Irradiation is a postharvest quarantine treatment option for exported commodities such as stone fruits and small fruits to prevent movement of the new invasive pest spotted wing drosophila, Drosophila suzukii (Walker) (Diptera: Drosophilidae). The effects of irradiation on larval and pupal development and adult reproduction in D. suzukii were examined. Larvae (Þrst, second, and third
instars) and pupae (1-2-d-old, 3-5-d-old, and 7-8-d-old) on diet were irradiated at target doses of 20, 30, 40, and 50 Gy in replicated factorial experiments and survival to the adult stage was recorded. Tolerance to radiation increased with increasing age and developmental stage. Males and females were equally susceptible.Aradiation dose of 40 Gy applied to Þrst- and second-instar larvae prevented adult emergence. The late-stage pupa was the most radiation-tolerant stage that occurs in fruit, and individuals irradiated at this stage readily emerged as adults; therefore, prevention of F1 adults was the desired treatment response for large-scale validation tests with naturally infested fruit. In largescale tests, a radiation dose of 80 Gy applied to late-stage pupae in sweet cherries or grapes resulted
in no production of F1 adults in 33,000 treated individuals, which meets the zero tolerance requirement
for market access. A minimum absorbed dose of 80 Gy is recommended for quarantine control of D. suzukii.