Biological
pest
control
"balance of nature"
Biological pest control relies upon other living organisms (parasites, predators, and pathogens) as pest control agents. These beneficial species are an important part of the ecological balance in every natural community. In some cases, biocontrol agents are reared and released in large numbers to suppress native or introduced pests (augmentation). In other cases, careful management of the environment (conservation) is sufficient to insure the welfare of natural enemy populations. Insect species that are accidently introduced from foreign countries often become pests because they have escaped from natural enemies in their homeland. Finding and importing these natural enemies is one important part of biological control.
Another facet of biological control is the use of resistant plant (or animal) genotypes. Natural host resistance may involve defensive chemicals that inhibit growth or development (antibiosis), physical or chemical characteristics that reduce palatability (antixenosis), or genetic traits that simply reduce the extent or severity of injury (tolerance).
Biocontrol agents include a wide variety of life forms, including vertebrates, invertebrates, fungi, and microorganisms. These beneficial species are common in most natural communities and, although their presence is often unnoticed, they help maintain the "balance of nature" by regulating the density of their host or prey population. Insect species often become "pests" when this ecological balance is disrupted by natural events or human intervention.
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