Interactions between Controlled Atmospheres and Low Temperature Tolerance: A Review of Biochemical Mechanisms

Abstract

Controlled atmosphere treatments using carbon dioxide, oxygen, and/or nitrogen, together with controlled temperature and humidity, form an important method for post-harvest sterilization against insect-infested fruit. However, in insects, the cross tolerance and biochemical interactions between the various stresses of modified gas conditions and low temperature may either elicit or block standard stress responses which can potentiate (or limit) lethal low temperature exposure. Thus, the success of such treatments is sometimes erratic and does not always result in the desired pest mortality. This review focuses on the biochemical modes of action whereby controlled atmospheres affect insects low temperature tolerance, making them more (or occasionally, less) susceptible to cold sterilization. Insights into the integrated biochemical modes of action may be used together with the pests' low temperature tolerance physiology to determine which treatments may be of value in post-harvest sterilization.

Keywords: biological control; pest management; stored product; thermal biology.

Figure 1

A schematic representation of the cross tolerance between controlled atmospheres (low oxygen and high carbon dioxide) with low temperature stress. The central shaded block represents the mechanisms for survival of low temperatures. Arrows indicate preceding steps in reactions, while solid lines indicate inhibition. The “skull and crossbones” icon represents processes that are likely to lead to mortality. RCH, rapid cold hardening; ATP, adenosine triphosphate; HIF, hypoxia inducible factor; LEA, late embryogenesis abundant proteins; HSPs, heat shock proteins; AFPs, anti-freeze proteins; ROS, reactive oxygen species; FA, fatty acids; NADPH, reduced form of nicotinamide adenine dinucleotide phosphate.