COLLEGE STATION – Genetic research, based on information from the recently released honey bee genome, has toppled some long-held beliefs about the honey bee that colonized Europe and the U.S.
According to research published recently in Science, an international professional journal published by the American Association for the Advancement of Science, the four most common subspecies of honey bee originated in Africa and entered Europe in two separate migrations, said Dr. Spencer Johnston, entomologist with the Texas Agricultural Experiment Station and one of the authors of the article.
A large number of different bee species exist in Asia, where it had long been thought the honey bee originated, Johnston said.
"Their origin in Africa was suggested in other studies, but our result shows it dramatically to be true," he said.
Taking genetic information from the honey bee genome sequencing effort, researchers from Texas A&M University, University of Illinois, Cornell University, Washington State University, University of Kansas and the University of California-Irvine, and one private producer traced the genealogy of honey bees. Two branches originate in Africa.
The honey bee is not native to North America; it was introduced from Europe for honey production in the early 1600s, Johnston said. Subspecies were introduced from Italy in 1859, and later from Spain, Portugal and elsewhere.
When honey bees collected in Europe and Africa were studied, they separated genetically into four distinct groups, he said.
However, the genome of U.S. bees "was a complete mix of the three different introduced European subspecies," he said.
That mixture is changing with the introduction of the fourth subspecies from Africa in 1990. The form that was Italian mixed with other strains has been crossbreeding with an Africanized-Spanish strain. In effect, the Italian mix is disappearing. This has not happened to the same extent with the European varieties.
"It is clear that introduced African bees mated with existing U.S. bees and that colonies with large portions of the African bee genome were able to out-compete the original U.S. mixture," he said.
"Why the Africanized honey bee successfully invaded the New World but has not moved across Europe, we don't know," Johnston added. "Maybe (the U.S. varieties) were selected (by beekeepers) for everything but competition."
An important goal of the research was to identify candidate genes that could be responsible for the overly defensive behavior in Africanized honey bees.
"It will be a race among researchers to find out which specific genes are involved in behavior," he said.
Journal
Science