Abstract: This study aims to determine the contact toxicity of Agastache rugosus essential oil against Tetranychus cinnabarinus and its effects on several protective enzymes activities. The contact toxicity of A. rugose essential oil against 5-day-old old female adults and eggs, and its oviposition inhibition activities were measured by spray application. The activities of protease and three protective enzymes (SOD, POD and CAT) were also measured in the female adults treated with the essential oil at three different concentrations (LC₃₀, LC₅₀ and LC₉₀) at 4, 8, 12, 16, 20 and 24 h post treatment. The mortality of female adults and inhibition of egg incubation were positively correlated with the concentrations applied, for which LC₅₀ values were 0.60% and 0.62%, respectively. Moreover, with the increasing of concentration, the contact toxicity, the oviposition inhibition rate and index all increased. Female adults were more sensitive to the treatment than eggs. At 4 h after treatment with different doses, protease and POD were activated, while SOD activity was inhibited. Protease was activated by 10.96%, 47.70% and 62.92% at the LC₃₀, LC₅₀ and LC₉₀, respectively; POD activities were 2.3, 1.5 and 0.3 times higher than those in the control group, respectively; SOD inhibition rates were 44.52%, 23.91% and 49.08%, respectively. CAT activities were activated at LC₃₀ and LC₅₀, the activation rates were 20.26% and 52.22%, respectively; at LC₉₀, CAT activity was inhibited by 62.21%. It is obvious that A. rugosus essential oil has a potential to kill the female adults and inhibit oviposition, which may be the results of abnormal physiological metabolism of protease and protective enzymes. Therefore, A. rugosus essential oil might be developed into a control agent against T. cinnabarinus.

Key words: Agastache rugosus essential oil, Tetranychus cinnabarinus, contact toxicity, protease, protective enzymes