Supercooling of Alaskan Beetle Larvae as a Winter Survival Strategy

TL;DR

Alaskan beetle larvae survive freezing winters by dehydrating and using glycerol to supercool their bodies, preventing ice formation.

Contribution

The study reveals atomic-level mechanisms of cryopreservation in beetle larvae using synchrotron diffraction.

Findings

Dehydration and glycerol replacement enable supercooling and vitrification in beetle larvae.

Molecular models show 4.2 ± 1.2 hydrogen bonds per glycerol molecule at 275 K.

Water clusters remain small enough to avoid ice crystal formation when body fluid is partially water.

Abstract

Insects are able to survive subfreezing temperatures by either limiting ice crystal formation in their bodies or through freeze avoidance. Beetle larvae are able to avoid freezing in winter by dehydrating in the fall months and replacing their body water content with high concentrations of glycerol. This enables the body fluid of the insect to supercool, and even vitrify, recovering unharmed when the temperature warms in the spring. Using nondestructive, high‐energy X‐ray synchrotron diffraction experiments, direct insight into how cryopreservation occurs at the atomic level within the beetle larvae has been obtained. The results shed light on the molecular‐level interactions associated with the mechanism responsible for surviving freezing temperatures. The molecular models of severely dehydrated Alaskan beetle larvae, based on glycerol‐water mixtures, yield a total of 4.2 ± 1.2 intermolecular hydrogen bonds per glycerol molecule at 275 K, in good agreement with existing molecular dynamics simulations. Most importantly, they show that if just over half the body fluid content is water, the water clusters are too small to form ice crystals that cause cellular damage.

Dehydrated Alaskan beetle larvae in Fairbanks, Alaska, adhere to the bark of trees that are embedded in ice in their natural winter microhabitat (bottom). This enables their bodies to deeply supercool and avoid freezing, in contrast to their fully hydrated summer form (top).© 2025 WILEY‐VCH GmbH

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