Sericulture notes culturing of different types of silkworm

Sericulture notes culturing of different types of silkworm

1. Sericulture

2. Introduction
•Sericulture –Sericos(G) –silk, Culture (E) –rearing
•Sericulture refers to the conscious mass-scale rearing of silk-producing
organizations in order to obtain silk from them
•Silk –fibrous protein of animal origin –insect and noninsectsilk
•Mussels –anchorage, spiders –prey, cocoons –protective sheath
•Head quarters of International Silk Association –Lyon, France
•Central Silk Board, Bangaluru
•Central Silk Technology Research Institute -Bangaluru
•Central Sericulture Research and Training Institute –Mysore

3. History of sericulture
•Lei-zu(Si Lung Chi) –empress –2687 BC
•Cocoon dropped in her tea cup –silky threads separated-she taught
this to people
•Source of silk was kept secret for more than 2000 years until the silk
road was opened at 114 BC
•Silk road/ silk route –historic trade route that dated from the second
century BC until the 14
th
Century A.D
•It stretched from Asia to Mediterranean traversing China, India, Persia,
Arabia, Greece and Italy
•Called as silk route because of the heavy silk trading that took place
during that period, which gave China a monopoly over the trade

4. Silk
•Valuable natural protein fibreproduced by certain inscets
•Lepidoptera –adult stage –silk secretion from salivary glands
•Silk used for construction of cocoons over pupae –protection
•Important silk producers –Bombycidaeand Saturnidae
•Silk –sericin (sticky material surrounding) and fibroin (structural centreof
silk)
•Fibroin made of aminoacids–Gly-Ser-Gly-Ala-Gly-Ala –beta pleated
sheets –hydrogen bonds between chains and sidechains from above and
below the plane of the hydrogen bond network
•High proportion of glycine (50 %) allows tight packing and the fibers are
strong and resistant to breaking
•Tensile strength due to many inter-seeded H2 bonds and when stretched the
force is applied to these numerous bonds –do not break
•Silk is resistant to most mineral acids except H2SO4 –precipitate –yellow

7. Properties of silk
•One cocoon yiedsabout 1000 feet
of silk thread
•Unwound from the cocoons and
reeled into threads of commercial
silk
•Natural fiber soft, shiny, strong and
durable
•Highly elastic and has long threads
•Easily absorbs water (11%) –low
density, absorbs 3 times own
weight
•Extremely light in weight, warmer
than cotton, can be easily dyed and
ironed –Queen of fibers
Uses of silk
•Manufacture woven materials and
knitted fabrics
•Fishing lines and sieves of flour
mills
•Insulation coil of telephone,
wireless receivers and tyresof
racing cars
•Wall coverings, window treatments,
rugs, bedding, wall hangings
•Parachutes, parachute chords,
racing cars, gunpowder bags
•Non absorbable surgical threads
•Silk under clothing – eczema
•Disposable cups to holograms

8. Taxonomic position
•Kingdom –Animalia
•Phylum -Arthropoda
•Class -Insecta
•Order -Lepidoptera
•Family –Bombycidae, Saturnidae

9. Different types of silkworm
Sl.
No.
Type of
silkworm
Scientific name Family
(Order :
Lepidoptera)
Hosts Remarks
1
2
3
4
Mulberry
Tassar
Eri
Muga
Bombyx mori
Anthereamylitta
Philasamiaricini
Antherea
assamensis
Bombicinae
Saturnidae
Saturnidae
Saturnidae
Morusspp. (Mulberry)
Indian Laurel, arjun
(Terminalia sp.)
Castor, Tapioca
SomandSoalu
Sericin content
25-30 %
Single strand
Sericin content
18-25 %, cocoon
pedunculate

10. TASAR SILKWORM

11. Eri silkworm

12. Muga silkworm

13. Mulberry silkworm

14. Tasarsilkworm
•> 90 %, Genus –Antheraea
•Cocoons –large, thick and
pedunculate, made of single unbroken
filaments
•4 types –Indian tropical tasar, Indian
temperate tasar, Chinese and japanese
•Indian tropical tasar–commonly
found in tropical India, Antherea
mylitta, multivoltine, cocoons grey
white, tough, pedunculate,
polyphagous (Primary host -
Ternminaliatomentosa, T.arjuna;
secondary host –Shorearobusta,
Zizyphussp.)
•Indian temperate/ oak tasar–A.
proylei, host -Quercus (Himalayas),
cocoons grey white in colour
•Chinese tasar–only in former USSR
countries, A. pernyi, Quercus, largest
silkworm, cocoons grey brown, silk
used for making embroidery threads
•Japanese tasar–Japan, oak, A.
yamamai, silk is greenish tinted used
for making fabrics and embroidery
threads

15. Muga silkworm
•Golden yellow lustrous silk
•A. assamensis
•Occurs in Brahmaputra valley and hills in Assam
•Unique monopoly of India
•Feeds on Som and soalutrees
•Rearing done outdoors
•Multivoltine, smaller than tasarcocoons
•Cocoons weakly pedunculate, large and strong

16. Eri silkworm
a)Wild eri/ Ailanthus silkworm –
Philasamiacynthia, bivoltine
b)Castor silkworm -P. ricini,
domesticated, multivoltine,
polyphagous, Primary host –
castor, tapioca
•Cocoons weakly pedunculate, open
at one end, non reelable, white or
brick red in colour

17. Anaphesilkworm
•Genus –Anaphe, F-Notodontidae, O –
Lepidoptera
•A. venta–most important one –seen in South
and Central Africa
•Polyphagous, most important host is
Triplochiton scleroxylon
•Used for the production of parachutes during
World War II
•Univoltinesused in velvet and plush making
•Moths are of moderate size and show sexual
dimorphism
•More elastic and stronger than mulberry silk

18. Gonometasilkworm
•Egger moth seen in African
savanna
•Cocoons found on Acacia
torticis
•Cocoons elongated, ellipsoidal
in shape, simple, shell hard
(shell ratio 22%)
•Cocoon is unreelable and silk
obtained by spinning
•Sericin content is high 45-55
%

