Fabrication,Characterization And Biological Activity Of Emamectin Benzoate Nanoformulation

Emamectin Benzoate(EB)is a highly potent semi-synthetic derivative of avermectin microbial source pesticide for animal husbandry medical treatment and plant pest control.However,the characteristics of its low water solubility and susceptibility of photodegradation,the commonly used pesticide formulations of EB,such as EC and ME,contain a large number of organic solvents and require multiple sprays to maintain the control effect,which greatly increases the risk of resistance of pests and pesticide residue.Nano pesticides have a small particle size,high dispersion,good adhesion,also,have the advantages of green & safe,high pesticide utilization rate.Using surfactants to obtain nanopesticides is low energy consumption,simple,and fast way to obtain nano pesticides.Nonylphenol polyoxyethylene ether sulfonate(NPSO)is a negatively charged anionic surfactant used as an emulsifier in liquid pesticide formulations.In this paper,the surfactant was screened surfactant and the surfactant nonylphenol polyoxyethylene ether sulfonate(NPSO)was selected,a modified nonylphenol polyoxyethylene ether sulfonate(m-NPSO)with a specific dispersion effect on EB was obtained.And based on this surfactant modification,an EB nanoformulation with no organic solvent and slow-release function was developed,and its physicochemical properties and biological activity were determined.The research results are as follows.1.Discuss the effect of five commonly used agricultural anionic surfactants on the dispersion of EB in water,and find that NPSO has a certain dispersing effect on EB,But the dispersion ability is limited;The factors such as the amount of NPSO,stirring temperature,and stirring intensity influence on the dispersing effect of EB in water were discussed.It is found that the dispersion effect is proportional to the amount of surfactant;temperature helps the dispersion of EB in water;the increase of the stirring intensity has no obvious effect on the dispersion of EB.2.Since the dispersing effect of NPSO on EB is unsatisfactory,NPSO was modified and obtain a surfactant with a specific dispersion effect on EB: m-NPSO.The m-NPSO was characterized by H-NMR and IR to confirm that the target modified product was obtained.3.1% EB nanoformulation was developed using m-NPSO.The formula structure is,EBTC 1%,m-NPSO 16%,30%PEI aqueous solution 16%,BY-125 4%,xanthan gum 1%.The prepared 1% EB nanoformulation were characterized by DLS,TEM,and FTIR,and their storage stability,slow-release performance,photolysis resistance,and surface tension were measured.The average particle size of the prepared 1% EB nanoformulation is 6.35 nm,and the storage stability is qualified.Within 50 hours of the sustained release time,the release of the EBTC is complete,the cumulative release of EBEC reached 70%,and the nanoformulation is 60%,the release of EBEC within 72 hours is complete,and the release of EB nanoformulation takes 120 hours completely,the EB nanoformulation shows a certain sustained release performance;Under ultraviolet light,EB nanoformulation showed a certain photolysis resistance,when the ultraviolet is irradiated for 3 hours,the photolysis rate of the EBTC reaches 55%,and the photolysis rate of the EB nanoformulation is only 2.5%;The surface tension data results show that the control sample 1% EBEC surface tension is38.22 m N/m,1% EB nanoformulation surface tension is 30.12 m N/m,1% EB nanoformulation has better wetting spreadability.4.Determination of toxicity of 1%EB Nanoformulation to adult Bactrocera dorsalis(Hendel)and Mythimna separata Walker under indoor conditions.EBTC and 1% EBEC were used as the control group,and clean water was used as the blank control.Toxicity of 3 to 5days old adults of B.dorsalis was measured using the drug film method.Under the same environment,the LC50 of 3 to 5-day adult B.dorsalis in 3 days 1% EB nanoformulation:1.459 mg/L,1% EBEC: 0.637 mg/L,and EBTC: 0.486 mg/L.The toxicity test to Mythimna separata Walker was carried out by the leaf soaking method.The toxicity of 1%EB Nano formulation,1%EB EC,and EBTC: 24 h LC50: 0.161mg/L,0.100 mg/L,0.096 mg/L,respectively;48h LC50 are: 0.067mg/L,0.054 mg/L,0.059 mg/L,respectively;72h LC50 are:0.033mg/L,0.037mg/L,0.044 mg/L,respectively.Using foliar spray to control Mythimna separata Walker,the advantages of the nano formulation are more obvious.In the long-lasting test,the concentration of 1% EB nanoformulation is 16 mg/L,and the mortality rate of the test adult is 77% for 9 days,and the mortality rate of the test adult is96% for 11days;at the same concentration,1% EBEC,the mortality rate of test adults is 56%for 9 days,the mortality rate of test adults is 87% for 11days;the concentration of 1% EB nanoformulation is 32 mg/L,the mortality rate of test adults has reached 93 % for 9days;under the same concentration and duration of action,the mortality rate of 1% EBEC is 72%.1% EB nanoformulation has better persistence.