Under a few centimeters of earth, at the end of winter, the soil quickly changes face. The snow melts, the rain accumulates, the shallow burrows fill with cold water. Yet right there, inside that mixture of mud and frost, the bumblebee queens manage to stay alive for at least a week. A study published in Proceedings of the Royal Society B: Biological Sciences he links this ability to a very rare combination of underwater breathing, very low metabolism and anaerobic support.
During diapause, a type of hibernation that can last six to nine months, queens spend the winter buried in the soil. It is a delicate phase: the ground retains water, the thaw weighs on the tunnels, the underground chambers can transform into small tanks. The rest of the colony runs out before winter; the following season starts again with future queens, those who come out of the ground in spring and found a new colony. This is why their resistance to flooding has enormous value even outside the laboratory.
The significance of the discovery is understood even better if we place it alongside the changing climate. Heavier rainfall and more frequent spring floods make the underground a less stable place just as these insects are going through the most fragile part of their cycle. Understanding how they survive means reading in advance how much margin for adaptation the pollinators on which ecosystems and blooms depend have.
Four queens mistakenly submerged in a laboratory refrigerator
This scientific story began with a tiny and decisive accident. Sabrina Rondeau was working on the effects of pesticides on bumblebees and kept some diapausing queens in test tubes filled with soil, stored in the refrigerator to mimic winter. The condensation filled some test tubes with water and four queens remained completely submerged. When the water was removed, the bees were still alive. From that episode a first study was born, published in 2024, which confirmed survival underwater for up to a week.
More recent work has gone beyond the initial surprise and looked for the mechanism. The researchers induced diapause in healthy queens by recreating the cold and dark of winter, then immersed them in flooded chambers. Some remained under water for a few hours, others for up to eight days. Throughout the test they followed metabolic rate and physiological changes, so as to understand where such an unusual seal for a terrestrial insect came from.
Carbon dioxide, lactate and recovery
The data that really shifts the discussion concerns carbon dioxide. The submerged queens continued to produce it at a low but measurable level, a sign that a gas exchange was going on even underwater. Metabolism dropped rapidly and then remained stable both after a few hours and after eight days of immersion. The researchers explain this stability with a very deep metabolic depression: during diapause the energy requirement is already reduced to the bare minimum, and under water it drops even further.
That submerged breath, however, only covers part of the needs. Queen bees also activate an additional anaerobic energy system and lactate accumulates in the body. When they are taken out of the water, the physiological bill comes immediately: for two or three days the metabolism shoots upwards, the organism disposes of the lactate and then gradually returns to the levels typical of diapause. In practice, staying alive underwater has a precise, measurable cost, and the body pays for it in recovery.
Part of the mystery remains open, because the exact physical mechanism by which this gas exchange occurs still requires further verification. The big picture, however, is already clear: bumblebee queens’ resilience to environmental extremes exists, has concrete physiological bases, and may become crucial as spring flood patterns change. For insects that carry the birth of entire colonies on their shoulders, spring also begins like this: from the bottom of a burrow full of water.
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