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Chapter – V Rearing of Silk Worms Fed with Spentwash Irrigated Mulberry

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5.1 INTRODUCTION

Sericulture is one of the eight large employment systems in which a large

percentage of rural people are engaged. It is not only an employment generating

activity but also it can serve as a tool for the enhancement of the status of rural

people, through economic development. The rearing of silkworms re-quires intensive

technical guidance on the spot. Silkworm rearing demands certain specific

environmental conditions particularly of temperature and humidity.

The silkworm is the larva or caterpillar of the domesticated silkmoth,

Bombyxmori (Latin: "silkworm of the mulberry tree"). It is an economically important

insect, being a primary producer of silk. A silkworm's preferred food is white

mulberry leaves, but it may also eat the leaves of any other mulberry tree

(i.e., Morusrubra or Morusnigra)as well as the Osage Orange. It is entirely dependent

on humans for its reproduction and does not occur naturally in the wild. Sericulture,

the practice of breeding silkworms for the production of raw silk, has been underway

for at least 5,000 years in China,452 from where it spread to Korea and Japan, and later

to India and the West. The silkworm was domesticated from the wild

silkmoth Bombyxmandarina which has a range from northern India to northern China,

Korea, Japan and far the eastern regions of Russia. The domesticated silkworm

derives from Chinese rather than Japanese or Korean stock.453, 454 it is unlikely that

silkworms were domestically bred before the Neolithic age: it was not until then that

the tools required to facilitate the manufacturing of larger quantities of silk thread had

been developed. The domesticated B. mori and the wild B. mandarina can still breed

and sometimes produce hybrids.455

Types:

Mulberry silkworms can be categorized into 3 different, but connected groups

or types. The major groups of silkworms fall under the univoltine ('uni-'=one,

'voltine'=brood frequency) and bivoltine categories. The Univoltine breed is generally

linked with the geographical area within greater Europe. The eggs of this type

hibernate during winter due to the cold climate, and cross fertilise only by spring,

generating silk only once annually. The second type of breed is called Bivoltine and is

normally found in Asian regions such as China, Japan, and Korea and India. The

breeding process of this type takes place twice annually, a feat made possible through


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the slightly warmer climates and the resulting two lifecycles. The Polyvoltine breed of

mulberry silkworm can only be located in the tropics. The eggs are laid by female

moths and hatch within nine to twelve days, so the resulting type can have up to 8

separate lifecycles throughout the year.456

Process:

Eggs take about fourteen days to hatch into larvae, which eat continuously.

They have a preference for white mulberry, having an attraction to the mulberry

odorant cis-jasmone. They are not monophagous since they can eat other species

of Morus as well as some other Moraceae. Their droppings are black. Hatchlings and

second-instar larvae are called kego and chawki in India. They are covered with tiny

black hairs. When the color of their heads turns darker, it indicates that they are about

to molt. After molting, the instar phase of the silkworm emerges white, naked, and

with little horns on the backs.

After they have molted four times, their bodies become slightly yellow and the

skin becomes tighter. The larvae will then enter the pupaphase of their life cycle and

enclose themselves in a cocoon made up of raw silk produced by the salivary glands.

The cocoon provides a vital layer of protection during the vulnerable, almost

motionless pupal state. Many other Lepidoptera produce cocoons, but only a few;

the Bombycidae, in particular the Bombyx genus, and the Saturniidae, in particular

the Antheraea genus—have been exploited for fabric production.

If the animal is allowed to survive after spinning its cocoon and through the

pupa phase of its life cycle, it will release proteolytic enzymes to make a hole in the

cocoon so that it can emerge as a moth. These enzymes are destructive to the silk and

can cause the silk fibers to break down from over a mile in length to segments of

random length, which ruins the silk threads. To prevent this, silkworm cocoons are

boiled. The heat kills the silkworms and the water makes the cocoons easier to

unravel. Often, the silkworm itself is eaten ( Cuisine). The moth – the adult phase of

the life cycle – cannot fly. Silkmoths have a wingspan of 3–5 cm (1.5–2 inches) and a

white hairy body. Females are about two to three times bulkier than males (for they

are carrying many eggs), but are similarly colored. Adult Bombycidae have reduced

mouth parts and do not feed, though a human caretaker can also feed them.


