Techniques of Rearing Silkworm

Rearing of mulberry silkworm

Rearing house (for 100 dfls.)

• Construct rearing house of 18 feet x 12 feet x10 feet size on an elevated and shady place to accommodate 100 dfls.
• Provide 3 feet balcony sounding 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 house flies or uzi flies.

Disinfection of rearing house and appliances With 5% Bleaching powder

• Dissolve 50g bleaching powder in 1 litre of water in a big plastic bucket, stir for 5-6 minutes and keep it for half an hour.
• Spray the clear solution in the rearing house and rearing appliances 3 days before rearing. With 2% formalin solution
• Dissolve 1 part of market available formalin with 17 parts of water.
• Spray the solution in the rearing house and appliances 3 days before rearing.
• Close the doors, windows and ventilators to make the room air tight.

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 and drier.

Packages of practices for new silkworm hybrids

Incubation and brushing

• Spread the eggs in one layer on a paraffin paper kept on a bamboo tray.
• Cover the eggs with another paraffin paper.
• Except rainy season, keep wet foam pads around the eggs covered by paraffin papers.
• Maintain the room temperature at 25-26 0C 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 with a chopper 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 cm and feed 3-4 times.
• Maintain temperature at 27-28 0C 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 cm2 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.
• Remove the paraffin paper and foam pad during moult.

Late age Rearing

• Use mulberry leaf only from 60 days old plantation.
• Provide 4 times feeding to the silk worm.
• Maintain rearing/ feeding room temperature at 25-26 0C and    relative humidity at 65-70%.
• Use tender leaves only for resuming (only one feeding after 3rd/4th    moult) then change to medium in 4th stage and coarser leaves in    5th age.
• Transfer the worm to more number of trays keeping the density of    the worm within 60-70 larvae per sq.ft.
• Clean the bed with the help of bed cleaning net thrice during 3rd    instar and daily during 4th and 5th instar.
• Replace the paraffin papers with clean news papers.
• Dust Labex half an hour before resumption of feeding when the    larvae come out of the moult.
• Apply labex daily half an hour before 2nd feeding during 5th instar.
• Provides cross ventilation.
• Provide correct bed spacing and feed adequately.

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 ripe worms (transparent, shortened larvae wondering in tray) for monlting.
• Mount in suitable mountages like rotary or bamboo mountages.
• Mount 40-45 worms per sq.ft. area.
• Keep the chandrakis rotating in leftward direction so that the worms are not got dumped in one position.
• For easy self mounting and better cocoon quality,rotary mountage is ideal.
• Remove diseased and dead worms.
• Maintain temperature at 27-28 0C and RH at 60-70%.
• Avoid temperature more than 28 0C and RH beyond 80%.
• Provide aeration to remove excess moisture.
• Avoid strong light.
• Harvest the cocoons on 5th day of mounting.
• Remove flimsy, stained and irregular size cocoons.

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, Labex on the larvae when the larvae come out of moult.

Source :

• Package of practices of Muga, Eri and Mulberry Sericulture for North Eastern region of India, 2005, Central Muga Eri Research & Training Institute, Lahdoigarh, Jorhat, Assam.
• Directory of Sericulture Technology 2008, Karnataka State Sericulture Research and Development Institute,Bangalore- 560 062.