Are pollinators sensitive to climate change, urbanization?

McCluney Lab continues research to discover bees’ sensitivity to climate change, urbanization

By Julie Carle

Pollination is a big deal. To all of us.

We don’t have to be farmers or gardeners to know that pollinators are key to some of the most essential foods that we eat. Bees, along with birds, bats and other insects, transport pollen from one flower to another, helping to form the seeds and fruits that we enjoy eating.

At Bowling Green State University, the lab of Dr. Kevin McCluney,  associate professor of biological sciences, is looking at the lives of bees. A grant from the U.S. Dept. of Agriculture’s National Institute of Food and Agriculture provides the funding to research how bees are impacted by climate change and urbanization.

The project, which runs through July 2024, builds on previous work by McCluney and Justin Burdine, as well as collaborators Drs. Elsa Youngsteadt from North Carolina State University and Clint Penick from Kennesaw State University. M.J. Lashbrook, a graduate student working on his doctoral degree in biology, joins McCluney and an undergraduate student on the project. Lashbrook comes to BGSU from Iowa, where he focused on pollinators from an ecological and conservation biology perspective for his master’s degree. He looks forward to adding the physiological perspective to his knowledge base.

The McCluney Lab’s previous bee research was led by then-doctoral student Burdine, now an assistant professor at Cornerstone University in Michigan. The research had a local focus, studying bees at Toledo area urban gardens. This grant expands the scope to bees in five sets of paired cities that represent a wide range of temperatures and precipitation: Toledo and Detroit, Raleigh and Durham in North Carolina, Atlanta and Athens in Georgia, Denver and Boulder in Colorado, and Phoenix and Tucson in Arizona. The BGSU team will work with local organizations such as botanical gardens in each location. 

They have identified six groups of bees that are considered “economically important and in large enough quantities in each of the cities.” They plan to study honey bees, bumble bees, carpenter bees, sweat bees, mason bees and leafcutting bees.

Including the health and abundance data will allow them to connect the bees’ thermal and water content tolerance with their actual health and abundance, he said. They also will study how often the bees visit different kinds of flowers and their efficiency at pollination.

They will use cucumber plants at each of the sites within the 10 cities. They hope to determine the bees’ sensitivity to climate change and the amount of pollination each species can do in each location, which establishes the aggregate pollination services, McCluney said.

“We will try to look at, in general, how well the cucumber plants are pollinated, and if some bee species aren’t doing a good job, maybe others will be able to pick up the slack.”

In locations such as Phoenix, the temperature and moisture “might be so high and dry that none of the species are able to do well there,” he said. “Maybe overall pollination declines because all of the species are negatively affected.” Or maybe the species found there will be well-adapted to those conditions. At the moment, the extent to which bees can quickly adapt to local climate is poorly understood. But data from previous research suggests that honey bees in Toledo are sensitive to dehydration and several species of bees in Raleigh are sensitive to overheating, suggesting some limits to local adaptation.

Comparing data from multiple sites at each of the multiple cities will allow the researchers “to look at changes within the city and between cities to provide an idea of how much the species is able to adapt to the changes in temperature,” he said.

“This obviously has implications for global climate change, and not just local urban climates,” McCluney said. “Can bee species adapt to deal with climate change?” he asked. “It’s not a direct measure of their adaptability to global climate change, but evidence from cities can provide important indirect information to understand the effects of climate change more broadly.” The question becomes, how adaptable are these species? Can they handle the changes they are increasingly experiencing or are they not able to adapt?

There is already some research that suggests the bees’ critical thermal maximum, which measures their upper thermal tolerance limit, is not very flexible, McCluney said. Their inability to evolve quickly could mean that species closer to the equator may be closer to their maximum temperature and not be able to evolve to higher levels.

In addition to the focus of the research on bees’ sensitivity to climate change and urbanization, McCluney said the research teams will have the opportunity to explore many “very basic science questions about adaptability and the traits of the organisms, like if they can fly a long way, does that mean they have a higher or lower thermal tolerance.”

“We’re working directly with gardeners and farmers whose livelihoods are affected by this and the research has real-world implications,” McCluney said. “Climate change due to either urbanization or to global change could be affecting productivity. We want to help figure out who is going to be most affected.”

Once that is known, then resources can be better targeted to help those affected to cope with these changes.