Queen bumblebees, the insects responsible for founding entire colonies each spring, may be far more resilient than scientists once believed. New research from the University of Ottawa shows that these bees can survive underwater for more than a week while in their winter dormancy—an unexpected ability that could help them endure seasonal flooding linked to climate change.
The discovery provides new insight into how these essential pollinators cope with extreme environmental conditions, particularly as spring weather becomes increasingly unpredictable in many parts of the world.
Why the Survival of Queen Bees Matters
For bumblebees, the queen determines the future of the entire colony. After surviving the winter, each queen emerges in spring to establish a new nest and produce workers that sustain the colony through the growing season.
If a queen fails to survive winter or early spring flooding, the colony never forms.
Understanding how queen bumblebees endure harsh conditions is therefore critical for scientists studying pollinators and the ecosystems that depend on them. Bees play a major role in pollinating crops and wild plants, supporting agriculture and biodiversity worldwide.
Life Underground During Winter Dormancy
The Role of Diapause
Queen bumblebees spend the winter buried in soil in a dormant state known as diapause, which resembles hibernation.
During diapause, their metabolism slows dramatically, allowing them to conserve energy for several months until temperatures rise. This low-energy state helps the insects survive long winters with minimal food or oxygen.
However, spring weather can complicate matters.
When snow melts and seasonal rains soak the ground, water can flood the underground chambers where the bees are dormant. Until recently, scientists assumed such flooding could easily drown the queens before they woke from their winter sleep.
But new findings suggest these insects are capable of surviving those conditions.
How Scientists Tested Underwater Survival
The research began with an unexpected observation.
“This study started from a discussion with my co-author and postdoctoral researcher, Sabrina Rondeau, whose recent findings showed that these queens can survive submersion for over a week, which is extraordinary for a terrestrial insect,” said Charles-Antoine Darveau, a professor of comparative physiology at the University of Ottawa. “We wanted to understand how that’s even possible.”
To investigate, researchers recreated winter conditions in a laboratory.
First, queen bumblebees were kept in diapause for four to five months to simulate natural overwintering. The scientists then submerged the dormant bees underwater for eight days.
Throughout the experiment, the team monitored the insects’ metabolic rate—the speed at which their bodies use energy—and observed several physiological changes. Honours student Skyelar L. Rojas also contributed to the research.
How Queen Bumblebees Survive Underwater
The scientists discovered that even while submerged, the queens continued exchanging gases with the surrounding water, allowing them to absorb small amounts of oxygen.
At the same time, their bodies maintained an extremely low metabolic rate.
“The first key is metabolic depression,” Darveau explained. “Their metabolism is already extremely low during diapause. That low energy demand makes survival possible.”
In simple terms, the bees require so little energy during dormancy that even limited oxygen is enough to keep them alive.
But oxygen exchange alone did not fully explain their survival.
A Backup Energy System Without Oxygen
The researchers also detected a significant buildup of lactic acid inside the bees’ bodies during submersion.
Lactic acid forms when cells produce energy without oxygen, a process known as anaerobic metabolism. While most animals rely on oxygen to generate energy, some organisms can temporarily switch to this alternative pathway when oxygen becomes scarce.
In the submerged queens, the presence of lactic acid showed that the insects had activated this backup system.
“They’re not relying on just one strategy,” Darveau said. “They combine underwater gas exchange with anaerobic metabolism. That flexibility is what allows them to survive these extreme conditions.”
Together, extremely low energy demands, limited oxygen absorption, and anaerobic metabolism enable the queens to endure several days underwater.
Recovery After Submersion
Surviving underwater does place temporary stress on the bees.
After eight days of submersion, researchers removed the queens from the water and observed a sharp increase in their metabolic rate for two to three days.
“That surge in metabolism coincides with clearing the accumulated lactate,” Darveau said. “It’s essentially a recovery phase. After about a week, their metabolism returns to normal diapause levels.”
Importantly, the queens remained in diapause during this process. The temporary increase in metabolism did not mean they had awakened early—it was simply their bodies recovering from the effects of anaerobic metabolism.
Once the recovery phase ended, the bees returned to their dormant state until spring.
What the Discovery Means for Pollinators
The findings highlight the remarkable resilience of bumblebees and offer new insight into how pollinators might cope with changing environmental conditions.
As climate change brings heavier rainfall and more frequent flooding in many regions, understanding these survival mechanisms could help scientists predict how bee populations will respond to extreme weather.
A Remarkably Tough Pollinator
Each queen bumblebee that survives winter becomes the founder of a new colony, supporting ecosystems and agriculture alike.
The new research reveals that these insects are tougher than previously believed—capable of surviving more than a week underwater while still in dormancy. That resilience could prove vital as pollinators face an increasingly unpredictable climate.
