Higher temperatures may benefit some bumble bee species, especially those that nest underground, but periods of extreme heat could still lead to population declines in the southeastern United States, according to research published on May 6.
The study is important because bumble bees are major pollinators in agricultural and natural systems. Understanding how climate change affects their colonies helps researchers and farmers prepare for future challenges. The research was led by Clint Penick, assistant professor of insect ecology at Auburn University, with contributions from Elsa Youngsteadt, associate professor of applied ecology at North Carolina State University.
“A lot of research on how higher temperatures affect living things has been done on individual animals,” said Penick. “But when it comes to social animals, such as ants and bumble bees, you have to look at the entire society.” He added that different roles within a colony must be fulfilled for it to thrive: “If any of those roles aren’t fulfilled, it’s difficult or impossible for the colony to thrive.”
Youngsteadt said: “We previously found that individual bumble bees reach stressfully hot body temperatures while foraging on warmer days. But it’s important to understand how that fits into the big picture for the entire colony. How do higher temperatures affect the nest, where the queen bee lives and where the next generation of bees is developing?” The study monitored both aboveground and underground nests using simulated environments and field observations across six locations from Georgia to Michigan.
The findings suggest that belowground nests are insulated from high heat above ground. In these cases, workers spend less time incubating brood and more time foraging as temperatures rise—a potential benefit. However, aboveground nests face greater risks during extreme heat events; workers must fan their wings more often to cool nests but may still be unable to prevent dangerous temperature spikes during severe heatwaves.
“There is an upper limit to how much the bees can do to cool down a nest,” Youngsteadt said. She noted that while currently only about nine hours per year are too hot even with fanning in Georgia’s climate, this could increase significantly with further warming: “In a warmer climate, that could go up to nearly 200 hours per year.”
Penick suggested practical steps based on these results: “One take-away from this is that we need to find ways to keep above-ground nest boxes cooler in order to improve bumble bee survival in agricultural settings.” Both Penick and Youngsteadt encouraged planting native flowering plants close together so bees travel shorter distances under stressful conditions.
The College of Agriculture and Life Sciences addresses issues in food production, natural resources management, community development initiatives across North Carolina through specialized facilities and extension centers operating statewide according to its official website. The college also collaborates with industry partners and government agencies for research aimed at improving quality of life through advances in agriculture and life sciences applications.
