The microbes which are used as biocontrol agents of pests include...

Biocontrol refers to the use of biological methods for controlling plant diseases and pests. The microbes used as biocontrol agents include bacteria, fungi, protozoans, and viruses.

Examples include:
Bacteria: Bacillus thuringiensis is used to control butterfly caterpillars.
Fungi: Trichoderma species are free-living fungi that are very common in the root ecosystems and are effective biocontrol agents of several plant pathogens.
Viruses: Baculoviruses are pathogens that attack insects and other arthropods, widely used as species-specific, narrow spectrum insecticidal applications.
Protozoans: Nosema locustae is used to control grasshoppers and other insects.

Algae, lichens, viroids, and prions are not used as biocontrol agents.

Answer: bacteria, fungi, protozoans and viruses