Many horticultural products are hosts for fruit flies, which are often considered high-risk quarantine pests by regulatory authorities. The presence of fruit flies in the main tropical and sub-tropical production areas of Australia, including Queensland, results in the imposition of quarantine barriers to the movement of fresh produce. These quarantine barriers greatly impede trade both within Australia and to overseas markets that are free of these pests. Postharvest disinfestation treatments are often required in order to overcome these quarantine barriers.

Currently there is a heavy reliance on the use of chemical treatments to meet postharvest quarantine requirements for interstate trade and export to New Zealand. However, the use of chemical treatments is under review by regulatory bodies and there is currently a strong consumer preference for products which receive minimal or no treatment with synthetic chemicals. It is likely that the availability of chemical treatments for disinfestation will severely restricted within the next few years when, if an alternative treatment is not in place, all exports of fruit fly host commodities to New Zealand will be severely constrained. It is therefore necessary to develop effective, preferably non-chemical, alternative quarantine treatments. Development of non-chemical postharvest treatments also leads to a reduction in the use of chemicals in the production process, improved health and safety for workers in packing sheds and lower chemical residues in product reaching the consumer.

The cucurbit and tomato industries are at present heavily on the use of chemical insecticides for postharvest disinfestation of export of fresh product to New Zealand and for interstate trade (Victoria, South Australia, Western Australia, and Tasmania). The aim of the project was to develop new disinfestation treatments against fruit flies which would meet the quarantine requirements for both New Zealand and interstate trade.

This research involved specific disinfestation experimentation, large scale treatment confirmatory trials and evaluation of the effects of heat treatments on fruit quality and shelf life. This project has resulted in the development on non-chemical, non-damaging postharvest heat treatments against fruit flies for the following commodities

• Zucchini
• Button squash
• Rockmelon
• Honeydew
• Watermelon
• Tomato

The project outcomes will ensure the maintenance of Australia’s ~$4 million annual cucurbit and $5.7 million annual tomato export markets to New Zealand and the $20 million interstate market for tomatoes if the current chemical treatments are not available in the future.