Using Biological Control to Control Pests

Biological control is an appealing choice to control pests, since there is no persistence of insecticides in the environment or the development of pesticide resistance. The release of natural enemies such as predators, parasites and pathogens to control pests is a type of biological control called augmentation. However, the act of purchasing and releasing natural enemies for the control of insect and mite pests can be disappointing, due to level of the control achieved. Natural enemies are living organisms, so their behavior under different environmental conditions can influence the degree of pest control achieved.
When multiple pests occur within an area, then sometimes natural enemies are needed for each pest. Commercial products available for use to control insects and mites include bacteria, fungi, viruses, nematodes, parasites and predators. Timing of the release of natural enemies is critical, since most require some time to affect the pest populations. Releases of these natural enemies at low pest densities are more effective than releases conducted to reduce high pest densities. Environmental conditions can change dramatically and outdoor releases of natural enemies can be negatively affected by high winds, rain, hot or cold weather and other insects in the ecosystem. In addition, many natural enemies attack only certain life stages, such as egg or larval stage of the pest so multiple releases may be necessary.
Companies selling natural enemies should provide consumers with directions on how to use their products and provide claims of product performance. Also, the purchaser of natural enemies must be aware of legal and biological limitations of augmentive biological control methods.
Sometimes by simply restricting the use of broad-spectrum insecticides will allow naturally occurring beneficial organisms to survive and control the pest. Remember that when insecticides are used, the residues can remain on the crop or site or insecticide drift from adjacent areas can remain toxic to natural enemies long after the insecticide was applied.