Meeting Abstract

P2.29  Sunday, Jan. 5 15:30  The effects of thermal history on cold tolerance in a montane leaf beetle SAYRE, JM*; BOYCHUK, EC; SINCLAIR, BJ; DAHLHOFF, EP; RANK, NE; Sonoma State University ; University of Western Ontario ; University of Western Ontario ; Santa Clara University ; Sonoma State University sayrej@seawolf.sonoma.edu

Montane ectotherms are often confronted with dangerously low temperatures, even in summer when individuals are active and completing their cycle of reproduction and development to adulthood. These extremes in temperature may increase in frequency with increased climate variability predicted for the future. We investigated the effect of exposure to stressfully cold temperatures for adults and larvae of the montane beetle Chrysomela aeneicollis to test the hypothesis that exposure to cold enhances cold tolerance. These insects live in the Sierra Nevada mountains of eastern California, where they experience sudden cold snaps of subzero temperatures at night, or prolonged cool periods during daytime summer thunderstorms. We evaluated effects of long-term acclimation (LTA, 5 d at 4°C) and rapid cold hardening (RCH, 2 hr at -2°C) on subsequent tolerance to a 2-hr exposure to freezing temperatures (-6°C for adults, -8°C for larvae). Both LTA and RCH enhanced cold tolerance in adults and third-instar larvae. Larger individuals recovered better from cold exposure than smaller ones, and females, being larger, recovered better than males. LTA also lowered freezing temperatures of larvae, but we found no relationship between freezing temperature and cold tolerance. Ongoing studies will determine if genetic differences affect the relationship between thermal history and cold tolerance.