Abstract: The LD₅₀values of fipronil to Chilo suppressalis(Walker) and Sesamia inferens(Walker) larvae were 0.1749 μg/g and 10.1352 μg/g,respectively.After the larvae were treated with sublethal dose(LD₁₅) of fipronil,the specific activity and the maximum velocity(v_max) values of carboxylesterase(CaE) and glutathione S-transferase(GST) in the larvae of C.suppressalis and S.inferens were all increased significantly,while those of mixed-functional oxidase(MFO) were decreased.The Michaelis-Menten constant(K_m) values of CaE and MFO in C.suppressalis larvae treated with sublethal dose of fipronil were markedly higher than those of the control,while that of GST showed no marked changes.In contrast,the K_m values of CaE,GST and MFO in S.inferens larvae treated with sublethal dose of fipronil were high-significantly decreased.It was suggested that the process of fipronil metabolism in the larvae of C.suppressalis and S.inferens might be much different and the difference in substrate affinity of detoxifying enzymes between the two stem borers were possibly resulted in their different susceptibilities to fipronil.

Key words: near infrared transmission spectroscopy, brown rice, grain quality, model, methodology

摘要： 氟虫腈对二化螟Chilo suppressalis (Walker)和大螟Sesamia inferens (Walker)幼虫的LD50值各为0.1749 μg/g和10.1352 μg/g。经氟虫腈亚致死剂量（LD15）处理后，二化螟和大螟幼虫羧酸酯酶（CaE）和谷胱甘肽S转移酶（GST）的比活力和最大反应速率（vmax）均显著增强，而多功能氧化酶（MFO）则显著降低。二化螟CaE和MFO的米氏常数（Km）经氟虫腈处理后均显著增高，而GST的无显著变化；大螟CaE、GST和MFO的Km均极显著降低。这表明氟虫腈在二化螟和大螟幼虫体内的代谢途径可能存在较大差异，而2种螟虫体内解毒酶对底物亲和力的不同可能导致两者对氟虫腈敏感性的差异。

关键词: 氟虫腈, 亚致死剂量, 二化螟, 大螟, 解毒酶