Evaluation of irradiation quarantine dose – induced DNA damage in Rhyzopertha dominica and its effect on wheat grains using comet assay

Abstract

Irradiation is a quarantine treatment option for stored product pests. In the present studies, we try to investigate the effect of low gamma irradiation doses in the range of 20–300 Gy on the different developmental stages of Rhyzopertha dominica in wheat grains. It was found that no adults emerged after irradiation of eggs, larvae, and pupae at 140, 240, and 260 Gy, respectively. Treatment of adult weevils at the radiation dose of 180 Gy resulted in 71.33% mortality after 14 days post-treatment and there was no adult emergence in the F1 generation. When the adult emergence of the F1 generation was used for the measuring effective irradiation dose and phytosanitary efficacy, 280 Gy was required for quarantine security of wheat weevils. The comet assay serves to verify the DNA damage induced by the phytosanitary irradiation dose, 280 Gy on the R. dominica, and wheat grains. DNA damage was measured as the percentage of comet tail DNA. A significant linear increase in DNA damage was observed in the irradiated adult stage of R. dominica but there is no DNA damage in the wheat grains. Also, the wheat grains viability (in terms of wheat germination) was not affected by the dose level, 280 Gy. Thus, an irradiation dose of 280 Gy is recommended as an effective phytosanitary irradiation dose for quarantine security to control lesser grain borer.