Study identifies virus killing honeybees in tandem with Varroa mites and human transport

A Varroa mite, the size and shape of a pinhead, on a bee

A virus that is decimating bee populations is emanating from Europe and spreading worldwide, says a study published in the journal Science by researchers at the University of California, Berkeley and the University of Exeter, a public research university in the United Kingdom. "The European honeybee Apis mellifera is overwhelmingly the source of cases of the Deformed Wing Virus infecting hives worldwide," Exeter reports. "The finding suggests that the pandemic is man-made rather than naturally occurring, with human trade and transportation of bees for crop pollination driving the spread." Bees are responsible for more than $15 billion in increased U.S. crop value each year.

"Although separately they are not major threats to bee populations, when the Varroa mite carries the disease, the combination is deadly, and has wiped out millions of honeybees over recent decades," reports Exeter. "Varroa feed on bee larvae while the Deformed Wing Virus kills off bees, a devastating double blow to colonies. The situation is adding to fears over the future of global bee populations, with major implications for biodiversity, agricultural biosecurity, global economies, and human health."

"Researchers analysed sequence data of Deformed Wing Virus samples across the globe from honeybees and Varroa mites, as well as the occurrence of Varroa," reports Exeter. "They used the information to reconstruct the spread of Deformed Wing Virus and found that the epidemic largely spread from Europe to North America, Australia and New Zealand. . . . The team also looked at samples from other species suspected of transmitting the disease, including different species of honeybee, mite and bumblebees, but concluded that the European honeybee was the key transmitter."

Lead author Dr. Lena Wilfert said in a statment: “This is the first study to conclude that Europe is the backbone of the global spread of the bee killing combination of Deformed Wing Virus and Varroa. ... This significantly strengthens the theory that human transportation of bees is responsible for the spread of this devastating disease. We must now maintain strict limits on the movement of bees, whether they are known to carry Varroa or not. It’s also really important that beekeepers at all levels take steps to control Varroa in their hives, as this viral disease can also affect wild pollinators.” (Read more)