Rearing of silkworm

1. SILKWORM REARING
(BLPI-003)
Resource Person:
Dr. K.Kamatchi
Assistant Professor of Zoology
Vivekananda College,
Tiruvedakam West, Madurai
IGNOU - Academic Counsellor
Code: GYYPK2432J/001
Vivekananda College, Tiruvedakam West
IGNOU - Study Centre - 43016

2. Sericulture
History of the sericulture
Central Silk Board and other organizations
Morphology and anatomy of silkworm
Morphology of mulberry plant
Diseases and pests of mulberry.
Diseases and pests of silkworm
Mulberry cultivation
Rearing Facilities
Rearing Appliances
Rearing Operations
Rearing Methods
Cocoon Qualities
Silk Reeling
Silk Twisting
Silk Weaving
Dyeing
Printing

3. Synopsis
• Introduction
• Rearing Facilities
• Rearing House
• Rearing Appliances
• Disinfection
• Rearing Operations
• Brushing
• Feeding
• Bed Cleaning
• Spacing
• Care during moulting
• Mounting of mature worms for spinning
• Harvesting of cocoons

4. REARING FACILITIES
• Rearing House:
• Silkworm is domesticated animal.
• It cannot tolerate seasonal fluctuations.
• It need an ideal rearing house.
• It has separate rooms for storing leaves
• Keeping rearing appliances.
• Rearing house must be brick-walled
• Roof – non conductor of heat-RCC roof
• Cement –plastered
• Not in water logged area
• North-south orientation
• Provision of broad verandah
• Planting shady trees
• Double door system

5. Rearing Appliances
• Rural based agro industry
• Appliances – cheap and locally available
• It differ from place to place
• CSB devising novel rearing appliances

6. • Appliances used for keeping the worms
being reared.
• Rearing Stand
• Rearing Trays
• Ant wells
• Paraffin Paper
• Chop Sticks
• Feathers

7. Rearing Stand:
• Locally available wood or bamboo.
• Height 2.5m
• Length 1.5m
• Width 0.65m
• 10-20 cross bars

8. Rearing Trays:
• Bamboo or plastic trays
• 138 cm diameter
• 6.5 cm depth

9. Ant Wells:
• Placed below the legs of rearing stand
• Prevent ants – crawling up
• Water poured
• CSR&TI give –Raksha rekha
• Chalk line – base of stand.

10. Paraffin Paper:
• Thick craft paper – paraffin wax coat
• Prevent evaporation of moisture
• Maintain high humidity
• Polythene sheets
• Dried banana leaves

11. Chop Sticks:
• Thin sticks of bamboo – 20 cm.
• Used like a forceps
• Picking worms
• Particularly diseased worms

12. Feather:
• Bird feathers
• White ones – preferable
• Brushing newly hatched larvae
• Spread the young worms.

13. Appliances used for feeding:
• Leaf basket
• Leaf chamber
• Chopping board
• Chopping knife
• Mats
• Feeding stand

14. Leaf Basket:
• Bamboo baskets – convenient size
• Collecting and transporting the leaves

15. Leaf Chamber:
• Store harvested leaves.
• Wet gunny cloth is placed.
• Water sprinkled periodically on cloth
• To keep leaves fresh.

16. Chopping board:
• Rectangular board
• Soft wood
• Used to cutting of leaves.

17. Chopping knife:
• Broad and sharp blade
• Cut without any splits

18. Mats:
• Below the chopping board
• Collect cut leaves.
• Clean paper may used.

19. Appliances used to support the
spinning larvae:
• Cocoonage or Mountage:
• Determine both quality and quantity of good cocoons.
• Weeds, straw and dry twigs
• Provide convenient space
• Not promote the formation of double cocoons
• Malformed cocoons and flimsy cocoons.
• Provision for drying of liquid excreta
• Easy mounting and harvesting
• Cheap, durable, easy to handle
• Occupy less space, allow free flow of air.

20. Chandrika:
• Bamboo spiral mountage – south india
• West Bengal and other parts of india
• 1.8m x 1.2m
• 4 – 5 cm width
• 1000 worms can be mount.

21. Types of Mountages:
• Screen type mountage
• Plastic mountage
• Polymer mountage
• Japanese low cost mountage

22. Japanese low cost mountage

23. Rearing Operations:
• Disinfection
• Brushing
• Maintenance of optimum temperature and humidity in the
rearing bed
• Feeding
• Bed cleaning
• Spacing
• Care during moulting
• Mounting of mature worms for spinning
• Harvesting of cocoons.

