Queen Bees Survive Winter Flooding by Breathing Underwater: Groundbreaking Study Reveals Mechanisms

In the quiet depths of winter, as snow melts and spring rains swell rivers and soak soils, a hidden drama unfolds underground. Bumblebee queens, the sole survivors of their colonies, enter a state of diapause—a hibernation-like dormancy—to endure the cold months. But what happens when their shallow burrows flood completely? Recent research from the University of Ottawa reveals a stunning adaptation: these queens can breathe underwater and survive submersion for up to eight days, safeguarding their vital role as colony founders.

This discovery, born from a serendipitous lab mishap years ago, underscores the resilience of bumblebee queens amid increasingly erratic weather patterns. As climate change intensifies winter flooding, understanding these survival strategies offers hope for pollinator populations crucial to ecosystems and agriculture. Bumblebee queens (Bombus impatiens, the common eastern bumblebee) burrow a few centimeters into soil, relying on profound metabolic slowdowns during diapause to conserve energy. Yet, flooding poses a lethal threat, filling chambers with water and cutting off air supplies.

🧬 The Biology of Bumblebee Queens and Diapause

Bumblebees differ markedly from their honeybee cousins. While honeybee colonies huddle together for winter warmth with the queen at the center, bumblebee societies dissolve by late summer. Workers and males perish, leaving only new queens to overwinter alone. These queens mate in autumn, then seek sheltered spots like leaf litter, grass clumps, or rodent burrows to dig in and enter diapause.

Diapause is a programmed dormancy triggered by shortening days and cooling temperatures. The queen's metabolism plummets—oxygen consumption drops by over 90%—allowing her to live off fat reserves accumulated during the active season. Her heart rate slows, movements cease, and she becomes unresponsive to stimuli. This state lasts six to nine months, ending when soil warms and days lengthen, prompting her to emerge, forage, and establish a new colony.

However, early spring floods from rapid snowmelt or heavy rains can submerge these sites. Prior assumptions held that queens would drown quickly without access to air. Enter the groundbreaking work challenging that view.

🔬 How the Discovery Unfolded

The story begins in 2022 during Sabrina Rondeau's PhD at the University of Guelph. Condensation from a frosty refrigerator filled tubes holding diapausing queens. Expecting fatalities, Rondeau drained the water and was astonished to find them alive. This sparked a 2024 study confirming survival up to seven days, but mechanisms remained elusive.

Now, at the University of Ottawa, Rondeau collaborated with Professor Charles-Antoine Darveau and honors student Skyelar L. Rojas. Their 2026 paper in Proceedings of the Royal Society B unveils the physiology: queens respire underwater, deploy anaerobic metabolism, and depress metabolism even further. Published with DOI 10.1098/rspb.2025.3141, the study details experiments with over 100 queens.

📊 The Experimental Approach

To mimic nature, researchers sourced queens from healthy Bombus impatiens colonies. They induced diapause by storing them in cold (4°C), dark refrigerators for 14-22 weeks, simulating winter. Queens were then placed in airtight respirometry chambers—custom devices measuring gas exchange.

• Control groups remained in air.
• Experimental groups endured complete submersion: some for hours, others up to eight days.
• Measurements tracked carbon dioxide (CO₂) output (proxy for metabolism), oxygen use, and lactate (anaerobic byproduct) before, during, and post-submersion.

Post-recovery, queens were monitored for a week. Survival exceeded 89%, comparable to controls. CO₂ production plunged upon immersion but stayed detectable, proving ongoing respiration. Lactate surged 15-fold, confirming anaerobic processes. Recovery saw a temporary metabolic spike to clear waste.

💧 Mechanisms of Underwater Survival

Three synergistic strategies enable this feat:

• Underwater Respiration: Queens extract dissolved oxygen via spiracles—their breathing pores. A suspected 'physical gill'—a thin air film trapped by hydrophobic body hairs—facilitates gas exchange with surrounding water, akin to some aquatic insects.
• Metabolic Depression: Baseline diapause metabolism falls 99%; submersion depresses it another 75-85%, slashing oxygen demand. CO₂ output drops massively yet persists.
• Anaerobic Metabolism: Without ample oxygen, queens shift to glycolysis, producing lactate for energy. Though toxic in excess, low diapause rates prevent overload.

Post-submersion, aerobic recovery clears lactate over days. This multi-layered resilience explains high survival rates even after prolonged flooding.

🌍 Conservation Implications in a Changing Climate

Bumblebees pollinate wildflowers and crops, supporting biodiversity and food security. Yet, populations decline from habitat loss, pesticides, and pathogens. Climate-driven floods threaten overwintering queens, potentially dooming colonies.

This study instills optimism: queens' adaptations buffer against intensified spring deluges. For instance, in eastern North America, erratic winters increase flood risks. Conservationists can prioritize flood-prone habitats with elevated nest sites or drainage. Researchers eye parallels in other insects facing inundation.

Read the full University of Ottawa press release for more insights.

🎓 Relevance to Higher Education and Research Careers

Such discoveries highlight the thrill of entomology and comparative physiology. Universities like Ottawa drive these advances through interdisciplinary labs blending ecology, biochemistry, and biophysics. Aspiring researchers can contribute via research jobs or postdoc positions in biology departments.

For students, this exemplifies serendipity in science—accidental observations sparking breakthroughs. Explore postdoctoral success tips or pursue faculty roles in pollinator studies. Institutions seek experts modeling insect resilience for climate models.

Photo by Boba Jaglicic on Unsplash

In summary, bumblebee queens' underwater survival prowess—via respiration, metabolic tweaks, and anaerobics—reveals nature's ingenuity. As floods rise, this resilience aids pollinator persistence. Stay informed on academic breakthroughs and share professor insights at Rate My Professor. Searching for biology or ecology roles? Check higher ed jobs, higher ed career advice, university jobs, or post a job on AcademicJobs.com.