THRIPS IN COTTON

THRIPS IN COTTON

Telugu name: Thamara purugu

Scientific name: Thrips tabaci

Identification of the Pest:

  • Destructive stage: Nymphs and adults.
  • Eggs: Minute, kidney shaped laid in slits in leaf tissues. Egg period: 5 days.
  • Nymphs: Very minute, slender, yellowish and microscopic.
  • Adult: Small, slender, yellowish to brown with fringed wings. 

Lifecycle:

1. Egg Stage:

  • Female thrips lay eggs inside plant tissues, usually in leaves, buds, or flowers.
  • Eggs are tiny and not visible to the naked eye.
  • They hatch within 2-5 days.

2. Larval Stage:

  • Tiny, wingless larvae emerge and begin feeding on the plant.
  • They are yellowish or light in color and feed on leaves and other tender parts..
  • This stage lasts 5-7 days.

3. Pupal Stage:

  • Mature larvae drop to the soil to pupate.
  • During this stage, they do not feed.
  • This stage lasts 2-4 days.

4. Adult Stage:

  • Adults emerge with slender bodies and fringed wings.
  • Adult thrips live for 20-30 days, during which they feed nd reproduce.
  • Adult females can lay 50-100 eggs in their lifetime.
  • Under favorable conditions, entire life cycle completes in 12-15 days.

Symptoms:

  • Leaf laceration under the under surface of leaves.
  • Silvery or brown necrotic spots of 3-5 mm.
  • Leaf wrinkling and upward curling.
  • Distorted leaves with white shiny patches.

Favourable conditions:

  • Thrips grow well in warm temperatures ranging from 25-30°C.
  • They prefer low to moderate humidity levels,typically below 70%
  • Dry weather promotes thrips activity and population growth.
  • They are more active during hot and dry periods.
  • Thrips prefer young and tender plant parts, such as newly emerged leaves and buds.
  • Rain can wash away thrips, so they prefer areas with less rainfall during their active period.

ETL: 50 Nymphs or adults/ 50 leaves.

Management:

Cultural practices:

  • Avoid overcrowding by maintaining proper spacing to ensure good air circulation, which reduces thrip infestation.
  • Sow cotton early to avoid peak thrip activity.
  • Remove weeds around the field, as they can serve as alternate hosts for thrips.
  • Regular irrigation reduces thrip populations by discouraging their breeding in dry conditions.
  • Follow Crop rotation,Alternate cotton with non-host crops to break the pest cycle.
  • Grow crops like sorghum or maize as a barrier to reduce thrip infestation.

Biological control:

  • Predatory insects: Lacewings (Chrysoperla) and ladybird beetles feed on thrips.

  • Parasitic wasps: Tiny wasps like Thripobius spp. parasitize thrips and control their population.

  • Sprays of entomopathogenic fungi like Beauveria bassiana or Verticillium.

Chemical control:

  • Use systemic insecticides like Imidacloprid during the early stages of infestation.
  • Use contact insecticides like Spinosad for severe infestation.
  • Rotate chemicals with different modes of action to avoid thrips resistance.
  • Excessive chemical use can harm beneficial insects and lead to resistance.

For Effective control of Thrips use Biopesticide “Dr.ELIMINATOR”@250 ml/acre.

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