Du Pont will provide Crop Genetics with up to $3.7 million over two years to develop virus products and mass-produce them at low cost.

Crop Genetics' virus product was developed in partnership with Du Pont, the chemical giant that will market the virus along with its more traditional insecticides.

"We were always confident inside the company," said Mr. Kelly last week, basking in the leap in Crop Genetics' stock price in over-the-counter trading.

Mr. Kolodny-Hirsch said Crop Genetics had since developed a number of refinements and was also exploring other approaches to commercial insect breeding.

Crop Genetics received approval for a virus-based insecticide fatal to armyworms that attack vegetables and flowers.

Biosys will exchange one share of its common stock for about 5.25 common shares of Crop Genetics.

Another big loser was Crop Genetics, a biotechnology company that makes and markets products to improve crop productivity.

In over-the-counter trading yesterday, Crop Genetics' stock shot up 72.2 percent, gaining $3.25, to $7.75.

Crop Genetics, based in Hanover, Md., submitted three such viruses to the Environmental Protection Agency for registration as a new pesticide last summer.

Crop Genetics, which is three years away from projected profitability, has what some analysts believe is an even more exciting technical approach.