19. Fagarasilkworm
•Indo-Australian, China and
Sudan
•13 spof Attacusproduce this silk
•Giant silk moth –Attacusatlas
•Cocoons light brown in colour
Coansilkworm
•Syrian silkworm
•Genus –Pachypasa, P. otus, P.
lineosa
•Cultivated in Europe until the
introduction of B. mori
•Cocoons white, yield of silk very
low
• Crimson-dyed apparels of
Dignitaries of Rome

20. Spider silk
•Soft, fine, strong, elastic
•Nephila madagascarensis,
Miranda aurantia, Epeira sp.
•Used for making cross bars in
optical instruments
•Mussel – fish wool – Pinna
squamosa
•Non commercial sericigenous
insects
•Moon moth – Actias selene
•Cashew caterpillar - Cricula
trifenestrata
•Mango caterpillar – Cricula sp.
•Cercropia moth – Philosammia
cercropia

21. Mulberry silkworm
•Bombyx mori
•Low land holding capacity
•Investment is high
•Economic return very high
•Rearing house and rearing appliances needed
•Mainly indoor rearing
•Moriculture
•Monophagous
•Mainly found in KA, TN, WB
•Hosts -M. alba, M.indica, M.serrata,
M.latifolia
•Automatic, semiautomatic reeling machines
Non mulberry silkworm
•Tasar, muga, eri
•High land holding capacity
•Investment very low
•Economic return very low
•No need of rearing house and appliances
•Outdoor rearing except Eri
•Arboriculture
•Polyphagous in nature
•Mainly found in Bihar, MP, Nagaland, Assam
•Hosts -Shorearobusta, Listeapolyantha,
Ricinus communis
•Reeling conducted by natwabhir, pedal
operated reeling, Trivedi type

22. •Egg (350 -450
eggs)
•Larva (4 moults)
•Pupa (chrysalis)
•Cocoon –white,
bed of pupa
whose outer
threads are
irregular while
the inner threads
are regular
•Adult

23. Silk glands
•Silk produced by the labial glands homologous with true salivary glands in
insects
•Situated lateral and ventral to the digestive canal and is of variable length
•In mulberry silkworm it is 4 times the body length and is folded so as to
envelop the hinder region of the gut
•Each gland is enlarged anteriorly into a reservoir which is produced into a
duct –the two ducts converge to open at the apex of a cylindrical organ
known as spinneret
•Posterior –Fibroin (active form –fibrinogen), Middle –Sericin (gum layer)
•Brins –two filaments coming out of 2 sides
•Bave–sericin layer of two brins then bind together into a single filament

24. Silk gland of B. mori

25. Terminology
•Breed–a stock of animals or plants within a species having a
distinctive appearance and typically having been developed by
deliberate selection
•Races–a population within a species that is distinct in some way esp.
a subspecies (Indigenous/ native –originating in a particular region/
country, Exotic/ nonnative –introduced into an area where they do
not occur naturally)
•Classification based on geographic distribution –Japanese race,
Chinese race, European race, South East Asian races

26. Classification based on voltinism
•Voltinism –the number of broods/ generations of an organism in a
year under natural environmental conditions
Sl. No.Univoltines Bivoltines Multivoltines
1 Produce one generation
per year
2 generations per year > 5-6 generations per year
2 Larval weight highLarval period short Larval duration short
3 Cocoons heavy Leaf cocoon ratio less Leaf cocoon ratio high
4 Quality of silk superiorQuality of cocoon inferior Cocoon compact, layer soft,
Length of filament short, fine,
clean, lustrous filament
5 Lay diapausing eggs Non hibernating and hibernating
eggs
Lay only nondiapausingeggs
6 Eg.European races Eg.NB4D2, NB 18, KA, NB7 Pure Mysore, C. nichi, Hisa
mysore
7 Not suitable for summer Cocoon weight, shell weight silk %
and filament length lesser than
other 2 races
Larvae robust, tolerate fluctuating
environmental conditions suited
to tropical climates

27. Classification based on moultinism
•Moulting/ ecdysis –the manner in which an animal routinely casts off
an outer layer or covering at specific points in its life cycle
Parameters Trimoulters TetramoultersPentamoulters
Moults Three times during larval
period
4 times 5 times
Larval duration Limited growth, short 15-
18 days
Medium 23-28
days
Long
Size Pupae and moth small
Cocoon weight Less Medium High
Cocoon filament Fine Fine More
Denier of silk
filament
1.6 to 1.7 2 to 2.5 Very heavy

28. Production of silk
•Two steps
a.Production of mulberry trees that provide leaves upon which the
worms feed – Moriculture
b.Care of silkworm from egg stage through completion of the cocoon
–Chawkirearing

29. a. Mulberry cultivation –Moriculture
•Morus spp. (M. alba, M. indica, M. cerata)
•Climate : up to 800 m MSL, rainfall – 600 mm – 2500 mm
•Optimum Temperature – 24-28, RH 65-80 %
•Soil –red loamy soil, saline and alkaline soils not preferred
•Varieties –Irrigated –Kanwa2, MR 2, S30, S36
•Semi irrigated –Kanwa2, MR 2
•Rainfed –S13, S34,

30. Propagation
•Sexual –seedlings –broadcasting in lines
•Asexual -cuttings, grafting, budding, layering.
•Mostly used –cuttings, planted in main field or nursery, rooted
saplings establish better in main field
•Cuttings –semi hardwood cuttings, 10-12 mm diameter, 15-20 cm
long with 3-4 active buds

31. Nursery
•Select 1800 sq.marea for 1 ha of main field
•Apply 600 Kg FYM @20t/ha and mix well
•Nursery bed of 4m x 1.5 m size
•Provide drainage channel and avoid shady area
•Pre treatment of cutting –1 Kg Azospirillumin 40l of water
•Keep the bottom end of the cuttings for 30 minutes in it
•Irrigate the nursery once in 3 days
•Termite attack –Malathion 5 D, Quinalphos 1.5 D
•Root rot/ collar rot –Carbendazim 50 WP (2g/l) and T. viridae0.5g/m2
•After weeding apply 100g of urea/m2 between 55 and 60 DAP

