Experimental studies on the cold tolerance of Alaskozetes antarcticus
The cold tolerance mechanism of the Antarctic terrestrial mite Alaskozetes antarcticus (Michael) was investigated in cultured animals. Freezing is fatal in this species and winter survival occurs by means of supercooling, which is enhanced by the presence of glycerol in the body. There is an inverse, linear relationship between the concentration of glycerol and the supercooling point, which may be as low as −30°C. Feeding detracts from supercooling ability by providing ice nucleators in the gut which initiate freezing at relatively high sub-zero temperatures. Experiments on the effects of various environmental factors showed that low temperature acclimation gave rise to increased glycerol concentrations and suppressed feeding, while desiccation also stimulated glycerol production. Photoperiod had no effect on cold tolerance in this species. The juvenile instars of A. antarcticus were found to possess a greater degree of low temperature tolerance than adults.