Using Biocontrol Agents Proactively in Pest Management

Acting at the right time is one of the most critical steps in a well-rounded pest control program, especially when implementing all tools available through an Integrated Pest Management (IPM) approach. While chemical control offers quick and efficient results, it should be used cautiously and only when truly needed—as a remedy, not a first response.

In the ongoing battle against insect pests and plant diseases, prevention is often more effective—and more sustainable—than cure. IPM integrates multiple methods, including cultural, physical, mechanical, chemical, and biological control. Although we often think of biological control as a response to an existing problem, some biocontrol agents are particularly powerful when used preventively.

Biological control agents—such as predatory insects, parasitic wasps, nematodes, and microbial products—can be introduced before pest populations reach damaging levels. Incorporating biocontrol agents early can suppress initial infestations, reduce the need for pesticide applications, and help create a more resilient, balanced growing system.

However, it's important to understand that not all biocontrol agents are suited for preventive use. Some require a pest population to be present to establish or be effective. Knowing which species can be used proactively—and under what conditions—is key to making a preventive biocontrol program successful. 

Why Use Biocontrol Preventively?

Preventive biocontrol is based on the concept of establishing beneficial organisms before pests become a problem. Just as in natural ecosystems, where predators and parasitoids are already present when their prey appears, growers can simulate this balance in greenhouses, nurseries, and even landscapes.

In contrast to curative applications—where beneficials are introduced after pests are already established—preventive releases give beneficials a head start, improving their ability to quickly suppress pest outbreaks.

In greenhouse settings, this approach is already a common practice. For instance, the parasitic wasp Encarsia formosa is often released early in the season to prevent whitefly infestations on poinsettias and gerbera daisies. These introductions typically begin when plants are small, and whiteflies are barely detectable—if at all.

When and How to Use Biocontrol Agents Preventively

Preventive biocontrol is most effective when pest pressure is expected but not yet visible. While we aim for clean, pest-free plants, the reality is that many crops—especially in greenhouses or high-value landscapes—are prone to recurring pest issues. For example, whiteflies in poinsettias or spider mites on roses are frequent seasonal problems.

Best Practices: 

Start Early
Introduce biocontrol agents before pests gain a foothold. For example, releasing predatory mites early in the season can help prevent a spider mite outbreak altogether.

Know Your Crop and Pest History
Use historical data to anticipate problems. If aphids consistently appear each spring, consider early releases of parasitoids like Aphidius colemani.

Match the Right Agent to the Pest
Not all biocontrol agents are effective for every pest. Select species based on life cycle, behavior, release methods, and environmental conditions. A helpful reference is the Guide for Biocontrol of Insects and Mites.

Establish Banker Plants
Banker plants can support beneficial insects even when pests are absent. For example, grain plants with cereal aphids help maintain parasitoid populations, while sweet alyssum provides pollen for minute pirate bugs, sustaining them until prey becomes available.

Combine with Monitoring
Use sticky traps, visual inspections, and digital tools to track both pests and beneficials. Monitoring helps you verify that your preventive strategy is working and guides additional releases if necessary.

Challenges to Consider

Preventive biocontrol requires planning and investment. Some challenges include:

• Timing and frequency of beneficial releases
• Environmental conditions that support beneficial survival
• Staff training and consistent scouting to assess effectiveness

Additionally, chemical compatibility is critical. Some pesticides can harm beneficial organisms. Always consult compatibility charts and labels to ensure that your chemical interventions don't inadvertently disrupt your biocontrol program.

Preventive use of biocontrol agents is not a silver bullet, but when integrated into an IPM framework, it becomes a powerful and sustainable way to manage pests proactively. With the right knowledge, timing, and support system, growers and land managers can shift from reactive pest control to a more balanced, long-term solution—saving crops, money, and the environment in the process.

References

Coop, L, B.S. Barker, and M. Rifozzinno. Biological Control. Accessed on 4 April 2025.

New York State Integrated Pest Management. How to use biocontrol. Accessed on 4 April 2025. 

Penn State Extension. IPM Tactic: Biological Control. Accessed on 4 April 2025.