32. Main field planting
•Transplant 90 -123 days of planting, No. of cutting/ ha –27,780 (60x 60 cm)
•Plant at a depth of 15 –20 cm
•Nutrient management –300: 120: 120 (NPK)
•Biofertilizers –Azospirillum@20Kg/ ha, Phosphobacterium@ 10Kg/ ha
•Mix biofertilizers with 50 Kg of FYM, irrigation after fertilizer
•Apply micro nutrients as per recommendation
•Planting –pit system, row system, strip system and kolarsystem
•Pit system –rainfed crop, wider spacing 40x 90cm, prune once in June and
Nov. 8-10 cm above ground
•Row system –irrigated crop, 45-60 cmx 45-60 cm, done at a height of 3-8cm
above ground level , harvest by bottom pruning
•Frequency of irrigation depends on humidity, stage of growth, soil type
•Flood, surface, sub surface, sprinkler, drip, check basin, furrow systems

33. Pruning
•To increase the leaf yield, production synchronized with silkworm rearing
•Fist form – cutting of mulberry plant each year at one place on main stem.
Stem becomes thick and fist shaped , more resistant to pest and diseases
•Non-fist form – pruning done such that 2-3 branches allowed to grow from
main stem and secondary branches also develop, less resistance to pest and
diseases
•Bottom/ ground – branches cut at the base of the stem at ground level, 5 times
pruning in a year, needs heavy doses of fertilizers and irrigation
•Middle - cutting the branches of bush mulberry at a height of 45 – 60 cm above
the ground level during Dec – Jan, stimulates sprouting of the lower buds
during winter
•Top clipping – done to produce more branches and leaves, clipping off the top
of the branch but not the whole branch, winter season, production & quality
improved

34. Harvesting
•Leaf picking, branch cutting, whole shoot harvest
•Harvest during early hours
•Largest glossy leaf upto4
th
from top –1
st
instar larvae
•Next 6-8 leaves –2
nd
instar larvae
•8-10
th
leaf –late stage larvae
•Size of the chopped leaf –0.5 to 1.0 sq.cm –upto2
nd
stage
•From brushing to the end of the second stage the larvae are fed with
tender leaves

35. Leaf preservation
•Silkworm grows best when fed with succulent leaves which are rich in
nutrients and moisture
•Leaves if not preserved properly, dry up and become unsuitable for
feeding
•The harvested leaves must be preserved in fresh condition in a wet
gunny cloth
•If the climate is too hot and dry, the leaves are preserved in a leaf
chamber which is lined with gunny cloth
•Cloth is kept wet by spraying water at frequent intervals

36. b. Silkworm rearing
•5 phases
•Selection of races of B. mori
•Rearing of silkworm –chawkiand late stage rearing
•Mountaging/ cocoon spinning
•Marketing
•Post cocoon processing –stifling, reeling and spinning

37. Selection of races of B. mori
•DFLs –Disease Free Layings–eggs procured from a quality center called
grainage
•Grainage–establishments where disease free & quality seeds are produced on
scientific lines
•Industrial silkworm seed is a hybrid between two silkworm races exploitation of
multivoltine hybrids
•When silkworm races are continuously breed for more than 6-7 generations,
without any selection for quality cocoon they loose their volatility and vigour
•Systematic seed organization – technique developed by scientists to maintain the
vigour of silkworm
•Pj stations/ basic seed farms – they release silkworm stocks continuously for
multiplication

38. •Two roles –to maintain the silkworm breeds released by the research
institute
•It releases silkworm stocks at required regular intervals to maintain the
stream of seed production
•Basic seed farms are the temple of seed organization and seed
production
•Should be maintained under highly hygienic conditions and manned
with highly qualified and experienced silkworm breeders
•Silkworm rearing in Pjfarm –optimum environmental condition for
worms, produce healthy and strong cocoons for egg production
•Hybrid reraing–rearing for commercial cocoon production where
emphasis for high silk content is made

39. •Disinfection –basic stocks are less resistant to diseases as compared to
hybrids
•The appliances are washed with 1 % bleaching powder solution followed by
3 % formalin solution
•Rearing house –fumigation of 3% formalin
•Washed equipment's are kept in a closed room, sprayed with 1 % bleaching
powder solution followed by 3 % formalin
•Open the doors and windows 24 hours after disinfection
•Done two days prior to brushing
•Feeding of tender leaves at final stage leads to improper growth of larvae
and incidence of diseases, heavy pupa that dies

40. DFL preparation
•On the day of moth emergence only healthy moths selected
•Selected male and female moths of the same race are allowed to couple
•Kept in cellules in oviposition room where T 25 degree and 75 % RH
•Darkness is provided for mating, 4-5 hrsafter mating male moth is rejected
to ensure all eggs are fertilized
•She is allowed to lay eggs on egg card and covered with cellule in
oviposition room (multivoltine –450 eggs, bivoltine –600 eggs)
•Next morning, the mother moths are examined to check whether they are
free from pebrinedisease (individual moth crushed, one drop of fluid taken
on a glass slide) moths dried in hot air oven, T 65 dgreefor 6-7 hrslayings
with 2% KOH solution grinding)
•A smear prepared by putting a cover glass, microscope 6X even if a single
moth shows pebrinedisease that whole lot of cocoon is discarded –action
taken to disinfect reraingroom and garinage

41. •Only layingswith large no. of eggs are selected for further breeding
•Washed in 2% formalin for 15 –20 min –surface sterilization again
washed in water to remove formalin
•About 100 such dfl’sin each of the races are selected
•In bivoltines–these dfl’sare stored in cold storage for hibernation –
6-10 months –preservation of basic stocks
•This will enable rearing of stocks only for one or two generations in a
year. This helps to avoid repeated multiplication and inbreeding
depression
•Multivoltines–no hibernation –dfl’sselected for rearing next
generation
•Supply of dfl’sbasic stock –30 dfl’sare reraedseparately in cellular
beds for stock maintenance, 70 dfl’sare reared as Pi stocks for P seed
production

42. Rearing equipment's
•Chawkirearing box with stand
•Bamboo tray (round)
•Rearing stand (wooden)
•Chandrike
•Leaf chamber
•Feeding stand (wooden)
•Chop sticks
•Feather
•Chopping board
•Chopping knife
•Basin stand (Iron)
•Ant well
•Foot cleaning tray

