title: Physiological and molecular mechanisms associated with cross tolerance between hypoxia and low temperature in Thaumatotibia leucotreta.
abstract: 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.
authors.affiliation: Department of Conservation Ecology and Entomology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa. Electronic address: boardman.leigh@gmail.com.
authors.forename: Leigh
authors.initials: L
authors.lastname: Boardman
authors.affiliation: Section for Genetics, Ecology & Evolution, Department of Bioscience, Aarhus University, Ny Munkegade 116, DK-8000 Aarhus C, Denmark.
authors.forename: Jesper G
authors.initials: JG
authors.lastname: Sørensen
authors.affiliation: Department of Conservation Ecology and Entomology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
authors.forename: John S
authors.initials: JS
authors.lastname: Terblanche
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001272:Atmosphere / Q000737:chemistry; D003080:Cold Temperature; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006358:Hot Temperature; D007814:Larva / Q000502:physiology; D008560:Membrane Fluidity / Q000502:physiology; D009036:Moths / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D018840:HSP70 Heat-Shock Proteins; D010100:Oxygen
keywords: Controlled atmospheres; Cryoprotectants; Heat shock protein 70; Low temperature