London, November 20 In a new study, scientists have determined that killer bees may be among the most feared of all insects because of their sting, but they aren't too smart.

Killer bees, which result from a cross between African honey bees and a Brazilian variety in the 1950s, have spread from Central American into the southern United States.

Increased intelligence had been suggested as one reason for this expansion.

Now, according to a report in New Scientist, a team led by Margaret Couvillon at the University of Sussex in Brighton, UK, found that this is not the case.

The team tested the abilities of both kinds of bee to associate a whiff of jasmine with a sugar reward.

"Surprisingly, we found that fewer Africanized honeybees learn to associate an odor with a reward. Additionally, fewer Africanized honeybees remembered the association a day later," according to the researchers.

"When researchers gave bees a second whiff, about half of European honeybees stuck out their tonguelike proboscises as soon as the odor wafted by again, anticipating another drop of sugar water. The bees acted like Pavlov's dogs, drooling at the sound of a bell they associate with food," Couvillon said.

"Only about half as many killer bees picked up the association after a single trial, the researchers found," she added.

Foraging style could explain this difference.

European honey bees tend travel vast distances in search of flowery meals and they revisit sites.

A keen memory and an ability to learn quickly would benefit this strategy.

Killer bees, on the other hand, don't wander far from their hives and they often visit new flowers, so learning might not be as important, Couvillon's team speculated.

"Perhaps learning has a cost. If it were cost-free, wouldn't we all be getting smarter?" Couvillon said. (ANI)