How do I tell if my greenhouse biological control program is working?
One cannot go by the philosophy of see no evil, hear no evil, and speak no evil for an effective IPM system. Someone must scout to verify a biological control program.
Increasing numbers of commercial greenhouses are utilizing biological control agents in their IPM (Integrated Pest Management) programs for the control of greenhouse pests. There is a learning curve with making a switch from conventional pesticides to beneficial insects or fungi. I believe that one of the most challenging adjustments that growers and owners must make and completely understand is the lack of “instant gratification.” When using an insecticide, soon after the application is made, there are visual signs of dead insects on your plant —such as with seeing the dead skins of aphids. For decades this has been the best method of determining if the chosen action was successful or not.
In the case of most biological control agents, there is a significant lag between release and results because many biological control agents must search out and find their insect that they either eat (predator) or inject an egg into or onto (parasitoid). Even if a biological control agent is released almost on top of the insect pest, nature must take its course and the biological agent must find and choose if that is the one it wants to eat or is it good enough for my offspring to live on or in. For parents out there, it reminds me of the challenges that are faced with a child who is a picky eater.
Many of the commercially available agents that are being produced in insectaries and marketed to greenhouses have been selected based on their performance on pest species in the greenhouse environment. The companies that provide the agents have research pertaining to their species specific to greenhouse pests, and more university-based research is becoming available.
So back to the question, how do I know they are working? A great scout is needed – a trained person that performs comprehensive scouting on a regular basis and has a deep understanding of greenhouse pests and beneficial insects. In particular, a great scout knows and understands the life cycles and behaviors of both pests and beneficials.
If your scouting system is like the monkeys who can hear, see and speak no evil, you will have a difficult time using biological control as part of your IPM program. Also, given the changing landscape of available pesticides, pest resistance, and the appearance of new pests, your IPM program is likely not giving you all it could. Stay tuned for more on biological control in your greenhouse.