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Sericulture Research & Development Council

Techniques of Rearing Silkworm

Rearing house (for 200-250dfls.)

  • Construct rearing house of 50 feet x 20 feet x10 feet size on an elevated and shady place to accommodate 200-250 dfls.
  • Provide 3 feet verandah surrounding the rearing house.
  • Provide sufficient windows and ventilators for free circulation of air inside the rearing house.
  • Cover the windows and ventilators with nylon net to restrict the entry of uzi flies.

Hybrids recommended

  • Multivoltine: PM × CSR2, L14 × CSR2
  • Bivoltine: CSR2 × CSR4, FC1 × FC2 (Double hybrid)

Disinfect the rearing house and appliances with recommended disinfectants

Rearing appliances

Power sprayer, rearing stands, rearing trays, foam pads, wax coated paraffin papers, nylon nets, basket for keeping leaves, gunny bags, rotary or bamboo mountages/or netrikes.

Incubation and brushing

  • Spread the eggs in one layer on a paraffin paper kept on a tray.
  • Cover the eggs with another paraffin paper.
  • Maintain the room temperature at 25-26°C and relative humidity at 80%.
  • When blue pinhead appears, wrap the eggs (25-50 dfls each) in a tissue paper and keep the eggs inside a black painted box or cover with black cloths or papers for 1-2 days.
  • On the next day, expose the eggs under diffused sunlight or under shade.

Brushing of newly hatched worms

  • Transfer the newly hatched worm carefully with a soft brush or feather to a paraffin coated paper kept on a rearing tray.
  • Feed the worms with tender leaves (3rd and 4th leaf from the apex of the branch) chopped into 0.5-1 cm size.

 

Chawki rearing

  • Distribute the worms uniformly in the trays.
  • Feed the silkworm with nutritious and succulent leaf.
  • Provide 3-4 times feeding with tender leaves of 0.5-2 cm cut pieces during 1st stage.
  • Provide leaves @ 5 kg/100 dfls for 1st and 18 kg/100 dfls for 2nd instar worms.
  • During 2nd stage, cut the leaf into 2-4 sq. cm and feed 3-4 times.
  • Maintain temperature at 27-28°C and relative humidity at 80-90%.
  • Every day before 2nd feeding, spread the bed to facilitate drying of leaf applied in the previous feeding.
  • Ensure bed cleaning once during 1st and 2nd moult and daily during 3rd stage with cotton cleaning net of 0.5 sq. cm mesh size.
  • Reduce bed thickness prior to moulting.
  • When 97% worms settle for moulting, stop feeding & apply slaked lime on the body of the worms.

 

Late age Rearing

  • Silkworms after second moult are shifted to shoot racks
  • Shoot rearing racks are made of iron, wood or bamboo
  • It is ideal to have 3 tiers
  • Width of the rack should not exceed 5 ft.
  • Bottom tier should be 1 ft above the ground level
  • Space between two tiers should be minimum 2 ft
  • Shoot for feed the larvae should be 50-60 days old.
  • 2 or 3 feedings/ day is recommended.
  • Bed cleaning is done only once on 4th day of 5th instar.
  • Provide cross ventilation.
  • Provide correct bed spacing (800-900 Sqft/100 dfls) and feed adequately (2500 kg shoot /100 dfls).

Care during moulting

  • Stop feeding when 90% worms enter into moult.
  • Spread the bed for proper drying and aeration.

Dust lime powder on the bed to keep the humidity low.

Mounting and Harvesting

  • Pick fully ripened worms for mounting.
  • Mount in suitable mountages like rotary, plastic collapsible or bamboo mountages
  • Mount 40-45 worms per sq. ft. area.
  • Remove diseased and dead worms.
  • Maintain temperature of 27-28°C and RH of 60-70%.
  • Provide aeration to remove excess moisture.
  • Avoid strong light.
  • Harvest the cocoons on 5th day of mounting.
  • Remove flimsy, stained and irregular sized cocoons.

Rearing and personal hygiene

  • Wash hand with a disinfectant prior to the entry of rearing house.
  • Avoid entry of person other than those involved in rearing.
  • Sprinkle 5% high grade bleaching powder around rearing house at 5-6 days interval.
  • Collect diseased worms and dispose properly (burn or bury them).
  • Clean the rearing floor with 2% bleaching powder solution before and after bed cleaning.
  • Use bed disinfectant, on the larvae when the larvae come out of moult.

Source

Central Sericultural Research & Training Institute, Mysore, Karnataka