RESPIRATORY RESPONSES TO CHILLING AND FREEZING IN 2 SUB-ANTARCTIC INSECTS

The effects of chilling (to temperatures above the supercooling point, SCP) and freezing on respiration of adults and larvae of two coleopte rans living on sub-Antarctic South Georgia (54 degrees S, 37 degrees W ), Hydromedion sparsutum and Pevimylops antarcticus (Coleoptera, Perim ylopidae), were quantified. Respiration rates of individual insects (l ive 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 pos ttreatment. The species possess a small amount of freeze tolerance in both adults and larvae. Chilling had no significant effects on respira tion rates of P. antarcticus and H. sparsutum, although mean levels we re depressed by 6-15%. Freezing produced considerable enhancement of r espiratory 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 e ffects on respiration rates and P. antarcticus showed the greatest met abolic response to freezing. (C) 1998 Academic Press.