Gamma irradiation for postharvest disinfestation of Ctenopseustis obliquana (Walker) (Lep., Tortricidae)

Gamma irradiation was examined for its potential as a quarantine treatment for eggs and larvae of the leafroller Ctenopseustis obliquana. One‐day‐old eggs were more radiosensitive than 5‐day‐old eggs, requiring 55.9 Gy and 269 Gy for 99% mortality, respectively. Effective disinfestation of C. obliquana could be achieved with a dose as small as 70.1 Gy, which would inhibit any oviposition by adults developing from irradiated 1‐day‐old and 5‐day‐old eggs, and 1st, 3rd and 5th instar larvae. Further quarantine security for these life stages could be achieved with a dose of 150 Gy which would inhibit adult emergence, or 215 Gy which would inhibit larvae from entering pupation. As these doses are unlikely to damage host fruit, gamma irradiation provides a potential alternative to methyl bromide fumigation.