水稻施用硅肥对稻纵卷叶螟幼虫保护酶和解毒酶活性的影响

【目的】研究施硅水稻对稻纵卷叶螟Cnaphalocrocis medinalis(Guenée)幼虫保护酶(过氧化氢酶CAT、过氧化物酶POD、超氧化物歧化酶SOD)和解毒酶(谷胱甘肽-S-转移酶GST、乙酰胆碱酯酶ACh E)活性的影响,为探明硅增强水稻抗稻纵卷叶螟的机理和稻纵卷叶螟的综合治理提供依据。【方法】采用感虫水稻品种TN1,设置2种施硅水平,即0.32 g Si/kg土壤(Si+)和不施硅(Si-),测定取食水稻24、48、72、96 h后3龄幼虫体内CAT、POD、SOD、GST、ACh E活性的动态变化。【结果】幼虫取食Si+水稻前期(24~48 h),CAT、POD、SOD活性呈上升趋势,并在48 h时达到最高值;取食后期(48~96 h),CAT、POD、SOD活性下降并在96 h时显著低于Si-处理。在Si-处理中,幼虫CAT和POD活性"先降低、再升高",SOD活性呈一直增大的趋势。取食Si+水稻幼虫GST活性始终显著高于Si-处理,而ACh E活性均低于Si-水稻,并在72 h和96 h时显著低于Si-水稻。处理间幼虫存活率存在显著差异,Si+水稻上1龄和3龄幼虫的存活率显著低于Si-水稻。这些结果说明,硅处理可能使稻纵卷叶螟幼虫产生应激反应引起保护酶活性在短时间内增大,但取食一段时间后保护酶活性下降。ACh E活性受到抑制,会引起昆虫神经传导的异常反应,造成昆虫死亡。【结论】硅可能通过参与植物的生理代谢过程,诱导植物增加次生代谢物的合成和积累,引起稻纵卷叶螟保护酶和解毒酶的活性变化,可能会影响稻纵卷叶螟的存活。

Effects of providing additional silicon to host plants on the activity of protective and detoxifying enzymes in Cnaphalocrocis medinalis larvae

[Objectives] To explore the effects of providing additional silicon (Si) to host plants on the activities of protective and detoxifying enzymes in Cnaphalocrocis medinalis larvae. Such information may provide evidence of Si-mediated resistance and improve management of insect pests in rice crops. [Methods] The treatment (Si+) group of C. medinalis larvae were fed the leaves of the susceptible rice cultivar Taichung Native 1 (TN1) grown on soil to which 0.32 Si/kg soil had been added. The control (Si-) group were fed the leaves of the same cultivar grown on soil to which no silicon had been added. Catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione-S-transferases (GST) and acetylcholinesterase (AChE) activity were measured in 3rd instar larvae of both the Si+ and Si- groups after these had fed for 24, 48, 72, and 96 h. [Results] CAT, POD and SOD activity were initially higher in the Si+ than in the Si- group but decreased after larvae had fed for 48 h, becoming significantly lower in the Si+ group after 96 h. Temporal trends in protective enzyme activity differed between the Si- and Si+ groups; CAT and POD activity in the Si+ group first decreased then increased, whereas SOD activity increased consistently throughout the experiment. The addition of Si increased GST activity but decreased AChE activity. Survival rates of 1st and 3rd instar larvae were significantly lower in the Si+ group. The relatively rapid initial increase in protective enzyme activity observed in the Si+ group may be a response to the higher Si content of the rice leaves they were fed. Inhibition of AChE activity can eventually lead to paralysis and larval death. [Conclusion] Si may be involved in plant physiological or metabolic processes that regulate the production and accumulation of secondary metabolic compounds that influence the protective and detoxification enzyme activity of C. medinalis larvae, ultimately affecting larval survival.