ISHS Acta Horticulturae 566: II International Symposium on Application of Modelling as an Innovative Technology in the Agri-Food Chain; MODEL-IT
HISTORY IS IMPORTANT: A KINETIC MODEL OF THE EFFECT OF TEMPERATURE-TIME HISTORY ON THE MORTALITY OF QUARANTINE PESTS AND ON FRUITENZYME SYSTEMS |
| Authors: | W.G. Laidlaw, B. Waddell |
| Keywords: | Models, Fruit flies, ACC Oxidase, Disinfestation, Heat treatment |
| Abstract:
Post-harvest quarantine treatments are required for tephritid (Diptera: Tephritidae) fruit fly hosts, such as papaya or mangoes before fruit can be exported to countries where the introduction of these serious pests would have unacceptable economic impacts. The temperature–time history of the conditions established in the treatment chamber determines a unique temperature-time history for every element of fruit-tissue. Lethal temperatures, those in the 43-50°C range, induce insect mortality and also cause degradation of enzyme systems, such as ACC Oxidase (ACCO), which may be associated with fruit ripening. Lower temperatures, 25-42°C, can induce "conditioning" in pests with consequent resistance to heat stress. The same lower temperatures can also increase enzyme activity and may impact positively on fruit-quality. The aim of our research is to use static temperature treatments to develop a kinetic model that can be used to describe pest mortality (including the effect of prior conditioning) and enzyme degradation (including any prior activation of enzyme) in chambers where the temperature is changing. Calculations using the kinetic model can lead to suggestions regarding treatment specifications which meet both bio-security and consumer quality requirements. For example, protocols which minimize the time fruit-tissue potentially containing pests is in the 34-38°C range are to be preferred. | |
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