Research: Rising temperatures threaten bumblebee populations

A bumblebee hovers over indigenous Fynbos vegetation in Cape Town, South Africa, March 24, 2006. A new report says climate change is threatening the bumblebee population. File photo by Nic Bothma/EPA

May 3 (UPI) — New research from the University of Guelph said Friday that temperatures are becoming too hot for bumblebees, threatening their role as plant pollinators and the food supply for humans and other animals.

Researchers said the rising heat is exceeding the optimal temperature for bumblebees, 86 to 89.6 degrees. Guelph environmental professor Peter Kevan said while bees have the ability to thermally regulate temperatures within their hives, that can only work for so long.


The article appeared online Friday in the scientific journal Frontiers.

“The decline in populations and ranges of several bumblebee species can be explained by problems with overheating of nests and young,” said Kevan, author of the paper.

“Limitations on bumblebee brood survival indicate that heat is likely an important factor, as heating the nest above 35 degrees Celsius is lethal, despite bumblebees’ remarkable ability to thermoregulate.”

Temperatures around the world have been rising over the past few decades, rewriting the weather record book with each passing year. The year 2023 was the hottest ever recorded and temperatures are on the verge of breaking that record this year.

“Excessively high temperatures are more harmful to most animals and plants than cold temperatures,” Kevan said. “When conditions are cold, organisms that do not metabolically regulate their body temperature simply slow down, but when temperatures rise too high, metabolic processes begin to break down and cease. Death ensues quickly.”

Kevan said pesticides, loss of housing, dwindling availability of wildflowers and disease also contribute to population declines. There are 250 different species of bumblebees, 49 of which can be found in the United States.