Considerations for Purchasing and Releasing Biological Control Products:
Bastiaan M. Drees, Professor and Extension Entomologist and
Allen Knutson, Professor and Extension Entomologist
Texas A&M University College Station, Texas
Purchasing and releasing natural enemies for control of insect and mite pests is an attractive alternative to the potential hazards associated with chemical insecticides (i.e., toxic effects on non target organisms, development of pesticide resistance and persistence in the environment). Furthermore, releasing natural enemies, such as lady beetles, is educational and fun for children and adults alike. However, consumers are sometimes disappointed with the level of pest control achieved by releasing natural enemies. Successful use of natural enemies requires the use of appropriate species under proper conditions. A better understanding of this method of biological control can help improve your chances of success.
What type of biological control is augmentation?
The release of natural enemies (predators, parasites and pathogens) to control pests is a type of biological control called augmentation. This approach uses commercially-available species that are applied in a timely manner to prevent population increases, or to suppress a pest population. Other types of biological control include importation (use of exotic natural enemies for pest control) and conservation (use of selected control tactics that spare natural enemies and cultural practices to modify the environment to favor natural enemies).
What are augmentive biological control products?
Commercial products available for use in augmentive biological control include microbial insecticides containing living pathogens (bacteria, fungi and viruses) and multicellular animals (nematodes, parasites and predators listed in Control Options Database). Other products occasionally used with biological control agents include synthetic honeydew, flowers to attract and conserve beneficial insects in and around pest-prone or pest-infested sites, and traps using colors or scents as attractants.
How can I best use these products?
Purchasing and releasing natural enemies for pest suppression is a rapidly developing technology but much is still to be learned to assure effective use of these products. Results are often difficult to evaluate and can be inconsistent because of differing conditions (e.g., environmental, meteorological, etc.). Natural enemies are living and their behavior under different environmental conditions can influence the degree of pestcontrol. Cost-effective use of augmentive releases requires an understanding of the pest(s), natural enemies, economic goals and theenvironment. Commercial uses often demand intensive monitoring or scouting of the cropping system.
Augmentive releases are meant to reduce populations at points in time. Releases at low pest densities are more effective than attempts to reduce high pest densities. Action levels or economic thresholds for release of natural enemies and effective release rate(s) have often not been established through scientific research.
Timing of the release of natural enemies is critical since most require some time to affect the pest population. In addition, many natural enemies attack only certain life stages (e.g., egg or larval stage) of the pest. Multiple releases may also be necessary to maintain pest suppression.
Biological control using parasites is generally pest-specific. When multiple pests occur (e.g., aphids, thrips plus beetles), natural enemies are needed for each pest. In cases where natural enemies are unavailable for augmentation, use of a selected pesticide that spares other natural enemies may be necessary.
Environmental conditions 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 (e.g., red imported fire ants). These factors are often unpredictable and result in erratic results from releases. Release of appropriate natural enemies in greenhouses and interiorscapes often provide more consistentresults.
Insecticide residues on the crop or site, or insecticide drift from adjacent areas, can remain toxic to natural enemies long after the pesticide was applied. Residues should be mitigated prior to releases.
What support can I expect from the companies selling these products?
Companies selling products and promoting their use should provide the consumer with directions on how to use their products, and support their claims of product performance. Insectaries and brokers, the companies producing and marketing parasites and predators, assure the delivery of viable natural enemies of the stated species or strain. They usually do not guarantee results from releases of these biological control agents even when used as directed. Although researchers and Extension faculty at The Texas A&M University System are involved in evaluating some of these products, suggestions for their most effective use are still being developed.
Are these products regulated by any laws?
Microbial insecticides (bacteria, fungi, viruses) are regulated like pesticides by the Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). Multicellular animals (arthropod predators, parasites, nematodes, etc.) are NOT registered or regulated by the EPA under FIFRA. Complaints regarding product performance can be reported to the Federal TradeCommission (FTC) in Arlington, Virginia (Telephone number: 202/326-2222).
The user of purchase-and-release natural enemies must be aware of legal and biological limitations of augmentive biological control methods. Just restricting frequent use of broad-spectrum insecticides often will allow a diverse group of naturally-occurringbeneficial organisms to survive, sometimes profoundly impacting pest population densities. As thecost of natural enemy products continues to decrease and delivery systems and methods areimproved, the economic feasibility of using these methods in commercial pest control will undoubtedly improve.
| hortIPM Publications | hortIPM Index |