Biological control is a bioeffector-method of controlling pests (including insects, mites, weeds and plant diseases) using other living organisms.

It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role. It can be an important component of integrated pest management (IPM) programs. There are three basic types of biological pest control strategies: importation (sometimes called classical biological control), augmentation and conservation.

Natural enemies of insect pests, also known as biological control agents, include predators, parasitoids, and pathogens. Biological control agents of plant diseases are most often referred to as antagonists. Biological control agents of weeds include seed predators, herbivores and plant pathogens.
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Allee effects are a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness (often measured as per capita population growth rate) of a population or species.

The generally accepted definition of Allee effect is positive density dependence, or the positive correlation between population density and individual fitness. It can sometimes be referred to as "undercrowding" and it is analogous (or considered synonymous by some) to "depensation" in the field of fishery sciences. Listed below are a few significant subcategories of Allee effect used in the ecology literature.
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