Sammy Ramsey has spent years carefully tracking a genus of tiny mites as they spread across Asia. This winter, the honey bee parasite expert and endowed professor of entomology at the University of Colorado received a series of concerning reports: Tropilaelaps mites appear to have arrived in Ukraine.
“Their presence in Ukraine is the biggest wake up call to the rest of the world about this parasite,” he said. Ukraine exports bees to Canada, so North America might not be too far behind.
American beekeepers are already familiar with tropilaelaps’ relative, the varroa destructor mite. But, tropilaelaps are both deadlier and harder to kill. When the mites reached India, entomologists estimated that they killed between 50% and 100% of the colonies they infested.
A similar death toll in the U.S. would have a devastating impact on, not only beekeeping, but agriculture as well. Nearly a third of the food that we eat comes from crops that rely on honeybees. According to the U.S. Department of Agriculture, pollinators contribute more than $18 billion to the U.S. economy annually, with honey bees leading the way.
“People say dogs are man’s best friend.” Ramsey said. “But, I feel like honey bees are competing for that top spot as well.”
Ramsey’s work on varroa mites cemented him a rising star in entomology. Using a mixture of conventional and unconventional imaging techniques, including observing the mites on live bees trapped in plexiglass photography chambers, he uncovered the details of the mites’ feeding behavior. Essentially, the parasite liquidates the honeybee’s liver, leaving them vulnerable to environmental toxins like pesticides.
Now in his 30s, Ramsey has already realized the dreams of many scientists. He has a tenure-track professorship and his own lab at the University of Colorado. He was also named a National Geographic Explorer last year. As someone who doesn’t quite fit the stereotype — he is black, gay and a devout Christian — he is outspoken about the need for more diverse voices in science.
“The very narrow conception of what a scientist looks like needs to be exploded,” he told actor Craig Robinson on the Hulu show Your Attention Please.
But, Ramsey does fit the mold in one important way: He is obsessed with honeybees. And, now that mites have emerged as a looming existential threat, he is putting all of his energy into solutions. He has traveled the world in search of novel ways to treat the parasites, including trips to Thailand and Bangladesh. Here in Colorado, he keeps 10 or so experimental hives at Boulder Valley Honey for the purpose of testing novel treatments for both varroa and tropilaelaps.
A deadly cocktail
Over the past two decades, U.S. honey bees have faced numerous environmental challenges. Invasive pests, disease and habitat destruction have strained colonies across the country. “The state of honey bees right now is precarious because they’re already dealing with a ridiculous amount of stress,” Ramsey said. “But we’re making it work.”
Thus far, U.S. beekeepers have been able to deal with lost colonies by splitting their surviving hives to create new ones. Yet, this approach only works if a certain portion of colonies remain healthy. The question now is if the honeybees can survive another even more destructive pest.
When a pregnant tropilaelaps mite arrives at a beehive, it is on a mission. It crawls, disturbingly quickly, through the colony and into the brood chamber — a honeycombed section of the hive where queen bees lay their eggs in an orderly pattern and worker bees tend to larvae as they mature. Then the mite searches until it finds a brood cell with an almost fully-grown larva inside. It hops in and waits for a worker to come and cap the cell with wax — sealing the parasite and its victim inside. Once the cell is capped, the mite lays one or two eggs, which hatch and develop into fully-grown mites in a matter of days. Throughout the process, the mite and her offspring gorge themselves on the fatty tissue of the pupa. When the mature bee emerges from the brood cell — and not all do — the mites hop out and look for a mate to start the process once again.
“The bees identify the dead or severely damaged pupae and rip them out,” said Steve Cook, a research entomologist at the USDA’s bee research laboratory in Beltsville, Maryland. “You begin to see this sort of shotgun brood pattern.”
The bees that do survive to emerge are left with a greatly weakened immune system, and the wounds left by the mite’s mandibles can lead to crippling physical deformities. They rarely survive for more than a few days. To make matters worse, tropilaelaps mites often transmit virulent diseases. Black queen cell virus infects and kills queen bee larvae, while deformed wing virus disrupts pupa development leaving bees disabled, partially paralyzed and flightless.
“You’ll see adult bees with these deformed wings crawling on the outside of the hive,” Cook said.
Without intervention, the entire colony will soon perish.
The destructor
Though tropilaelaps have yet to reach North America, beekeepers have been dealing with the aptly named varroa destructor mite for four decades. Since varroa arrived in Florida in the late 1980s, they have become a ubiquitous source of death and disease. In 2018, 90% of the honey bee colonies sampled by the USDA’s National Honey Bee Survey tested positive for the mites. Research ranks varroa as the leading cause of “colony collapse disorder,” which kills between a quarter and a half of U.S. bee colonies each year.