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Cocoon:

The cocoon is made of a thread of raw silk from 300 to about 900 meters

(1,000 to 3,000 feet) long. The fibers are very fine and lustrous, about 10 micrometers

(1/2,500th of an inch) in diameter. About 2,000 to 3,000 cocoons are required to make

a pound of silk (0.4kg). At least 70 million pounds of raw silk are produced each year,

requiring nearly 10 billion pounds of cocoons.457

Domestication:

The domesticated variety, compared to the wild form, has increased cocoon

size, growth rate and efficiency of its digestion. It has also gained tolerance to human

presence and handling and living in crowded conditions. It also cannot fly and lacks

fear of potential predators. These changes have made it entirely dependent upon

humans for survival.458

Silkworm breeding:

The silkworm is one of the world's most genetically modified animals.

Silkworms were first domesticated in China over 5000 years ago.459,460 Since then, the

silk production capacity of the species has increased nearly tenfold. Silkworm is one

of the few organisms wherein the principles of genetics and breeding were applied to

harvest maximum output. It is next only to maize in exploiting the principles

of heterosis and cross breeding. Silkworm breeding is aimed at the overall

improvement of silkworm from a commercial point of view. The major objectives of

silkworm breeding are improving fecundity (the egg laying capacity of a breed),

healthiness of larvae, quantity of cocoon and silk production, disease resistance, etc.

Healthiness of larvae leads to a healthy cocoon crop. Healthiness is dependent on

factors such as better pupation rate, fewer dead larvae in the mountage, shorter larval

duration (the shorter the larval duration, the lesser the chances of infection) and bluish

tinged fifth instar larvae (it is observed that bluish colored fifth instar larvae are

healthier than the reddish brown ones). Quantity of cocoon and silk produced is

directly related to the pupation rate and larval weight. Healthier larvae have greater

pupation rates and cocoon weights. Quality of cocoon and silk depends on a number

of factors including genetics. Specific purposes apart from commercial purpose are

given attention by advanced countries to breed development for specific purposes like

sericin production, sex limited breeds, thin/thick filament production etc. Disease


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resistance breeding is important, as the major reason for crop losses is pathogen

infection. Efforts are being made to select breeds which are tolerant or resistant to

various pathogens.461

Silkworm legends

In China, there is a legend that the discovery of the silkworm's silk was by an

ancient empress Lei Zu, the wife of the Yellow Emperorand the daughter of XiLing-

Shi. She was drinking tea under a tree when a silk cocoon fell into her tea. As she

picked it out and started to wrap the silk thread around her finger, she slowly felt a

warm sensation. When the silk ran out, she saw a small larva. In an instant, she

realized that this caterpillar larva was the source of the silk. She taught this to the

people and it became widespread. There are many more legends about the silkworm.

The Chinese guarded their knowledge of silk, but, according to one story, a

Chinese princess given in marriage to a Khotan prince brought to the oasis the secret

of silk-manufacture, "hiding silkworms in her hair as part of her dowry", probably in

the first half of the 1st century CE.462 It is also said that about AD 550, Christian

monks smuggled silkworms, in a hollow stick, out of China and sold the secret to

the Byzantine Empire.

Silkworm diseases:

Nosemabombycis is a microsporidium that kills 100% of silkworms hatched

from infected eggs. This disease can be carried over from worms to moths, then eggs

and worms again. This microsporidium comes from the food that silkworms eat. If

silkworms get this microsporidium in their worm stage, there are no visible

symptoms. However, mother moths will pass the disease onto the eggs, and 100% of

worms hatching from the diseased eggs will die in their worm stage. To prevent this

disease, it is therefore extremely important to rule out all eggs from infected moths by

checking the moth’s body fluid under a microscope.

