Abstract: Berberine is one of the alkloids in Coptis chinensis Franch. Berberine hydrochloride was extracted from fresh roots of Coptis chinensis from Huaxi, Guiyang. The extract was crystalized and the content was measured with spectrophotometer. The crystalized product contains 91% berberine hydrochloride. The percentage of berberine hydrochloride in the Coptis chinensis is 11.56%. The result of bioassay in laboratory showed that berberine hyddrochloride has very strong contact toxicity and relatively good antifeeding activity to Brevicoryne brassicae (Linnaeus).1% berberine hydrochloride solution of ethanol was prepared and used to treat the aphid typically. After 96 hours, mortality rate was 92.5%。Its rectified mortality and LC₅₀ were 91.4% and (2.289±0.0215)g/L respectively. The regression equation is Y=7.712+1.027X. The coefficient of correlation is 0.958, reaching to the significance level. 1% berberine hydrochloride solution of ethanol was also used to treat cabbage leaves. Aphids were subsequently introduced on them. After 24 hours, the landing rate of aphids on the treated and control leave surfaces were 20.6% and 79.4% respectively. The antifeeding effect was 74.04%, AFC₅₀＝(4.055±00215)g/L. The regression equation is Y＝9.115+1.719X. Coefficient of correlation is 0.998, at very significance level.

Key words: Coptis chinensis, berberine hgdrochloride, Brevicoryne brassicae, contact toxicity, antifeeding activity