Gamma irradiation as a disinfestation and quarantine treatment for faba bean seeds infested with <i>Bruchus dentipes</i> Baudi (Col., Bruchidae)

Abstract

Abstract A study was conducted to investigate the effectiveness of gamma irradiation as a disinfestation and quarantine treatment for faba bean seeds which contain larvae and pupae of the faba bean seed beetle, Bruchus dentipes Baudi. The results showed that a dose of 90 Gy applied to the larval stage caused 100% mortality of the treated larvae regardless of their age or instar. A dose of 300 Gy applied to the late pupal stage caused 93.8% mortality and rendered the emerged adults unable to fly. In subsequent confirmatory trials in which 100 000 infested seeds were treated, no adults emerged, which assures quarantine security to probit 9 at the 95% confidence level. Our studies indicate that ionising radiation could be an alternative to chemical fumigants for disinfestation and/or quarantine treatment of faba bean seeds infested with B. dentipes. A dose of 90 Gy applied to faba bean seeds when the pest population is still in the larval stage, during the first 3 months after harvest, is suggested. To minimise losses in seed quality, however, irradiation treatment should be done as early as possible after harvest.