Indole alkaloid contents of five winter wheat varieties at different growth stages, and the relationship between indole alkaloids and carboxylesterase activities of Sitobion avenae (F.) from wheat ears of different varieties were studied. The results indicated that KOK1679 and My295, highly and moderately aphid-resistant varieties, had a high indole alkaloid content during vegetative growth. During their reproduction growth, resistant varieties had a high alkaloid content in penultimate leaves, and indole alkaloid contents of KOK1679 were significantly higher than that of other varieties in wheat ears. The indole alkaloid contents of all varieties were low in flag leaves except for Han4564. A significant correlation was shown between carboxylesterase activity in aphids collected from wheat ears and indole alkaloid contents in ears of the wheat varieties (r ¼ 0.9646).