Biocontrol vs. Resident Thrips: A Smarter IPM Strategy for Greenhouse Cucumbers
- Andrei Darie
- May 28
- 3 min read
How to Delay Infestation, Build Early Control, and Get Biocontrol Working in Time.
When There’s No Time for a Clean-Out Between Cucumber Crops, Conventional IPM Advice Fails
For many greenhouse cucumber Growers, quick turnover between crops has become the new standard. When replanting starts just 3–7 days after crop removal, chances are you might be stuck with a resident population of Western Flower Thrips.
Feeling stuck in a cycle of early infestation, early intervention, and biocontrol failure can be frustrating, especially when you're trying to do everything right. It means the typical IPM playbook wasn’t written for your production pace.
Why Traditional IPM Advice Fails in Fast-Cycle Cucumbers
Standard programs are designed around the assumptions that the greenhouse is clean with low initial thrips pressure. But in quick-turnover cucumber production, thrips survive between crops, hiding in cracks in the floor and structure. If the biocontrol program only starts after planting, it's already behind schedule.
Early sprays may seem necessary, but they leave residues that hinder the egg-laying of Amblyseius swirskii and impair Orius insidiosus establishment. Bios don’t stand a chance if they’re disrupted before they even establish, and this can cause Growers and IPM Specialists to lose confidence in their bios program. What if the problem isn’t the bios, but the timing?
Redefining the First 21 Days of IPM
Cucumber crops with quick-turnover require a restructured approach to early IPM. The goal: outpace resident thrips before they outpace you. That means starting in propagation, measuring performance with egg counts and time-to-infestation, and supporting bios' establishment with supplementary food.
Early-Stage Biocontrol Blueprint
Timing | Actions | Purpose |
At propagation | Apply Amblyseius swirskii (sachets or loose) & Stratiolaelaps scimitus before spacing | Establish early predator presence on your plants, in anticipation of thrips |
At transplant | Add Dalotia coriaria in breeding-release pails or loose & install sticky traps | Target thrips pupae + detect early infestations |
After planting | Apply Amblyseius swirskii (sachets or loose) & follow-up withprey mite application 1 week after(e.g., Carpoglyphus) | Stimulate Amblyseius swirskii egg-laying and reproduction |
Weeks 1–5 (high-wire crops) | Apply Orius insidiosus weekly for 5 weeks (5/m²) with feeding stations containing Ephestia eggs & prey mites | Suppress adult thrips + build a stable Orius insidiosus population (1/m²) |
What Works & Why
Delayed Infestation = Better ROI Growers introducing Swirskii and Stratiolaelaps in propagation typically see a longer delay until thrips detection. That window gives bios time to establish, begin egg-laying, and reduces the need for early sprays.
Egg-Laying = Real Establishment Indicator Seeing Swirskii mites in the crop isn’t enough. Seeing Swirskii eggs is the most practical indicator of establishment success, and the generations that hatch in your crops will be more adapted and effective in your crops. Supplemental feeding with prey mites can enhance egg-laying in the absence of thrips.
Orius can Succeed in High-Wire Crops, but Needs Support Many Orius programs in cucumber crops due to the lack of feeding support. It can take 5 weeks of consistent Orius releases, combined with feeding stations containing Ephestia kuehniella and prey mites, to establish one adult per square meter. At Crop Defenders, we've formulated this into Power Meal for easy application.
Track and Manage Early IPM Success
You may not be able to shift your crop schedule or enforce a clean-out. But you can control how early and how effectively your IPM starts, and there is one key metric you can use to measure and manage this: Time to First Infestation.
If thrips infested your last crop within 14 days of planting, what can you do to increase that time to 21 days, or more, in the next crop?
This isn’t about doing more. It’s about being more strategic in approach.
How Crop Defenders can Help
At Crop Defenders, we don’t just ship bios. We partner with Growers to implement tailored strategies that deliver results, within budget. We do this with:
Locally Reared Bios, Delivered Fast Multiple delivery days per week. Fresher product. No long waits.
Digital IPM Planning Tools Visualize your bios program - cost, frequency, timing - with streamlined strategy and budget forecasting tools.
Customized Protocols We tailor your strategy to your microclimates, turnover window, and production goals.
An Effective IPM Program Doesn’t Always Require a Clean Slate, Just a Better Start
You don’t need to tear everything down between crops. You just need to start your biocontrol program earlier. If you'd like guidance to make planning easier, just schedule a call to connect with our IPM Consultants.
Biocontrol fails when it starts too late. Start early, support fully, and you’ll see the difference: fewer sprays, stronger establishment, and more predictable results.
