Abstract: 【Aim】 This study aims to explore the effects of silicon (Si) amendment to rice plants on the activities of protective and detoxification enzymes in the brown planthopper (Nilaparvata lugens) adults feeding on the treated rice plants, so as to provide evidence for the utilization of Si-mediated resistance in the management of insect pests in rice crops. 【Methods】 N. lugens adults feeding on susceptible rice plants (cultivar TN1) grown in nutrient solutions added with 112 mg Si/L sodium silicate (Na₂SiO₃·9H₂O)(Si+) or without addition of sodium silicate (Si-). The activities of protective enzymes ［catalase (CAT), peroxidase (POD) and superoxide (SOD)］ and detoxification enzymes ［glutathione-S-transferase (GST), carboxylesterase (CarE) and mixedfunctional oxidase (MFO)］ in N. lugens adults after feeding on the Si+ and Si- rice plants (hereafter referred as Si+ and Si- adults, respectively) for 24, 48, 72, and 96 h were measured by enzyme activity assay. 【Results】 In the Si+ adults at 24 and 48 h feeding on the rice plants the POD activities were significantly increased by 101.2% and 55.2%, respectively, and the SOD activity by 78.2% and 19.6%, respectively, as compared to those in the Si- adults. The activities of CAT and SOD in the Si+ adults at 72 h after feeding on the rice plants were significantly increased by 16.5% and 29.7%, respectively, as compared to those in the Si- adults. When the feeding duration was elongated to 96 h, the activities of CAT and POD in the Si+ adults declined slightly, and their SOD activity significantly decreased by 12.6%, as compared to those in the Si- adults. The addition of Si generally increased the activities of GST and MFO but decreased the CarE activity. In the Si+ adults, the GST activities increased significantly by 57.2%, 200.7%, 84.7% and 45.9%, respectively, at 24, 48, 72 and 96 h after feeding, the MFO activities increased significantly by 70.2% and 28.3%, respectively, at 72 and 96 h after feeding, whereas the CarE activities significantly decreased by 38.1% and 32.0%, respectively, at 72 and 96 h after feeding, as compared to those in the Si- adults. 【Conclusion】 Si amendment to rice plants influences the activities of protective and detoxification enzymes in N. lugens adults feeding on the treated rice plants, which may in return affect the physiological metabolism of N. lugens.

Key words: Nilaparvata lugens, silicon, rice, protective enzymes, detoxification enzymes