Biological control is the planned manipulation of predators, parasites or diseases to reduce the damaging impact of crop pests.
All organisms have natural enemies in their environment that limit their populations.
Disease and parasites may weaken or directly kill individuals and predators remove the inexperienced, the sick or the old from a population. In general, these checks and balances on populations are positive and serve to maintain a healthy equilibrium. While natural control occurs in agricultural systems, frequently the balance is tipped in favor of the pest. Producers can improve on natural control by purposefully manipulating natural enemies to reduce pest populations. Importation refers to the process where an exotic pest is controlled by natural enemies which are imported from the pests country of origin.