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【目的】探讨氟铃脲对斜纹夜蛾Spodoptera litura酚氧化酶活性的影响。【方法】应用酶动力学法,在确定斜纹夜蛾酚氧化酶最适反应条件基础上,测定氟铃脲与酚氧化酶直接作用及氟铃脲处理幼虫后酚氧化酶的活性。【结果】以邻苯二酚为底物,斜纹夜蛾酚氧化酶的最适pH6.5,最适温度30℃。氟铃脲没有和酚氧化酶结构中的铜离子结合,而是直接与酶蛋白发生作用。氟铃脲浓度低于1153mg/L对离体酚氧化酶有激活作用,在138mg/L激活作用最大,浓度高于1153mg/L则产生抑制作用。用46mg/L和92mg/L亚致死剂量氟铃脲连续处理5龄幼虫不同时间后,酚氧化酶活性均显著提高,且高浓度的激活作用大于低浓度的激活作用。进一步测定药剂处理幼虫24,48和72h的血淋巴、表皮和头部酚氧化酶活性,随着氟铃脲处理时间延长,两个剂量的氟铃脲对血淋巴、表皮及头部酚氧化酶的激活作用逐渐增大,氟铃脲对血淋巴酚氧化酶的激活作用最大,表皮次之,头部最低。氟铃脲处理幼虫后,其预蛹和蛹酚氧化酶的活性也显著提高,表现出一定的后效应。【结论】一定浓度范围内,氟铃脲对斜纹夜蛾酚氧化酶具有激活作用。
【Objective】 To investigate the effect of hexaflumuron on the phenoloxidase activity of Spodoptera litura in Spodoptera litura. 【Method】 The enzymatic kinetic method was used to determine the direct effect of hexaflumuron and phenoloxidase and the activity of phenoloxidase after the treatment with hexaflumuron on the basis of the determination of the optimum reaction conditions for phenoloxidase of Spodoptera litura. 【Result】 With catechol as substrate, the optimum pH value of phenoloxidase for Spodoptera litura was 6.5 and the optimal temperature was 30 ℃. Hexaflumuron does not bind to copper ions in the structure of phenoloxidase, but acts directly on the enzyme protein. When the concentration of hexaflumuron was lower than 1153mg / L, the activation of exogenous phenoloxidase was the highest, and the maximal activation was at 138mg / L, while the inhibitory effect was observed when the concentration was higher than 1153mg / L. After continuous treatment of 5th instar larvae with sub-lethal doses of 46mg / L and 92mg / L, the phenoloxidase activity was significantly increased at different time points, and the activation of high concentration was greater than that of low concentration. The activities of phenoloxidase in hemolymph, epidermis and head of larvae at 24, 48 and 72h were further measured. With the prolonging of the time of hexaflumuron, two doses of hexaflumuron did not inhibit the activity of phenoloxidase Activated gradually, and hexaflumuron has the highest activation on the hemolymph phenoloxidase, followed by the epidermis and the lowest in the head. After treated with hexaflumuron, the activity of phenoloxidase in pre-pupa and pupae also increased significantly after the treatment with hexaflumuron, indicating a certain after-effect. CONCLUSION: Hexaflumuron can activate phenoloxidase of Spodoptera litura in a certain concentration range.