Physiological and molecular mechanisms associated with cross tolerance between hypoxia and low temperature in Thaumatotibia leucotreta

• Published in: Journal of insect physiology 2015-11, Vol.82, p.75-84
• Main Authors: Boardman, Leigh, Sørensen, Jesper G., Terblanche, John S.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Animals; Atmosphere - chemistry; Cold Temperature; Controlled atmospheres; Cryoprotectants; Heat shock protein 70; Hot Temperature; HSP70 Heat-Shock Proteins - metabolism; Larva - physiology; Low temperature; Membrane Fluidity - physiology; Moths - physiology; Oxygen - metabolism; Stress, Physiological
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2015.09.001

[Display omitted] •Low temperature stress responses included increases in membrane fluidity and HSP70.•Neither mechanical stress nor high temperatures impacted low temperature tolerance.•Hypoxia increased water loss, but was not associated with haemocyte apoptosis.•Mechanisms of hypoxia tolerance may overlap with those of low temperature tolerance.•Controlled atmosphere research can exploit specific key mechanisms identified here. Biochemical adaptations allow insects to withstand exposures to hypoxia and/or hypothermia. Exposure to hypoxia may interact either synergistically or antagonistically with standard low temperature stress responses yet this has not been systematically researched and no clear mechanism has been identified to date. Using larvae of false codling moth Thaumatotibia leucotreta, a pest of southern Africa, we investigated the physiological and molecular responses to hypoxia or temperature stress pre-treatments, followed by a standard low temperature exposure. Survival rates were significantly influenced by pre-treatment conditions, although T. leucotreta shows relatively high basal resistance to various stressors (4% variation in larval survival across all pre-treatments). Results showed that mild pre-treatments with chilling and hypoxia increased resistance to low temperatures and that these responses were correlated with increased membrane fluidity (increased UFA:SFA) and/or alterations in heat shock protein 70 (HSP70); while general mechanical stress (shaking) and heat (2h at 35°C) do not elicit cross tolerance (no change in survival or molecular responses). We therefore found support for some limited cold hardening and cross tolerance responses. Given that combined exposure to hypoxia and low temperature is used to sterilize commodities in post-harvest pest management programs, researchers can now exploit these mechanisms involved in cross tolerance to develop more targeted control methods.