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Biological Control : A Guide to Natural Enemies in North America Anthony Shelton, Ph.D., Professor of Entomology, Cornell University

The Need, Status, and Potential for Biological Control

With the advent of synthetic insecticides in the 1950s, easy control of insect pests appeared at hand. However, it soon became obvious that there were problems associated with the use of insecticides. Some insect pests became resistant, and some nontarget organisms were adversely affected, and pest resurgence occurred. Additionally, environmental and health concerns arose.

Today, the protection of food and fiber crops from insect, mite, disease, and weed pests in conventional agricultural systems still relies primarily on the use of chemical pesticides. However, continued reliance solely on conventional pesticides has drawbacks. The integrated pest management strategy described in this guide promotes nonchemical pest control tactics such as use of pest-resistant plants, cultural control methods, and biological control. Pesticides should be used only to prevent an economic loss and rarely should be used in a prophylactic manner.

The need to develop alternatives to conventional pesticides may be more acute in some commodities than in others. For example, vegetables and fruits are considered minor crops in many areas, and new insecticides are less likely to be registered or existing ones re-registered. Populations of many major vegetable and fruit insect pests possess resistance to insecticides. Also, vegetable and fruit growers, especially fresh market producers with small and diverse operations and roadside stands, are highly visible to the public. The application of pesticides is frequently obvious and may result in conflicts with urban neighbors. Alternatives that would reduce the need for pesticide use could help alleviate some of these conflicts.

All insect pests have natural enemies. The use of these organisms to manage pests is known as biological control. Conservation of natural enemies is probably the most important biological control practice readily available. Through the use of selective insecticides and the judicious use of broader spectrum materials, natural enemies can exist and exert their impact on pest populations. The future of biological control is promising, but this tactic will constitute just one of many pest management options. Many obstacles will need to be overcome before biological control can reach its full potential.

Traditionally, educational and extension efforts have not provided growers with the necessary information to help identify natural enemies or determine their presence in fields. The importance of natural enemies cannot be over-emphasized, and making educators (e.g., extension agents) and growers aware of their existence would be a first and very important step -- a primary purpose of this guide.

Before biological control will advance, much more emphasis needs to be placed on investigating indigenous natural enemies and their impact on the pests they attack. With this information it may be possible to foster or enhance the efficacy of natural enemies through manipulation of the crop habitat, changes in cultural practices, or changes in pesticide application practices. In addition, the introduction of new natural enemies through classical biological control programs holds much promise. The development of successful biological control programs will be challenging, but holds great potential.

Taken from:

Hoffmann, M. P. and Frodsham, A. C. (1993) Natural Enemies of Insect Pests. Cooperative Extension, Cornell University, Ithaca, NY. 63 pp.

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Podisus maculiventris feeding on a Colorado potato beetle larva

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