Discovery and Development of Microbial Biological Control Agents

The use of microbial biocontrol agents as biopesticides has become an attractive insect pest management choice due to concerns regarding effects of chemical pesticide residues on human and animal health. In the biopesticide approach, an endemic microbial pathogen of an insect pest is identified that is capable of rapidly infecting and killing the target pest when the focal area is inundated. Initial screenings focus on finding aggressive pathogens of the target insect pest. The host range of these pathogens is then evaluated to ensure their safety. Formulations are subsequently developed to ensure effective application in the field. Once developed, the microbial biocontrol agent is used in a manner similar to a chemical pesticide. The mode of action, however, is such that the infective propagules produce multiple infections in the insect pest resulting in death. Because the biocontrol agent is restricted in its host range, only microbial propagules which contact and infect susceptible pests survive. Long-term persistence in the environment normally does not occur, so typically the inundation approach to microbial biocontrol does not produce multi-year control of the pest. Thus, seasonal application of the biocontrol agent is required, which provides the commercial incentive for development.