Effects of Three Botanical Insecticides Against Pieris rapae L.

The result of bioassay indicated that 0.1% rhodojaponin-Ⅲ EC had the same effect of antifeedant and toxic activity against the 3rd instar larvae of Pieris rapae L.,while but the antifeedant activity of 0.3% azadirachtin EC and 2.5% rotenone EC on this pest were stronger than its toxic activity,the variation of them were 185.44-fold and 13.78-fold,respectively.The result of pot testing showed that 0.1% rhodojaponin-Ⅲ EC had obvious control effect on the pest and good effects on protecting leaves,the pest mortality rate in the first to the third day was 92.45%～100% after treatment,and the leave protecting effect was 96.63%～98.18% in the third day with dilutions of 2 000～6 000 times.0.3% azadirachtin EC gave only 20.00%～34.00% mortality rate on the pest in the first day,but provided 91.34%～96.13% leave protecting effect in the third day with dilutions of 1 000～2 000 times.2.5% rotenone EC gave the lowest effect against the Pieris rapae L.with dilutions of 500～1 500 times.