Abstract:

The acaricidal activities of thirty extracts from ten plants were evaluated against Tetranychus cinnabarinus. The results indicated that, the T. cinnabarinus mortality rate was significantly higher when treated by 2 mg/ml of the petroleum extract from phellodendron amurense, Cercospora euodiae, or Radix Glycyrrhizae, chloroform extract from Taraxacum offcinale Wigg or methanol extract from Gardenia jasminoides Ellis. The most effective crude extract was from Gardenia jasminoides Ellis using methanol as extractant, with 83.67% of mortality rate ; The chloroform extract from Prunella vulgaris Linn led to the lowest mortality rate of 4.33％. According to the results of primary screening test，the contact toxicities of five herbal extracts against T. cinnabarinus were further tested . The results -provedthat the acaricidal activities of methanol extract from Gardenia jasminoides Ellis was highest,with LC5o value of 1.46mg/ml．