The following is a good article from the New England Greenhouse Update website on preparing for using biological controls in greenhouses before the spring season.
If you are planning to use biocontrol for pest management in your greenhouse for spring crops, then it is time to prepare now. Management, growers and staff all need to be on-board and involved. A biological control program should never be started in the middle of a growing season. Begin a biocontrol program that will be at the start of a new crop cycle. Biocontrol prevents problems, it does not fix problems, which is why planning needs to be done now.
Begin by reviewing pest problems from this past year and VERY IMPORTANT, avoid pesticide use 3-4 months prior to using biological control. When crops are in the greenhouse, develop and start a consistent monitoring procedure. Set a start date for using biological control. Develop a strategy based on your production planning, that is right for your particular situation. Start using biological control agents in your propagation area, right from the start. If you are buy in rooted or unrooted cuttings ask your supplier/broker to supply specific information on what pesticides may have been using on the cuttings. Toxic pesticide residues either on in or around the greenhouse or on plant material is one of the main reasons for failure using biocontrol control agents. It is important to phase out the use of pest control materials in the organophosphate, carbamate, and pyrethroid chemical classes prior to releasing natural enemies since many materials in these chemical classes can persist for four months or longer in the greenhouse.
For more information on the compatibility of pest control materials with natural enemies refer to on-line databases under side effects, such as Koppert, Inc., or Biobest . Talk with your supplier of natural enemies, too. Research is continuing on the compatibility of pest control materials with natural enemies.
During the transition period, before using biocontrol, growers might use products that are not necessarily compatible with natural enemies, but have a short residual effect of less than 2 weeks. Examples of these pesticides are abamectin (Avid), imidacloprid (Marathon, Tristar), dinotefuran (Safari) and pyriproxyfen (Sanmite). Products that are compatible and have short residual include bifenazate(Floramite) and pymetrozine (Endeavor).
Article by Tina Smith, UMass Extension and Leanne Pundt, UConn in the New England Greenhouse Update http://www.negreenhouseupdate.info/index.php/updates