Using UV-B Light to Combat Thrips in Tomato Crops
The future of pest control might be as simple as adjusting a light bulb.
Imagine a pest so small you can barely see it, yet so destructive it can devastate entire greenhouse tomato crops. Meet the western flower thrips—a tiny insect that causes massive economic losses worldwide. But scientists have discovered an ingenious weapon hidden in plain sight: a specific type of ultraviolet light that can suppress thrips populations without resorting to chemical pesticides.
Western flower thrips (Frankliniella occidentalis) are minuscule insects, measuring just 1.2 to 1.5 millimeters in length—barely visible to the naked eye4 . Despite their small size, they pose an enormous threat to agriculture.
Size of western flower thrips
Population increase per generation at 30°C
What makes thrips particularly challenging to control is their thigmotactic behavior—they prefer to hide in concealed spaces like flower buds and under calyces where pesticides can't reach3 . Additionally, they've developed resistance to many insecticides, making chemical control increasingly ineffective2 3 .
Ultraviolet-B radiation (280-315 nm) is a component of sunlight that plants can perceive through a specialized photoreceptor called UVR8 (UV Resistance Locus 8)6 . Unlike the more harmful UV-C, UV-B at controlled levels doesn't damage plants but instead acts as an important environmental signal that triggers defensive responses5 6 .
This phenomenon represents a form of "eustress"—a positive stress that enhances the plant's ability to withstand greater challenges5 .
Researchers have discovered that applying supplemental UV-B in controlled environments can prime plant defenses, making them more resistant to pest attacks. The effect is particularly pronounced in greenhouse settings where standard glazing materials often filter out natural UV radiation5 6 .
| Type of UV | Wavelength Range | Reaches Earth's Surface? | Primary Effects on Plants |
|---|---|---|---|
| UV-A | 315-400 nm | Yes | Influences photomorphogenesis, photosynthesis |
| UV-B | 280-315 nm | Partially | Activates defense pathways through UVR8 photoreceptor |
| UV-C | 100-280 nm | No | Directly damages DNA, used for surface sterilization |
In 2025, a groundbreaking study published in Pest Management Science set out to determine the most effective way to use UV-B light against western flower thrips in controlled environment tomato production2 . This research represented a significant advancement in optimizing UV application protocols.
Tomato plants (Solanum lycopersicum L.) were exposed to seven different UV-B LED treatments varying in duration: 0, 0.5, 1, 2, 4, 8, and 24 hours of daily exposure2 .
Researchers used advanced imaging technology to monitor plant responses to different UV regimens, assessing vegetation indices to determine how plants recovered from potential UV stress2 .
Based on initial assessments, the 4-hour exposure emerged as particularly promising. The team then tested this duration under various conditions:
The researchers evaluated thrips oviposition preference (where females choose to lay eggs) and egg hatching rates across the different treatment conditions2 .
The findings revealed a Goldilocks effect—where both too little and too much UV exposure proved suboptimal:
Tomato plants exposed to UV-B for 4 hours showed recovery from initial UV-induced stress based on vegetation indices, indicating they had acclimated to the treatment2 .
Surprisingly, tomato plants treated with 4 hours of UV-B became more attractive to ovipositing thrips—females actually preferred to lay eggs on them compared to untreated control plants2 .
This is where the clever mechanism emerged: despite the increased egg-laying, the hatching rates of WFT eggs laid in UV-treated plants were significantly suppressed. The UV treatment had covertly compromised egg viability2 .
The 4-hour exposure effectively suppressed hatching regardless of whether it was applied during the day or at night, or whether it was projected from above or below the leaves2 .
| Daily UV-B Exposure | Plant Stress Response | Thrips Oviposition Preference | Egg Hatching Success |
|---|---|---|---|
| 0 hours (control) | Baseline | Baseline | Baseline |
| 0.5-1 hours | Minimal | Slight increase | Moderate suppression |
| 4 hours | Acclimation observed | Significantly preferred | Significant suppression |
| 8-24 hours | Potentially stressful | Variable | Less effective than 4 hours |
The successful implementation of UV-based pest control requires specific tools and technologies. Here are the essential components used in the featured experiment and related studies:
| Tool/Technology | Function in Research | Application Notes |
|---|---|---|
| UV-B LED Systems | Provide precise wavelength control | Enable specific UV-B doses without harmful UV-C2 |
| Hyperspectral Imaging Cameras | Measure plant stress responses and recovery | Track vegetation indices non-destructively2 |
| Climate-Controlled Chambers | Maintain consistent environmental conditions | Isolate UV effects from other variables5 8 |
| Jasmine Acid Signaling Mutants (def-1) | Determine defense mechanisms | Identify JA-dependent pathways8 |
| Trichome-Deficient Mutants (od-2) | Assess physical defense contributions | Separate chemical vs. physical defenses8 |
| Wind Tunnels | Study insect flight behavior and host selection | Evaluate attraction and landing patterns |
| BrCH2CONH-PEG1-N3 | Bench Chemicals | |
| 6,6-Diphenylhex-5-enal | Bench Chemicals | |
| 5-nitroso-1H-imidazole | Bench Chemicals | |
| Threonine, 4,4-dichloro- | Bench Chemicals | |
| 2-Mercaptothienothiazole | Bench Chemicals |
The implications of this research extend far beyond laboratory curiosity. UV-B treatment represents a promising component of integrated pest management (IPM) strategies for controlled environment agriculture4 6 .
Research on chrysanthemums has demonstrated that UV-mediated resistance to thrips can persist after the end of UV treatment, suggesting that temporary exposure during critical growth stages might provide lasting protection5 .
While the 2025 tomato study provides compelling evidence for UV-B efficacy, several questions remain for future research:
What makes UV technology particularly exciting is its potential for automation and precision. As LED technology advances and becomes more affordable, we could envision smart greenhouse systems that apply brief, targeted UV treatments during specific crop stages or at times when pest pressure is highest.
The innovative use of UV-B light to control western flower thrips represents a fascinating convergence of entomology, plant physiology, and technology. By harnessing the plant's own defense systems and subtly manipulating pest behavior, researchers have developed an approach that is both effective and environmentally sound.
As we move toward more sustainable agricultural systems, such precision pest management strategies will become increasingly valuable. The simple adjustment of light spectra offers a powerful tool that reduces pesticide use while maintaining crop health and yield.
The next time you see a tomato growing in a greenhouse, remember—the secret to its protection might not be in a spray tank, but in the very light that helps it grow.
This article was based on scientific research published in peer-reviewed journals including Pest Management Science, Florida Entomologist, and other academic sources. For more detailed information, please refer to the original studies.