Rapid responses to high temperature and desiccation but not to low temperature in the freeze tolerant sub-Antarctic caterpillar Pringleophaga marioni (Lepidoptera, Tineidae).
A broad definition of rapid cold hardening (RCH) is that it is the process whereby insects increase their survival of a sub-zero temperature after a brief (h) pre-exposure to a less severe low temperature. The effects of various pre-treatments on survival of two h at -7.9 degrees C were investigated in the freeze tolerant sub-Antarctic caterpillar Pringleophaga marioni (Lepidoptera: Tineidae), the first time RCH has been investigated in a freeze tolerant arthropod. All caterpillars froze when exposed to -7.9 degrees C, and none of the low temperature pre-treatments (-5, 0, 5 and 15 degrees C, as well as -5 degrees C and 0 degrees C with a delay before freezing) nor slow cooling (0.1 degrees C/min) elicited any improvement in survival of -7.9 degrees C as compared to controls. However, high temperature treatments (25, 30 and 35 degrees C), desiccation and acclimation for 5 days at 0 degrees C did result in significant increases in survival of the test temperature, possibly as a result of heat shock protein production. Haemolymph osmolality was elevated only by the 35 degrees C pre-treatment. It is suggested that the unpredictable environment of Marion Island means that P. marioni must always be physiologically prepared to survive cold snaps, and that this year-round cold hardiness therefore supersedes a rapid cold hardening response.
Sinclair
Brent J
BJ
Spatial, Physiological and Conservation Ecology Group, Department of Zoology, University of Stellenbosch, Private Bag X1, Matieland 7002, South Africa. slchown@sun.ac.za
Chown
Steven L
SL
D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001110:Arctic Regions; D003890:Desiccation; D004777:Environment; D005615:Freezing; D007915:Lepidoptera / Q000254:growth & development / Q000502:physiology*; D013696:Temperature