Botrytis bassiana is a fungus that destroys the entire silkworm body. This

fungus usually appears when silkworms are raised under cold conditions with high

humidity. This disease is not passed on to the eggs from moths, as the infected

silkworms cannot survive to the moth stage. This fungus can spread to other insects.

Grasserie: If grasserie is observed in chawkie stage, then the chawkie larvae must

have been infected while hatching or during chawkie rearing. Infected eggs can be


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disinfected by cleaning their surface prior to hatching. Infections can occur as a result

of improper hygiene in the chawkie rearing house. This disease develops faster in

early instar rearing.

Pebrine is a disease caused by a parasitic microsporidian,

NosemabombycisNageli. Diseased larvae show slow growth, an undersized, pale and

flaccid body, and poor appetite. Tiny black spots appear on larval integument.

Additionally, dead larvae will remain rubbery and do not undergo putrefaction after

death.

Traditional Chinese medicine:

In Traditional Chinese medicine, silkworm is the source of the "stiff

silkworm", which is made from dried 4th or 5th instar larvae which have died

of white muscardine disease (a lethal fungal infection). Its uses are to

dispel flatulence, dissolve phlegm and relieve spasms.

Types of Silk:

Silk is a fibrous protein of animal origin. A number of animals secrete silk

which is used by them for anchorage (muscles), entangling their prey (spiders), or

forming a protective sheath with or without other material (Lepidopteran co-coons).

Nearly 400-500 species are known to produce silk but only very few are

commercially exploited. They are the following:


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Table 5.1 :Types of Silk

Sl. No.

Variety of Silk

Name of Silk Worm

1 Mulberry silk Nearly 95% of the commercial silk comes from the mulberry silkworms Bombyxmori.

2 Tasar silk Important species of silk insects exploited for tasar silk production are: a ) Tropical tasar -Antheracamylitta(India

b. Temperate tasar -A. proylei (India)

c. Chinese tasar-A. pemyi(China & Russia)

d. Japanese tasar-A. yamamai(Japan) MA

3 Muga Silk Muga silk is obtained from the 'cocoon of silk insect belong to the species of A. assamensis(India).

4 Eri Silk Eri silk is obtained from the silk insect Samiacynthiaricini.

5 Anaphe silk Anaphe silk is produced by species of the genus Anaphe, in the Southern and Central Africa and is used in velvet and plush. It is more elastic and stronger than mulberry silk. The species spin cocoons in communes or groups. The fluffy material is spun to produce Anaphe silk.

6 Fagara silk This is produced from the pedunculate cocoons of the giant silk moth Attacusaitasinhabiting in the Indo-Australian biogeographic region, China and Sudan.

7 Coan Silk Coan silk is used to make the crimson-dye and apparel worn by the dignitaries of Rome is produced by the larvae of Pachypasaotusfound in the mediterranean region.

8 Mussel Silk The byssus threads (filamental structures) of the mussel Pinna squamosal are spun into a silk called fish wool in Italy.

9 Spider silk The silk secreted by some spiders including NephiiamadagascarensusandMirandaaurentiais used to produce spider silk. Though not exploited in textile industry, spider silk is used to produce the cross bars in optical instruments.

Commercial silk from sources other than mulberry silkworm is collectively

called Non mulberry silk. As mulberry silk constitutes nearly 95% of the total silk

production, silk in popular terms may refer only to mulberry silk and sericulture only

to the rearing of mulberry silkworms. India is the only country in the world which is

producing all the four varieties of silk viz. mulberry, tasar, eri and muga. It has the

world monopoly for muga, a golden yellow silk, produced mainly in the state of

Assam.


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Production of mulberry raw silk is mainly confined to the states of Karnataka,

Andhra Pradesh, West Bengal, Tamil Nadu and Jammu & Kashmir which together

account for more than 99% of the country's total mulberry raw silk production. India

produces mulberry both under rainfed and irrigated conditions. Mulberry is a fast

growing hardy plant and its leaves can be harvested several times in a year.

