Honey bee invaders exploit the genetic resources of their predecessors

Entomology professor Charles Whitfield (right) and postdoctoral researcher Amro Zayed sought to understand how African honey bees can move into new territories and dominate the bees that had arrived in... Click here for more information.

Like any species that aspires to rule the world, the honey bee, Apis mellifera, invades new territories in repeated assaults. A new study demonstrates that when these honey bees arrive in a place that has already been invaded, the newcomers benefit from the genetic endowment of their predecessors.

The findings appear online the week of Feb. 25 in Proceedings of the National Academy of Sciences.

The researchers, University of Illinois entomology professor Charles Whitfield and postdoctoral researcher Amro Zayed, analyzed specific markers of change in the genes of honey bees in Africa, Europe, Asia, and the Americas. They also focused on geographic regions – such as Brazil in South America – where multiple honey bee invasions had occurred.

The researchers were looking for tiny variations in the sequences of nucleotides that make up all genes. Certain versions of these single nucleotide polymorphisms (SNPs, or “snips”) are more common to African honey bees, while others occur more frequently in honey bees in western Europe, eastern Europe, or Asia.

By comparing these SNPs in bees from different geographic territories, and by looking at the frequency at which particular alleles, or variants, occur in functional and nonfunctional parts of the honey bee genome, the researchers were able to determine that the invading bees were not just randomly acquiring genetic material from their predecessors by interbreeding with them, but that certain genes from the previously introduced bees were giving the newcomers an advantage.

An earlier study led by Whitfield and published in Science in 2006 showed that A. mellifera originated in Africa and not Asia, as some had previously hypothesized.

That study revealed that the honey bee had expanded its territory into Eurasia at least twice, resulting in populations in eastern and western Europe that were quite different from one another.