Study on the non-preferable plants extracts against Pieris rapae L.

Based on the theory of co-evolution between plants and insects, many plants release secondary metabolites to protect them from being infected by insect pests. 11 plants were used in the paper to determine the effect of repelling the pest,Pieris rapae L,away from the plants, deterring the egg laying of adult, and causing death by toxicity. An interference index of population control (IIPC) was constructed to evaluate the effect of plant extracts. The result showed that 2 plants extracts, Xantgium sibiricum Patrin and Bougainvillea glabra Choisy,had good effect against the pest Pieris rapae L. and the IIPC were 0.127,0.192 respectively,that is,the control efficacy were 87.3%,80.8% respectively.