Recent genetic analyses have proved that honeybees originated in Africa and not in Asia, as previously thought. "Every honey bee alive today had a common ancestor in Africa" concluded the team.

"Our analysis indicates that the honey bee, Apis mellifera, originated in Africa and spread into Europe by at least two ancient migrations," said Charles W. Whitfield, a professor of entomology at the University of Illinois at Urbana-Champaign.

The genus Apis contains 10 species, nine of which endemic to Asia. The only exception, Apis mellifera, the common honeybee, is found from sub-Saharan Africa to Central Asia to Northern Europe, and it is represented by more than two dozen distinct geographical subspecies.

From Africa, the species spread to Europe and Asia, creating distinct genetic lineages (subspecies), including the Italian bee, used extensively for agricultural pollination. "The migrations resulted in two European populations that are geographically close, but genetically quite different," Whitfield said.

"In fact, the two European subspecies are more related to honey bees in Africa than to each other."

Europeans introduced in the Americas at least 10 subspecies from different parts of Europe, Near East and Northern Africa beginning with 1622. In 1956, a South African savanna subspecies, A. m. scutellata, the killer bee (photo), was brought to Brazil in order to increase honey production. These aggressive African bees rapidly spread in all directions, from South America to North America, hybridizing and displacing previously introduced European honey bees. "Clearly, these African 'killer' bees are more aggressive and exhibit other traits that beekeepers and bee breeders dislike," Whitfield said.

"By studying variation in the honey bee genome, we can not only monitor the movement of these bees, we can also identify the genes that cause the variations - and that will allow us to better understand the differences."

1,136 SNP (single nucleotide polymorphism) markers, which are simple DNA variations, were used to precisely figure the movements of bee subspecies and their relationship to one another. "An SNP marker can tell you a lot about which bee is related to which bee, and where a particular bee came from," said Whitfield.

"We need to understand the bees, where they came from, and what is happening to them today to ensure they continue their vital work of pollination, which is so crucial to the world's economy", said Neil Tsutsui, assistant professor of ecology and evolutionary biology.

The scientists found that, in the Americas, the genes of some subspecies appeared to be replaced by African genes, while genes of other subspecies were more resistant to this replacement. "This finding, said Tsutsui, is important because the spread of Africanized bees northward from South America in recent years has had some negative consequences; not only are these bees more dangerous to humans because of their propensity to sting in large numbers, but they are also difficult to rear commercially for pollination and the production of honey and other products."

Researchers want to identify the genes that confer these "killer" bees their aggressive characteristics, in order to eliminate them. The honeybee, an important economic pollinator, suffers now a decline in the US due to the killer bee, especially in warmer southern parts. And 80 % of all flowering plants are entomophil, relying on pollinators for fertilization in order to produce fruits and seeds. Only in California, about 1.4 million colonies of honeybees are necessary to pollinate 550,000 acres of almond trees.