Kathryn Gardner studies bumblebees. "Not honeybees," she quickly emphasizes to show her disapproval for all who might dare confuse the two. Her sternness lasts only a moment before she cracks a playful smile. "There's a big difference," she insists. "And a bit of an unspoken rivalry between those of us who study the two types."
Gardner, 27, has been raising bumblebee colonies at Cornell since she began graduate school here four years ago. Working under her adviser, Nicholas Calderone, associate professor of entomology, she has now become the resident expert on the insect. "If I left today, there would be no one here who could raise bumblebees with the success rate that I have -- which is about 80 percent," she says with pride. Her secret? Lots of care and nurturing and some tricks of the trade she brought to Cornell from the University of Puget Sound in Tacoma, Wash., where as an undergraduate Gardner first fell in love with the furry bumbling insects.
During the summer, she typically raises as many as 35 colonies at a time in a shack on the outskirts of the east side of campus. The colonies serve as the test subjects for part of her Ph.D. thesis, which, simply put, asks, "What determines whether a newborn female larva will become a worker bee or a queen bee?" To those who study social insects like bees, ants and a few other types that organize themselves into societal classes with different tasks, this is known as "caste determination."
Besides research, Gardner also teaches in local schools, sometimes taking one or two of her bee colonies into the classroom. This has earned her the nickname "The Bee Lady" among the students.
Although the question of what it takes to be born a queen seems basic, the answer is unknown -- at least for her species, Bombus impatiens, the native and by far most common bumblebee in upstate New York.
"It's not genetic," she says. "Worker bees and queen bees have the exact same genome." This means that when a female larva emerges from its egg, it could still go either way. It is contrary to what one might originally think. "The genetics of social insects are just wacky. It's so different from how we do it," muses Gardner. "But it makes sense if you think about it. Workers are sterile. And any genetic coding that says you're sterile will not be passed on," she says.
The question of caste determination has already been solved for honeybees, points out Gardner: It's nutrition. Larvae that are fed large quantities of "highly nutritious" food during the first three days of life develop into queens. The food is a mixture of pollen, honey and glandular secretions regurgitated by the workers for the larvae, she says. Therefore, the more workers there are, the more food each larva gets. As a colony grows bigger, the number of workers increases while the queen continues to lay the same number of larvae. Therefore, larvae born late in the life of the colony will become new queens.
For another species of bumblebee, B. terrestris, caste depends on queen dominance. Explains Gardner, "In the early spring and early stages of the colony, when the queen is young, robust and vigorous, she is very dominant, putting out a lot of queen pheromones that signal to the workers, 'Hey, I'm here; I'm the queen; I'm the ruler; I'm still good.' As she ages, the colony grows and her influence on the workers diminishes. At that point, when she loses her queenliness, the workers will start rearing new queens for the new season."
However, there are enough other differences between Gardner's bumblebees and other species of bees that she cannot assume that they determine caste in the same way. Last summer, she conducted experiments varying the workers-to-larvae ratio, which gave inconclusive results. Her work remains in progress, though she suspects that nutrition will prove to be more of a determinant than anything else.
Why study bumblebees? Aside from purely scientific interests, Gardner points out that companies are now selling B. impatiens commercially for greenhouse pollination. "From an economic standpoint, it would be good to know how and why colonies start producing queens, simply because once a colony starts producing queens, they stop producing workers," Gardner says. "Workers are the ones who do the pollinating. So if they start making queens really early, it's not so good for your tomatoes."
Over the course of the winter and spring, Gardner has been experimenting with raising bees indoors at a time when queens outside are burrowed under the dirt in hibernation. To view them, she leads the way into a tiny humidified room near the back of her lab, where colonies line the shelves in shoe-box-sized wooden boxes that Gardner built herself. Plexiglass tops allow ideal viewing of the black and yellow fuzzy insects that buzz and crawl busily and somewhat clumsily about the cluster of wax combs they have built, occasionally nibbling at chunks of pollen Gardner has given them or sipping at small test tubes containing sugar water that stick through holes in the box. "They are so cute," she marvels. "I spend a lot of my time just watching them; I find it endlessly fascinating."
"Working with the bees is really relaxing," she says, "simply because I have to be totally calm and kind of Zen about it. If I'm at all frantic or shaky or scared, it's awful. Bees sense that. They get frustrated; they get angry. But if I'm really deliberate about my movements, it goes really well."
When Gardner finishes her Ph.D. next year, she plans to become a high school biology teacher. "I've been teaching and doing other types of educational outreach longer than I've been doing research, and I've always loved it," she says. Gardner practices teaching through a Cornell Science Inquiry Partnership (CSIP) National Science Foundation fellowship, which sends her into local middle and high school science classrooms for science presentations. "CSIP really lets me see what it's like to teach in a high school classroom: the trials and tribulations that are frustrating but really rewarding," she says.
She carefully removes a male bee from one of her colonies by pinching its leg with a long pair of tweezers and places it in her palm. "I let the kids hold the male bees because they have no stingers," she says. Suddenly, the bee flies away. "Don't worry," she says, "I'll catch him later."
Thomas Oberst is an intern at the Cornell News Service.