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Many field crop and greenhouse vegetable producers inquire about the best use of natural enemies and commercial biological control agents. Biological control agents or BCAs include small parasitic wasps as well as predators. There are also pathogens that cause disease in insects but that is a separate topic of discussion. Always start by conserving natural enemies and knowing the major species in order to include them in your IPM plans. In general, closed farming systems like greenhouses and netted high tunnels see more success with biological control agents compared to open field production systems. Here are additional tips for successful use of BCAs:

Lacewing larvae for biological control.

  • Use correct species at the right time and dosage: Choose species that are easy to handle and effective. This step takes time to learn.  Farmer have their favorite species of predators, e.g., the lacewing and lady beetle larvae. The trick is to release them at the right time synchronized with the life cycle of the pest and in the right numbers using the best methods. Don’t scatter lacewings that come in bottles like spreading fertilizer.  Use small cups hung in the foliage and gently pour out the larvae.  Don’t do too little too late. Use biocontrol agents ahead of a pest outbreak after full identification. Parasitic wasps can be very specific for aphid and whitefly species.  Do not buy them in a rush. Also, purchase them early during the week, not late in the week to avoid beneficial insects dying in shipment.
  • Vendors: We have purchased and tested natural enemies from many different online vendors including Arbico Organics, Gardens Alive, Kopert,  and Rincon-Vitova Insectaries among others. Growers can purchase many different species of BCAs that are packaged in certain numbers in bottles (predators) or strips (parasitic wasps). They all seem to provide good products and customer services in case of a problem. If you have concerns, give the vendor a call and discuss with a technical service representative.  Before calling, make sure you know the pest species you are trying to manage and approximate area where you want to implement a biological control plan. Vendors can then stagger the mailing of BCAs on a weekly basis and not ship all at once.
  • HTPE benefits: High tunnel pest exclusion (HTPE) systems using shade cloth have added benefits in terms of integration with natural enemies. For example, the use of a 50 percent shade-cloth based exclusion system can help contain adult lacewings which are voracious feeders of small insects like aphids, whiteflies, and thrips under high tunnels. When using an insect barrier fabric or row cover, gardeners can also introduce natural enemies under the fabric and close tight to let the natural enemies feed on small insects.
  • Trap crop benefits: Trap crops can increase plant biodiversity and reduce pest infestations on the main crop.  This can result in an overall reduced need for overhead spray applications. In large IPM research plots and field demonstrations, we have experienced an increase in parasitic tachinid flies and predators like syrphid flies, lady beetles, and spiders on trap crops that actively feed on leaffooted bugs and other large pests.

A true IPM approach integrates various pest prevention, control, and biocontrol tactics into an environmental-friendly solution. Contact Cooperative Extension in your state for details about IPM tactics and design a plan that suits your farm. The new Organic Vegetable IPM Slide Chart has many trap crop, pest exclusion, and bioinsecticide use recommendations that can help protect natural enemies. Visit the www.alabamabeginningfarmer.com for various learning materials and videos on IPM.

Trade and brand names used in this publication are given for information purposes only. No guarantee, endorsement, or discrimination among comparable products is intended or implied by the Alabama Cooperative Extension System.

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