没食子酸对美国白蛾幼虫营养效应及解毒酶活性的影响

美国白蛾是我国重大外来入侵害虫,寄主范围十分广泛。酚类物质是最广泛的植物次生代谢物之一,在植物抵御昆虫取食的化学防御中具有重要作用。本研究通过人工饲料添加没食子酸的方法,探究不同浓度的没食子酸对美国白蛾幼虫的营养效应及解毒酶和乙酰胆碱酯酶活性的影响。结果表明,各浓度(1.0%、1.5%、2.0%、2.5%、3.0%)没食子酸对美国白蛾4龄幼虫的近似消化率、食物利用率、相对取食量和相对生长率均具有显著影响(P<0.05),近似消化率和相对取食量不同程度下降,食物利用率和相对生长率则不同程度上升。不同浓度的没食子酸处理对美国白蛾幼虫的乙酰胆碱酯酶、羧酸酯酶、谷胱甘肽S-转移酶和细胞色素P450的活性均具有显著影响(P<0.05)。1.0%没食子酸作用时间不同,美国白蛾4龄幼虫的乙酰胆碱酯酶、羧酸酯酶、谷胱甘肽S-转移酶和细胞色素P450的活性差异显著(P<0.05)。没食子酸能够始终诱导细胞色素P450的活性,而羧酸酯酶的活性却受到抑制。不同浓度的没食子酸对乙酰胆碱酯酶作用总体上不明显,但较低浓度时(1.0%)对乙酰胆碱酯酶活性却随处理时间延长而抑制作用加强。较低浓度(1.0%~1.5%)的没食子酸对谷胱甘肽S-转移酶的活性有一定诱导作用,但随着没食子酸浓度提高谷胱甘肽S-转移酶的活性却受到一定程度的抑制。没食子酸能抑制美国白蛾幼虫的取食,并且对解毒酶和乙酰胆碱酯酶的活性表现出一定的时间效应和剂量效应,表明美国白蛾幼虫可能通过调节食物利用和解毒代谢等多种途径降低没食子酸的毒害作用,从而对含没食子酸的寄主植物产生适应。

Effects of gallic acid on the nutritional efficiency and detoxificationenzymes in Hyphantria cunea larvae

Hyphantria cunea is a major invasive pest in China and has a wide range of hosts.Phenolics is a kind of general secondary metabolites in plants and play an important role in chemical defense against phytophagous insects.In this study,the method of adding gallic acid to artificial diet was used to analyze the influence of gallic acid on the nutritional efficiency and the activities of acetylcholinesterase and detoxification enzymes of H.cunea larvae.The results indicated that the nutritional efficiency(approximate digestibility,efficiency of conversion of ingested food,relative consumption rate,relative growth rate)of H.cunea larvae were significantly impacted by tested concentrations of gallic acid(1.0%,1.5%,2.0%,2.5%,3.0%)(P<0.05).Approximate digestibility and relative consumption rate of H.cunea larvae were descended while its efficiency of conversion of ingested food and relative growth rate were ascended with treatment of gallic acid.The activities of acetylcholinesterase,carboxylesterase,glutathione-S-transferase and cytochrome P450 significantly affected by gallic acid with different concentrations(P<0.05).Four enzymes activities of H.cunea were also significantly affected by 1.0%gallic acid with different treatment time(P<0.05).Gallic acid could always induce the activity of cytochrome P450.However,the activity of carboxylesterase was inhibited by gallic acid.Different concentrations of gallic acid have no significant effect on acetylcholinesterase.Instead,the inhibition on the activity of acetylcholinesterase caused by 1%gallic acid was gradually enhanced as treatment time went on.Lower concentrations(1.0%~1.5%)of gallic acid had a certain induction on the activity of glutathione S-transferase.However,the activity of glutathione S-transferase was inhibited with gallic acid concentration increasing.The feeding of H.cunea larvae was inhibited by gallic acid while the effects of gallic acid on the activities of detoxification enzymes and acetylcholinesterase of H.cunea larvae were depended on dosage and time.It indicated that the larvae of H.cunea could reduce the toxic effect of gallic acid by regulating its food utilization and detoxification metabolism,thereby adapt the defense mechanism of host plants.