Meeting Abstract

46.2  Saturday, Jan. 5  Cross tolerance between modified atmospheres and low temperature in insects BOARDMAN, L*; SØRENSEN , JG; GROUT, TG; TERBLANCHE, JS; Stellenbosch University, South Africa; Aarhus University, Silkeborg, Denmark; Citrus Research International, Nelspruit, South Africa; Stellenbosch University, South Africa lboardman@sun.ac.za

Insect tolerance to low temperature treatments for post-harvest disinfestation of crops depends on the insects’ basal ability to withstand or repair the stress associated with long-term low temperature exposure, or the ability to rapidly develop biochemical protection. Changes may be induced at the whole animal level (e.g. respiration rate, water balance), or at the molecular level (e.g. induction of cryoprotective metabolites and proteins). Post-harvest disinfestation treatments can be augmented with modified atmospheres (e.g. high carbon dioxide and/or low oxygen) to improve their efficacy. Theoretically, the potential overlaps in the mechanisms which insects can use to counteract low temperature and modified atmosphere stressors may result in cross tolerance. Here, we examine different levels of responses after exposure to temperature and/or gas stress in larvae of the false codling moth, Thaumatotibia leucotreta, an agricultural pest of southern Africa. Larvae were exposed to a range of temperature conditions (0°C, 25°C, 35°C), high carbon dioxide (6% CO₂) and low oxygen (2% O₂) treatments, both separately, as well as in various combinations, for different durations prior to a standard post-harvest disinfestation exposure at -1°C. During these experiments, larvae were assayed for mortality, body water content, body lipid content, cell viability, membrane lipid composition, heat shock protein 70 and cryoprotectant expression levels. The results from these experiments will be discussed in the context of a range of mechanistic hypotheses proposed to explain insect low temperature tolerance and cross tolerance.