Effect of freeze temperature on ice formation and long-term survival of the woolly bear caterpillar ( Pyrrharctia isabella)

Tissue ice content and post-freeze survival were documented for caterpillars of the arctiid moth Pyrrharctia isabella. Tissue ice content was inversely dependent on freeze temperature (−3 °C=24.4%, −6 °C=40.2%, −10 °C=48.7%) but values were substantially less than expected given hemolymph osmolality...

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Bibliographic Details
Published in:Journal of insect physiology 2002-12, Vol.48 (12), p.1133-1137
Main Authors: Layne, Jack R, Blakeley, Deborah L
Format: Article
Language:English
Subjects:
Freeze tolerance
Glycerol
Ice content
Pyrrharctia isabella
Survival
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Summary:Tissue ice content and post-freeze survival were documented for caterpillars of the arctiid moth Pyrrharctia isabella. Tissue ice content was inversely dependent on freeze temperature (−3 °C=24.4%, −6 °C=40.2%, −10 °C=48.7%) but values were substantially less than expected given hemolymph osmolality. Accumulation of glycerol (200–300 mM) in the hemolymph helped to colligatively reduce the amount of freezable water. Caterpillars engaged in locomotion within minutes after thawing but mortality occurred over the ensuing weeks, with the highest level (52.2%) occurring in the −10 °C fast thaw group. Pupation rates ranged between 45.7 to 52.4% of caterpillars in a test group. Adult emergence exceeded 60% of the pupae in the –3 and –6 °C test groups. Hence, P. isabella caterpillars survived ecologically relevant freezes and continued their life cycles to adulthood.
ISSN:0022-1910
1879-1611
DOI:10.1016/S0022-1910(02)00206-8