茚虫威对草地贪夜蛾的毒力及解毒酶的诱导作用

茚虫威对鳞翅目害虫幼虫具有卓越的杀虫活性,是替代传统杀虫剂及治理抗药性害虫的理想药剂。为了明确茚虫威对草地贪夜蛾的生物活性及对其主要解毒酶活性的影响,为使用茚虫威科学防治草地贪夜蛾提供参考,本研究采用浸叶法测定了广西南宁草地贪夜蛾种群3龄幼虫对茚虫威敏感性及增效醚(PBO)、磷酸三苯酯(TPP)、顺丁烯二酸二乙酯(DEM)对茚虫威的增效作用;并测定了亚致死浓度(LC_(20))茚虫威对草地贪夜蛾体内MFO、GSTs和CarE酶的诱导作用。结果表明,茚虫威对草地贪夜蛾的LC_(20)、LC_(50)和LC_(90)分别为8.95、20.62 mg/L和73.57 mg/L。DEM、PBO和TPP对茚虫威的增效倍数依次为2.24、2.05和0.50倍。亚致死浓度(LC_(20))茚虫威处理后对3龄幼虫体内GSTs的活性和MFO含量与无药剂处理(CK)相比显著升高(P0.05),而CarE活性无显著变化(P0.05)。本文结果显示,广西草地贪夜蛾仍可以用推荐剂量80 mg/L茚虫威防治,而代谢抑制剂PBO和DEM对茚虫威有明显的增效作用,且GSTs活性和MFO含量在茚虫威诱导后显著升高,初步推测这两种解毒酶可能影响将来草地贪夜蛾对茚虫威的抗药性发展。

Toxicity of indoxacarb to Spodoptera frugiperda and induction of its detoxifying enzymes

Indoxacarb has excellent insecticidal activity against the larvae of lepidoptera pests. It is an ideal agent to replace traditional insecticides and control resistance pest. To provide guideline for its scientific application, the biological activity of indoxacarb and its induction to the detoxifying enzymes of Spodoptera frugiperda were investigated in this study. The sensitivity of 3rd instar larvae to indoxacarb and the synergistic effects of PBO, TPP and DEM to indoxacarb were determined by leaf dipping method. In addition, the induction of MFO, GSTs and CarE enzyme by LC20 of indoxacarb was determined. The results showed that the LC20, LC50 and LC90 values of indoxacarb were 8.95, 20.62 mg/L and 73.57 mg/L, respectively. The synergistic ratios of DEM, PBO and TPP to indoxacarb were 2.24, 2.05 and 0.50, respectively. Treatment with LC20 of indoxacarb significantly increased the GSTs activity and MFO content in the 3rd instar larva compared with that of untreated control (CK) ( P < 0.05), but showed no effect on the CarE activity ( P >0.05). These results suggested that the indoxacarb could still be used to prevent and control the S. frugiperda at the recommended dose of 80 mg/L, while the metabolic inhibitors PBO and DEM had obvious synergistic effects on indoxacarb, and GSTs activity and MFO content were significantly induced by LC20 of indoxacarb. It was preliminarily speculated that these two enzymes might be involved in the development of indoxacarb resistance in future.