University of Maine professor Frank Drummond is the last known person to hold a Maine-born rusty patched bumblebee, although his memories of the occasion are foggy, frustratingly so; no scientist wants to be imprecise. He knows it was 2009, because his student workers were engaged in a typical few days of specimen collecting in Stockton Springs, just north of Searsport, that summer. Among the many specimens they brought to him were a few of the rusty patched bumblebee, which is slated to be formally added to the federal endangered species list this week.
Drummond was pleased. Bombus affinis had once been abundant in Maine; indeed, when Drummond first started collecting bees here in 1989, they made up about 20 percent of the state’s overall native bumblebee population. If you grew up in Maine as late as the 1980s, this bee, with its little scruff of rusty fur on the middle band of its “back,” was very likely one of the bumblebees you were most used to seeing. But it had grown scarce by the late 1990s, suggesting a collapsing population, and by 2009, Drummond was excited enough to call Anne Averill, a colleague from the University of Massachusetts Amherst, to let her know about his student’s find.
He had no notion these would be the last Bombus affinis he’d see.
There are 49 kinds of bumblebees found in the United States, and the rusty patched is close in looks to two other native Maine bumblebees, the brown-belted and the tri-colored. So close that wildlife biologist Beth Swartz of the Maine Department of Inland Fisheries and Wildlife regularly hears from Mainers who insist their yards are full of those allegedly rare rusty patched bumblebees. Why does this one, barely discernibly different bee matter so much?
The simplest answer is what it may portend for all bumblebees, which matter because of their role, and that of all pollinators, in sustaining and nourishing us.
“Without them, our forests, parks, meadows and shrublands, and the abundant, vibrant life they support, cannot survive,” Tom Melius, a regional director with U.S. Fish and Wildlife, said in the announcement that the rusty patched bumblebee would be listed as endangered. “And our crops (would) require laborious, costly pollination by hand.”
After the Stockton Springs find in 2009, the rusty patched specimens were sent off to a lab for molecular studies. They would have been packed on dry ice at minus 80 degrees, Drummond says, and sent express mail, standard operating procedure. But the specimens never came back. Somewhere along the line they went missing. Drummond blames no one. Well, maybe himself a little.
“I didn’t realize that it was such an important specimen,” he said. If he had, he said, he would have put it away for posterity.
Its true significance was revealed only later, when he looked back on data sets and realized that UMaine collections from 2005 and 2007 included no Bombus affinis. They went from rare to gone – although bee advocates hold out hope that isn’t true – in a matter of a few years.
The rusty patched bumblebee is hardly the only bee species in trouble; the populations of two of the other 16 species native to Maine have dwindled rapidly as well, although less dramatically. But honey bee colony collapse disorder has gotten far more press, in part because of those non-native pollinators’ value to American agriculture. That term implies an actual illness but simply encompasses all the possible ailments and reasons for large-scale die-off in honey bee hives.
Colony collapse disorder has also been more closely observed; the beekeepers who care for traveling colonies of “professional” pollinators can open up a hive and see the evidence of die-offs in front of them. But while it may lack a catch phrase name, the plight of the native bumblebee is similar and equally mysterious, happening in such a way that even an expert might miss it.
“With some of these catastrophic events you don’t realize it until it has already happened,” Drummond said. “It wasn’t even in my mind that this was possibly the last time that this bee was going to be the last one we saw.”
LOST BUT LISTED
The rusty patched bumblebee is the first in the United States to receive the endangered designation under the Endangered Species Act and the first bee altogether in the continental U.S. (seven species of yellow-faced bees native to Hawaii were listed late in 2016). The nonprofit conservation group the Xerces Society, which petitioned the U.S. Fish and Wildlife Service on behalf of the rusty patched bumblebee in 2013, hailed the listing as the bee’s best chance of survival before extinction.
There are only 250 species of bumblebees worldwide, so the fact that Maine has been home to 17 of them represents a strong diversity, said Kalyn Bickerman-Martens, a University of Maine doctoral candidate working on native bee conservation. One way that bumblebees are distinct from honeybees is that they do not thrive in tropical conditions. “Instead of increasing their diversity as you get closer to the equator, they actually increase as you get further from it,” Bickerman-Martens said.
The rusty patched bumblebee’s range once extended across 28 states, throughout the Northeast and out to South Dakota, as well as in two Canadian provinces, where it has already been listed as endangered. It can still be found in Minnesota, Illinois and Wisconsin, which Rich Hatfield, who runs Xerces’ bumblebee conservation program, describes as its “last strongholds.”
