Microbial Control of Insects, Weeds, and Plant Pathogens

Abstract

Microbial control is here defined as “The utilization of pathogens for the management of pest populations.” Nematodes, although not microorganisms, are considered to be “microbial control” agents because of the techniques involved in their utilization. Various types of microorganisms have been used in biological control, among them bacteria, viruses, fungi, and protozoa. The most important groups of microbial agents are discussed in this chapter. In the broadest consideration, pathogens are important naturally occurring biological control agents. In nature, microbial pathogens frequently cause epiphytotics and epizootics, which help maintain the balance of plant and animal populations. The role of microbes in the dynamics of organisms was observed early on by biologists, who eventually initiated studies to attempt to manipulate pathogens for pest control. This was the genesis of the microbial control tactic that in recent years has become a more significant weapon in the pest control arsenal. Microbial control has predominantly involved the artificial manipulation of pathogens, especially viruses, bacteria, fungi, protozoans, and nematodes formulated as sprays or dusts to suppress outbreaks or threatened outbreaks of pest arthropods (or weeds). Environmental manipulation (e.g., irrigation practice) is also utilized to enhance activity of certain pathogens and thus effect microbial control, although this is as yet a relatively poorly developed aspect of the tactic.