In order to delay the resistance of Locusta migratoria manilensis to malathion and definite the dynamic change of detoxification enzymes in the process of resistance of L. migratoria manilensis, Meyen to malathion. The toxicity of malathion to the third - instar nymph of L. migratoria manilensis was studied by immersion method and the activities of biochemical enzymes were assayed by kinetic method in the laboratory. The results showed that the LC50 value was 448. 89mg/L after the treatment of malathion for 48h. With the concentration 7.48 - 187mg/L of malathion, the activities of acetylcholinesterase, esterase and glutathione - S - transferases ( CDNB) were significantly inhibited and presented a tendency of decreasing in lower concentration but then increasing in higher concentration. However, the activity of glutathione - S - transferases ( DCNB) was significantly induced and showed a tendency of increasing in lower concentration but then decreasing in higher concentration. These results indicates that acetylcholinesterase, esterase and glutathione - S - transferases all involved in the detoxification of L. migratoria manilensis to malathion and malathion achieves its insecticidal effect mainly by inhibiting the activities of biochemical enzymes. Combining with the biochemical mechanism of malathion resistance, adding the inhibitors of above enzymes can delay insects resistance to malathion, and play anrnimportant role in the resistance management of malathion.%为有效延缓东亚飞蝗对马拉硫磷的抗药性,明确相关解毒代谢酶在抗药性产生过程中的动态变化,本试验在马拉硫磷对东亚飞蝗3龄蝗蝻毒力测定的基础上,测定了相关解毒代谢酶的活力.结果表明,马拉硫磷处理48 h后其LC50值为448.89 mg/L.马拉硫磷低浓度(7.48-187 mg/L)显著抑制东亚飞蝗乙酰胆碱酯酶、全酯酶和CDNB为底物时谷胱H肽-S-转移酶的活性,处理间酶活性随着马拉硫磷浓度的升高出现先降低后升高的趋势; 马拉硫磷对DCNB为底物时谷胱甘肽-S-转移酶活性呈显著诱导作用,处理间酶活随马拉硫磷浓度升高出现先升高后降低的趋势;马拉硫磷对多功能氧化酶活性影响差异不显著.以上结果说明,乙酰胆碱酯酶、全酯酶和谷胱甘肽-S-转移酶均参与了东亚飞蝗对马拉硫磷的解毒代谢过程;马拉硫磷通过抑制昆虫体内相关解毒代谢酶活性从而达到其杀虫效果.综合前人对马拉硫磷抗性研究结果可以看出,以上生化酶抑制剂的添加可以在一定程度上延缓昆虫对马拉硫磷抗性的产生,并在抗性治理中发挥一定作用.
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