Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2003
Publication Date: October 1, 2003
Citation: Follett, P.A., Armstrong, J.W. A generic irradiation dose for postharvest control of fruit flies worldwide. In Proc. Australian Postharvest Horticultural Conference, Brisbane, Australia, 10/1-3/2003.
Interpretive Summary: Irradiation is the ideal technology for developing generic treatments: it is effective against most insects and mites at dose levels that do not affect the quality of most types of fresh fruits, vegetables and horticultural commodities. Many years ago 150 Gy was recommended as a generic treatment for all tephritid fruit flies. Hawaii's fruit flies have approved irradiation dose of 210, 225, and 250 Gy for melon fly, Mediterranean fruit fly and oriental fruit fly, and this prevented adoption of the generic irradiation treatment. Results are presented showing that melon fly is the most radiotolerant species, and 150 Gy is an effective dose to control all three species, consistent with the proposed generic dose of 150 Gy. Generic doses are appealing because they would greatly accelerate the process of approving irradiation quarantine treatments for specific crops, and thereby rapidly expand exports.
A generic quarantine treatment, one that provides quarantine security for a wide range of pests with minimal adverse effects for a broad range of commodities, is the holy grail of quarantine entomology. Irradiation is the ideal technology for developing generic treatments: it is effective against most insects and mites at dose levels that do not affect the quality of most types of fresh fruits, vegetables and horticultural commodities. In 1986, based on data for many fruit fly species and a limited number of other insect pests, the International Consultative Group on Food Irradiation (ICGFI) recommended a generic irradiation dose of 150 Gy for tephritid fruit flies and 300 Gy for other insects. To date, no country has adopted generic doses. Hawaii's pest fruit flies have been the "flies in the ointment" when presenting the case for a generic irradiation quarantine treatment dose of 150 Gy for Tephritidae. Approved irradiation quarantine treatment doses for melon fly, Bactrocera cucurbitae, Medfly, Ceratitis capitata, and oriental fruit fly, Bactrocera dorsalis infesting fruits and vegetables for export from Hawaii to the U.S. mainland are 210, 225, and 250 Gy, respectively. Irradiation studies were initiated to determine whether these doses are unnecessarily high and could be reduced. Results from dose response and large-scale tests demonstrated that melon fly was the most tolerant species and all species could be controlled with 150 Gy or less. Treating 93,000 late third instar melon flies at 150 Gy resulted in no survivors to the adult stage. The data support a generic dose of 150 Gy for tephritids. Lowering the irradiation dose for these quarantine insects would reduce costs and increase capacity for treatment facilities by decreasing the required treatment time. Generic doses are appealing because they would greatly accelerate the process of approving irradiation quarantine treatments for specific crops, and thereby rapidly expand exports.