Abstract:

To screen the new botanical acaricide, the biological activities of 8 species of plant extracts were measured in laboratory by leaching stem immersion method. The results showed that: the biological activities of Platycladus orientalis (L.) France, Euphorbia australis L., Rumex japonicas Houtt and Punica granatum Linn. at the concentration of 20 mg/mL were high, with corrected mortality over 90%, 24 hours after treatment. According to the results of the above, the contact toxicities of these 4 plant extracts against Tetranychus cinnabarinus were tested and the LC50 value of the 4 plant extracts, ranging from low to high, with plant Platycladus orientalis (L.) France at (5.3221±0.0325) mg/mL, followed by plant Euphorbia australis L. at [(6.2726±0.0264) mg/mL], plant Rumex japonicas Houtt at [(7.9278±0.0256) mg/mL] and Punica granatum Linn. at [(9.2979±0.0194) mg/mL]. In addition, killing eggs role and Spawning inhibition of Platycladus orientalis (L.) France and Euphorbia australis L. were studied. And Killing eggs poisonous forces were respectively 36.4650 mg/mL, 96.8368 mg/mL of platycladus orientalis (L.) France and Euphorbia australis L. at the concentration of 20 mg/mL for 24 hours, their oviposition inhibition were 66.81%, 48.29%, and their repellency rate were 68.86%, 35.40%.