The ultimate goal in treating harmful insects in the landscape is reducing the risk of insecticide exposure to people and animals through alternative controls.
One of those controls is the use of certain biological organisms, byproducts of biological organisms and products that affect the growth and development of pests to manage pest populations.
Several of these natural organisms have been isolated and harnessed for use in order to control a variety of agricultural pests.
Predators are the most recognized biological control organisms. These are active hunters that are usually larger than their prey and they must consume large quantities of prey to complete their life cycle. They play a limited but important role in pest management.
The most commonly recognized predators are lady bugs and lacewings. Lady bugs typically prey on all stages of aphids, scale insects and spider mites. Lacewings feed primarily on aphids.
Predators do not typically produce the rapid results homeowners expect and therefore may not be aesthetically acceptable. Other limitations include the need for hundreds of predators to effect any major control.
These are organisms that live in or on another organism (called the host) typically to the parasite's benefit and the host's detriment.
Wasps develop inside the host after eggs are laid in or on the host by the female wasp.
Parasites are more efficient biological controls because they are host specific.
The use of insecticides should be carefully managed when parasites and predators are present to avoid disrupting the natural predator prey balance.
These are soil-inhabiting worms that are parasitic on plants and animals. They have been most most effective against beetle and moth borer larvae.
These are single-celled organisms and the oldest commercially marketed biological insecticides. Bacteria must be ingested in order to cause toxicological effects on the pest. Most pathogenic bacteria contain a crystalline sport and toxin. When the spore enters the pest's digestive enzymes to eat holes in its gut, thereby releasing the bacteria and gut contents into the blood. These events lead to an infection that eventually kills the pest.
These are multi-cellular organisms closely related to plants that cause diseases in a variety of pests. They infect the pest through spores that require moisture and humidity in order to germinate and penetrate the outer skeleton of the pest. Infected pests die from toxins produced by the fungus.
These are incomplete cellular organisms composed of either DNA or RNA. They are entirely host dependent, relying on the host for their development and replication. Naturally occurring viruses frequently control caterpillar and sawfly outbreaks.
Biological control methods can be used as part of an overall integrated pest management (IPM) program to reduce the legal, environmental, and public safety hazards of chemicals. In addition, it may be a more economical alternative to some insecticides. Unlike most insecticides, biological controls are often very specific for a particular pest. Other helpful insects, animals, or people can go completely unaffected or disturbed by their use. There is less danger of impact on the environment and water quality.