Thrips Pest Biology and Feeding Damage
Thrips (including *Scirtothrips dorsalis*, *Thrips tabaci*, and *Frankliniella schultzei*) are microscopic, slender insects with fringed wings. They utilize asymmetrical rasping-sucking mouthparts to lacerate epidermal plant cells and suck liberated sap.
Attacked foliage displays characteristic upward leaf curling, silvery streaks, chlorotic stippling, and necrotic leaf margins. Thrips also act as vectors for devastating tospoviruses like Groundnut Bud Necrosis Virus (GBNV) and Watermelon Silver Mottle Virus.
- Target species: Chilli thrips (*Scirtothrips dorsalis*) and Onion thrips (*Thrips tabaci*)
- Feeding symptoms: Silvery leaf patches, upward leaf cupping, floral drying, and fruit scarring
- Vector threats: Transmission of tospoviruses causing systemic bud necrosis and chlorosis
- Cryptic habitat: Hide inside unopened leaf buds, floral calyxes, and underside leaf crevices
CIBRC Approved Chemical Formulations and Modes of Action
Because thrips develop resistance rapidly to legacy single-site insecticides, managing outbreaks requires rotating chemistry groups with translaminar mobility.
Rotating between spinosyns, diamides, chordotonal modulators, and isoxazolines ensures mortality across multiple physiological pathways.
- Spinosyns: Spinetoram 11.7% SC (IRAC Group 5, nAChR allosteric modulators delivering fast knockdown)
- Isoxazolines: Fluxametamide 10% EC (IRAC Group 30, novel GABA receptor antagonist)
- Phenylpyrazoles: Fipronil 5% SC (GABA-gated chloride channel blocker with soil and foliar systemic activity)
- Chordotonal modulators: Flonicamid 50% WG (halts feeding within hours while sparing beneficial predators)
- Neonicotinoids: Acetamiprid 20% SP and Dinotefuran 20% SG for early vegetative pressure
Integrated Pest Management (IPM) Protocols
Chemical intervention should be anchored within an IPM framework. Install blue sticky traps across fields, as thrips are strongly attracted to specific blue wavelengths, facilitating early monitoring.
Spray during cool morning or evening hours using fine-droplet hollow cone nozzles calibrated to reach lower leaf surfaces and unopened apical buds.
- Trapping: Install 15 to 20 blue sticky traps per hectare for early adult detection
- Spray pressure: Maintain calibrated pressure to force droplets into closed floral and terminal buds
- Rotation protocol: Never use the same chemical class consecutively across overlapping generations
- Biological conservation: Conserve predatory anthocorid bugs (*Orius* spp.) and phytoseiid predatory mites
Official source
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Central Insecticides Board and Registration Committee (CIBRC) ↗Related on KisanPe
Common questions
Why are blue sticky traps preferred over yellow traps for thrips?
Thrips exhibit strong visual phototaxis toward blue spectral wavelengths, making blue sticky traps more selective and efficient for thrips monitoring than general yellow traps.
What is the primary cause of upward leaf curling in chilli plants?
Upward leaf curling ('Murda' disease) in chilli is primarily caused by chilli thrips (*Scirtothrips dorsalis*) rasping tender tissue on upper leaf surfaces, whereas downward curling is caused by yellow mites.
How does Spinetoram control thrips hiding inside flowers?
Spinetoram possesses translaminar action, penetrating into deep floral structures and leaf layers where thrips shelter from surface sprays.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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