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

SIMPLE SUMMARY: This study was conducted to evaluate the effect of gamma radiation at a dosage of 0.10, 0.25, 0.50, and 1.00 kGy on the mortality percentages of Sitophilus oryzae adults, their effects on weevil sterility, and seed germination. The dosage of 1.00 kGy caused 100% mortality after 96 h of irradiation. Moreover, the use of irradiation at a dosage of 1.00 kGy against S. oryzae adults has strong damage on histological alterations. It also has a negative impact on the germination percentage. Thus, the use of gamma radiation is a very important alternative method to protect stored grains and their products against rice weevils. On the contrary, it is not recommended to use irradiated grains for farming. 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 LD(50) 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% (LD(50)) 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.