吡虫啉对意大利蜜蜂乙酰胆碱酯酶的亚致死效应

Effect of sublethal doses of imidacloprid on Acetylcholinesterase activity in Apis mellifera

【目的】确定吡虫啉对意大利蜜蜂Apis mellifera的致死中浓度,探究吡虫啉对意大利蜜蜂乙酰胆碱酯酶的亚致死效应。【方法】本文采用药膜法、点滴法和饲喂法测定吡虫啉对意大利蜜蜂的毒力曲线,及蜜蜂接触吡虫啉后头部乙酰胆碱酯酶活性的变化。应用RT-q PCR技术研究饲喂LC5浓度吡虫啉后,蜜蜂乙酰胆碱酯酶基因Ace1和Ace2的m RNA相对表达量。【结果】饲喂法、点滴法和药膜法3种方法测定的吡虫啉对意大利蜜蜂的致死中浓度分别是7.15 mg/L、0.078 ng/蜂和51 ng/cm2。3种作用方式下,吡虫啉均抑制了乙酰胆碱酯酶活性;随着浓度增加,ACh E酶活性处于下降状态,但降低较少。LC5浓度的吡虫啉对蜜蜂ACh E活性具有明显影响,24 h内ACh E活性呈现增强-抑制-增强的趋势。饲喂蜜蜂LC5亚致死浓度的吡虫啉后,Ace1和Ace2被诱导表达,但在1、2和16 h与对照无明显差异。【结论】亚致死浓度的吡虫啉对蜜蜂乙酰胆碱酯活性具有抑制作用,并且存在明显的剂量效应和时间效应,对Ace1和Ace2具有诱导效应,酶活性水平和m RNA相对表达水平不一致。

[Objectives] To determine the median lethal concentration of imidacloprid and explore the sublethal effect of imidacloprid on acetylcholinesterase （ACHE） in Apis mellifera. [Methods] The toxicity of imidacloprid was determined by feeding trials, topical application and the residual film method. AChE activity and the relative expression of acetylcholinesterase mRNA genes （Acel and Ace2） in the head of .4. mellifera were measured after exposure to different concentrations of imidacloprid after different periods of time. [Results] LC50 values determined by the three methods were 7.15 mg/L, 0.078 rig/bee and 51 ng/cm2, respectively. Imidacloprid inhibited AChE activity within 24 h. The enzymatic activity of AChE was volatile with increasing pesticide concentration, fluctuating with the dose and period of imidacloprid exposure. mRNA expression of the Ace1 and Ace2 genes was induced within 24 h, but not after 1 b, 2 h and 16 h exposure. [Conclusion] The results show that the effect of imidacloprid on AChE depends on both the period of exposure and dosage. The AChE activity in the heads of honeybees may be inhibited by sub lethal doses of imidacloprid, but the induced mRNA expression patterns of Acel and Ace2 was inconsistent with AChE activity.