Biological control included bacteriotherapy, bacteriophage therapy, malaria therapy, probiotics, and the use of living maggots. In all cases the organisms themselves rather than a product of their metabolism were used as the potentially curative agent. Biological control is a method of plant disease management by inhibiting plant pathogens, improving plant immunity, and/or modifying the environment through the effects of beneficial microorganisms, compounds, or healthy cropping systems. The biological control method involves the use of the living organisms which act as the predators for the pests and harmful insects. The main advantage of the biological control method in the control of agricultural pests is that they are self-perpetuating. Microbes act as biocontrol agents in three ways, either they cause diseases in the pests or compete with them or kill them. Biotechnology has extended widely and has developed many biocontrol agents. Microbial control agents can be effective and used as alternatives to chemical insecticides. A microbial toxin can be defined as a biological toxin material derived from a microorganism, such as a bacterium or fungus. Pathogenic effect of those microorganisms on the target pests are so species specific.

Biological control is the use of living organisms to suppress pest populations, making them less damaging than they would otherwise be. Natural enemies of insects play an important role in limiting the densities of potential pests. These natural enemies include predators, parasitoids, and pathogens. The biological control method involves the use of the living organisms which act as the predators for the pests and harmful insects. The main advantage of the biological control method in the control of agricultural pests is that they are self-perpetuating. The principal attributes of an effective biological control agent are: efficient searching ability, high parasitism or predation rate, high reproductive potential, minimal handling time, ability to survive at low prey densities and ability to adapt to a wide range of environmental conditions. Regulating the Ecosystem to Protect and Promote Natural Enemies or Competitors of Pathogens. Plant disease often results from a disordered ecosystem. The success of biological control relies on a healthy ecosystem provided by predators, competitors, promoters, and other species. Microbial biological control agents (MBCAs) are applied to crops for biological control of plant pathogens where they act via a range of modes of action. Some MBCAs interact with plants by inducing resistance or priming plants without any direct interaction with the targeted pathogen. Biological control is a method of plant disease management by inhibiting plant pathogens, improving plant immunity, and/or modifying the environment through the effects of beneficial microorganisms, compounds, or healthy cropping systems