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A mite called Varroa destructor sounds like it belongs in a sci-fi film, not in beehives where they have been wreaking havoc since the late 1980s. That’s when the parasitic mites arrived on U.S. soil from Asia.
For years, pesticides were thought to be the leading cause of increased die-offs among honeybees. But new studies suggest that Varroa might be affecting bee health much more than we thought.
“By far, Varroa mite is the biggest issue that beekeepers deal with,” Dan Wyns, a tech transfer team member with the Bee Informed Partnership, a nonprofit working with commercial beekeepers to develop best practices for monitoring bee colony health, says.
These mites are invasive arachnids and have infested upwards of 50% of American hives. That’s where they lay their eggs in the broods’ cell, where the queen has also laid her eggs. The bee is already weakened by the time it’s born from these infested cells, and it has a shortened lifespan as the mite rides on its back.
Scientists thought Varroa mites feeding on bees were the equivalent of deer ticks on mammals. But new research suggests the mite actually feeds on the bee’s fat bodies, which is the apiary equivalent of a liver.
The fat body “detoxifies pesticides, regulates hormone levels, it produces the honeybee’s primary immune response to microbial invaders,” Samuel Ramsey, an entomologist at the USDA bee research lab in Beltsville, Md., says.
And that’s just three of its nine functions, Ramsey added.
Varroa mites cause deformities and health issues for bees, but they also make it more likely that bees will get sick when they’re exposed to chemicals in their environment.
“We know that it negatively impacts the bee’s ability to detoxify pesticides,” Ramsey said.
While there are some commercially available treatments for Varroa, Wyns says their effectiveness is still widely varied.
One of the ways beekeepers are combatting these parasites and preventing the bee population from cratering completely is by splitting hives. Beekeepers remove some bees from one hive and put them into a smaller hive called a nucleus. They then bring in a new queen, who brings new eggs, and the hive is effectively split in two.
But maintaining hive numbers is a huge challenge for beekeepers. Over the last few years, Jeff Lee, a commercial beekeeper from North Carolina, said he faced a 50% attrition rate.
“This last year, I had the most losses I have ever had and I’m reading the literature and I’m trying to do everything I can to keep the bees healthy,” Wyns said. “The bees just kept getting smaller and smaller and nothing’s left in the colony. I couldn’t explain it.”
On Episode 5 of the Business of Bees, hosts Adam Allington and David Schultz learn that colony collapse isn’t the only challenge bees are facing these days.
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