Bioactivity of extracts from dried powder of Portulaca oleracea L. against Aphis gossypii

Dried powder of Portulaca oleracea L. were extracted by the dipping method with methanol, ethanol, acetone, ethyl acetate, ether, trichloromethane, dichloromethane, benzene and petroleum ether, and bioactivity of the extracts against Aphis gossypii Glover including contact toxicity and antifeeding toxicity were approached. The results indicated that the methanol extract showed the highest contact toxicity with 6.63 mg·mL -1 (dried powder) of LC_ 50 among the 9 different extracts and the dichloromethane extract had the highest antifeeding toxicity with antifeeding rate 83.03% at the quality concentration 100 mg·mL -1 (dried powder) in the extracts after 24 h. After 48 h, the contact toxicity of the acetone extract was the highest with LC_ 50 1.88 mg·mL -1 and the dichloromethane extract had the highest antifeeding toxicity with antifeeding rate 83.97% at the quality concentration 100 mg·mL -1. Under the concentration of 25 mg·mL -1, the antifeeding rate of the petroleum ether extract was the highest, reached to 71.25% and 81.20% after 24 and 48 h respectively. The sequence of bioassay results for both contact toxicity and antifeeding toxicity of the 9 extracts from P. oleracea were also arranged respectively.