"Rats eventually outsmart even the best poisons. 'It doesn't take them long to figure out, 'Hey, Uncle Charlie croaked after eating that,'" Mr. Lamb said."

"'We basically bait, trap and kill,' he said of the status quo. 'If we just continue to do that, every year we'll have the same expense and the same result.'"

"Dr. Mayer's invention, by contrast, induces an early-onset menopause, eliminating future generations of pests.

"'It's a very natural thing,' she said. 'We're just accelerating it in these animals.'"

"The product metabolizes into inactive compounds within hours of being ingested, she said, a feature crucial to its development for use in rice fields in Asia, where farmers needed something that wouldn't sicken other animals and children. The chemical won't leach into water or climb back up the food chain to affect other species."