亚致死浓度多杀菌素对西花蓟马解毒酶系活力的影响

Effect of Sublethal Concentration of Spinosad on the Activity of Detoxifying Enzymes in the Western Flower Thrips,Frankliniella occidentalis(Thysanoptera:Thripidae)

采用亚致死浓度(LC25)多杀菌素对西花蓟马Frankliniella occidentalis相对敏感(SS)种群进行连续选育,获得亚致死(Sub)种群。处理36代后,Sub种群对多杀菌素的敏感性下降到SS种群的5.2倍。用SS和Sub种群各自的LC10和LC25浓度多杀菌素分别处理两种群的2龄若虫,1、6、12、24和48h后测定羧酸酯酶(CarE)、谷胱甘肽S-转移酶(GSTs)和多功能氧化酶(MFOs)的比活力。结果表明,Sub种群对照组CarE和GSTs比活力在除第48h外的其他时间段都高于SS种群对照组,且6h时两者CarE比活力差异显著,Sub种群是SS种群的1.37倍;Sub种群对照组MFOs比活力在各时间段都高于SS种群对照组,在1和6h时差异显著,前者分别是后者的1.62和1.36倍。再经各自的LC10和LC25浓度多杀菌素处理后,在各时间段Sub种群的CarE比活力均高于SS种群;LC25浓度处理后,Sub种群的GSTs和MFOs比活力虽在短时间内低于SS种群,但随处理时间的延长其比活力均高于SS种群。说明SS种群经亚致死浓度多杀菌素选育36代后,其体内CarE、GSTs和MFOs比活力有上升趋势;继续用亚致死浓度多杀菌素处理,则Sub种群体内解毒酶活力的动态调节能力要强于SS种群。

A sublethal strain of western flower thrips （WFr）, Frankliniella occidentalis （Sub） was obtained by selecting the relative susceptible strain of WFT （SS） with LC25 of spinosad. After 36 generations of selection,its sensitivity to spinosad decreased 5.2-fold compared to the SS strain. The second instar larvae of the SS and Sub strains were treated with LC10 or LC25 of spinosad and the specific activity of the detoxifying enzymes was determined after 1, 6, 12, 24 and 48h, respectively. The results showed that for the untreated control group the specific activity of the carboxylesterase （CarE） and the glutathione S-transferase （GSTs） in the Sub strain were higher than those in the SS strain except 48 h after treatment. In addition, the difference of CarE activity between the two strains after treatment for 6 h was significant, the difference was 1.37-fold. The activity of the mixed-function oxidases （MFOs） of the Sub strain were higher than those of the SS strain, and showed significant difference between 1 h and 6 h after treatment. The differences were 1.62-fold and 1.36- fold,respectively. For the spinosad treated groups at LC10 or LC25, the CarE activity in the Sub strain was higher than that in the SS strain. The GSTs and MFOs activity in the Sub strain was lower than that in the SS strain shortly after treatment by LC25 of spinosad, but turned to be higher with the time prolonged. The results indicated that after the SS strain was seletced with sublethal concentration of spinosad for more than 36 generations, the activity of the detoxification enzymes showed an increasing trend. The Sub strain had stronger ability of regulating the detoxifying enzymes than that of the SS strain when treated with sublethal concentration of spinosad.