Rickards, J., Kelleher, M.J. and Storey, K.B. 1987. Strategies of freeze avoidance in larvae of the goldenrod gall moth, Epiblema scudderiana: Winter profiles of a natural population. J. Insect Physiol. 33, 443-450.

STRATEGIES OF FREEZE AVOIDANCE IN LARVAE OF THE GOLDENROD GALL MOTH, EPIBLEMA SCUDDERIANA: WINTER PROFILES OF A NATURAL POPULATION

JULIAN RICKARDS, MARY JANE KELLEHER and KENNETH B. STOREY


Abstract
Larvae of the goldenrod gall moth, Epiblema scudderiana (Clemens) utilize a freeze-avoidance strategy for winter survival. Cold-hardiness adaptations of an outdoor population of the species were profiled over the 1984-85 winter. Over the autumn months supercooling points of the larvae dropped from -13.9 + 2.3C to -37.8 + 2.8C (the lowest winter temperature recorded was -26C), water content of the larvac decreased from 57.2 + 1.2 to 24.8 + 1.6C to of fresh weight, and glycerol content of the larvae rose to an average of 2030 micromol/g wet weight or 18.7% of fresh weight. All parameters stabilized over the mid-winter months. Glycerol production was largely accounted for by the loss of stored glycogen while lipid and protein reserves remained nearly constant over the winter months. Supercooling-point depression and glycerol synthesis both appeared to be initiated after the first overnight exposures to subzero temperatures. Highest rates of glycerol production, about 60 micromol/g/d, were achieved with mean dally temperatures of about 0C and subzero nights. Glycerol content was rapidly cleared in the spring but only 20% of the resulting carbon was restored as glycogen.