Behavioral and Physiological Adaptations to Cold in a Freeze-Tolerant Arctic Insect

Abstract

Insects inhabiting the polar and temperate zones commonly overwinter in diapause or quiescent states (Tauber et al., 1986). Although diapause has traditionally been implicated with cold hardiness, diapause is probably phylogeneti-cally unrelated to cold hardiness (see Chapter 8). Nevertheless, both diapause and cold hardiness are usually induced by the same environmental cues, such as temperature, photoperiod, thermoperiod, or nutrition (Beck, 1983). Despite the vast differences in environmental constraints between arctic and temperate bi-omes, cold-tolerant insects typical of these regions have adopted similar modes of overwintering: freeze tolerance or freeze avoidance. In response to a different set of environmental stimuli, have the arctic species evolved any mechanisms of overwintering that differ from their temperate relatives? Arctic insects that survive inclement winters and short summer seasons show adaptations to cold that are uncommon or unique to cold tolerant species (Miller, 1982). One such species is Gynaephora groenlandica.