There is a need to develop effective, non-damaging, non-polluting, non-carcinogenic procedures for insect disinfestation and disease control in fresh horticultural products. The loss of ethylene dibromide as a fumigant and the uncertainties of other fumigants, has meant that alternatives are needed. The most likely possibilities include irradiation, heat, cold and controlled atmospheres. Irradiation doses required for sterilization of insects cause only minor physiological changes, while controlled atmospheres appear to require longer periods of exposure than the postharvest life of most tropical fruit. The sensitivity of tropical commodities to temperatures less than 10°C makes cold treatments inappropriate for most tropical commodities. Heat treatments seem to be most promising. For papaya, the requirement is that the fruit core temperature reach 47.2°C, this can occasionally disrupt fruit ripening. The sensitivity to heat is modified by seasonal, variety and rate of heating factors. The sensitivity can be related to the heat shock response and the presence of heat shock proteins.