A B S T R A C TThe western flower thrips, Frankliniella occidentalis (Pergande), is a good working model for studies of irradiation as a quarantine treatment on agricultural products against this insect group. A study was conducted to evaluate the mortality of this species, resulting from different dosages of gamma irradiation. Field populations were collected and exposed to 0.5, 1.0, and 1.5 kGy in a 60-Cobalt irradiator. In a first experiment, 645 adult F. occidentalis per treatment were used. Adult mortality reached 35% to 67% after 1 h exposure, significantly higher than the control. In a second experiment with the same dosages and storage at 5-6°C, evaluations were done at days 8 and 14 on at least 200 adults. Mortality increased significantly with the dosage of irradiation over time, and reached 95% with the higher dosage. In general, there were no differences between 8 and 14 days under cold storage for a given dosage. From a quarantine point of view, it is suggested to evaluate the combined effect of higher irradiation dosages and colder storage, as well as the effects of the treatments on fertility and fecundity of thrips.

Summary The effect of γ‐irradiation on the quality of chives was evaluated. The samples were irradiated at 1.0 and 2.0 kGy, stored at 4 °C for 10 days and used for microbiological (aerobic mesophilic, moulds and yeasts, E. coli and Salmonella sp), biochemical (vitamin C and lipoperoxide (MDA) contents and superoxide dismutase (SOD) and guaiacol peroxidase (POX) activity) and sensorial evaluation. For irradiated samples, the total counts of aerobic mesophilic and moulds and yeasts showed a reduction of 6 log cycles during storage, and colour analysis showed no significant difference (P > 0.05) for the b*‐value. The contents of vitamin C were not significantly affected by irradiation and storage time. The MDA contents and SOD activity changed insignificantly at both γ‐irradiation levels after storage, while POX was significantly increased (P ≤ 0.05) at 1 kGy. Samples irradiated at 2.0 kGy presented sensorial acceptance after the storage. These results show that γ‐irradiation increases the shelf life of chives without significant changes in their quality.