Abstract: Microbial insecticidal seed coating agents are not available. This study aims to develop an insecticidal and disease-preventing compound microbial seed coating agent with three strains of bacillus with insecticidal and disease-preventing functions and their metabolites as the main components. The type and dosage of the auxiliaries for the seed coating agent were determined through analyses of the physicochemical properties of various additives and their influence on the growth of the 3 strains of Bacillus, which was formulated as: B. velezensis ZLP-101 (≥2×10⁹cfu/mL), B. amyloliquefaciens ZLP-01(≥2×10⁸cfu/mL), and B. subtilis ZLP-121 (1×10⁸cfu/mL) mixed in a volume ratio of 1:1:1, supplemented by the film-forming agent sodium alginate 3%, the chemical synergist high efficiency cypermethrin 0.01%, the colorant acid magenta 0.2%, the thickener xanthan gum 0.1%, and the dispersant sodium lignosulfonate 2%. The agent was tested using potted maize plants in the laboratory, which showed that the efficacy of the biological seed coating agent against underground pest grubs was 70.71%, and the control efficacy of maize blight was 83.64%. The relevant indicators of this coating agent comply with the national standards for suspension seed coating agents and microbial fungal agents, which can be used for corn coating, control of soil-borne diseases and underground insect pests, and has great application potential in seed coating of other crops.

Key words: Bacillus subtilis, Rhizoctonia solani, microbial seed coating