Study probes roaches' ability to adapt

For decades, people have been getting rid of cockroaches by setting out bait mixed with poison. But in a Florida test kitchen in the 1980s, something went wrong. A killer product stopped working. Cockroach populations kept rising.

Researchers finally hit on the explanation: In a remarkably rapid display of evolution, many of the cockroaches had lost their sweet tooth, rejecting the corn syrup meant to attract them.

In as little as five years, the sugar-rejecting trait had become so widespread that the bait had been rendered useless.

The findings illustrate the evolutionary prowess that has helped make cockroaches so hard to stamp out.

In a study published yesterday in Science, North Carolina State University entomologist Jules Silverman and others explain the genetic mutation that enabled some roaches to survive and multiply.

The key is certain neurons that signal the brain about foods. In normal cockroaches, glucose excites neurons that tell the brain "Sweet!" In the mutants, glucose also activates neurons that say "Yuck!" The "Yuck!" neurons dampen the signal from the others, so the brain gets the message the taste is awful. -- AP