Study On The Bioactivities Of Essential Oils And Their Mixtures With Acaridicides Against Pest Mites

In this paper, the bioactivities, the mode of action and synergistic mixture of 7 kinds of essential oils, including Cinnamon oil, Eucalyptus oil, Porrectum oil, Turpentine oil, Staranise oil, Sesame oil and Castor oil against pest mites, had been investigated, and based on the enhancement action of the mixture of essential oils on acaridicide, a new formulation with essential oils and acaridicide was developed. The main results were outlined as follows:1. The mode actions of the essential oils against Tetranychus truncates Ehara and Panonychus citri (McGregor)were mainly contact action, ovicide and repellence. The results of bioassay showed that Castor oil and Cinnamon oil got more contact toxicity against T. truncates than other oils tested, LC₅₀ were 3.57 ml·L^-1,4.90 ml·L^-1, respectively. Cinnamon oil had the most contact toxicity against P. citri in the oils, whose LC50 was 3.96ml·L^-1 Cinnamon oil also got the most ovicidal activity against T. truncates and P. citri, the ovicidal rates were 92.31% and 94.10%, respectively, at the dilution of 25-fold. Sesame oil and Porrectum oil showed more repellent activity against T. truncates than the others, the values of repellent rates were 81.30% and 77.33%, respectively, at the dilution of 1000-fold, and Sesame oil got the most effective in repellent activity against P. citri ,the repellent rate was 52.09% at the dilution of 1000-fold.2. Toxicities of five prescriptions mixed with several essential oils against the two mites were measured. The results suggested that the mixtures of the essential oils showed good synergism action to the mites and the 4^th prescription be the best one. The toxicities of the 4th prescription against T. truncates were more effective than that of single essential oil, the value of LC₅₀ was 1.86ml·L^-1. At the dilution of 25-fold, the ovicidal rates of the 4^th prescription on T.