Abstract: 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.

Key words: glucosinolates, Brevicoryne brassicae, plant part preference, HPLC, EPG