43. Pre incubation care of silkworm eggs
•Care during transport, well aerated, prevents from desiccation
•25 degree Celsius, 80 % RH, 16: 8 L:D –ideal
•Transport –carry them in containers or packets with holes on it and loosely
packed
•To avoid desiccation –wrap the packet with green leaves or wet cloths/
blotting paper
•Transport during cooler days
•To eliminate surface contamination –egg’s surface should be soaked in 2%
formalin for 10 min.
•Should not be done if the eggs have already developed head pigmentation

44. Incubation
•The process of facilitating the growth and development of the embryo
inside the egg till hatching
•It involves providing the required ambiance to the egg which includes
the required T, RH, aeration, light etc.
•The most modern way of incubating eggs is to spread them in trays in
the incubator which has facilities to control the T, RH, light hours
•Usually farmers place the egg sheets or loose eggs spread in the
rearing tray on paraffin paper, cover them with another tray, and then
with a moist cloth. When T increases eggs are incubated in earthen
pots which are kept on wet sand and covered with wet cloths

45. Black boxing
•Done at > 50 % eggs reach pinhead stage
•By around 8
th
or 9
th
day from the day of laying, embryos develop eye spots
which are visible as a black spot on the eggs –become sensitive to light
with accelerated growth –pinhead stage
•Eggs at pinhead stage are kept under total darkness either by wrapping them
in black paper or keeping them in a black box or dark room for the next 2
days-black boxing
•This retards the development of embryo which have already reached
pinhead stage and also helps in synchronization in hatching all eggs
together on the same day
•Different methods –black paper method, black cloth method or wooden box
method
•Duration ranges from 48 –72 H after the head pigmentation stage

46. Chawkirearing
•Chawki–young silkworms usually up to the end of second instar,
looks like tiny ants
Characterestics
•Tiny and delicate –chances of damage are higher during handling
•Require highly nutritive and easily digestible food
•Require slightly higher T (28 degree) & RH (80%)
•Growth rate is slightly higher, Resistant to high T & high RH
•Weak against pesticides, gases

47. •Chawkirearing involves providing the young silkworm tender
succulent leaves cut to size, maintaining their freshness by preserving
the leaf moisture content, providing its required environment during
feeding and moultingand sanitation
Leaf quality for chawkirearing
•Feed on the surface of the leaves being too small and tender
•Leaves should be tender , soft and succulent with 80 % moisture and
high nutritive value (27% protein, 11 % carbs, minerals and vit)
•First 4 largest glossy leaf from top – for first instar larvae
•Such tender leaves are fed to silkworms each time they resume feeding
after moult

48. Chawkirearing practices
•Chawkirearing starts after brushing silkworms into the rearing trays
•Tiny worms which feed on the surface of the leaves should be able to
reach the surface of the leaf more easily and speedier
•Provide chopped leaves of about 1cm2 size
•As the worm grows in size, the size of the chopped leaves can be
increased
•Silkworms are fed 3-4 times a day depending on the climate
•During rainy season/ cooler climate –2 feedings sufficient, hot/ dry
climate –no. of feedings higher
•3 feedings per day on an average –8.00 am, 2.00 pm, 8.00 pm
•20 Kg tender leaves for rearing 100 dfl’sof the first 2 instars –varies
based on the breed and size of worm

49. •To prevent loss of moisture from leaves and maintain them fresh –worms are maintained
on a paraffin paper in the rearing tray
•After feeding,thebediscoveredwithanothersheetofparaffinpaperandthe edges of
bothsheetsfoldedtogether known as wrapping up
•ifparaffin paper not available use polythene sheets of 400 gauge thickness
•Before eachfeedingtheparaffinpapercoverisremovedandbedgentlyspread andleft
overleafisallowedtodry
•The fresh chopped leaves are then fed and covered with paraffin paper again
•The fresh chopped leaves are then fed and covered with paraffin paper again
•The rearing trays after feeding are usually piled up one above the other on small stand
altogether looking like a box and therefore called box method of chawkirearing
•If thetraysarekeptintherearingstand,itisknown as stand rearing –most preferred
•As thesilkwormgrowsinsizeitsbodybecomestootightandbrittletoholdthebody. As
a result of which its movements becomes difficult and mouth parts look small compared
to its head. At this stage they stop feeding and moults.Moultinglastsforabout20-24hrs.
•First moult–3 days after brushing, second moult4 days after first moult
•As thelarvaapproaches moultingstage, its body becomes lustrous and shining,
prothoracic segment becomes bulged, head becomes narrow, pointed and black, loose
appetite become weak

50. •As the worms prepare for moult, leaves are cut into smaller size and thinly
spread to meet the requirement of the fewer feeding worms
•Remove paraffinpaperandwetpaper,sprinkleslakedlimeoverthebedto
drytherearingbed,provideadequateventilation
•95 % worms come out of moult, dust bed disinfectant (Vijetha, Ankusk,
Resham Jyothi, TNAU seridust, Sanjeevini)
•Feed inhalfanhourgap
•Moultedlarva looks ash colouredwith broader mouth portion and feed
actively
•As the left over leaf accumulates the rearing bed thickness increases
resulting in multiplication of various pathogens

51. Bed cleaning
•The silkworms have to be transferred to a clean tray and the bed
refuge discarded and this process is called bed cleaning
•Done byspreadinganetofmeshsizeof 1cm2 on the rearing bed
followed by feeding and transferring the worms along with the net
after one more feeding
•Cleaning toomanytimesduringyoungstagesresultinunconscious
discardingofwormsleftoverinthebedwhichwereunabletomove
overthenet
•Usually one cleaning is done during the entire chawkistage

53. Commercial chawkirearing centres(CRC)
•The purpose of chawkirearing is to grow quality silkworms under disease free
environment to reduce the cost and duration with farmers and to improve the cocoon
quality and productivity
•So poorfarmerswhocannotaffordtoprovidethemicroclimatecan purchase silkworm as
chawkiworms
•Cocoon productivityfromCRCsuppliedwormsisabout20–25%higher
•CRCprovidesuitablerearinghouseforchawkirearingwithrequiredrearingappliances
wellmaintainedandirrigatedexclusivechawkimulberrygardenandwelltrainedman
power
•Advantages-provideproper egg incubation and good hatching, robust and disease free
chawkiworms, prevents crop loss and cocoon crop stabilization, increased yield of good
quality cocoons, reduction in production cost of cocoons, higher profits, synchronization
of crops, distribution of labourfor other works

