Honey bee invaders exploit the genetic resources of their predecessors

Africanized honey bees first appeared in south Texas in 1990, and quickly spread to other parts of the Southwest United States. Click here for more information.

The earlier analysis also confirmed and extended results of previous studies showing that African honey bees had mixed with but largely displaced their predecessors in the New World, which were primarily of western European stock. When the European old-timers mixed with the African newcomers, their offspring looked, and in most respects behaved, like the African honey bees.

These more aggressive, “Africanized” bees (so-called “killer bees”) received a lot of media attention in the U.S. as they moved north from South America. According to the U.S. Department of Agriculture, the first Africanized honey bees appeared in Texas in 1990. In less than a decade they had also spread to southern California, Arizona, Nevada and New Mexico.

Whitfield and Zayed wanted to understand the evolutionary mechanism that allowed the African honey bees to move into these new territories and dominate the bees that had arrived in the New World centuries earlier from eastern and western Europe.

Their analysis of about 440 SNPs selected randomly from throughout the Africanized honey bee genome showed that most of the alleles were common to African honey bees. But of the alleles common to European bees, those found in functional parts of the genome (in genes) were showing up more frequently than those in nonfunctional regions (between genes).

“We asked the question: Is hybridization an essentially random process?” Zayed said. When the African honey bees mated with the western European honey bees that had been in South America for centuries, one might expect that the hybrid offspring would randomly pick up both the functional and nonfunctional parts of the genome, he said.