Preparation Of Abamectin Nanocapsules And Its Against Root-knot Nematode(Meloidogyne Incognita) Disease

Root-knot nematode disease is a damaging disease to crops which causes huge economic losses around the world annually.With the increasing area of vegetables in protected of China,the occurrence and damage of root-knot nematode disease have also increased year by year.At present,chemical control is still the main method for controlling root-knot nematode,among which abamectin is the most commonly used agent.Our previous research found that the poor mobility of abamectin in the soil during irrigation application compromises their performance around the plant root system and causes enormous waste.In this study,abamectin nanocapsules were successfully prepared using nanotechnology,using epoxy resin polymer and sodium lignosulfonate as nanocarriers,and inverse emulsification and interfacial polymerization.The physicochemical properties of the nanocapsules were analyzed and characterized by various analytical methods.Through a series of experiments such as biological activity,fluorescence tracing,and soil distribution of pesticides,the interaction between the nanocapsules and nematodes,soil and plants was studied,and the mechanism of action of abamectin nanocapsules was revealed.Finally,pot plants and field experiments were used.Finally,pot and field experiments were used to verify the application effect of abamectin nanocapsules.The main results are as follows:1.Abamectin nanocapsules were successfully prepared by inverse emulsification and interfacial polymerization,using epoxy resin and sodium lignosulfonate as materials.SEM and TEM images showed that the nanocapsules had smooth spherical structure,the average particle size was 141.5nm,and the encapsulation efficiency of the samples was 93.4%.FTIR analysis and Zeta potential analysis showed that the epoxy ring of the epoxy resin was broken and cross-linked to form a polymer under the catalysis of DMP,and abamectin did not react with the capsule shell.During the formation of the capsule,the sodium lignosulfonate did not undergo a chemical reaction,but was physically embedded into the capsule shell.Compared with the conventional microcapsules（4.4μm）,the nanocapsules showed a faster release rate.After 18h,the cumulative release rate of NC reached 73.3%,while that of MC was only 48.4%.2.The virulence of abamectin nanocapsules（NC）and three other abamectin formulations（SC,ME,MC）on M.incognita J2 and their effects on egg hatching were determined by bioassay tests.The results showed that compared with the other three conventional formulations,the nanocapelles had higher nematocidal activity.The LC₅₀ value of NC was 0.96 mg/L,the LC₅₀ values of SC、ME and MC were 1.43 mg/L、1.27 mg/L and 4.46 mg/L,respectively.At the same treatment concentration,the egg hatching rate of NC treatment was significantly lower than that of other preparations.3.The behavioral characteristics of nematodes and plant roots were tracked by fluorescent tracer test.By analyzing the fluorescence distribution of the agent and the fluorescence in different nematode positions,the results proved that the nanoparticles entered M.incognita and D.destructor body.The fluorescence distribution of cucumber roots showed that NC could enter the roots of plants,and MC and ME were blocked outside the roots under the same conditions.The root protection test showed that compared with other abamectin preparations,NC treatment can significantly reduce the infestation of nematodes and protect plant roots.4.Soil adsorption,column leaching,soil thin layer chromatography,and soil distribution of chemicals were used to study the adsorption,leaching,and soil distribution characteristics of abamectin formulations.The results showed that NC significantly reduced the adsorption coefficient of abamectin in the soil,and the concentrations of abamectin in the nanocapsule group were higher in the vertical range of 5-20 cm and the horizontal range of 3-18 cm than the concentrations in the conventional formulations SC,ME and MC.and the concentration of the medicament in the vertical 5-20cm and horizontal 3-18cm was significantly higher than SC,ME and MC.Abamectin was encapsulated by nanocapsules,which significantly reduces the adsorption strength in the soil.At the same time,due to the advantage of nanometer size,it is easier to move with the water in the soil.Uniform distribution of bacteriocin in the soil.Abamectin was encapsulated by nanocapsules,which significantly reduces the adsorption strength in the soil.At the same time,because of the advantage of nanoscale size,it is easier to move with water in soil,which is beneficial for pesticides to pass through the gaps in soil,reach the deep soil and realize the even distribution of pesticides in soil.5.The pot and field experiments were used to verify the control effect of abamectin nanocapsules on root-knot nematode disease.In the pot experiment,the highest control effect of NC was 83.0%,which was significantly higher than that of SC,ME and MC treatments.In the field experiments,the control effect of NC treatment under drip irrigation and root irrigation was more than 80%at 60 days,and the control effect at 90 days was more than 70%,which was 30-40%higher than that of other abamectin preparations.These results demonstrate that abamectin epoxy resin nanopesticides are a good prospect for application to control M.incognita and improve the pesticide’s utilization efficiency.