54. Disinfection and hygiene maintenance
•Early instars are (I, II & III) are most susceptible to diseases compared
to late instars, bivoltine more susceptible
•Quantity of disinfectant solution –based on the floor area –effective
disinfection –1.5 l/ m2 floor area
•Recommended disinfectants
•2% bleaching powder in 0.3 % slaked lime solution
•2.5 % Sanitech/ Serichlorin 0.5 % slaked lime solution
•0.05 % Asthrasolution
•Effective disinfection –by drenching spray of disinfectant solution in
all the nook and cornorby the CRC using power sprayer

55. Disinfection schedule
•Completion of rearing –first disinfection of CRC and appliances with 2%
BP
•3 days before brushing –cleaning and washing of CRC building, rearing
tray disinfection
•2 days before brushing –2
nd
disinfection of CRC and appliances
•1 day before brushing –dusting 5% BP in slaked lime powder surrounding
environments of CRC. Open the windows of CRC for ventilation and to free
the gases accumulated
•Worms settling for 1
st
moult-50 g slaked lime powder
•Worms in 1
st
moult–Vijetha/ Ankush 50g
•Worms settling for 2
nd
moult–150g slaked lime powder
•Disinfcetantsare dusted as thin layer uniformly @ 3g/ sq.ftusing a duster/
muslin cloth

56. Measures to maintain hygiene
•Wash hands and feet with the recommended disinfectant solution before entering
the CRC and also after attending rearing
•Wash hands with disinfectant after every bed cleaning
•Collect diseased/ dead/ weak larvae from the rearing bed with forceps/ chopsticks
into a basin containing disinfectant solution and destroy them by burning
•Collect silkworm bed refuse into litter basket/ vinyl sheet meant for it
•Prevent flooring of bed refuse during bed cleaning
•Disinfect the leaf storage room along with the rearing room
•Store mulberry leaves in a separate room and cover with wet gunny cloth
•Dust slaked lime powder on the rearing bed when the worms settle for moult
•Disinfect silkworm body and rearing set by dusting Ankush/ Vijethaafter moulting
and before resumption
•Rear chawkilarvae under recommended optimum T, RH, and spacing conditions
for healthy growth
•Feed silkworms with quality mulberry leaves for robust chawki

57. Transportation of chawkilarvae
•After chawkicertification the young silkwormsnduring the moultare
transported in a vehicle to the farmers during cool hours of the day.
•Care should be taken that young worms are not disturbed during the
transportation
•C: B ratio = 1: 1.51

58. Late age silkworm rearing
•3
rd
, 4
th
and 5
th
instar larvae are considered as late-age worms
•Reraedin a bamboo tray
•Newspapers are spread over the trays to absorb excess moisture in leaves
and faecalpellets
•T & H requirement comes down as the stage advances
•Leaves of medium maturity are fed (6
th
leaf) to 3
rd
and 4
th
age and coarse
leaves are fed in the 5
th
st6age
•Over matures and yellow leaves should be rejected, since they may induce
disease outbreak
•Bed disinfectants after 3
rd
moult800g/ 100 dfls, 4
th
moult–1000g/ 100 dfls,
final stage -2000g/ 100 dfls

59. Moulting
•Remove the paraffin papers
•Evenly spread the larvae in the rearing bed 6-8 H before settling for
moult
•Provide air circulation to avoid excess humidity inside the room
•Provide stove/ heaters to raise the room T during winter
•Apply lime powder 60 min before resumption of feeding daily during
rainy/ winter seasons to reduce dampness in bamboo trays

60. Mounting and different methods of mounting
•Mountages – the device that helps or supports the silkworms for
comfortable spinning of their cocoons is called cocoonage or
mountage
•It enables the ripe worm to spin cocoon
•Play and important role in quality cocoon production
•Types of material used, finishing of moutages, and space available for
spinning determine both the quality and quantity of cocoons

61. Chandrika
•Most common form of mountagein India
•Rectangular mat on which a spiral bamboo tape is tied
•1.8x1.2m,4-5cmbroad,spacebetweenthespirals is 4-5 cm
•Advantages–canbeeasily manufactured and stored, provides easy
passage of air for quick drying of excreta to avoid staining, easy to
transport and disinfect, low cost and low weight

62. Screen type mountages
•It is made of bamboo or wooden or plastic reapers on which, instead of spiral
bamboo tape, longitudinal strips with triangular peaks are placed. The screen can
be folded and stored.
•Thismountagecan be kept clean and well-ventilated and hence, cocoons spun on
this mountageare of good quality.
•It is more durable than chandrika. But occurrences of double cocoons are frequent
in it.

63. Plastic mountage
•Made of plastic instead of bamboo
•More durable,easytoclean,notpronetorodent attack
•Produce lessernumberofdoublecocoons
•Once invetstednot further maintenance, care/ expenditure needed
•Costly thanChandrika
•Cocoons produced on these mountagesare more flimsy and not
unirformin size and hence not frequently used by farmers

64. Japanese low cost mountage
•In this modified Japanese mountage, a wooden frame of 4 longitudinal rods is
attached bymeans of cross-spokes at two ends to a central axis. Each rod has a
number of pegs placed at equal distances. These pegs are connected by long
threads to twisted rice straw in a regular pattern like that of charpoy
•The size of frame and the number of pegs can be modified according to the
requirement of the rearer. This mountageis cheap, more durable a less chances of
disease spread.

65. Bamboo strip mountage
•Made of bamboo stirps that are either nailed on wooden reaper or placed in
grooves of wooden reapers. Several such frames are placed one above the other
with the lower one keeping on four uniform bricks or wooden blocks. This
mountagesare cheap, durable, easy to handle, and harvest the cocoons.

66. Bottle brush mountage
•This recently introduced mountage
consists of a thick coconut or jute fibre
rope into which 6-9″ sticks (midrib of
coconut leaves) are inserted very
closely. These are used by the worms
as support. The worms spin their
cocoons in the space between the
sticks. This mountageis very cheap;
can be made easily and occupies little
space compared to Chandrika.

