Biocontrol agent and application thereof in prevention and control of spodoptera frugiperda

The invention discloses a biocontrol agent and application thereof in prevention and control of spodoptera frugiperda. The biocontrol agent comprises entomopathogenic nematodes, cane sugar, leaf acetate and a nutritional additive, the entomopathogenic nematodes are Steinernema carpocapsae, and the entomopathogenic nematodes are the Steinernema carpocapsae. The content of the leaf acetate in the biocontrol agent is 1 to 1.3 percent; the nutritional additive is prepared from the following components in parts by mass: 3 to 6 parts of peptone, 4 to 5.5 parts of beef extract, 3 to 4.5 parts of agar powder, 3 to 4.5 parts of wheat flour, 3.2 to 4.7 parts of corn oil, 10 to 12 parts of corn leaf alcohol extract and 5.2 to 5.7 parts of yolk powder; according to the method, the entomopathogenic nematodes are used for preventing and controlling the spodoptera frugiperda, larvae of the spodoptera frugiperda and female insects in the mating period are mainly trapped and killed under the dual effects of the cane sugar and