The roach does it again

Everyone knows that cockroaches are the ultimate survivors,with enough evolutionary tricks up their carapaces to have thrived for 350 million years.

But the nature of the adaptation that researchers described recently in the journal Science is impressive even for such an ancient lineage,experts say. Some populations of cockroaches evolved a simple,highly effective defence against sweet-tasting poison baits: They switched their internal chemistry around so that glucose tastes bitter. Ayako Wada-Katsumata,Jules Silverman and Coby Schal,all at North Carolina State University,set out to explain a well-known phenomenon: Populations of cockroaches avoid poison bait that is laced with glucose,which is supposed to attract them. This behaviour first appeared in the 90s,said Jim Fredericks,chief entomologist at the US National Pest Management Association,shortly after exterminators started using poison baits instead of spraying to battle roaches.

JAMES GORMAN