Rearing House and Rearing Appliances of Mulberry Silkworm

Rearing House

Purpose: A dedicated structure is essential for silkworm rearing. The house should provide an environment that promotes the healthy growth of silkworms.

Design Considerations:

• Ventilation: Adequate cross-ventilation is necessary. The house should have a sufficient number of windows to ensure airflow while keeping the air circulation even.
• Air-tightness for Disinfection: The house should be able to be sealed during disinfection procedures.
• Temperature and Humidity Control: The ideal temperature for silkworm growth is between 26-28°C, with a relative humidity (RH) of 60-70%. These conditions help promote the silkworm’s growth while keeping operational costs minimal.
• Avoid: Damp conditions, Air stagnation, Direct sunlight and intense radiation, Strong air drafts Ensure: Stable temperature and humidity, Proper ventilation

Rearing Room Features:

• Area: The rearing area must be planned based on the number of eggs (DFLs). A floor rearing system requires 2 sq.ft per DFL, while shoot rearing requires 3 sq.ft per DFL.
• Rooms: The rearing house should include:
  • Main rearing hall: Where most of the rearing will take place.
  • Ante room (8×8 ft): To assist in airlock and help with maintaining conditions.
  • Leaf preservation room: To store mulberry leaves.
  • Chawki room: A separate room for early-stage larvae (especially in the two-plot rearing system). This room should measure around 10’ x 14’ with a height of 9-10 ft per acre of garden.
  • Location: Ideally, the rearing house should face the east-west direction for optimal sunlight and wind direction.

• Construction Considerations:
  • Area: A rearing house with an area of 480 sq. ft is required to rear 100 DFLs.
  • Materials: Use washable flooring, provisions for effective disinfection, and natural shading elements (such as trees).
  • Environmental Control: Include measures to ensure the maintenance of temperature and humidity conditions within the house.

Preparation of Rearing House

• Pre-disinfection:
  • Disinfect the rearing house 3-4 days before rearing begins.
  • Use chlorine dioxide for disinfection. Spray it on equipment, walls, and floors to eliminate harmful organisms.
  • The house should remain closed for 24 hours after disinfection to allow the chemicals to work.
  • After 24 hours, open doors and windows to air out the room before commencing rearing.

Rearing Appliances

• Non-recurring (General) Disinfection mask, protective gum shoes, Sprayer for disinfecting, Room heater, water air cooler, Kerosene blow lamp, wet and dry thermometer, Forceps (6”), black box, and bed cleaning nets
• Non-recurring (Specific) Egg transportation box, Leaf chopping board, shoot rearing rack, Egg incubation chamber, leaf chopping knife, chandrike (rearing tools), Loose egg incubation frame, plastic basin, Chawki rearing trays, earthen pot, Rearing bottom stand, feeding stand, litter basket
• Recurring; Paraffin paper, formalin, Bleaching powder, lime powder, Bed disinfectants, slides, and cover slips. Gunny cloth, cora cloth

Disinfection Procedures

• After rearing:
  • Spray the rearing house with 2% formalin mixed with 0.3% slaked lime, or 2.5% chlorine dioxide with 0.5% slaked lime at 2 liters per m² area.
  • For rearing equipment, dip them in a 2% bleach solution and let them dry under the sun.
  • Dust bleaching powder and slaked lime around the house at 200 g/m², followed by sprinkling water (1 liter per m² of floor area).

Incubation of Eggs and Hatching

• Egg Management:
  • Spread the egg sheets in a single layer in the chawki tray.
  • Maintain a temperature of 25°C and a humidity level of 80%. Use paraffin paper and wet foam pads to retain moisture.
  • Darkening the eggs: When eggs reach the head pigmentation stage (48 hours before hatching), they must be kept in the dark (using black paper or black boxing) to encourage uniform hatching.
  • Hatching: Expose the eggs to light on the expected day of hatching. Most eggs will hatch within 2-3 hours.
  • Low-cost Egg Preservation: Eggs can be stored in an earthen incubation chamber. The chamber maintains humidity and protects the eggs from environmental fluctuations.

Brushing (Feeding)

• Brushing Method:
  • The hatched larvae must be fed immediately. Brush them onto paraffin paper in a rearing tray or onto a blue polythene sheet.
  • Chopped tender mulberry leaves (1 cm² in size) are sprinkled over the larvae to encourage them to crawl onto the leaves.
  • After about 8-10 minutes, the egg sheet is gently tapped, and worms still attached are removed using a feather.
  • A rearing bed is then prepared, and additional leaves are provided if needed.:
  • Use wet foam pads and paraffin paper to prevent the leaves from drying out, and to ensure that the humidity stays within the required range.

Key Takeaways for Silkworm Rearing:

• The rearing house must be designed to control temperature, humidity, and ventilation efficiently.
• Pre-disinfection and proper maintenance of the rearing environment is critical for the health of silkworms.
• Proper rearing appliances (specific and non-recurring) ensure smooth operation and hygiene.
• Egg incubation and hatching must be done under controlled conditions for uniform development.
• Feeding and leaf management are key to ensuring the silkworms grow successfully.