Rapid Cold-Hardening: Physiological Mechanisms & Ecological Significance

 

More than 15 years ago we reported a rapid cold-hardening (RCH) response that protects various species of insects against cold shock (non-freezing) injury (Chen et al. 1987; Lee et al. 1987). The RCH response is an extremely swift physiological response that occurs within minutes to hours after mild chilling. We hypothesize that this rapid cold-hardening process allows organisms to "instantaneously" track changes in environmental temperature that occur diurnally. Recently, we demonstrated the ecological relevance of this phenomenon by showing that rapid cold-hardening is induced at slow cooling rates and thermoperiods that occur in nature (Kelty et al. 1996; Kelty and Lee 2001; Shreve et al. 2004). In addition to enhancing cold tolerance, this process modulates chill coma temperatures, enhances locomotion and increases mating success.

Although rapid cold-hardening occurs in a wide range of insects and related animals, little is known about the physiological mechanisms underpinning this response. Our future studies will focus on rapid changes in the membrane and the role of stress proteins (heat shock proteins) in promoting this protective response. We seek a more comprehensive understanding of the integrated physiological events that both enhance cold tolerance and allow insects to adjust their physiological performance to match changes in environmental temperature. This research may provide a foundation for new strategies and tools for disruption of insect populations and for the long-term storage of insects and other organisms at low temperature. Portions of this NSF-supported research are conducted in collaboration with Dr. David L. Denlinger, Department of Entomology, Ohio State University.