The role of water, ice nucleators, and inoculation in insect cold survival

Abstract

Over the past century and especially the last few decades a significant progress has been made in our understanding of the mechanisms that underlie the capacity of insects and other ectothermic animals to survive at subzero temperatures. Although we now understand relatively well the complexity of the cold tolerance phenomenon, from the molecular to the ecological level, some aspects remain elusive. This review summarizes current knowledge on the mechanisms of cold tolerance and focuses on the three following issues that remain unsolved in this field: 1) the role of water in preservation of biological structures in organisms that exploit dehydration as a part of their cold survival strategy, 2) the cause of ice nucleation in freeze-intolerant organisms below the temperature range of the activity of ice nucleating proteins and above the temperature of homogeneous nucleation of water, and 3) the capacity of some primarily freeze-intolerant insects to tolerate freezing upon inoculation with ice at high subzero temperatures.