Respiratory responses to chilling and freezing in two sub-antarctic insects.
The effects of chilling (to temperatures above the supercooling point, SCP) and freezing on respiration of adults and larvae of two coleopterans living on sub-Antarctic South Georgia (54 degrees S, 37 degrees W), Hydromedion sparsutum and Perimylops antarcticus (Coleoptera, Perimylopidae), were quantified. Respiration rates of individual insects (live weights, 11-21 mg) were measured at 10 degrees C prior to chilling (-4 degrees C) or freezing (SCP range -3.8 to -5.3 degrees C) and posttreatment. The species possess a small amount of freeze tolerance in both adults and larvae. Chilling had no significant effects on respiration rates of P. antarcticus and H. sparsutum, although mean levels were depressed by 6-15%. Freezing produced considerable enhancement of respiratory activity. Mean values increased postfreezing in larvae (+34%) of H. sparsutum and in both larvae (+44%) (P < 0.01) and adults (77%) (P < 0.05) of P. antarcticus. Chilling and freezing had different effects on respiration rates and P. antarcticus showed the greatest metabolic response to freezing.
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom.
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Block
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Worland
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Bale
D000222:Adaptation, Physiological; D000818:Animals; D000864:Antarctic Regions; D003080:Cold Temperature; D005615:Freezing; D007313:Insecta / Q000502:physiology*; D012119:Respiration; D012143:Respiratory Physiological Phenomena