November 18, 2009 5:18 PM
Killer Bees: Nasty Sting, Not So Smart
Ewen Callaway, Reporter
A new study has compared the wits of Africanized killer honey bees with those of a more docile European breed.
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.
A team led by Margaret Couvillon at the University of Sussex in Brighton, UK, 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," the team write.
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 says.
"Only about half as many killer bees picked up the association after a single trial, the researchers found," Science News reports.
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 speculates.
"Perhaps learning has a cost," Couvillon says. "If it were cost-free, wouldn't we all be getting smarter?"