Study On The Preparation Technology Of High-efficiency,Low-toxicity And Lowresidue Vector Inhibitor

With the continuous advancement of the "toilet revolution",the environment of rural toilets in my country has been greatly improved.However,in general,the penetration rate of rural sanitary toilets in my country is not high,and farmers’ awareness of preventing and controlling mosquitoes and other vectors is weak.The farmers have the habit of raising livestock,so the rural areas are still the weakest link in the prevention and control of disease vectors.At the same time,as people’s needs for a better life increase,more and more attention is paid to the ecological environment.The development of highly efficient,low-toxic,low-residue vector inhibitors to assist the vector prevention and control of rural toilets has become the focus.In this paper,the green and safe insecticidal active ingredient dextromethrin and plant essential oils are used to prepare microcapsule suspensions,which are intended to be used for the prevention and control of rural disease vectors.Through the micro-drop method,determine the best mixing effect of d-phenothrin and plant essential oils,and get the best ratio of insecticidal active ingredients.Then through the emulsion polymerization method,to explore the best preparation conditions of the microcapsule suspension.Finally,the properties,quality control and toxicity of the microcapsule suspension were tested.The main conclusions obtained are as follows:(1)Among the three essential oils of linalool,citronella oil,and lemon oil,the best blending effect with d-phenothrin is citronella oil,and the best blending ratio is 4:1;The virulence regression equations of dextromethrin,citronella oil,and mixed agents were obtained,respectively: y=1.6377x+3.323,y=2.51587x+4.01455,y=1.8768x+4.2338,and the median lethal concentrations for housefly are 0.738 μg/μL,0.192 μg/μl,0.186 μg/μl;When citronella oil is mixed with d-phenothrin in a ratio of 4:1,the activity coefficient is3.97 and the toxicity index K=4.13.Citronella oil has a significant synergistic effect on d-phenothrin.(2)When the amount of emulsifier increases,the median diameter of the microcapsule suspension gradually decreases,and the preparation stability gradually increases.However,if the amount of emulsifier is too much,the increase in the concentration of continuous phase particles causes the stability of the preparation to decrease again.Finally,the best emulsifier dosage is determined to be(mass ratio)9.23%.With the decrease of the core-wall ratio,the encapsulated effective ingredients gradually increase,and the increase of the monomer amount also promotes the thickening of the capsule wall,which increases the average particle size and the stability of the preparation.Continue to reduce the core-to-wall ratio,and the appearance of hollow polymers leads to poor preparation stability.Finally,it is determined that the best core-to-wall ratio is0.67.As the emulsification time increases,the median diameter of the microcapsule suspension gradually decreases.However,if the emulsification time is too long,the interaction between the particles will increase and sedimentation will occur,the active ingredients will be demulsified,and the stability of the formulation will decrease.Finally,the best emulsification time was determined to be 20 min.(3)According to the stability of the microcapsule suspension agent,the composition ratio(mass ratio)of the microcapsule suspension agent is determined: sodium lauryl sulfate 9.35%,n-pentanol 3.11%,methyl methacrylate 2%,styrene 2%,citronella oil2.14%,d-phenothrin 0.53%,azobisisobutyronitrile 0.67%,deionized water 80.18%.(4)Making d-phenothrin and citronella oil into a microcapsule suspension will not reduce its contact toxicity to houseflies,and the 24 h lethality rate to houseflies can reach85%.This meets the requirements of high efficiency of vector bioinhibitors;The drug loading rate of d-phenothrin in the microcapsule suspension is 91.9%,and the embedding rate is 60.59%;The microcapsule suspension can effectively release dextromethrin for 7consecutive days,the single release rate reaches the peak on the 5th day,and the cumulative release rate can reach 90% on the 8th day,which has a good sustained-release effect;The prepared microcapsule suspension meets relevant quality control standards.