Important antagonists of harmful insects, mites and nematodes are beneficial organisms (predators, parasitoids, entomopathogenic nematodes) and their pathogens (viruses, bacteria, fungi and other microorganisms). They represent an important resource for biological plant protection measures. Macrobial and microbial antagonists are characterized by a high selectivity and low or non-existent effects on non-target organisms. They thus provide the basis for particularly environmentally friendly plant protection methods.