Silk is known as the queen of textiles because of its unmatched structure,

softness and its rich appearance. It has ruled unchallenged in history as an exclusive

textile and its dominant position has not changed despite the advent and challenge of

modern synthetics. In fact, there is a resurgence of demand for silk the world over.

Sericulture involves several activities such as (1) mulberry cultivation (2)

production of leaves of the host plant, (3) rearing of silkworms and production of

cocoons, (4) reeling of cocoons resulting in production of silk filament, (5) weaving,

and (6) finishing and production of fabrics.

The activities relating to plant cultivation and production of reeling cocoons

are agriculture oriented and are best suited to the rural sector. The reeling of raw silk

and production of hand-spun silk yarns are cottage based industries. This can be set

up in both rural and semi urban centres employing hand and/or power driven

appliances with skilled labour.

In addition to these activities, the fabrication of rearing equipment and

production of silkworm seeds scientifically at centres is called grainages and it is an

integral part of the sericulture activities.

Biology of Mulberry Silk Worm:

In India 200 races mulberry silk worms are maintained in their different

breeding centres. They are broadly classified mainly based on moults, voltinism, place

of origin and commercial usage.

1. Classification based on the number of larval moults:

On the basis of the number of moults which they undergo during their larval

life, B. moriis divided into three groups: trimoultcrs, tetramoultes and pentamoulters.

Most of the commercially exploited races are tetramoulters with five larval instars.


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2. Classification based on voltinism:

Voltinism refers to the number of breeds raised per year. Voltinism is a

genetically determined heritable character under hormonal control. Based on

voltinismB.moriis divided into three type of races: univoltines, bivoltines, and poly or

multi-voltines as given in Table 5.1.

Univoltine races produce only one generation per year. The eggs laid remain

in a diapausing (quiet) condition till the next spring. Larvae of univoltines are very

sensitive to temperature and other environmental conditions. They are unsuitable for

summer and autumn rearing by artificial breaking of egg diapause. The larval period

is very long. All European races are Univoltines. The cocoons produced are

commercially very superior.

Bivoltine races have two generations per year, the first generation adults

developing from eggs hatched in spring lay non dipausing eggs. The second

generation adults developing from these eggs lay eggs which remain in the dormant

state till next spring. The larval duration is as long as univoltines.

Larvae are robust and tolerate environmental fluctuations. They can be used

for 'Summer and autumn rearing and three crops can be raised per year. The cocoons

are commercially superior. Japanese and Chinese races have both uni and bivoltine

varieties.

Multi or polyvoltines have more than three generations per year. The larval

duration is short, and larvae are resistant to high temperature and high humidity.

Larvae and cocoons are small in size. Commercially cocoons are of poor quality. The

adults lay non-diapausing eggs.463

Table 5.2: Characteristics of different races based on Voltinism of mulberry

silkworm

Sl.No Characteristics features

Univoltines and bivoltines

Multivoltines

1 Egg Diapausing/ non diapausing

Non diapausing

2 Length of silk filament in cocoon

1000-1600 m 300-400 m

3 Shell ratio 15-25 % 10-12 % 4 Raw silk 80-85 % 40-45%


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Classification based on place of origin:

Based on their place of origin B. moriis classified into Chinese, Japanese,

European and Indian races. These races can be distinguished one from another on the

basis of morphological characters of egg, larva, cocoon and adult, biological

characters like duration of life cycle diapause characters, rubber of larval moults and

resistance to environmental factors and diseases and commercial characters of the

cocoon like length of filament, thickness of filament, percentage of deformed co-

coons etc.

