LAWRENCE — The cellophane bee might be the ultimate spring breaker. A solitary bee that nests in the ground, it's one of the very first pollinators to emerge every year — often before the snowmelt.
Now, scholarship from the University of Kansas shows the bee is specially equipped by evolution to handle the harsh shocks and cold temperatures of early spring.
Like any spring breaker, it knows how to bounce back. Compared to honeybees, cellophane bees recover from "chill coma" about twice as quickly and can handle much lower temperatures.
The study, relying on bee collection and research carried out by faculty, graduate and undergraduate researchers on KU's Lawrence campus, appears in Ecology and Evolution .
"Over 75% of bees are solitary, but most of what we know about bees comes from studies on social bees like honeybees and bumblebees," said Victor Gonzalez, research associate with the KU Biodiversity Institute & Natural History Museum and lead author of the new study. "The cellophane bee is native to North America — a solitary bee that nests in the ground. Most solitary bees have very short lives as adults. The species we study lives only four or five weeks. It's called a cellophane bee because when it makes a nest, it creates cells that look like clear paper, similar to cellophane."
Gonzalez, who also serves as a courtesy researcher in the Department of Ecology & Evolutionary Biology at KU, said while the cellophane bee starts emerging around spring break, by mid-May the adults die.
"The larvae hatch quickly and become adults, but they remain in the ground until the following year," he said.
The KU researchers collected wild bees on campus, measured their size, exposed them to controlled temperature conditions, tracked recovery and gauged results between bee sexes and species.
A few key findings:
- Colletes inaequalis (the cellophane bee's scientific name) can handle cold a lot better than honeybees, an adaptation tied to emerging in early spring.
- But honeybees tolerate heat better, perhaps a danger sign that cellophane bees are particularly threatened from warming temperatures tied to manmade activity.
- Sex and body size don't seem to affect thermal tolerance in cellophane bees. The males are smaller, but they're just as hardy as females when the mercury drops.
- Repeated exposure to cold makes recovery slower.
Gonzalez's KU co-authors are Deborah Smith, professor of ecology & evolutionary biology, and graduate students Natalie Herbison and Andres Herrera. They are joined by Kennan Oyen of the U.S. Department of Agriculture.
According to Gonzalez, the cellophane bees are vital pollinators in the ecosystem with importance to some agricultural producers.
"These early spring bees pollinate early spring crops and flowers, such as apples and blueberries," he said. "However, they are harder to be commercialized like honeybees because they're solitary and ground nesters. They need areas to nest, and, unlike honeybees, which have colonies of thousands, solitary bees exist in much smaller numbers. Even so, they're important for local plants."
This study of bees on the KU campus sheds light on how species will fare during climate change more broadly. The team also built on KU's long history of bee research, including studies of campus bee species by the late KU professor and world-expert on bees, Charles Michener .
"What we wanted to see is how these bees are coping with changes in temperature during the spring," Gonzalez said. "Sometimes, when they're flying, it still snows. But spring is coming earlier and becoming warmer. Weather patterns are changing, and we want to know how bees adapt. There are records from the 1980s from some of Michener's students showing that males emerge first from the ground about two weeks before females."
Building on this earlier KU research, the team found these early emerging males must find food. When they can't, males have far lower rates of survival after exposure to cold.
"Food impacts survival, while repeated exposures to cold affect their ability to function normally," Gonzalez said. "Being exposed to multiple snow days impairs them behaviorally. They can't recover from these cold events if they're exposed more than once. This is important because males are emerging from the nests, and if there are several snow days after that with no food, they're going to die. If they do recover and survive, they may not be able to fly properly. Survival is hard work, and with more erratic changes in climate we're experiencing, this might be impacting these populations. There is further work we can do to assess this."