U.S. Fish and Wildlife Service estimates the rusty patched population has declined by 87 percent. And that decline has been startlingly rapid. In the last decade, it’s been found in only six counties in the Northeast, including Waldo and Knox in Maine. Drummond’s student’s discovery represents one of those two findings.
BEES ON THE BARRENS
In Maine, pollinators play a particularly significant role in agriculture, most visibly in the cultivation of wild blueberries, which generated a $47 million crop in 2016. Maine farmers import more bees seasonally than any other state aside from California.
That’s not to say that native pollinators don’t get a piece of the pollinating blueberry pie. While the majority of the bees “working” on the wild blueberry crop in Maine arrive via truck from out of state (58,883 hives in 2016) native pollinators do show up. This year an “abundance” of native pollinators were on the barrens, said Nancy McBrady, the executive director of the Wild Blueberry Commission, which was one reason farmers imported 12,000 fewer hives than usual last spring.
“If we could rely entirely on native pollinators, we would,” McBrady said. “But the scale of our operation is such that we need to supplement by bringing in honey bees.”
The Wild Blueberry Commission commented on the proposed listing, but did not oppose it, she said.
“No, absolutely not,” McBrady said. “We were saying first and foremost we are very dependent on and want to have a healthy pollinator population. We would not exist but for pollinators.”
It’s a complex relationship though, because with a federal listing comes federal regulations. Growers will likely have to apply for permits in some situations.
“There is just a lot of ambiguity in the rule right now,” McBrady said. “We’re kind of in suspended animation.”
Another complexity lies with the question of what made the bumblebee colonies disappear in the first place. One theory is that native pollinators have been exposed to parasites and pathogens carried by the migrant honeybees, which Drummond describes as “filthy with disease.” He’s studied a “spillover” effect that happens when an infected bee and a native bumblebee sup on the same flower. Sharing dirty dishes, so to speak.
“We find that the bumblebees that are in areas that are close to where honeybees are tend to have a much higher amount of these viruses than others,” Drummond said. “That does suggest that these viruses are moving from the honeybees to the native bees.”
But it doesn’t mean they’re getting sick, he cautioned. “Some folks confuse the idea of exposure with actual disease.” More research is underway. “The story hasn’t been finished yet.”
Some subscribe to the theory that if the rusty patched bumblebee died out because of a disease, the source would likely be a commercial bumblebee. There are such a thing as commercial, cultivated bumblebees and while they don’t move around in quite the numbers honeybees do, they do travel, and sometimes may resettle. Take Bombus impatiens, which Drummond said was once fairly uncommon in Maine and now makes up 20 percent of what you’d find on an average summer day. That could be the result of climate change, he said, or it could be from commercial bumblebees getting out of, say, greenhouses and propagating. Maine blueberry farmers bring in about 2,000 colonies of bumblebees every year, he said.
Doctoral candidate Bickerman-Martens has been studying a fungal pathogen called Nosema bombi (known as N. bombi) that is prevalent in collapsing colonies. A theory blaming a particularly bad strain of N. bombi that rode in to America on commercial bumblebees from Europe was popular for a while, but a study released a few months ago seems to disprove that, suggesting that the domestic commercial bumblebees infected the wild bees.
That’s what Rich Hatfield of Xerces believes. His hunch is that commercial bumblebees brought into cranberry bogs in Massachusetts carried the disease, and it radiated from there, infecting others, particularly the rusty patched bumblebee. Geographically, it makes sense, but Hatfield was quick to caution that he’s speculating. “I have zero evidence for this,” he said.
Drummond said work by colleagues about six years ago, studying the pathogens on commercial bumblebees, casts doubt on this theory. “They could find almost no pathogens,” he said, “meaning that these companies maybe had a problem at one time, but they’ve cleaned up.”
Other theories include widespread pesticide use throughout the rusty patched bumblebee’s former habitat. “I am really skeptical about whether that is the cause here,” Drummond said.
Neither climate change nor changing habitat should be ruled out, Drummond said. “Maine is the most forested state in the country right now, 93 percent of the landscape is forest.” That’s not good habitat for bumblebees. “If you have large amounts of contiguous forest, that is kind of the kiss of death for bees.”
Whatever the scenario, the rapid disappearance indicates that the rusty patched bumblebee had a harder time resisting it than some of its close relatives. And that is likely just the genetic luck of the draw.
ALONE IN WINTER
The rusty patched bumblebee queen, like all bumblebee queens, heads into winter with what would be a daunting and lonely prospect for most of us; she’s alone. “With honey bees, they overwinter together in a big ball, Bickerman-Martens said, “whereas the bumblebee is responsible for building the entire colony by herself,”
The rusty patched also have superior pollinating skills when it comes to deep flowers, like nightshades, Bickerman-Martens said. “They will grab them and vibrate intensely. They are basically making flowers into salt shakers. Honey bees can’t do that.”
