Interactions between domesticated species and wildlife often pose a threat because species can act as vectors for diseases and parasites. New research shows that the interaction between wild bumblebees and domestic honeybees via the wildflowers the pollinate could be cause for concern. The study, which was published recently in the journal PLOS ONE, suggests that domestic honeybees are passing viruses to wild honeybees, which are already endangered.
“We show this spillover is likely occurring through flowers that both kinds of bees share," says Samantha Alger, a scientist at the University of Vermont who led the new research. "Many wild pollinators are in trouble and this finding could help us protect bumblebees. This has implications for how we manage domestic bees and where we locate them."
To conduct the study, Alger and her colleagues analyzed 19 sites throughout Vermont. They were looking for the presence of two RNA viruses found in honeybees: deformed wing virus and black queen cell virus. The research team determined that the presence of the viruses was higher in bumblebees collected less than 300 meters from commercial beehives. They also found that honeybees had active deformed wing virus infections in areas closer to commercial apiaries.
But the presence of the viruses on the bees wasn’t necessarily the most thrilling conclusion of the researchers’ findings. Perhaps more importantly, the research team was able to pinpoint that the commercial bees were passing these viruses to the wild bees through flowers. In fact, of the flowers they sampled from sites close to commercial apiaries, 19% had the presence of one of the two viruses. Compare that to the flowers from the sites far from apiaries, which had no sign of the viruses. "I thought this was going to be like looking for a needle in a haystack. What are the chances that you're going to pick a flower and find a bee virus on it?" says Alger. "Finding this many was surprising."
This is the first study that shows that viruses can be "horizontally transmitted," through flowers and it has significant implications for apiary management. "Careful monitoring and treating of diseased honeybee colonies could protect wild bees from these viruses as well as other pathogens or parasites," commented Alison Brody, senior author and a professor in UVM's Department of Biology.
"This research suggests that we might want to keep apiaries outside of areas where there are vulnerable pollinator species, like the rusty patched bumblebees," Alger explains, "especially because we have so much more to learn about what these viruses are actually doing to bumblebees.” While honeybees serve an important role in our agricultural industry, the fact that they are non-native means they threaten native bumblebees. “They're livestock animals," Alger says. "A huge misconception in the public is that honeybees serve as the iconic image for pollinator conservation. That's ridiculous. It's like making chickens the iconic image of bird conservation."