中文摘要：

褐软蚧（Coccus hesperidum）是一种世界性的农林害虫，在我国分布广泛，金橘（Fortunella margarita）是其主要的寄主之一，而黑色软蚧蚜小蜂（Coccophagus yoshidae）是它的重要寄生性天敌．研究了茉莉酸甲酯（MeJA）作为外源信号分子处理植物，对金橘-褐软蚧-黑色软蚧蚜小蜂三营养层次的影响和在蚧虫生物防治上的意义．结果显示，褐软蚧危害后，会明显诱导寄主植物金橘叶片内胰凝乳蛋白酶抑制剂（Chym PI）增加和多酚氧化酶（PPO）活性的上升．与健康植株相比，轻微受害的金橘叶片Chym PI增加了4．02倍、PPO活性上升了1．11倍，而严重受害的金橘叶片Chym PI增加了6．38倍、PPO活性上升了1．33倍．应用MeJA处理进一步提高了两种物质的含量和活性，其中，轻微受害的金橘叶片ChymPI提高60．8％、PPO活性上升了28．4％，严重受害的金橘叶片Chym PI增加了10．2％、PPO活性上升了3．1％．试验发现，褐软蚧初孵化若虫更倾向选择MeJA未处理的金橘叶片上固定取食（63．8％），在处理植株叶片上仅为22．6％，说明MeJA处理的金橘叶片对该虫产生了明显的拒避作用．与此相反，黑色软蚧蚜小蜂趋向MeJA处理金橘叶片气味源的比例为59．6％，比未处理的高出1倍．说明MeJA处理后金橘叶片挥发性气味对小蜂产生了明显的招引效果．

英文摘要：

Coccus hesperidun is one of the important agricultural and forestry pest arourd the world and it is also widely distributed in China. Kumquat, Fortunella margarita, is one of the scale insect＇ s perfect host plants. Coccophagus yoshidae is its importance parasitoid. Methyl jasmonate（MeJA） as an exogenous sig- nal molecule was applied to treat the host plant to investigate the effect on the tritrophie relationship of Kumquat-C. hesperidun- parasitoid and the significance in the biological control of the scale insect. The results showed that under the damage of C. hesperidun, kumquat plants were induced and produced more chrymoltrypsin proteinase inhabitor（ChymPI） and polyphenol oxidase（PPO）. Compared with the healthy plants,ChymPI was increased by 4.02 times and the activity of PPO was promoted by 1.11 times in the leaves of the slight damaged plants,however,these two kinds of materials increased by 6.38 times and 1.33 times,respectively,in the heavy damaged leaves. After treated with MeJA,the ChymPI and PPO were further promoted by 60.8% and 28.4%, respectively, in the slight damaged leaves. And the two values increased by 10.2% and 3.1% ,respectively,in the heavy damaged leaves. The trials showed that the crawlers of C. hesperidun preferred to settle on those leaves from the plants untreated with MeJA and the rate reached 63.8%. In contrast,the percentage of the scale insect was 22.6% selected on the leaves treated with MeJA. It indicated that the leaves treated with MeJA exhibited repellency effect to the nymphs of the scale insect. However,59.6% of the parasitoid,C, yoshidae,ran to the volatile source from the plants treated with MeJA,it was more one times than that to the untreated one. This result argued that the volatiles from the kumquat plants treated with MeJA have possessed of the attraction to the parasitoid of the scale insect.