| In the face of the difficult situation for exploring the new pesticides, the development of the mixture pesticides had become one of the main developing directions, meanwhile, the mixture pesticides such as plant-pesticide and chemical-pesticide had recently been in high prominence in the research for its outstanding advantages. Acontium flavum Hand.-Mazz. was a suitable insecticidal plant, however, the studies of Acontium flavum Hand.-Mazz. had been mainly focused on the bioactivity of its crude extract, the information of mixing this plant with chemical pesticides had hardly been reported. In this article, Plutella xylostella L. was as insecticidal target, the toxicities of mixtures of total alkaloids from Acontium flavum Hand.-Mazz. and chemical pesticides were studied, screening the group that presented synergy after mixture, the best ratio of the two alkaloids was optimized, and then the Emulsion in Water was prepared, the field efficacy experiment were conducted. The main results obtained in this article were as follows:1、Insecticidal activity of the different solvents extracts from Acontium flavum Hand.-Mazz. against Plutella xylostella was comparedInsecticidal activity of the extract from Acontium flavum Hand.-Mazz. with different solvents (including95%ethanol, petroleum ether, dichloromethane, ethyl acetate and methyl alcohol) against Plutella xylostella were tested, the result showed that each of the solvent extracts had some contacting toxicity to the target insets and gave a contacting active as follows:95%ethanol>petroleum ether> dichloromethane> methyl alcohol> ethyl acetate.2、Study on action mode of the different parts of Acontium flavum Hand.-Mazz. against Plutella xylostellaDifferent parts of Acontium flavum Hand.-Mazz. such as root, stem, seed, leaf and pod were separated, and their ethanol extracts were obtained. Four different methods such as dipping, leaf-dipping, leaf added and feeding were adopted respectively to test the different bioactivities of contacting, anti-feeding, stomach poison and inhibition of growth and development. The results showed that ethanol extracts of different parts of Acontium flavum Hand.-Mazz. had obvious contacting, anti-feeding and stomach poison activity against Plutella xylostella similarly, but the growth inhibition activities was relatively weak. Furthermore, ethanol extracts from different parts of A. flavum Hand.-Mazz. such as root, pod, stem, seed and leaf showed the different bioactivities against P. xylostella. In the five parts, the extracts of root, pod and stem displayed stronger activities than the others.3、Study on bioactivity of the different insecticides against Plutella xylostellaThe toxicities of alkaloid from Acontium flavum Hand.-Mazz. and synthetic chemical insecticides against Plutella xylostella L. were compared. The results showed that Avermectins had the highest activity with the lowest lethal concentration, and the contact toxicity showed as follows:Avermectins> Emamectin benzoate> Carbosulfan> Acetamiprid> Malathion> Alkaloids from Acontium flavum Hand.-Mazz.>lambda-cyhalothrin>Imidacloprid.4、Co-toxicity of mixtures of alkaloid from Acontium flavum Hand.-Mazz. and seven synthetic chemical insecticides against plutella xylostellaThe toxicities of mixtures of alkaloid from Acontium flavum Hand.-Mazz. and seven synthetic chemical insecticides against Plutella xylostella L. were compared. The effects of co-toxicity were evaluated by the methods of Bliss, Three coordinates and Sun respectively. Furthermore, the best distribution of composite was optimized, the results showed that the mixtures of alkaloid from A. flavum Hand.-Mazz. and Lambda-cyhalothrin had obvious synergism, and the co-toxicity coefficient (CTC) was173.28under the proportion of4:1.5、Study on the distribution of water emulsion of the mixture of alkaloid from Acontium flavum Hand.-Mazz. and Lambda-cyhalothrinUsing solubility, flow dispersity, cool and hot stability as target, solvent, emulsifier and co-emulsifier were choosed, the formula of distribution of water emulsion were determined through the orthogonal test, as a result,20%of the solvent,4%of cryoprotectant,8%of emulsifier,7%of co-mulsifier,10%of drug, and tap water was added to100%. The distribution of water emulsion was prepared by formula, with alkaloids from Acontium flavum Hand.-Mazz. and Lambda-cyhalothrin as active constituent, and insecticidal activity were evaluated with different concentrations against Plutella xylostella. The results indicated that this preparations exhibited obvious activity which was superior to the simple distribution content, the LC50were0.60mg/mL and1.10mg/mL at72h, respectively.6、The biosafety evaluation and the field trials of water emulsionCarassius auratus, one of the sensitive biologicals, was selected as the research object, and the polarity toxicity experiment of the water emulsion on Carassius auratus was tested by static bioassay tests. The results showed that the water emulsion had low toxicity on Carassius auratus with the lethal concentration of50%was3510mg/L after96h, therefore, we can draw a conclusion that it was safe to aquatic organism and surrounding environment.The water emulsion was prepared by magnetic stirring, tap water was as solvent blank, the field trials of the water emulsion against Plutella xylostella and Wolfberry aphis were investigated. The result displayed that the control efficiency of the water emulsion against Plutella xylostella L and Wolfberry aphis were92.79%and94.49%, respectively, showed the effective control efficiency compared to chemical pesticides (87.69%), meanwile, the water emulsion can keep efficiency within11days, which was longer than traditional chemical pesticides which has only8days. |
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