The commercial trade in honeybees has helped to spread a deadly bee virus around the globe over the past century.

Credit: Stephen Martin, Univ. Salford

Deformed wing virus reduces the winter survival of European honeybees (Apis mellifera), and could be a factor in the large colony losses seen in some parts of the world. To find out how the virus became pandemic, Lena Wilfert at the University of Exeter, UK, and her colleagues analysed the virus's genome to reconstruct its evolutionary and geographical history. The team found that the virus has spread from Europe in the past century, in part because of the trade in commercial colonies. New carriers of the virus also contributed: the Varroa mite (Varroa destructor) began to infect European honeybees about 50 years ago, when this pandemic started.

Tighter controls on commercial colonies are needed to slow the virus's spread, the authors say.

Science 351, 594–597 (2016)