RELATION BETWEEN TIME OF FREEZING AND TEMPERATURE IN SUPERCOOLED LARVAE OF CEPHUS CINCTUS NORT.

Abstract

Larvae of Cephus cinctus were held at constant temperatures between[long dash]15 and[long dash]30[degree]C and the incidence of freezing was recorded. A linear relation with high correlation coefficient was obtained when the logarithm of mean freezing time was plotted against temperature. Mean time to freeze doubles with each 0.53[degree] rise in temperature; within the range studied, it increased from 1.2 seconds at -30[degree] to more than a year at[long dash]17[degree]. A family of freezing curves showing the course of freezing at a series of constant temperatures permits approximation of the course of freezing during a regime of fluctuating temperatures such as would occur naturally in hibernacula. From this paper and two preceding ones by the writer, it is now apparent that the general temperature range within which an insect nucleates and freezes is determined by intrinsic factors (nucleating agents and body water), whereas the specific freezing temperature within this range is determined by extrinsic factors (cooling pattern and the element of chance that attends nucleus formation.).