Commercial Races:

Each country, in an attempt to improve silk yield has evolved a number of

hybrids. The commercially important Indian races are :

a) Kalimpong A (KA) :Bivoltine race with oval cocoons.

b) Nichi (NB4D2) :Bivoltine or multivoltine cocoons, ground nut shaped with a

constriction in the middle.

c) Nandi: AhybridbetweenKA x NB4D2.

d) The constriction in the cocoon is very shallow.

e) Pure Mysore (PM): Multivoltine. One side of the cocoons is broad and the

other is pointed (ie. egg shaped)

f) Tamil Nadu white: Multivoltine white cocoons (TNW) with pointed ends.

Bivoltine hybrids:

The development and introduction of CSR2 x CSR4 have significantly

contributed not only to the quantitative but also to the qualitative improvement of raw

silk production, which in turn triggered a revolutionary change in overall qualitative

and quantitative silk output of the country. The productive hybrid CSR2 x CSR4 was

the first bivoltine hybrid introduced in the field with full rearing package.

The hot climatic conditions of tropics prevailing particularly in summer are

not conducive to rear high yielding bivoltine hybrids. Considering the importance of

developing robust breeds for rearing especially during unfavourable season of the

year, CSR18x CSR19 was evolved.


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Table 5.3: Silkworm hybrids

Bivoltine hybrids

Parentage Characters

CSR2 Shunrei x

Shogetsu

• Developed during 1990s.

• Productive breed with better post cocoon parameters.

• Plain larvae with bluish white body colour.

• Bright white oval shaped cocoon with fine to medium grains.

• Cocoon shell ratio: 24-26%.

• Raw silk percentage: 19-20%.

• Fibre quality: 2A~4A grade.

CSR4 BNlB x

BCS25

Out crossed

with NB4D2

• Developed during 1990s.

• Productive breed with better post cocoon parameters.


• Bright white dumbbell shaped cocoons with fine to medium grains.

• Cocoon shell ratio: 22-23%.

• Raw silk percentage: 17-18%.

• Fibre quality: 2A~4A grade.

CSR2 XCSR4 • The hybrids viz., CSR2 x CSR4 (Shell ratio >23.0% and raw silk% 19-20) were authorized (1997) and are being exploited commercially on a large scale at farmers level during favourable months.


• Cocoons are bright white with intermediate shape and medium grains.

• Rearing during favourable months in southern states and spring in Jammu and Kashmir province, Uttaranchal, Himachal Pradesh, etc.,

CSR18x CSR19

• Developed during 1990s • Robust hybrid developed under high

temperature (36±1°C) and high humidity 85±5% RH) conditions.

• Marked and plain larvae with reddish tinge in colour (Sex-limited).

• Larval duration one day less than productive hybrid (CSR2 x CSR4).


184

• Creamish white cocoons. • Cocoon yield ranges from 50-60 kg/100 dfls. • Renditta of 6.0-6.5 and silk 2A~3A grade.

Multivoltine hybrid Kolar Gold PM x CSR2 • This hybrid displays high fecundity besides

survival of more than 95 per cent and raw silk more than 20 per cent. It was widely accepted by farmers in Andhra Pradesh, Karnataka and Tamil Nadu. The average yield is around 65-70 kg/100 dfls

Life Cycle of Mulberry Silk Worm:

The life cycle stages of the silkworm moth Bombyxmori

Phylum, Arthropoda; Class, Insecta; Order, Lepidoptera

The silk worm larval life is divided into five instars, separated by four molts. Four

distinct stages of development complete one generation of the species;ova, larvae,

pupa and imago.The common name silkworm or caterpillar is used for the larvae of

the moth Bombyxmori.

Mulberry silk worm is a holometabolous insect and passes through four

morphologically different stages in its life cycle egg, larva, pupa and adult (Fig. 5.1).

The duration of each stage varies according to the race (table 2) and according

to the climatic conditions and the quality of the food given.

Table 5.4: Duration of different stages of life cycle in different races of mulberry

silk worm

Sl.No Particulars Uni/ bivoltine Multivoltine

1 Egg 11-14 days (after break of diapause)

9-12 days

2 Larva 24-26 days 20-24 days

3 Pupa 12-15 days 10-12 days

4 Adult life span (imago)

6-10 days 3-4 days

Chapter – V

1. STAGE

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185

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186

Fig. 5.2: Silk moth and fresh pale yellow eggs

On the photoshown above the female silk moth can be seen partly upper left

and male silk moth is in the middle. The size difference is easy to see. The fresh pale

yellow eggs will turn to grey.

