芥子油苷在甘蓝蚜寄主部位选择行为中的作用

利用刺吸电位技术（EPG）记录甘蓝蚜Brevicoryne brassicae在芥菜Sinapis alba 不同部位上的取食行为，同时用高压液相色谱（HPLC）分析芥菜相应部位的芥子油苷(glucosinolates)含量，据此分析芥子油苷在甘蓝蚜对寄主部位偏好行为中的作用。选择芥菜三个部位进行取食行为记录和化学分析，即新出完全叶(第7片)的叶片、叶柄，以及花茎。相对于其它两个部位，甘蓝蚜的口针在花茎上用较少的刺探次数和较短的时间到达韧皮部；一旦口针进入韧皮部持续吸食阶段，蚜虫在三个部位的取食行为没有太大的差异。只在花茎的表皮和皮层中测定到较高含量的白芥子苷（glucosinalbin）。因此，本实验的结果证明，白芥子苷是甘蓝蚜寄主部位选择的关键信号化学物质或取食促进剂。

Role of glucosinolates in the host plant part preferences by the cabbage aphid,Brevicoryne brassicae

Feeding behavior of the cabbage aphid ( Brevicoryne brassicae ) was recorded with electrical penetration graph (EPG) and glucosinolates in tissues of mustard ( Sinapis alba ) parts were analyzed with HPLC to investigate the roles of glucosinolates in the host plant part preference by the aphid. Three plant parts of mustard were chosen for EPG recording and chemical analysis, i.e., the laminas and petioles of the 7th fully expanded leaves, and stems of flower buds. Stylets of the aphids on the stems could reach the phloem with less probes and shorter time compared to those of aphids on other two parts. And no significant differences were found in feeding behaviors among aphids on three plant parts once sustained ingestion started in the phloem. Only sinalbin of three glucosinolates was found from epidermis and cortex in the stems of flower buds. Our results indicate that sinalbin is an important indicative chemical or feeding stimulant in host plant part preference by the cabbage aphid.