Biological control (biocontrol) is the use of living organisms to reduce pest abundance and damage. Biocontrol agents are often consumers of pests; thus herbivores are used to reduce weeds, while predators or parasites are used to reduce insect and other animal pests. Pathogens and competitors that interact with pests are also used in biocontrol. Biologically based pest management includes biocontrol and other techniques, such as the use of pheromones to disrupt mating by pests. Agricultural and forest pests are the main targets of biocontrol, although biocontrol is also used against threats to human health (such as mosquitoes) and the environment (such as certain weeds). Biocontrol may operate as an alternative to pesticides and other control techniques or may be included in an integrated pest management system. The successful practice of biocontrol typically requires knowledge of the ecology of pests and their biocontrol agents and may also involve techniques based on other scientific disciplines, including physiology, animal behavior, genetics, and biochemistry. The three major methods of biocontrol are importation, augmentation, and conservation.