Irradiation for phytosanitary treatment of the Queensland fruit fly Bactrocera tryoni Froggatt benefits international trade

Abstract

Radiation is a well understood and established technology which has been researched and reviewed extensively for over 100 years. The capability of irradiation to substantially improve the international bilateral trade of horticultural commodities has only just been gaining recognition, particularly over the last 10 years. The poor rate of adoption of irradiation as a method of disinfesting food can be attributed to the conservative attitude of some importing countries and consumer perception, particularly when it's associated with the word “nuclear”. The world's leading food health and safety bodies including the World Health Organisation, Food Standards Australia New Zealand and the United Nations Food and Agriculture Organizations have all reported that food irradiation is a safe and effective treatment to a wide range of insect pests and kills bacteria. Educating consumers about benefits and safety of irradiated food is considered the key to irradiation becoming accepted widely amongst Australia's international trading partners.Irradiated fresh fruit and vegetables are not accepted by several importing Asian countries or the European Union but there are several other countries that do use and accept phytosanitary irradiated treated fruits. As a technology, irradiation offers a range of benefits for fresh horticultural food producers, exporters and importers. Low-dose irradiation provides a rapid treatment that does not alter the temperature of the commodity, is free of residues, fruit remains nutritionally adequate, and can enhance shelf life and colouring of some fruits. Some research has reported that there is a reduction in vitamin A and C in treated fruits at higher dose rates.One of Australia's major phytosanitary pests of concern for international trade is the Queensland Fruit Fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Methyl bromide and cold treatment are treatment methods commonly used for international trade. However, methyl bromide is a greenhouse gas and has occupational health concerns. Cold treatment takes several weeks to complete and is unsuitable for air freight. Time frames for lemons, for instance, vary from fourteen to sixteen days (for Qfly) plus temperature ramp down and then ramp up after treatment; ramping often takes three days each. Given the limitations of other conventional post-harvest treatments, irradiation is well suited for fruit fly disinfestation of commodities to be airfreighted to countries demanding fresh fruit with no residues.