People Are Spreading a Virus That’s Killing the World’s Bees
The transportation of European honeybees that pollinate a third of the food supply is driving a deadly disease infecting beehives around the world, according to a study published Thursday in the journal Science.
“What we can say in our research is that the spread of this deadly virus across continents would not have been possible without the human-aided transmission of the European honeybee,” said Lena Wilfert, the study’s lead author and an evolutionary geneticist at the University of Exeter in the United Kingdom.
The disease is called deformed wing virus, and it’s just one of a number of culprits impacting the health of pollinators. Researchers have also linked parasitic mites, viruses, bacteria, fungal diseases, and intensifying pesticide use to the overall decline in bee populations worldwide.
In the United States, the number of honeybee hives, which add $15 billion in value to the agriculture industry, fell 59 percent from 1947 to 2005.
The discovery that humans are responsible for a significant threat to bees could help scientists and policy makers contain the disease.
The researchers obtained honeybees preserved in archives and were able to map 100 years of bee DNA from 17 countries. That allowed them to pinpoint the evolutionary origin of deformed wing virus, which they traced to Apis mellifera, also known as the European honeybee.
By itself, deformed wing virus is not deadly to honeybees. It’s more akin to a common cold—a nuisance but survivable—when transmitted between adult bees. European honeybees were infected with the virus when they began to be shipped around the world in the 1600s to pollinate crops, according to the scientists.
But over the past 50 years, the spread of a mite, the aptly named Varroa destructor, has transformed the bee’s common cold into a full-on plague. The tiny blood-sucking mites feed on adult honeybees and transmit the deformed wing virus to bee larvae. The unborn bees either die or hatch with misshapen wings, resulting in depleted colonies.
“Beekeepers reported coming back to their hives after winter and finding the bees were just dead,” Wilfert said.
She fears the recent combination of deformed wing virus with Varroa has transformed the European honeybee from a farmer’s best friend into a lethal disease spreader.
A 2014 study in the journal Nature found deformed wing virus had spread to wild bumblebee populations in the United Kingdom, dramatically shortening the life of the pollinators.
“It’s a big problem that we can identify in honeybees, because we monitor them and we can see it spread,” Wilfert said. “But for wild bee populations, they don’t have beekeepers watching out for them, and we don’t see the problem until it is too late.”
She said countries need to establish stricter regulations on bee transport, including all bee-related products, to curtail the virus. She pointed to Australia and a few islands in Hawaii, which have effectively limited the spread of Varroa, and hopes global regulations on honeybee transport put in place in the past decade will start to contain the disease.
“When you’re working on this type of research, you can forget that what we know now wasn’t common knowledge even 10 years ago,” Wilfert said. “We’ve only recently come to understand the role viruses play in the health of honeybee populations. Now that we have a better understanding of how they spread and how to stop them, I’m hopeful we’ve seen the peak of Varroa and deformed wing virus.”