Technical Abstract: Hawaii is a pioneer in the use of phytosanitary irradiation. Irradiation is an approved treatment to control quarantine insect pests in 17 fruits and 7 vegetables for export from Hawaii to the U.S. mainland. The commercial x-ray irradiation facility, Hawaii Pride LLC, has been shipping tropical fruits and vegetables to the U.S. mainland using irradiation since 2000. Hawaiian purple sweet potato is the highest volume product with annual exports of more than 12 million lbs (5,500 tonnes). The advent of generic radiation treatments for tephritid fruit flies (150 Gy) and other insects (400 Gy) has accelerated commodity export approvals and facilitated adoption by foreign trading partners. Current impediments to wider adoption include the labelling requirement, the 1 kGy limit for fresh horticultural products, and non-acceptance of phytosanitary irradiation in Japan and the European Union. USDA APHIS has restricted the use of modified atmosphere packaging (MAP) for irradiated fresh fruits exported to the U.S due to possible increased radiotolerance in the target insects. Data are presented for response of melon fly in papaya to several types of MAP with radiation treatment at 45-65 Gy. Low oxygen atmospheres can increase insect radiotolerance, but the effect is dependent on oxygen concentration and radiation dose.