Bee populations are plummeting again, and this time not because of neonicotinoid pesticides: Now, a virus is taking hold worldwide, and it looks like humans are to blame for its spread.
The disease—called the deformed wing virus—is especially deadly when carried by the parasitic Varroa mite. Together, the mite and the virus wiped out millions of bees within a few decades, as the Varroa mites feed on bee larvae and the virus it carries kills off bees of all ages.
Which means that the bee populations are devastated twice over—bringing new concerns about the fate of the little creatures that pollinate $16 billion worth of crops per year in the US alone.
What’s the buzz?
According to the paper published in Science, the virus isn’t just spreading naturally, but instead is being driven by human movement and bee transportation. To reach this conclusion, the researchers examined the phylogeography—simply speaking, genetics and geographic locations—of Varroa mites and the deformed wing virus.
Through this work, they discovered that the virus seems to have spread from one main region: Europe. From there, it has reached North America (Hawaii in particular), Australia, Asia, and New Zealand.
In terms of the spread of the mites and virus, there appears to be some forward and backward movement of the virus between Asia and Europe, but none between the geographically closer Australasia and Asia; it’s unidirectional in those cases, mostly just being carried over from Europe. The researchers believe this suggests that the virus does not spread normally, but it carried such distances via human methods.
“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,” said coauthor Lena Wilfert, from the University of Exeter’s Centre for Ecology and Conservation, in a statement.
“This demonstrates that the spread of this combination is largely man-made—if the spread was naturally occurring, we would expect to see transmission between countries that are close to each other, but we found that, for example, the New Zealand virus population originated in Europe. This significantly strengthens the theory that human transportation of bees is responsible for the spread of this devastating disease.”
More bees, please
The solution, then, to saving the global populations of pollinators seems clear—although it may sting a little.
“We must now maintain strict limits on the movement of bees, whether they are known to carry Varroa or not,” said Wilfert. “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.”
But researchers believe that, with such controls, we can turn things around.
“The key insight of our work is that the global virus pandemic in honey bees is manmade not natural,” says senior author Mike Boots, a professor at the University of California, Berkeley, and the University of Exeter. “It’s therefore within our hands to mitigate this and future disease problems.”