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BIOLOGICAL CONTROL OF

PEST.

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BIOLOGICAL CONTROLDEFINITION

“The use of living organisms to suppress the population of a specific pest organism, making it less abundant or less damaging than it would otherwise be”

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WHAT ARE NATURAL ENEMIES?

Natural enemies are living organisms that:

Kill pests

Decrease pest reproductive potential

Compete with pest organisms for use of your plants.

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WHO KILLS PESTS?1) Predators2) Parasites3) Pathogens Sterilization

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TYPES OF BIOLOGICAL PEST CONTROL There are three basic types of biological

pest control strategies: importation (sometimes called classical

biological control), augmentation and conservation. Importation: Importation involves the introduction of

a pest's natural enemies to a new locale where they do not occur naturally.

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Classical biological control is long lasting and inexpensive. Other than the initial costs of collection, importation, and rearing, little expense is incurred. When a natural enemy is successfully established it rarely requires additional input and it continues to kill the pest with no direct help from humans and at no cost. However importation does not always work. It is usually most effective against exotic pests and less so against native insect pests. The reasons for failure are not often known but may include the release of too few individuals, poor adaptation of the natural enemy to environmental conditions at the release location, and lack of synchrony between the life cycle of the natural enemy and host pest.

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AUGMENTATION

Augmentation involves the supplemental release of natural enemies, boosting the naturally occurring population.

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CONSERVATION

enhance conditions for existing natural enemy survival and reproduction.

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BIOLOGICAL CONTROL AGENTS

Predators Predators are mainly free-living species that

directly consume a large number of prey during their whole lifetime.

Ladybugs, and in particular their larvae which are active between May and July in the northern hemisphere, are voracious predators of aphids, and will also consume mites, scale insects and small caterpillars.

Dragonflies are important predators of mosquitoes.

Lady bird beetle(ladybug)

Larva eating aphids

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PARASITOIDS Parasitoids lay their eggs on or in the

body of an insect host, which is then used as a food for developing larvae. The host is ultimately killed. Most insect parasitoids are wasps or flies, and usually have a very narrow host range.

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PATHOGEN Pathogenic micro-organisms include 

bacteria, fungi, and viruses. They kill or debilitate their host and are relatively host-specific. Various microbial insect diseases occur naturally, but may also be used asbiological pesticides

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Insect Mummy covered with Fungal Spores

Infected Larva

Viral fluid

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STERILIZATION

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ADVANTAGES OF BIOLOGICAL CONTROL:

high level of control at low cost self-perpetuating at little cost after initial effort very few harmful effects on man, environment etc some NE’s reproduce rapidly some NE’s search out hosts some NE’s survive even at low host densities

DISADVANTAGES OF BIOLOGICAL CONTROL

• Not effective against Direct Pests where any damage is unacceptable

• Some level of damage occurs and must be acceptable

• Must be implemented over large areas

• May take years to become effective

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