昆虫病原线虫和噻虫嗪混用对韭蛆的杀虫效果及其体内保护酶和解毒酶活性的影响

Bioefficacy of the combined application of entomopathogenic nematodes and thiamethoxam and its effects on the protective and detoxification enzyme activities in Bradysia odoriphaga( Diptera: Sciaridae) larvae

【目的】害虫受到病原生物、化学农药作用后,会引起其体内生理生化的变化。本研究旨在阐明昆虫病原线虫和噻虫嗪联合作用下对韭菜迟眼蕈蚊Bradysia odoriphaga幼虫(韭蛆)的杀虫效果及体内保护酶和解毒酶活性的影响。【方法】采用培养皿滤纸法测定了芫菁夜蛾斯氏线虫Steinernema feltiae SF-SN(Sf)(60头/幼虫)与噻虫嗪(15 mg/L)混用对韭菜迟眼蕈蚊3龄幼虫的LT_(50);采用生化分析法比较分析不同时间下两者混用对其幼虫体内酶液蛋白质含量和体内酶[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽-S-转移酶(GSTs)和乙酰胆碱酯酶(AChE)]活性的影响。【结果】Sf与噻虫嗪混用处理韭菜迟眼蕈蚊3龄幼虫,其LT_(50)值为41.05 h,比单独使用Sf(LT_(50):167.93 h)和噻虫嗪(LT_(50):72.82 h)时分别缩短了126.88 h和31.77 h;处理后24-72 h,两者混用时对试虫的校正死亡率均显著高于两者单用,且在处理72 h时,校正死亡率达到96.61%。与对照组相比,两者混用处理后12,24和36 h时,韭蛆体内酶液蛋白质含量分别提高了13.88%,46.87%和57.99%,均显著高于对照组、Sf处理组和噻虫嗪处理组。处理24 h时,两者混用组SOD,CAT,AChE和GTSs活性分别比对照降低了47.48%,28.73%,71.04%和29.97%;处理36 h时,酶活性分别比对照降低了46.34%,42.22%,58.37%和11.87%,均显著低于对照组、Sf处理组和噻虫嗪组,比单剂具有更强的抑制作用。【结论】Sf和噻虫嗪联合作用韭菜迟眼蕈蚊3龄幼虫后,其LT_(50)值比两者单用时显著缩短,且对幼虫体内SOD,CAT,AChE和GSTs活性均具有更强的抑制作用。

【Aim】Pathogenic organisms or chemical pesticides can induce the defense responses of insects,and the physiological adaptation of insects might differ under the combined application of pathogenic organisms and chemical pesticides.This study aims to investigate the effects of combined application of entomopathogenic nematodes and thiamethoxam on Bradysia odoriphaga.【Methods】The LT 50 value of the combined application of Steinernema feltiae SF-SN strain(Sf)(60 IJs/larva)and thiamethoxam(15 mg/L)against the 3rd instar larvae of B.odoriphaga was determined with filter paper culture method in the laboratory,and its effects on the protein content of enzyme solution and the activities of superoxide dismutase(SOD),catalase(CAT),glutathione-S-transferases(GSTs)and acetylcholinesterase(AChE)in B.odoriphaga larvae at different time after treatment were assayed by biochemical analysis.【Results】The LT 50 value(41.05 h)of the combined application of Sf and thiamethoxam against the 3rd instar larvae of B.odoriphaga decreased by about 126.88 h and 31.77 h,respectively,as compared with those in treatments with the respective single agents with(Sf LT 50:167.93 h)and thiamethoxam(LT 50:72.82 h).During 24-72 h after treatment,the corrected mortality rates of B.odoriphaga larvae in the combined treatment group were significantly higher than those in treatments with the respective single agent,and reached the peak(96.61%)at 72 h.The protein contents of enzyme solution in B.odoriphaga larvae in the combined treatment group at 12,24 and 36 h after treatment increased by 13.88%,46.87%and 57.99%,respectively,as compared with the control group,and were significantly higher than those in the control group,Sf treatment group and thiamethoxam treatment group.The activities of SOD,CAT,AChE and GTSs in larvae in the combined treatment group decreased by 47.48%,28.73%,71.04%and 29.97%at 24 h after treatment,and by 46.34%,42.22%,58.37%and 11.87%at 36 h,respectively,as compared with the control.The activities of the four enzymes in the combined treatment group were significantly lower than those in the control group,Sf treatment group and thiamethoxam treatment group at 24 h and 36 h after treatment.【Conclusion】The LT 50 value of the combined application of Sf and thiamethoxam against the 3rd instar larvae of B.odoriphaga is significantly lower than those in treatments with the respective single agent,and the combined treatment can significantly restrain the activities of SOD,CAT,AChE and GTSs in larvae.