The Secret Life of Bees

By Sally West Johnson ’72        
Illustration by Chris Buzelli

By the time of the early September cold snaps, bumblebee season is winding down around Addison County. The orange, trumpet-shaped flowers of jewelweed have all but disappeared from the fields, and the tiny, purple flowers of knapweed that once blanketed meadows are mostly gone. Only the lush yellow of goldenrod remains.

At the moment, we’re in Wright Park, the swath of public land at the north end of Middlebury. For reasons no one quite understands, Wright Park has turned out to have that magic combination of flowers and bee-friendly nesting places that researchers look for when they set out to study a bee population. By the side of the field, Patrick Sedney ’08 and I huddle against the chilly breeze, he with his odd-looking assortment of bee-research paraphernalia (nets, microdots, and small jars set into ice packs). In the middle of the field, Luke Yoquinto ’08 flails the air gently with a bee net, incongruously, like some child in a fairy tale. When he finds a likely suspect, Patrick will glue a numbered microdot to its back, then release it back to the wild. By following its meanderings through the field, Patrick wants to find out where it goes, what it does and, most important, which flowers it will choose to light on in its never-ending search for nectar.

Yoquinto and Sedney are seniors, biology majors both, who designed their projects under the supervision of Dr. Helen Young, the department chair and resident pollinator expert.

It’s worth saying at the outset that Young et al. are not studying honeybees, those famously disappearing insects that are responsible for most of the world’s plant pollination. Honeybee hives are models of efficiency, holding up to 10,000 honeybees who communicate through what’s called a waggle dance to show others where to find the best nectar. On the other hand, bumblebees, in their many incarnations, are more poorly understood. They live in small, underground nests of up to 50 individuals. And unlike the honeybee, they do not communicate the best nectar-gathering spots with a waggle dance. This is more of an every-bee-for-herself ethic. (Almost all bees in a nest are female.) 

While the honeybee hitched a ride with Europeans to North America—the Europeans brought them over to serve as a source of sugar after discovering that the New World lacked a sugar source—bees of the genus Bombus are native to this continent. Unlike honeybees, bumblebees produce just enough honey to feed the small nest (hive connotes a man-made structure; nests are dug by the insects)—hence there is no market for bumblebee honey.

What the researchers want to know is why bees make the choices they do: why they prefer certain color flowers to other colors, why they limit their nectar gathering to one plant exclusively, then jump ship and find another flower to exploit, why they forage from bottom to top on a flowering stalk and never from top to bottom.

This is all within the realm of what is called basic or pure science (as opposed to applied science). Basic science can be defined as science that leads to development of theories or tests existing theories. In asking and answering a series of questions about bumblebee habits, Young and her crew hope to take these individual answers—each of which may seem small in itself—and add them to a larger whole. She describes it as “chipping away at the block until a shape begins to emerge.” In this case, Young, Sedney, and Yoquinto are chipping away at the block of information that is the biology of the bumblebee. “Bees are incredibly important pollinators of both crops and wildflowers,” Young explains. “But without fully understanding the biology, it’s dangerous to make predictions. How will global warming affect the bumblebee population, for instance? We really don’t know.”

J. J. Thomson, the discoverer of the electron, described pure science as research made “solely with the view of extending our knowledge of the Laws of Nature.” Once this knowledge is learned and understood, it can then be applied in any number of ways.

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The summer of 2007 began as a study of bumblebees and jewelweed, but Young couldn’t find a field with enough bees and plants to get meaningful results, so she cut her students loose to pursue their own ideas.

Yoquinto, for instance, wanted to know why bees forage from bottom to top on a vertical flowering stalk such as purple loosestrife. In this field of evolutionary ecology, it’s assumed that bees, like other pollinators, will practice “optimal foraging,” so it must also be assumed that these bees are foraging in a manner that most benefits them, even if it’s not immediately obvious to humans. He can control certain variables—increasing or decreasing the amount of nectar in a flower, for instance, by using an insulin syringe to add or subtract nectar—to see whether he can change the outcome.

