Killer Bees Bare Their Genes

30 March 1998 7:30 pm

Researchers have located regions in the DNA of bees that appear to harbor one or more genes that make so-called "killer bees" so aggressive. But experts say the finding, reported in the current issue of Genetics, for now won't aid efforts to stop the troublesome spread of "mean" genes to domesticated honeybees.

North American killer bees are hybrids, the offspring of relatively placid European bees--the kind favored by honey producers--and an aggressive African species that earned its nickname by reputedly stinging to death small animals. Since entering Brazil in 1956, the African bees have commingled with bees living in South and Central America. By 1991, almost all Mexican bees were "Africanized," and the hybrids have since slipped across the border into the United States, occupying parts of Texas, New Mexico, Arizona, and southern California. The invasion has been a disaster for beekeepers: Africanized bees require more careful handling and produce less honey than bees of pure European stock.

Entomologists have wondered whether the killer bees' defensive behavior is the product of many genes or just a few with a big influence. To find out, a team led by Greg Hunt of Purdue University in West Lafayette, Indiana, bred 162 colonies of Africanized bees in Mexico. They rated each colony's aggressiveness by counting how many bees stung a small black leather patch attached to a pole and waved in front of the hive for 1 minute. A genetic analysis showed that the more aggressive bees tended to share five specific genetic regions, one of which originated with African bees.

The study "is really good stuff if you are interested in understanding bee behavior," says Robert Danka, an entomologist with the U.S. Department of Agriculture's Honeybee Laboratory in Baton Rouge, Louisiana. However, he says, "it is a long way from having any practical application for beekeepers. It's still easier to see if you've got bad bees by kicking the box."

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