中文摘要：

莲草直胸跳甲Agasicles hygrophila是入侵杂草喜旱莲子草的专食性天敌。为进一步明确莲草直胸跳甲寄主专一性的分子机制,通过分析其转录组数据克隆羧酸酯酶（carboxylesterases,Car Es）基因,采用RT-PCR技术从其体内获得1个羧酸酯酶B簇基因并进行生物信息学分析,同时利用实时定量PCR方法检测其在不同身体部位及不同发育阶段的表达特性,并对饥饿处理、取食靶标植物喜旱莲子草和非靶标植物莙荙后该基因的表达水平进行比较。结果显示,克隆得到1条莲草直胸跳甲羧酸酯酶基因的c DNA全长序列,长度为1 851 bp,开放阅读框长度为1 647 bp,编码548个氨基酸,以该基因推导的氨基酸序列与其它物种的Car Es进行聚类分析,发现此基因为羧酸酯酶B簇家族成员,命名为Ah Ces B1（Gen Bank登录号KT032151）。实时定量PCR检测结果显示,Ah Ces B1基因在莲草直胸跳甲3龄期表达量最高,成虫期和蛹期表达量次之,卵、1龄和2龄期表达量相对较低。Ah Ces B1基因在头和中肠的表达量较低,在其余身体部分表达量较高。取食莙荙后Ah Ces B1表达量显著增高,为饥饿处理的13.7倍,而取食喜旱莲子草与饥饿处理并无显著差异。表明莲草直胸跳甲Ah Ces B1在不同发育阶段和成虫不同身体部位具有不同的表达水平,而非寄主植物莙荙可以诱导该基因的表达,推测羧酸酯酶在莲草直胸跳甲代谢次生物质中发挥着重要作用。

英文摘要：

The alligator weed flea beetle, Agasicles hygrophila （Coleoptera： Chrysomelidae）, has been successfully introduced into China as a biological control agent against the invasive weed Alternanthera philoxeroides. To understand the molecular mechanism of host specificity ofA. hygrophila, a carboxy- lesterase gene, AhCesB1 were cloned from A. hygrophila through bioinformatics analysis of the A. hy- grophila transcriptome database generated in laboratory. A 1 851 bp cDNA of carboxylesterases （CarEs） was sequenced and the cDNA contained an open reading frame of 1 647 bp encoding 548 amino acid residues. Based on the phylogenetic tree and sequence similarity, the flea beetle CarE gene might be- long to the clade B, and therefore was designated as AhCesB1 （GenBank acc. no. KT032151）. The tran- script level of the AhCesB1 gene was then analyzed in A. hygrophila at different developmental stages and in various body parts, after feeding different plants or starvation by using qPCR. The highest tran- script level of AhCesB1 was observed in the third-instar larva, followed by adult stage and pupa stage of A. hygrophila. Relatively low expression was found in egg, first- and second-instar stages. The expres- sion of AhCesB1 was higher in the remaining body parts than in the head and midgut. The transcript lev- el was not significantly different between feeding on A. philoxeroides or starvation. However, the ex- pression of AhCesB1 was upregulated by feeding on Beta vulgaris var. cicla, which was 13.7 fold high- er than those feeding on A. philoxeroides or starvation.