Gamma Radiation: An Eco-Friendly Control Method for the Rice Weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

Abstract

The rice weevil, Sitophilus oryzae (L.), is the most destructive insect pest of stored cereals worldwide. The current study was conducted to determine the lethal, reproductive, and histological effects of gamma irradiation on S. oryzae adults. In addition, the impact on germination, chlorophyll, and proline content in wheat seedlings from treated grains was determined. Wheat grains were infested with rice weevil adults and then irradiated by gamma rays. Gamma radiation was applied at a dosage of 0.10, 0.25, 0.50, and 1.00 kGy. Mortality percentage and LD50 were recorded after 48, 72, 96, and 120 h of treatment. The dosage of 1.00 kGy caused 100% mortality after 96 h of irradiation. The required dosage of gamma radiation to kill 50% (LD50) of adults after 48 h was 1.51 kGy. All tested doses caused complete sterility to 24 h old adults. A histological alteration was noticed at a dosage of 1.00 kGy, which showed cytoplasmic vacuolization, tissues exhibiting signs of putrefaction, and necrosis of cells; furthermore, gamma irradiation affected chlorophyll a and b. The highest amounts were detected in wheat seedlings from grains irradiated at 0.10 kGy. There was a significant increase in plant proline content at the higher doses (0.50 and 1.00 kGy) compared with seedlings from nonirradiated grains. It could be concluded that gamma radiation can be used as an eco-friendly trend to control stored-product pests without any residual effects.