New Potent Microbial Insecticide.

By isolating and characterizing the biochemical properties of a newfound natural insecticide, scientists at the University of Wisconsin-Madison have taken an important step toward augmenting biological pest control. The new weapon is a family of insecticidal toxins produced by Photorhabdus luminescens, a bacterium that, in nature, infects and kills insects with the help of a tiny worm or nematode.

The toxins produced by Photorhabdus are active against a wide range of insects and at least as potent as the insect-killing poisons produced by Bacillus thuringiensis (Bt), the reigning king of natural insecticides, according to Richard ffrench-Constant, professor of toxicology. "These new toxins are highly efficient killers of insects and they hold for the future the same promise first revealed in Bt more than 30 years ago."

Widely used for decades in the home, in forests, and on farms, Bt is considered to be a safe, effective, and environmentally benign weapon in the war on insect pests. Moreover, in the last few years, the genes that govern the production of the Bt toxin have been moved from the bacterium into crop plants, which account for 20% of the U.S. cotton crop and nearly 10,000,000 acres of transgenic corn, mostly in the Midwest.

As a form of biological pest control, Bt is the only bacterium from which widespread commercial insecticidal applications have been possible, giving it, in effect, a microbial...