New queens are anointed in the late fall. They mate and then hibernate, typically in soil.
“A lot of bumblebees nest in an old rodent’s nest, a nest in the soil that has been abandoned by field mice,” Drummond said. “They tend to like some sort of insulating material to nest in, whether it’s the hair of rodents or the stuffing of upholstery or an old mattress.”
In the spring, these queens make wax cups in the nest with honey and pollen and lay the eggs that were fertilized in the fall. Provided no predators find them (from bears to skunks, plenty of wood creatures would devour the queen), daughters are born in the middle of June and serve as worker bees until the new queens are designated. The male bees are born at the end of summer and live only a few weeks, long enough to begin the cycle again.
When naturalist and author Bernd Heinrich was working on his 1979 book “Bumblebee Economics” (reissued in 2004), he witnessed this cycle repeating all around him in Western Maine. The rusty patched bumblebee was a regular visitor to his flower beds. He hasn’t seen this species in years, and very seldom the yellow-banded (terricola) or yellow (fervidus) species, either. The flowers haven’t changed, it’s just that the visitors are nearly gone, save a few queens in the spring. “This is the same site where I did (a) study of them,” he wrote in an email. “Is it weather?”
ON THE HUNT
In the first order of business after the listing, U.S. Fish and Wildlife Service will look for any remaining populations of rusty patched bumblebees. Not that others haven’t been trying (filmmaker Clay Bolt made a short film, “A Ghost in the Making” about his own quest), but this will be a federal effort. Mark McCollough is the service’s biologist in Maine charged with the search, with the hope that the bees could be captured, the population rebuilt and then released back to the wild once stable.
He’ll have some help from the volunteer effort behind the Maine Bumble Bee Atlas, which is tracking populations in the state to determine densities. The atlas is supported by two grants – one from the U.S. Fish & Wildlife Service’s State Wildlife Grants Program, and the other from the Maine Outdoor Heritage Fund, which receives proceeds from a state lottery scratch ticket. The project was initiated in 2015 and quickly drew throngs of volunteers, with hundreds more on the waiting list. Bickerman-Martens coordinates the group along with Swartz. They’ve trained 175 citizen bee hunters and thanks to them, have already added about 10,000 new records to the database.
“It is pretty amazing,” Swartz said. “I only anticipated we would get about 1,000 new records that first year. But pollinators are of such interest to people now.”
Bickerman-Martens is hopeful, saying the more specimens gathered, the better those chances get.
“I think that if it is here they are going to find it,” Bickerman-Martens said.
Discouragingly, a study of native bees in Virginia turned up just one rusty patched bumblebee in a pool of 35,000 collected specimens. The New Hampshire Agricultural Experiment Station recently completed its first assessment of the state’s native bee population in the White Mountain National Forest and found a “relatively high abundance” of the yellow-banded bumblebee, which is listed as a species of greatest conservation. But there were no rusty patched bumblebees.
Given how rare they are, does it make sense for a volunteer to snag a specimen if they see one, or would they be harming a colony’s chance of survival? It’s a good question, Swartz said. “But to be honest with you, I am hoping we do collect one because that’s the only way we’ll know if we have them.”
Another option? Doing as Maine Bumble Bee Atlas volunteer Amy Campbell does, taking only photographs. But time stamp them; like Frank Drummond, Campbell has a special place in the annals of the last days of Maine’s rusty patched bumblebees. She took the last known photograph of a Bombus affinis in the state. Her memory of that encounter is gone. She knows only that it was taken with a camera she used between 1995 and 2005. Maybe it was taken in Rockport, maybe at a local nature center. Her focus was on a flower the bee was feeding on, coincidentally a rusty foxglove. “It was back in the day when I thought a bumblebee was just a bumblebee,” she said.
In April 2014, after she found it tucked away in a file marked “insects on flowers” she uploaded it to Xerces’ Bumble Bee Watch for identification.
Rich Hatfield reviews those submissions. He commented swiftly: “Thank you, great find.”
And it was. But can it happen again?
Mary Pols can be contacted at 791-6456 or at:
Correction: This story was revised at 12:50 p.m., Feb. 6, 2017, to correctly identify the funding sources for the Maine Bumble Bee Atlas. The project is supported by two grants, one from the U.S. Fish & Wildlife Service’s State Wildlife Grants Program, and the other from the Maine Outdoor Heritage Fund, which receives proceeds from a state lottery scratch ticket.