Journal of insect physiology
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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 degrees C=24.4%, -6 degrees C=40.2%, -10 degrees 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. ⋯ 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 degrees C test groups. Hence, P. isabella caterpillars survived ecologically relevant freezes and continued their life cycles to adulthood.