Researchers from the University of California, Berkeley and University of Exeter have discovered that the European honeybee Apis mellifera is the source of the devastating Deformed Wing Virus (DWV) bee disease and that the spread is caused by humans, particularly due to the transport and sales of bees for crop pollination, according to Tech Times.

"People didn't on purpose do this. People don't go to the trouble of sending bee queens to the States for stupid reasons. They do it to get better hives or honey, to get more pollination. Until recently we didn't understand how common it is to spread diseases that way," said Lena Wilfren, a lecturer at the University of Exeter and the lead author of the study, according to The Washington Post.

But despite not having the intention to create and spread the disease, Wilfren adds that "somewhere we have messed up the ecology. We need to be careful with this stuff. The more complex the systems are, the more unpredictable."

The researchers also explained that the DWV disease alone does not wipe out the honeybees. A Varroa mite plays a significant role as the disease-carrier. It feeds on the bee larvae, and when the larvae affected by Varroa is also hit with DWV, then the bees die. The Varroa-DWV combination has resulted in the deaths of millions of honeybee populations over the past decades.

The researchers are calling for tighter controls on importing honeybees, such as mandatory health screenings and more checks on movements across borders, and that greater efforts must be made to stop at least one of the factors from entering what countries remain unaffected so that scientists can use it as a place for refuge and conservation of the honeybees, BBC News reported.

The study was published in the Feb. 5 issue of the journal Science.