67. Rotary mountage
•It has pieces of cardboard to form 13 rows, consisting of 12 sections and each and
amounting to 156 sections. Ten pieces are put into frame as a set. When this frame
is hung up with wire holding at by ends, the frame can be turned around two axes.
This frame produces fewer spoiled cocoons and raises the reelabilityof cocoons.
Good cocoon percentage is more than 80. It is the best type and suitable for large
scale silkworm rearing because it does not only lead to increased cocoon quality
but also saves labourin mounting and harvesting.

68. Pests and diseases of
silkworm

69. PebrineDiseases
•In Hindi this disease isknownas 'kata’.
•Causative agent and infection: Nosema bombycis
•Infection-Transovarion(through ovary) or orally(consumption of infected leaves)
•Also from diseased and dead larva.
•Microspores are oval and refractile.
•Spores hatch in digestive tract, reaches blood and affects all organs

76. Control:
•Disinfection of rearing house and equipmentswith 2% formalin
•Rearing bed should be kept dry
•Destruction of infected worms.

84. Symptoms:
•Slow stunted growth, larval stage is prolonged.
•Midgut becomes opaque and pale yellow.
•Worms expellswhitish excreta and spoils bed.
•Goblet cells ruptures releasing polyhedrainto
alimentary canal.
•It passes out with excreta, spreading the disease.

85. Control :
•Rearing of silkworms under hygienic
conditions
•Proper ventilation and spacing.
•Practicing personal and rearing hygiene.
•Collect the diseased larvae and ensuring its
proper disposal.
•Maintaining optimum temperature and
humidity in the rearing house.

87. Control Measues
•Exclusion method: Provide wire mesh/nylon net
on all windows/doors.
•Cracks and crevices should be sealed
•Place uzitrapsinside the rearing house to trap
Uzifliesemerging inside.
•Biological control: Release Nesolynxthymus(a pupal parasitoid of the uzifly) inside
rearing house on 2nd day of V instar.

90. Assessment of Cocoons
•Cocoons produced are to be marketed. Following points/ characters are generally
consideredto assess the cocoons in fixing the price.
A. Cocoon Weight:
•Cocoons are being sold on a weight basis. You will find that the weight of the
cocoons gradually decreases due to moisture loss and consumption of fat till the
pupa transforms into moth and emerges. So, immediately after harvest, defloss,
sort, and weigh the good cocoons. This will be the weight of green cocoons. Make
a label indicating race or combination, date of spinning, green weight, etc. while
taking to the market.

91. B) Rendita:
•It represents the quantity of green (fresh) cocoons required to produce1 kg. of raw silk. If 10 kg.
of green (fresh) cocoon of a lot is required to produce1 kg raw silk, then Renditaof that lot is
10. It is an indicator of price fixation of the cocoon when purchased for reeling.
C) Shell Ration : It indicates the quantity of silk shell in terms of cocoon weight and expressed in
percentage. This value gives a clear indication of quantity of raw silk that can be reeled from a lot
of fresh cocoons. It is used for estimating Renditaand ultimately helps in price fixation.
To find out weight of a single cocoon, take 50 cocoons randomly from the sorted out good
cocoons, calculate single cocoon weight using the following formula:
Average single cocoon weight (g.) = Weight of the 50 good cocoons/ 50
•Then, cut the cocoons and record the shell weight. Calculate shell ratio percentage by using the
formula:
Shell ratio (%) = Shell weight/ Cocoon weight *100
•In multi X bi-hybrids, generally it ranges between 12 and 16 whereas, it is between 18 and 23 in bivoltine
hybrids.
•Activity- If 50 nos. of good cocoons weighs 75 gm. and their empty cocoon shell
weighs 8 gm., calculate average single cocoon weight and shell ratio percentage.
•Work out this problem in your record

92. D) Assessment of Cocoons for Defective Cocoon Percentage: If the lot is not
sorted properly, you can assess percentage of defective cocoons in a lot. For this,
take one kg of cocoon from the lot at random. Sort out defective cocoons like
double, flimsy, melted, pierced etc. Count and weigh good and defective cocoons
separately. Assess defective cocoon percentage by the following formula:
Defective cocoon(%) = Wt. of defective in one kg/ Wt. of cocoon
taken (1kg.) * 100
•Activity - One kg. of cocoon contains 250 gm of defective cocoons.
Calculate defective cocoon percentage.
•Work out this problem in your record

93. Defective cocoons –types
•The cocoons are sorted into:
a) Good b) Double c) Uzi pierced d) Flimsy or thin-shelled e) Melted or stained and f) Thin-
end cocoons.
•Sorting will improve the product image and marketability. Reelersalways prefer uniform
shapes in a lot. Uniform shape improves reeling performance and silk quality. Sorted-out
defective cocoons can be sold at different rates.
1. Melted and Stained Cocoons: If spinning larvae or pupae die inside the cocoon during
spinning or transportation, it causes melting or inner soiling. Sometime, inner melted material
ooze out and cocoon gets stained. Staining of cocoons may be due to urination also.
2. Flimsy or Thin-Shelled Cocoons: Weak or undernourished silkworms are spun loose or less
compact cocoons. These become flimsy or thin-shelled. Reliability of these cocoons is poor.

94. 3. Deformed Cocoons: Weak larvae or improper mountagecauses deformed
cocoons. These cocoons affect the reelabilityand quality of raw silk.
4. Thin-end Cocoons: Thin-end cocoons may be due to genetic character of the
silkwormraces or may be due to improper rearing and a spinning environment.
These cocoons affect reeling performance.
5. Pierced Cocoons: Cocoons may be pierced due to the emergence of maggotsof
parasitic Uzi fly or emergence of silkworm moth. These are unsuitable for reeling.
6. Double Cocoons: Double cocoons are abnormally large mostly with oval shape
with two or more pupae inside. This may be due to genetic character overcrowding
in the mountage. Improper mountagealso causes double cocoons. Two or
sometimes more filaments are entangled in these cocoons. These cocoons can’t be
reeled normally, can be reeled into a special type of silk, called 'dupion'.

