Deadly Honeybee Diseases Spreading To Wild Bumblebees In Large Numbers, Study Finds
Diseases which probably originated from managed honeybee populations have become "widespread" in wild bumblebees, researchers say in a study published today in Nature. Surveying 26 sites in the United Kingdom, researchers found that 11 percent of bumblebees were infected with deformed wing virus and seven percent infected with the fungal parasite Nosema ceranae. In honeybees, such diseases have contributed to colony collapse.
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"Wild and managed bees are in decline at national and global scales," lead author Matthias Fürst said in a statement. "Given their central role in pollinating wildflowers and crops, it is essential that we understand what lies behind these declines. Our results suggest that emerging diseases, spread from managed bees, may be an important cause of wild bee decline."
Bees infected with these diseases have shorter lifespans, which not only leads to their own demise but that of their fellow bees. Bees infected with the disease aren't able to go out and collect food or look after other members of their colony.
The researchers are not completely sure that bumblebees caught the diseases from honeybees, but it is likely. Eighty-eight percent of the honeybees that the researchers looked at carried the deformed wing virus, which bumblebees could have gotten while foraging from the same flowers as honeybees. Bumblebees also sometimes raid honeybee hives to steal nectar, which could also lead to their infection.
"We're only catching individuals that are alive and healthy and able to go out and forage," principal author Mark J.F. Brown told the Los Angeles Times. "It's likely that the prevalence numbers that we report are lower than they actually are."
As entomology professor May Berenbaum of University of Illinois put it, "the spillover for bees is turning into [a] boilover." (Berenbaum wasn't part of the study.)
Even if bumblebee infection levels are lower than they are with honeybees, the threat could be just as great or greater. Bumblebee hives are much less populous than honeybee hives: there are tens of thousands of honeybees in a hive compared to only a few hundred in a bumblebee hive. Bumblebee hives can't afford to lose too many members. "It's like Wal-Mart versus a mom-and-pop store," said Berenbaum.
According to the BBC, the researchers want to investigate whether neonicotinoid pesticides have made bees susceptible to disease. A recent paper suggested that chemicals in the pesticides have weakened bee immune systems. The European Commission has restricted the use of these pesticides for two years.
"I think the important take-home message is that we need to be concerned not just about our managed pollinators, but our wild pollinators as well," Brown said.
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