Preparation of Emamectin Benzoate·Hexaflumuron Granules Based on Response Surface Methodology

In order to obtain particles with an optimal loading rate and encapsulation efficiency and to explore the effects of sodium alginate, carboxymethyl chitosan, and bentonite on the particle loading rate and encapsulation rate, the preparation parameters of particles were optimized by the response surface method. A series of particles with constantly changing components were prepared, and the particle loading rate and encapsulation rate were determined. The release experiment of granules in different mass release media was implemented, and the optimal loading rate and encapsulation efficiency of particles were used to control the fall armyworm (FAW). The results showed that when the amount of sodium alginate was 1.83%, that of carboxymethyl chitosan was 0.41% and that of bentonite was 0.37%. The maximum theoretical value based on the response surface simulation was 92.63%, and the actual value at this ratio was 91.61%, which was 98.90% of the theoretical value. The release assay indicated that the mechanism of particle release in 2, 4, and 6 mL of the release medium was non-Fickian diffusion, and the controlled mechanism in 25 mL of the medium was Fickian diffusion. The beads were spread directly into maize leaf whorls in field production; at 14 days after application, the efficacy reached 91.28-98.82%. The combination of emamectin benzoate and hexaflumuron granules has a good control effect on the FAW.