[en] As insects increase in radio tolerance as they develop and usually several developmental stages of pest may present in fresh shipped commodity, it is important to know the radiation susceptibility of stages of the target insect before the establishment of ionizing radiation quarantine treatments. This study was performed to determine the radio tolerance of pupae of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidade), to gamma radiation. This specie is considered as on of the most serious worldwide pests for temperate fruits, especially peaches. Pupae of 3 days old were exposed to 0 (control), 25, 50, 75, 100, 125, 150, 175, 200, 250, 300 and 350 Gy of gamma radiation of source Cobalt-60, type Gammacell-220 at dose rate of 0,508 kGy/hour. Each treatment had 4 repetitions with 10 pupae in the total 40 pupae per treatment. Surviving pupae allowed to feed on an artificial diet. After irradiation the insects were keep in room with climatic conditions of 25 ±5 deg C and 70 ±5% RH. The results showed that the sterilizing dose to adults was 200Gy and that the dose of 350Gy was not sufficient to kill all pupae of insects. (author)