Bumblebees are not early risers. It’s nearly noon and none are out in the wildflower-filled meadow where Michelle Duennes, a researcher at the University of California, Riverside, looks for them and listens for buzzing.
“It should be bee city out here,” she says, eyeing the deep-purple lupine and delicate fuchsia shooting stars. Duennes is collecting bumblebees from all over California to study their health. This morning’s site is near Sonora Pass, high in the Sierra Nevada.
Bee declines, both of bumblebees and honeybees, have hit populations around the world. Figuring out why is important because bees are vital pollinators of plants that feed the world. California bumblebees are in danger too, and Central Valley farms rely on their services.
Duennes and her collaborators are collecting bees to figure out what role climate change, poor nutrition and vulnerability to pesticides and parasites play in bee declines. The information they gain could help people working to save bees.
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Duennes’ enthusiasm for bees is apparent from the bumblebee pins on her hat and the bee-embellished socks in her galoshes. She’s also sporting a T-shirt with a logo of two bee species she is collecting and the words “Sierra Nevada Bumble Bee Health Project.”
People would ask her what she was doing while she collected bees in Yosemite, so she designed the shirt to alert onlookers to her role as a researcher. She’s eager to talk about the bumblebees she studies – two of the most common in California. Today she’s searching for yellow-faced bumblebees, found all over the state from the Bay Area to the Central Valley and Southern California. This bee is slick black with one yellow stripe on its abdomen, midnight blue wings and its characteristic yellow face.
“They are by far the stinkiest bees,” she notes. “Usually a bumblebee colony will smell really good ’cause of the pollen and the nectar.” But these made her lab smell terrible.
She’s investigating how different factors affect the bees’ health across all her sites. For instance, bees near the Central Valley are more likely to be exposed to pesticides drifting from farms. And across their Sierran range, the bees experience a variety of climates and feed at different flowers.
Ultimately, Duennes hopes to design a bee health panel for farmers to do “checkups” on the bees near them. For instance, it might reveal if a change in pesticide use could protect the bees and benefit the farmers too.
Bumblebees also help pollinate many crops such as blueberries and alfalfa. “I would hope that lots of people would know how important (bumblebees) are to the food that they eat every day,” says Duennes.
On a good day, Duennes quickly catches the 20 bees she needs of each species, but today half an hour passes and she still hasn’t caught one.
Finally, a bee appears on a Western Bistort, a small white flower that looks like a bottlebrush, which Duennes says smells like diapers. She springs through the wet squishy grass and swiftly pops her net over the flower with a gleeful shout.
Duennes holds up the tip of the net and the bee moves to the top, toward the sunlight. She pinches the net closed and coaxes the bee into a plastic laboratory tube, covering the opening with the net so it doesn’t escape. She brings the opening of the tube to the lens of her glasses, which are too slick for the bee to grip.
The bee falls into the tube and she caps it. She sticks a flower in too so she’ll remember what type she found it on, and the bee feeds on it contentedly.
“They only sting me when I grab them straight up in the net. They’re really calm.”
She’s looking for worker bees, which are all female, that collect pollen in baskets on their legs. She speaks about – and occasionally to – them with the kind of affection people show their pets.
“Come on, babies, time to wake up,” she says as she scours the field.
The day is warming, and Duennes is worried the bees she’s caught will overheat. “Let’s get these ladies in ice,” she says, heading back to the roadside where her portable research station is set up inside a pop-up tent.
Falling in love with bees
Duennes got her start as a naturalist by bringing strange mushrooms gathered from her wooded Kentucky backyard to her high school biology teacher for help identifying them.
“I was always outside getting dirty messing around with plants, getting poison ivy,” she said. Even so, she found insects creepy until a class trip led by a college entomology professor at Mount St. Joseph University introduced her to the “fascinating world of insects” with all their amazing colors. “I fell in love,” she said.
Driven by her enchantment with bugs, she started work on a doctoral degree at the University of Illinois, Urbana-Champaign, in entomology, the study of insects. Around that time, there were many reports of colony collapse disorder, when a mysterious disappearance of worker bees leaves an abandoned queen and nest. That prompted her to hone in on bees.
She started working with bumblebees because of their importance to agriculture. But she also felt an emotional connection to them and appreciates their beauty and variety of colors.
“It helps that they’re really cute,” she said. “They’re like the pandas of the insect world.”
Her Ph.D. took her to Mexico and Central America to study how the mountainous landscape shaped the genetic diversity of a bee that has stripes of the usual yellow and black but also orange, red, black and white. She found what was once thought to be one population was actually four, and by the end of her doctorate, she had identified a new species.
Her findings were important for those working to conserve the bees, and she developed a passion for conservation that’s part of her work as a postdoctoral fellow at UC Riverside in the lab of S. Hollis Woodard.
“With Michelle, her enthusiasm is contagious,” said Sydney Cameron, Duennes’ thesis advisor who oversaw her Ph.D. research. “It’s infectious. She’s just super in love with the work that she does.”
Frozen in time
Back at the tent, Duennes drops the tubes holding the bees into a tank filled with liquid nitrogen, which is extremely cold, and knocks them out so she can collect pollen samples.
“They’re frozen in time, kind of like Han Solo in ‘Star Wars,’ ” she says.
Using a pair of tweezers she snips off a corbicula, a pollen basket that looks like a golden bead, from each leg and puts it in an alcohol-filled tube to analyze later.
The pollen gives her insight on which flowers the bees visit and their nutritional value. She’ll analyze it for much of the same information found on our nutrition labels: carbohydrate, protein and lipids, including fats. She wants to figure out if being near the intense agriculture of the Central Valley affects the nutritional quality of what the bees eat.
Later in her sterile lab, she’ll dissect the bees and scoop out the fat body, an organ lining the bee’s abdomen that helps them store energy.
Duennes will use it for genetic analysis. Certain genes fire up when bees are stressed by factors in their environment. She’ll see if the activity of those genes correlates with poor nutrition or pesticide exposure. She’ll also check if the bees harbor any parasites.
“Everybody gets upset when I tell them I kill bees. I don’t like killing them. That’s not why I study them,” she said. “I study them because I love them. If you want to study the gut parasites of a tiny little insect you can’t really do it without taking their guts out.”
By collecting bees at different altitudes – near the Central Valley and in the forests of the Sierra Nevada – Duennes looks at how different climates affect the bees. It’s also a natural experiment to look at the effects of a changing climate.
Longer summers and warmer temperatures may mean shorter hibernation times for bees. It’s not clear what effect this might have on them. Duennes said queens usually look a bit ragged after hibernation. A shorter winter means they might emerge less worn and with more fat reserves. But climate change may also change the seasonality of the flowers they rely on and the parasites that threaten them.
Duennes also raises bees in the lab as a controlled study on those same factors of bee health. She’ll raise queen bees and put them to sleep in a freezer to see how they fare after different lengths of hibernation.
Duennes has collected 800 bees this season, often chasing them in meadows six days a week. She’s logged thousands of miles traveling to her dispersed sites.
But she still has hundreds more to catch and will have to visit this meadow high in the Sierra again. It turns out it’s too early in the season for the bumblebees here.