt, which paralyzes the digestive systems of insects and caterpillars with nonacidic "stomachs." Bt has for decades been sprayed on vegetable crops and trees to protect them from insect pests; it appears to have no effect on humans or other animals with acidic digestive tracts.

Indoor tests show engineered, Bt-containing microbes multiply in the sap of corn plants as the plants grow, killing European corn borers that attempt to feed on the stalks. Researchers plan eventually to inoculate corn seed with the engineered organism, but the first tests call for one-month-old corn plants to be "vaccinated" directly.

Although the gene-spliced microbe is perfectly at home in corn stalks, it fails to migrate into the kernels, or seeds. That's good news not only for picky eaters, but for investors, too: With the high-tech corn plants producing old-fashioned kernels, says a Crop Genetics document, "the company can continue to enjoy repeat sales of its inoculated seeds."