Yoquinto plans to raise a bee colony in an indoor cage this winter, allowing him even more control of the variables. He’ll feed them sugar water and bee pollen, which is essentially the same thing as the nectar that they drink from plants in the wild. (Bees lap nectar with their tongues the way a dog laps water. Bumblebees have a long tongue, which gives them exclusive access to the nectar of certain flowers.)

Sedney’s project is also of his own devising. What is well known about bees is that they will focus on one type of plant, ignoring all others, until one day they simply switch plants. What nobody quite understands is why this happens or what triggers the decision—if one can call it that—to change plants. “One thesis is that they have to learn the process of extracting nectar, and to learn it for more than one plant at a time would be inefficient,” says Sedney, noting that the extraction process for each plant is different.

He has tried to influence their choices by putting a “choice stick” in their flight paths—a long pole with room at the end for two flowers—to see whether he can induce them to switch by enhancing the nectar content of a flower or making that flower somehow more desirable. So far, his data, painstakingly collected over weeks and months, have been inconclusive—which is why patience is an essential trait for a scientist.

Sedney is testing his own theory, which is that bees retain a visual picture of their flower of choice in their brain and that they are, in effect, programmed to go find that flower. “The choice of one flower over another is important to the pollination process,” he explains. Plant reproduction is enhanced if pollen arriving at a flower is from the same species of plant as the recipient of the pollen. If bees move indiscriminately between plant species, seed production (and hence the production of the next generation) will be severely reduced. Sedney also points out another key area. “People are discovering the importance of native habitat. Is it important to leave wild fields around crop plantations to draw more bees and improve pollination?” Numerous studies, he says, indicate that, yes, smaller farms that adjoin native habitats have greater crop yield of insect-pollinated plants than farms located farther away from such areas. “It seems harsh to say this,” adds Young, “but humans generally have a very negative impact on pollinators,” more from ignorance than intention. Mowing fields too early in the spring, for instance can ruin a population of bumblebee nests from which the site may never fully recover. In addition, monocultural farming practices—growing acre after acre of wheat or corn—can have a negative impact on pollinators. Monocultures, by nature, leave little native habitat between rows of crops, Young explains. Bees require “edges” for nesting, the edge between meadow and forest, for instance. Monocultures provide little “edge.” Yet the economic incentive for farmers—“the Maine blueberry crop,” Young acknowledges, “is worth about $56 million a year”— is hard to contest.

Yet that doesn’t stop Young from being discouraged. With bumblebees, she sees humans responding (or not responding) the way they usually do in these situations—standing by as a system breaks down, then scrambling to fix it once it is truly broken. She advocates agricultural practices that would help promote native habitat and increase species diversity; in other words a return to the way farming used to be before the advent of giant machines and genetically engineered crops. Family farms raised a little of everything, ate what they needed and sold the rest. “Agricultural practices have devastated pollinator populations,” she says sadly, searching for even one example of how human interaction has been beneficial. “I can’t think of one case where the outcome has been improved by contact with humans.” 

Her own project—involving jewelweed and bumblebees—is likely to take at least a few more years to complete, given that she can do fieldwork only in the summer months. (In fact, because each experiment often leads to more questions, it is easy to imagine spending decades working on this system.) Her question right now is: how does a bumblebee assess the amount of nectar in a given flower? She’s observed that bumblebees will approach a flower, such as jewelweed, and within seconds will decide whether or not they will pollinate that flower. Young’s hypothesis is that the bees are determining both the nectar quality and quantity of that flower. But how are they doing this? An intriguing idea is that the bees are using a logical thought process. Because bees leave odors on the petals of flowers they visit, perhaps bumblebees are detecting that other bees have visited a particular flower and deducing that there must not be much nectar left. “My suspicion,” Young says, “is that they’re going through a checklist.” As to what that checklist might be ... well, she doesn’t know. Yet.

Once Young has results, they can be applied to agricultural systems—improving crop yield by learning what flower features enhance pollinator visits, for instance. But she insists that her passion in this discipline is driven purely by curiosity.

“Putting everything in terms of how it will benefit humans is short-sighted and uncreative,” she says. “We have to figure out how to live in ways that benefit all populations, not just the human ones.”

Sally West Johnson ’72 is a writer in Middlebury and a frequent contibutor to the magazine.