24. Disinfection:
• It must be effective against the pathogens.
• Application must be simple, easy and take minimum time.
• Harmless to man and domestic animals.
• Cheap and easily available.
• Physical methods
• Chemical methods

25. Physical methods:
• Sun drying
• Disinfection by steaming
• Disinfection by Hot Air

26. Sun Drying:
• Expose the appliances to direct sun light
• Cheap method
• Suitable only for tropics
• Cannot suitable for temperate
• Also in winter and rainy seasons
• Some appliances damaged

27. Disinfection by Steaming:
• Good sterilizing agent
• Disinfecting the rearing room
• Initial cost is high
• Harmful to bamboo and wood.

28. Disinfection by Hot Air:
• It is a good sterilizing method

29. Chemical methods:
• Disinfectant may be solid, liquid, gas
• It should have a broad spectrum activity
• non- toxic to man and animals.
• Have a capacity to avoid combination with organic matter
• Non-corroding and non-standing over the equipment and
surface
• Readily mix with water
• Have detergent property
• No offensive odour
• Available readily in large quantities at a fair price.

30. Disinfectants are:
• Chlorine
• Iodine
• Phenol
• Quaternary Ammonium Compounds
• Formaldehyde
• Spraying with 2% Formalin
• Spraying of Bleaching powder
• Fumigating with formaldehyde gas

31. Brushing:
• Hatching – Photoperiodic response
• Sunshine in the early morning – noon
• Newly hatched larvae – black and bristly
• Ants
• Process of separating them – egg shell
• Transferring to rearing bed
• Best time – 10 a.m.
• Unhatched eggs – return to black box
• Brushed the next day

32. Brushing from loose eggs in egg
boxes:
• 75% of eggs – blue egg stage
• Cover of box removed
• Thin muslin cloth or fine meshed net placed above
• Small amount of fresh, chopped mulberry leaves spread over
the net
• Larvae crawled up
• Feather method
• Husk method
• Cloth/paper/net method

33. Maintenance of Optimum
Conditions for Rearing:
• Productivity and Profitability depends upon healthy and
hygienic rearing.
• Giving quality leaves
• Optimum environmental conditions
• Temperature
• Humidity

34. Temperature:
Larval age Temperature
I instar 26 - 28°C
II instar 26 - 28°C
III instar 24 - 26°C
IV instar 24 - 26°C
V instar 23 - 24°C

35. Humidity:
Triple role
1. Affects growth of larvae and quality of
cocoons
2. Quality of leaves
3. Induces diseases
Larval age Humidity optimum
I instar 85%
II instar 85%
III instar 80%
IV instar 75%
V instar 70%

36. Feeding:
• The quality of the cocoons harvested depends – quality of
leaves fed during rearing.
• Satisfy both appetite and nutritional requirements.
• Summer six feedings / day (7 a.m., 11 a.m., 2 p.m., 5 p.m.,
8 p.m., and 11 pm.)
• Other seasons five feeding enough
• Give chopped leaves for larvae

37. Bed cleaning:
• In the rearing tray after feeding the unconsumed leaves and
the feacal matter of the larvae to be removed by this
method.
• Clean with husk
• Clean with net
• Combined net and husk method

38. Spacing:
• Silkworm developed rapidly from age to age.
• Increase several times their original weight and size.
• 15 times – hatching – I instar
• 4 to 5 times – II and III instar
• 25 times – IV and V instar
• Total increase in weight from hatching – V instar 7,000 -
10,000 times.
• So rearing space has to be extended

39. Moulting:
• Moulting occurs four times during the larval life.
• Sensitive period lasting for 15-30 hours.
• During this time worm does not feed
• Wriggles out of old skin and come out of new and soft skin.
• Bed should be dry.
• Pre-moult – worms shining body with a dark small sized
head and move to the periphery of bed.
• Moult – stop feeding.
• Post moult – large head, loose and less shiny skin – more
appetite.

40. Mounting:
• It is the final and most busy operation
• V instar larva attaining full growth.
• Let is for spinning – select suitable place
• Ripe worm
• Translucent colour
• Stop feeding – move to the edge of the bed.
• They transfer to the mountages.

41. Methods of Mounting:
• Hand Picking:
• Ripe worms are picked one by one by hand
• Collected in a tray and transferred to mountages
• Some worm to be injured
• More labours
• Worms uniformly distributed in mountages.
• Injured and diseased worms removed.
• Simultaneous mounting
• Net method
• Branch method
• Free mounting

42. Process of Spinning:
• Mature larva passes out its last excreta
• After emptying its gut, it secretes first silk droplet
• It is hardens and sticks on the mountage.
• Anchorage spot.
• Sericin – secreted by silk gland.
• 1.5 cm/ second.

43. Harvesting:
• Aim of the silkworm rearing is to harvest the cocoons
produced and sell them to the reeling agencies.
• Time of harvest – 3-4th day of mounting
• Early harvest injured the pupa.
• Late harvest – the moth emerge and pierced the cocoon.
• Cocoons are harvested by hand
• Remove faccal pellets on them
• Sorted size, defective cocoons