In April, Ramsey took a few hours to check on his experimental hives a few miles east of the university. As Boulder Valley Honey owner and founder Chris Borke watched, Ramsey pulled a bee-covered frame of honeycomb out of the first hive and held it up to his eyes. After a few seconds he exclaimed “aha!” A varroa mite had latched onto the shoulder of a worker bee. The mite was barely discernible — a tiny red dot — but Ramsey is adept at finding them.
“All beekeepers have them nowadays,” Borke explained. “They’re difficult to manage.”
Varroa destructor’s life cycle is quite similar to that of tropilaelaps, with one important difference. In addition to invading brood cells, varroa mites can feed on adult bees. This allows the mites to spread quickly to new hives by traveling on the backs of worker bees.
This difference may explain tropilaelaps’ relatively slow spread, but it is not cause for reassurance. Tropilaelaps reproduces much faster than varroa. Once it makes it into a colony, it can spread exponentially throughout the hive and quickly invade nearly all of the brood cells. Tropilaelaps mites also tend to bite their victims in multiple places, while varroa create only one wound.
As a result, tropilaelaps infestations are more rapid, more deadly and harder to control at the colony level. “If we thought that varroa was bad, well, it looks like tropilaelaps is just in a different league,” said Dennis vanEngelsdorp, a professor of entomology at the University of Maryland and leader of the USDA National Honey Bee Survey.
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With the threat of a future honey bee pandemic in mind, a team of USDA scientists and policymakers developed an annual survey meant to detect tropilaelaps if it arrives in America. Each year, state inspectors sample around 1,000 honey bee colonies around the country for signs of tropilaelaps. If an inspector finds the mites, they are required to contact the USDA, which will work with state authorities to develop a containment and mitigation plan.
The survey aims to prevent the mites from spreading throughout the country, but there’s also a chance that by the time we know tropilaelaps is here it will already be too late.
“It just takes one distribution point for a parasite to get out of control,” Ramsey said.
If tropilaelaps arrived on U.S. soil today, beekeepers would have very few tools to defend against them. Most of the literature on mite control is specific to varroa, so attempts at eradicating tropilaelaps would be, scientifically, a shot in the dark.
“There is so little about this organism that has actually been documented at this point because it has remained in what are typically deemed ‘developing nations,’” Ramsey said.
Yet, beekeepers in Asian countries have dealt with the mites for decades, sometimes with modest success. As alarm around tropilaelaps is growing internationally, these techniques are finally getting some scientific attention.
Acid and paint sticks
Ramsey and his lab have made multiple trips to Thailand with one goal in mind: finding and testing a surefire way to kill tropilaelaps in honey bee colonies. In particular, he heard that Thai beekeepers were using formic acid, a food preservative and chemical component of the venom in a honey bee stinger, to treat infested colonies. Formic acid is a common treatment for varroa in the U.S.
But the beekeepers that Ramsey met were reluctant to reveal their trade secrets, especially to a foreigner.
One day, Ramsey was trying to pry information from a particularly reticent beekeeper, and getting nowhere. The man dodged each question with vague and confusing answers, until one of the beekeeper’s assistants interrupted the conversation by tapping Ramsey on the shoulder.
“He was like, ‘are you Black Thai?’” Ramsey said. The young apprentice recognized Ramsey from his after-hours viral Youtube channel, where he sings Thai pop songs with R&B inflection. “He showed the beekeeper the video and he got really excited,” Ramsey said. “Then he opened up a ton.”
Ramsey learned that the beekeeper treated tropilaelaps by dipping paint stirrers in industrial-grade formic acid and sticking them under the entrance to the colonies. And it was working, for the most part. Because the paint-stirrer method produced an unpredictable amount of formic acid, some of the colonies were poisoned and died. But many others survived with a lower mite population than before.
Once he saw it with his own eyes, Ramsey wasted no time coordinating a study to find the perfect dosage of formic acid to treat a tropilaelaps infestation. The preliminary results, though not yet published, are quite promising, but it’s not a silver bullet. When American beekeepers started using chemicals to treat varroa infections, the mites quickly developed resistance.
“We went through three rounds of this before we figured out we need multiple chemicals at the same time,” Ramsey said. “Otherwise we’re just going to end up on the resistance treadmill forever.”
Ramsey’s lab is now busy testing two other methods to control tropilaelaps. One employs a proprietary chemical, while the other subjects the hive to a cycle of heating and cooling that might prove lethal to the mites while avoiding harm to the bees.
Now that tropilaelaps is “knocking on the door of Europe,” as Cook puts it, the USDA is scrambling to support research like Ramsey’s. In addition, the agency is footing the bill for a group of state inspectors to travel to Thailand with Auburn University entomologist Geoffrey Williams this spring. The hope is that the inspectors will learn how to identify the mites by seeing them in person.
Ramsey still wonders if enough is being done.
“Let’s think about the pandemic for a moment,” he said. “Can you imagine if in 2019, as soon as we heard about COVID-19 spreading in China, we had started studying COVID, learning about it — we could have had a vaccine before the summer of 2020 arrived.”