February 2012 Plant Health

Pest Monitoring and Maximizing Use of Beneficial Insects By Julie Graesch

Many growers no longer rely exclusively on conventional pesticides to control pests. Most have increased their use of mechanical and biological control methods.
While pesticide resistance issues have driven much of this change in management philosophy, many growers are now discovering how well biological control agents work and how to easily incorporate them into pest management programs.

Beneficial, or insect parasitic, nematodes have become more widely adopted because of their flexibility for tank-mix applications, as they are compatible with other pest control products and insecticides. They are often rotated with insecticides to help manage pests that are or may become resistant.

Other beneficial organisms pair well with insect parasitic nematodes, such as predatory beetles and mites, parasitoids and entomopathogenic fungi to manage insect populations.
Development of pest management strategies that marry mechanical, biological and chemical control methods are foundations of integrated pest management (IPM). The growers that see the most success in IPM programs take the time to educate themselves about using beneficial nematodes, and learn how to integrate biological and chemical control methods.

The six guiding principles of IPM include :
1. Establishment of action, or economic, thresholds aimed to control, but not to completely eradicate, pest populations.
2. Regular monitoring, scouting and record keeping to accurately identify and quantify pest populations over time.
3. Development of cultural practices to maintain healthy plants without excess water, fertilizer and pesticide inputs.
4. Utilization of mechanical barriers or methods that physically prevent or remove insects from a greenhouse or nursery.
5. Use of biological control agents to manage insect populations.
6. Applying conventional synthetic insecticides responsibly, by only treating when necessary and rotating modes of action to limit potential for targeted pests to develop resistance.

Importance of Monitoring

A limitation of many biological control agents is that they cannot quickly control high insect pest populations. Regular monitoring and scouting early in a crop cycle is important to identify the presence of pests.

Studying previous pest monitoring and control records will identify what pests were present, at what time of year, what control measure(s) were used, and effectiveness of control measures in controlling the pest. With this knowledge, growers can develop biologically-based IPM programs that minimize the potential of pests reaching economic thresholds.
If pests do reach thresholds, conventional insecticides that are compatible with biological control agents can quickly reduce pest populations to manageable levels. Economic thresholds vary depending on grower preference, crop species and stage, crop susceptibility and growing conditions.

Several key practices are recommended for pest monitoring.
1. Schedule time for monitoring and scouting. Scouting and monitoring are essential to a successful IPM program. Scouting should take place once or twice a week throughout the entire production season — no exceptions.
2. Monitor early. Begin monitoring as soon as new plants and cuttings arrive to help identify pests before the populations rise. Quarantine incoming plant material in order to prevent introduction of pests to other areas of the facility. Continue to monitor pest populations throughout the season.
3. Determine infestation levels. Use sticky card counts, potato slices, beating trays and other pest monitoring tools to determine population density and subsequent control measures.
• Sticky cards are an inexpensive and effective tool for monitoring flying pests. They help determine when and where the insect appears.
• Potato slices attract larval stages of many pests, especially fungus gnat larvae. Place potato slices on the soil surface and check every few days.
• Randomly pick up plants while monitoring to look for flightless insects. Study the tops and undersides of leaves and flowers for signs or symptoms of insects.
• Some insects will fall from a plant when disturbed. Place a white piece of paper or cloth and tap or gently shake a plant to dislodge insects. Quickly capture, identify and record the dislodged insects.
• Look for signs of damage from insect pests. Some insects have chewing mouthparts while others have piercing sucking mouth parts, and insects
usually leave characteristic and diagnostic signs.
4. Keep detailed records. Record the species and number of pests found while monitoring. Create a map or outline of areas that had higher infestation levels. Keeping these detailed records helps determine when certain insects become a problem and when to implement control measures.
5. Treat preventatively. Because biological control agents work best with low pest populations, it is important to prevent high infestations from occurring. Make regular applications of beneficial nematodes and other pest control methods that you choose. Pest proof netting or other physical barriers often are the first line of defense. When feasible, plants should be selected with resistance to common pests. Likewise, banker or buffer plants also can be effective.

Regular pest monitoring is essential to develop effective IPM programs, and to help guide management and application decisions. Being proactive in controlling insect pests with a combination of biological and chemical control agents will help keep your plants healthy and your customers happy.