Phytosanitary irradiation of Tephritid fruit flies

Authors: Follett, Peter

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/18/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: This book chapter synthesizes the author's 25 years of experience at USDA irradiating fruit flies and other insects for phytosanitary purposes. Tephritid fruit flies are the most important high-risk pests in traded fresh fruits and vegetables. Phytosanitary irradiation is a highly effective and versatile quarantine treatment that prevents the movement of exotic invasive fruit flies to new areas, thus providing a means for market access. USDA and the IPPC/FAO have approved a generic dose of 150 Gy for all fruit flies which has facilitated the rapid increase of its use in certain countries, including Australia and Mexico. The USA is the largest importer of irradiated fresh fruits. Several issues present barriers to the wider use of phytosanitary irradiation including the labeling requirement, consumer and retailer perceptions, and the limited number of countries that have approved the use of irradiation for phytosanitary purposes.

Technical Abstract: Tephritid fruit flies are the most important high-risk quarantine pests of fresh fruits and vegetables worldwide and a major impediment to trade and market access. Phytosanitary treatments such as irradiation disinfest host commodities of quarantine insect pests before the commodities are exported to areas where the pests do not occur. Irradiation at doses less than 1 kGy is an effective phytosanitary measure with minimal adverse effects on the quality of most fresh commodities. The source of ionizing radiation can be gamma rays produced by radionuclides (60Co or 137Cs) or electrons or X-rays generated from machine sources. The USA, Australia, and New Zealand have adopted generic doses of 150 Gy for tephritid fruit flies and 400 Gy for all other insects, except for Lepidopteran pupae and adults, on all hosts. The International Plant Protection Convention has also recommended a generic dose of 150 Gy for tephritid fruit flies. Lower doses have been approved for certain fruit fly species such as the 100 Gy dose for Mediterranean fruit fly, Ceratitis capitata, the 116 Gy dose for Oriental fruit fly, Bactrocera dorsalis, and the 70 Gy dose for fruit flies in the genus Anastrepha. Tephritid fruit flies have been used as model insects to study questions about methodology in quarantine treatment development, including using natural versus artificial infestation, using laboratory versus wild strains of flies, and the effect of modified atmospheres on treatment efficacy. Several issues may present barriers to the wider use of phytosanitary irradiation including the labeling requirement, consumer perception, and the limited number of countries that have approved the use of irradiation for phytosanitary purposes. The development of small-scale, cabinet-style X-ray machines could provide in-house treatment capability when treating only a small volume of fruit is needed. The availability of first-ever generic dose treatments against fruit flies and other insects makes irradiation an attractive option compared with other postharvest quarantine treatments and is driving the rapid expansion of this technology in certain countries.