LAUSR

Abstract Cold sterilisation may be supplemented with elevated CO 2 (hypercapnia) to increase pest mortality however, in some cases, such treatment combinations have generated unexpected high levels of pest survival. Consequently, determining the mechanistic basis of potential interactions or any cross resistance between CO 2 and low temperature stress is critical for effective pest disinfestation through cold sterilization. Here, using larvae of false codling moth Thaumatotibia leucotreta , a crop pest in southern Africa, we explored the effects of various hypercapnic pre-treatments on larval survival to standard cold exposures, and a diverse array of biochemical traits that may be indicative of key cellular stress responses or damage and repair processes. Short ( 96%). Longer 24 h pre-treatments (hypercapnia + cold) followed by 5 d cold exposure led to significant differences in larval survival (0–80%), with the recovery conditions between exposures greatly affecting larval survival. In contrast with the short-term cold exposures, larvae from the long-term experiments had increased haemocyte mortality, protein concentration and heat shock protein 70 levels, while the concentrations of key cryoprotective sugars were decreased. No changes in membrane lipids could be attributed to the presence of CO 2 . These molecular correlates can be used as testable hypotheses for future work to further identify the mode of action of CO 2 reducing (or enhancing) cold tolerance in these insects. From an insect physiology standpoint, chronic hypercapnic cold sterilization protocols appear to be a viable post-harvest option for control of T. leucotreta .