The Siberian timberman Acanthocinus aedilis: a freeze-tolerant beetle with low supercooling points |
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Authors: | E Kristiansen N G Li A I Averensky A E Laugsand K E Zachariassen |
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Institution: | (1) Laboratory of Ecophysiology and Toxicology, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway;(2) Institute for Biological Problems of Cryolithozone, Siberian Branch of the Russian Academy of Science, Yakutsk, Russia |
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Abstract: | Larvae of the Siberian timberman beetle Acanthocinus aedilis display a number of unique features, which may have important implications for the field of cold hardiness in general. Their
supercooling points are scattered over a wide temperature range, and some individuals have supercooling points in the low
range of other longhorn beetles. However, they differ from other longhorn beetles in being tolerant to freezing, and in the
frozen state they tolerate cooling to below −37°C. In this respect they also differ from the European timberman beetles, which
have moderate supercooling capacity and die if they freeze. The combination of freezing tolerance and low supercooling points
is unusual and shows that freezing at a high subzero temperature is not an absolute requirement for freezing tolerance. Like
other longhorn beetles, but in contrast to other freeze-tolerant insects, the larvae of the Siberian timberman have a low
cuticular water permeability and can thus stay supercooled for long periods without a great water loss. This suggests that
a major function of the extracellular ice nucleators of some freeze-tolerant insects may be to prevent intolerable water loss
in insects with high cuticular water permeability, rather than to create a protective extracellular freezing as has generally
been assumed. The freezing tolerance of the Siberian timberman larvae is likely to be an adaptation to the extreme winter
cold of Siberia. |
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Keywords: | Acanthocinus aedilis Freezing tolerance Supercooling Ice nucleating agents Metabolic rate Water balance |
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