Thrips are one of the most persistent pests in greenhouse environments. Though tiny, they cause significant damage by scraping plant surfaces and sucking out the cell contents, resulting in silvery scars and deformed leaves, flowers, or fruit.
Thrips are among the most persistent pests in greenhouse environments. Though tiny, they cause significant damage by scraping the plant surface and sucking out their contents, leaving behind distinctive silvery marks and deformed leaves, flowers, and fruit. Because they reproduce quickly and are capable of spreading plant viruses, thrips infestations can escalate fast. Recognizing the early signs is critical for keeping populations under control.
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Feeding Damage:
Thrips feed by scraping the plant surface and sucking out cell contents. This destroys chlorophyll and creates silvery patches with small black specks. These are thrip droppings and can often help distinguish thrip injury from other causes.
2. Structural/plant deformity
Feeding on young leaves, buds, and flowers interferes with normal growth. This can lead to curled or twisted leaves, misshapen buds, and flowers that fail to open. On crops like cucumber, thrips damage can even result in deformed fruit, sometimes even when populations are low.
Main Virus Groups Transmitted by Thrips
Thrips are the only insect vectors of tospoviruses, which cause ringspots, necrotic lesions, leaf distortion, stunting, and poor fruit set. Tomatoes, peppers, onions, beans, lettuce, and ornamentals are especially affected.
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Virus Group |
Viruses |
Crops Affected |
Main Thrips Vectors |
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Tospoviruses |
Tomato Spotted Wilt Virus (TSWV) Impatiens necrotic spot virus (INSV) Iris Yellow Spot Virus (IYSV) |
Tomato, pepper, onion, lettuce, bean, ornamentals |
Western Flower Thrips (Frankliniella occidentalis), Onion Thrips (Thrips tabaci) |
Managing Thrips-Transmitted Viruses
Thrips acquire viruses during their larval stage, and once infected, they remain infectious for life. This makes prevention more effective than reacting after damage is visible.
Key strategies include:
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Using resistant crop varieties where available
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Keeping thrips populations very low
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Monitoring with sticky traps and crop scouting
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Combining biological control with sanitation and exclusion
Early Detection Can Make A Big Difference
Feeding scars, distorted leaves, and unopened buds are early warning signs of thrip activity. Acting quickly helps prevent crop losses and reduces the chance of virus spread. Regular scouting and fast intervention support healthier crops and maintain the effectiveness of biocontrol programs.