Study On The Pesticide Microemulsion Of Acetone Extract From Artemisia Annua L. And Acaricidal Activity Evaluation

Mites,particularly phytophagous pest mites,are one of the important harmful organisms in fruit trees,forest,vegetables,flowers,crops and so on.Because of small individual size,short generation cycle,high mutation rate,mites was thought as a kind of pest which was more difficult to be controlled.Now mites resistanted to many chemical pesticide because of frequent and irrational drug use.Developing green,safe and environmental pesticides is an effective way for solving the lack of excellent acaricides.Artemisia annua L.is an annual herbaceous plant,belongs to Compositae Artemisia,has high medicinal value.Artemisinin extracted from Artemisia annua L.is most important drug for malaria and has significant value in medicine.Furthermore,Artemisia annua L.has strong insecticidal and antibacterial activity in agricultural area,especially actone extract from leaf of Artemisia annua L. has strong acaricidal activity.So it has important value for practical application and extensive popularization to develop acetone extract from Artemisia annua L.to a commercial formulation.Based on structure theories of microemulsion(ME),the extract from Artemisia annua L. microemulsifier was successfully developed.The optimal prescription was reported as follows:The content of acetone extract from Artemisia annua L.is 5%(mass fraction,same as follows); the optimum solvent is 15%DMF;the proportion of the mixture of surfactant,Tween-80 and Termul 2507,is 1:1,which totally occupied 15%weight of the formulation.The other component is tap water.A HPLC analytical method for acetone extract from Artemisia annua L.ME has been established of which the standad deviation coefficient of variation(CV) and average recovery were 0.001423,0.477%and 98.99%-100.22%,respectively.According to the related universal standard of pesticide,the quality indexes for acetone extract from Artemisia annua L.ME were established.The technical indexes of 5%acetone extract from Artemisia annua L.ME are as follow:The content of scopoletin is more than 0.0235%;the composition should appear to be a brown transparent homogeneous phase liquid;the pH value between 4.0 and 7.0;the transparent temperature range is -2-70℃;the formulation could be mixing and dissolving with water at any ratio and the diluent is transparent homogeneous phase liquid without suspended and sediments;the freeze-thaw test indicates that the frozen formulation could recover independently at the room temperature;after heat storage at temperature of 54±2℃,the decomposition rate of scopoletin should be lower than 3%.The results of bioassay showed that 5%extract of Artemisia annua L.ME had better contact toxicity against Tetranychus cinnabarinus,Panonychus citri and Petrobia harti.The LC₅₀(48h) were 117.095mg/L,153.303mg/L and 82.170mg/L respectively to adults of three kinds of phytophagous mites.The LC₅₀(48h) was 102.209mg/L to nymphs of Tetranychus cinnabarinus. Meanwhile,it was found that egg hatch of Tetranychus cinnabarinus was delayed,but the formulation had a little influence on hatching rate finally.The result of field trials showed that the Tetranychus cinnabarinus could be effectively controlled by spraying with a 400 fold 5%extract of Artemisia annua L.ME,the control effect was 88.38%in 14d,The control effect of the mixture which was 5%extract of Artemisia annua L.ME diluting 1000 fold and 24%spirodiciofen SC diluting 8000 fold was 79.54%in 30d,it can be a way to control panonychus citri in citrus orchard.