95. Harvest
•Harvest signifies to the collection and gathering of produced cocoons from
spinning tray or mountage.
•Harvest cocoons at 6th day after completion of full 5 days in mountage, counted
from the last day of mounting.
•Delayed harvest will lead to weight loss of cocoons

96. •Methods for harvesting of silk cocoons varies, depending upon the mountage
(spinning tray) used.
•Whatever the methods of harvest, first you remove litters and left-over of leaves,
dead or un-spun larva, naked pupa (without cocoon), flimsy and melted cocoons
from the mountage. Flimsy and melted cocoons may spoil the good cocoons by
spilling stain.
•Chandrika is most commonly used in our country -by hand, simply by moving
your fingers in between the ridges.
•In case of plastic collapsible mountages, you may harvest manually by hand
picking.
•Rotary card board mountages, harvesting by hand -difficult and time consuming -
wooden harvester for quick harvesting. First part is a wooden frame on which
cardboard mountagecan be fixed. Another is pusher, made up of wooden pegs,
that fits with the hole of mountages. After removing dead worms, flimsy and
stained cocoons, fix cardboard mountageon the harvester. Then, place the wooden
pusher on the holes and push gently so that cocoons come out of cardboard hole,
collect the cocoons by hand by folding the mountages

98. Some machines developed by CSR&TI, Mysore
•Cocoon Harvester: It is made up of iron or wood. It consists of two parts and is
used for harvesting cocoons from rotary mountages. Cardboard mountagesare
inserted into the wooden frame and cocoons are pushed out using a pusher made
of the same size as the holes of the mountage
•Cocoon Deflosser: Hand-operated and motorized cocoon deflossingmachines of
different capacities are available for fast deflossingof the cocoons. The motorized
machines have capacity to defloss100 kg cocoons per hour.
•After harvesting, spread the cocoons in trays with maximum of two layers of
cocoon. Heaping of cocoons may lead to accumulation of moisture and heat and
ultimately melting of cocoons.

99. Deflosser (Electric run) Deflosser (hand operated)
Cocoon Harvester

100. •Transport the cocoons in a right way and Choose the right market for your cocoons.
Transportation
•Transportation is a very important factor because often it affects the quality of cocoons.
Pack the cocoons loosely, preferably in bamboo baskets or plastic crates or plastic nets.
Transport the cocoon during the early cool hours as live pupa inside may die and melt
leads to staining of cocoons. This will lower the quality of cocoons and get low price.
Marketing
•Choose the right market. There are separate markets for different types of cocoons like
seed cocoons and reeling cocoon. There are many established Govt. controlled markets in
cocoon producing areas, where, market authorities first check the cocoons for complete
pupation then arranges for display and bidding of cocoons and as a producer you will sell
your produce to highest bidder. In that way, youmayget the right price for cocoons. The
reelersdo not prefer mixing of different lots of cocoons. So, don't mix different lots.

101. Post cocoon processing
1. Stifling –process of killing the pupae inside without interfering with the structure of
the silk shell around it.
2. Reeling
a.Brushing or Deflossingis the removal of the floss to find out the actual reeling ends
of the cocoon that can undergo continuous reeling.
b.End picking –Process of collecting ends of all cocoons are separated out and
gathered together for reeling
c.Casting
d.Binding
e.Traversing
3. Chemical processing/ Degumming –removal of sericin and other impurities from raw
silk which imparts lustrous and softness to silk
4. Re reeling –to overcome the defects of silk during reeling, it is first reeled on small
reels and later transferred to standard-sized hanks. This process is known as re reeling
5. Lacing and skeining

102. Cocoon stifling
•Stifling treatments are applied to silk cocoons in order to kill the
pupae, preventing the emergence of moths and allowing to preserve
the silk during long periods of time.
Different methods
1.Sun drying
2.Boiling/ steam stifling
3.Hot air drying

103. Sun drying
•Killing and drying the pupae by prolonged
exposure of freshly harvested cocoons to
scorching hot sun
•Can be preserved for a long period,
• Immediately after the harvest of cocoons they are
thinly spread out on mats & kept in the hot sun
from morning to night for several days till the
pupae are killed & the cocoons completely dried
•Sun-dried cocoons are very light & when shaken
make a rattling sound
•Simple and cheap, not suitable for modern reeling
•Strength of the bave is very much affected in this
method
•Increases wastage of silk in reeling

104. Boiling/ steam stifling
•The process of removing the threads from the killed cocoon is called “reeling”
•Cocoons cooked first in hot water at 95 – 100 degrees for 10 – 15 minutes to soften
the adhesion of silk threads among themselves, loosening the threads to separate
freely & facilitate the unbinding of silk threads
•This is called cooking – enables the sericin protein to get softened and makes
unwinding easy without breaks
•Immediately after stifling, the cocoons are spread on spacious ventilated shelves
and left for 3 to 4 days for partial drying prior to reeling, the cocoons must be
turned over frequently to prevent the growth of mould
•If left for extended periods such as more than a month, the risk of mold is
pronounced even with frequent turning & satisfactory ventilation. The damage is
especially acute during the rainy season
•However, it kills the pupa inside & does not dry it
•Pupa normally contains moisture in the form of body fluids (65% of body weight)
•Makes pupa fragile & weak. Such pupa when kept stored as layers the pupae in the
lower layers getting crushed is more

105. Disadvantages of steam stifling
•Steam stifling of cocoons has certain drawbacks. Steam stifling only kills the pupa
inside and does not dry it. The pupa normally contains moisture in the form of
body fluids, to the extent of nearly 65 per cent of its own weight. This large
moisture content makes the pupa fragile and weak, and so such cocoons cannot be
kept stored in thick layers, because of the risk of the pupae in the lower layers
getting crushed under the weight of the cocoons above and the body fluids
spoiling the silk of the cocoons.

106. Hot air drying
•Shelf-carrier/Cabinet type dryer:
Shelfcarrier type drying
performs the drying operations in
a chamber which has shelf carrier
with many trays. The cocoons are
dried by the flow of hot air
current.

107. •The cooking process is done for softening the sericin to facilitate easy unwinding
of the silk filament at the same time. The sericin should be retained with the
fibroin to facilitate agglunationof filaments in the thread forming. The sericin
content of the silk filament ranges from 25 to 30 per cent, which varies in different
races. In cooking process 7 to 8 per cent of sericin is dissolved.
Cooking of cocoons

108. Deflossing
•Cocoons covered with a soft and loose layer of silk filaments, which is called floss
•Removing of the flossy layer from the cocoon is called Deflossing
•Deflossingis a pre-requisite for extraction of silk (Reeling).
•During the process of reeling, floss is removed by brushing. In this process, some
portion of reelablesilk also goes as waste
•Deflossedcocoons minimize the loss during reeling.
•Cocoons used for egg production are also deflossedfor assessment of quality and
easy emergence of moth
•You can deflossthe cocoons manually -time consuming and labourintensive -
many manual or power operated deflossingmachines are available.
•Cost of deflossingby machines is about 40-50 times cheaper than manual.
•Deflossedcocoons will fetch higher price as the buyer can assess the quality and
silk content very quickly.

109. Deflossing Deflossedcocoons

110. Reeling
•After boiling (cooking) and brushing, reeling started. Reeling is the extraction of
continuous silk thread of desired thickness from the cocoon without any break. Before
reeling, light brushing of the cocoon surface is done to find out the tip of the silk filament.
•Then the ends are all separated out and gathered together, this is called end picking.
Generally, filaments from multiple cocoons are combined together and transferred onto
the reeling or spinning machine, which then automatically unravels the cocoons and
simultaneously create a single strand of silk from the cocoons.
•Throughout the reeling process, the cocoons remain in boiling water. When one cocoon gets exhausted, the second
one is immediately substituted to reel a continuous and uniform yarn. So the important steps in reeling are brushing,
end picking, casting, binding and traversing. The individual filament must be inter-wined or twisted and cemented
firmly so that the reeled filament does not break during subsequent processing of fabrics. This twisting and
cementing is done with the help of a special device, called Croissure, which remains attached with the reeling
machine.
•Croissurehelps in twisting and agglutinating the have as well as it squeezes out excess water from the reeled thread
to make it dry. Reeling can be done by 3 systems:

111. 1. Charka
•In this manually operated system, inferior quality or defective cocoons are reeled.
Here cooking and reeling are done in one basin. Following cooking at high
temperature, the soften cocoons float in basin.Thereeling ends are then taken out
from 4-5 cocoons and twisted around themselves with the help of charkha reel. to
make uniform thread. Charkha reeling machine is traditionally home-made and
used mainly in villages for small scale silk production. It uses chambontype of
simple croissurewhere threads from two reeling ends are interwindedtoform few
spirals. So the silk reeled by charkha is of poor quality.

112. Cottage basin system
•In this system, cooking and reeling are done separately. Boiling water basin is
used for cooking while reeling is done in a hot water basin kept near the cooking
basin. Cottage basin reeling machine uses travellettecroissure. It consists of 3
pulleys to enable the thread to interwinearound itself and also better removal of
water and gum spots from the thread.
•Cottage basin is also attached with traverse or distributor which is a modified hot
rod. After being squeezed by the croissure, the thread is further dried as it passes
on the traverse before reaching the reel. So cottage basin yields silk of good
quality with uniform thickness. In India, as much as 806 tonnessilk are produced
by 4000 cottage basin systems.

113. 3. Filature system
•In this power-driven multi-end reeling device, cooking and reeling are done
separately. It is a modern device where continuous reeling is done from cocoons of
superior quality. The silk produced by filature is also of superior quality because
of increased cleanliness and uniformity in thickness of the fibre. However, only
8% of the total silk production in India is contributed by filature.

116. Chemical Processing of Raw Silk
•The raw silk thread, thus produced is rigid, stiff and not soft in touch and also lacks in lustredue to
presence of sericin and other impurities on the surface.
•Degumming of silk: Degumming is the removal or elimination of sericin and other impurities
from raw silk. It is carried out to impart the lustrous and softness on silk. Degumming is generally
carried out by following treatments:
•(a) Extraction with water: In this process, silk thread is treated in hot water (100-130°C) for 30
minutes to 4 hours, which can cause degumming of sericin. It is a safer process with minimum
degradation to the silk fibre.
•(b) Treatment with alkali/acid: Degumming with alkali or acid depends on pH, temperature, time
of treatment, strength and nature of the reagents used. Alkalis used for degumming include sodium
carbonate and bicarbonate, caustic soda, trisodium phosphate etc. Alkali treatment should be done
for 30 minutes to 2 hours at a pH > 8.5. In a similar; way acid treatment at pH < 3.0 can eliminate
sericin.
•(c) Digestion with enzymes: Enzymatic digestion by proteolytic enzymes like trypsin (pH 8.0),
papain (pH 5.2), chymotrypsin, and pepsin at a temperature of 40-50°C were proved to be useful
for degumming.

117. •Weighting of silk: Removal of sericin from the silk fibreresults in weight loss of 22-
25%. Thus the silk becomes further expensive. Therefore, such weight loss can be
compensated by treating the silk with suitable compounds that adds weight or fix colour
to the silk.
•Re-Reeling: Sometimes silk after being reeled on device like charkha or cottage basin,
may suffer from some defects like short length, broken threads, entanglements, hard gum
spots, etc. These problems may create wastages of thread during subsequent throwing and
twisting. To overcome these defects silk is first reeled on small reels and later is
transferred to standard sized hanks. This process is called re-reeling.
•Lacing and Skeining: Re-reeled silk hunk is then tied with a colouredsilk thread by the
two ends. The hunk is then divided into five parts and is laced with a cotton thread. This
lacing prevents entangling of the silk in later operation.Thecleaned and laced hunks are
then put on a skeiningmachine to be skeined. During this process, the hunk is twisted and
folded upon itself to form a number of tight spirals or skeins . The skeiningprevents
ruffling and further entanglement of filaments during packing. The skeins are then made
into books. In a book, eight skeins are placed in horizontal row and five in vertical row.
Each book is then tied with separate cotton bands at three different places and wrapped
with tissue paper. Books are kept in bales of twenty kg weight. Thus, silk threads are kept
in store house as bales. Store house should be free from humidity and air.

119. Practical record
Expt1. Different types of Silkworm
Expt2. Life cycle of Bombyx mori
Expt3. Life cycle of Eri silkworm
Expt4. Appliances for chawkirearing
Expt5. Natural enemies of silkworm
Expt6.Helpful insects
Expt7.Lacinsectlifecycle
Expt8. Forms of lac
Expt9. Natural enemies of lac