Newly laid eggs are a creamy yellow, after a few days the fertile live eggs will

be grey. Keep the eggs cool. In the winter this is easy, but the eggs must be placed in

the fridge as soon as it starts to warm up for spring. The eggs should not be freezed,

keep in the warmest part of the fridge.

The silkworm eggs will hatch 2 weeks after removed them from the fridge.

2. STAGE 2 - LARVA: 27 DAYS (5 instars)

The larvae of B. mori, like other lepidopteran larvae is of the cruciform or

polypod type with abdominal prolegs. The larva moults, three, four or five times and

has four, five and six larval instars (stage of insect between molts). The final larval

instar after full growth empties its gut, stops feeding, and spins the cocoon of silk

around it. The last instar larva is 10 cm long.

After four days the first molt will occur. After hatching the tiny larvae grow

the best if they are fed on the new soft leaves of the mulberry plant, larger leaves as

they grow. The silkworms (larvae) do nothing but eat. They will not crawl away. The

silkworms are to be placed on the leaves at room temperature, but not in direct

sunlight. Everything must be kept clean. The tiny silkworms are to be transferred

using a small paint brush the first few days, older larvae can be gently picked up with

hands onto a clean tray. Fresh mulberry leaves are to be given and half eaten leaves

removed from the day before, every day.


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Fig. 5.3 : Older larvae and fresh mulberry leaves

3. STAGE 3 - PUPA: 14 DAYS

The pupalmoult occurs within the cocoon spun by the final instar larva. Pupae

can be seen only by cutting open the cocoon. Pupae are soft and white soon after the

moult but become hard and brown, with the tanning of the pupal cuticle. The pupa is a

non-motile and non-feeding stage. The larval organs are degenerated and adult organs

are differentiated during this stage.

The silkworm will spin a silk cocoon as protection for the pupa. Cocoons are

shades of white, cream and yellow. The glittering shine of the silk gives an impression

of silver and shades of gold. After a final molt inside the cocoon, the larva changes

into the brown pupa. Further changes inside the pupa result in an emerging moth.

Fig. 5.4: Silk Cocoon

ADULT: STAGE 4 - IMAGO: 5 - 7 DAYS

The moths have lost their flight due to several centuries of domestication. It

does not feed during its short life span of three to six days. The size of the moth is

about 4 cm x 2 cm.


188

An adult silk moth emerges from the cocoon about two weeks after

completion. This is the adult stage of the silkworm, Bombyxmori. The body of the

moth is covered in short fine hair and wings are creamy white with faint brown lines..

Females are larger and less active than the males. Male moths move about beating

their wings seeking females.

If adults copulate in captivity, the female will lay eggs within 24 hours. The

female usually lies the eggs on the vertical side of the box or tray. Cover the whole

surface with sheets of paper making it easier to remove the eggs for storage.465

5.2 REARING TECHNOLOGY

Rearing Conditions:

Mulberry silkworm is a delicate, domesticated insect which cannot tolerate

diurnal and seasonal fluctuations in the environmental conditions. Hence, they are

reared in special rearing houses where natural changes in the environmental

conditions outside are reduced to the minimum so that silkworms receive more

uniform conditions.

Rearing houses may be brick-walled, cement plastered, permanent structures

or mud walled structures. Within the room, the rearing stand should be kept in that

part which is least exposed to sunlight. It is not possible for all silkworm rearers to

install thermostatically controlled air heating or air-cooling devices. Temperature and

humidity inside the room are regulated by hanging wet gunny clothes on the doors

and windows in hot season and by keeping a burning oven or charcoal stove in

winter.466

Rearing Appliances:

Sericulture is a rural based agro-industry and accordingly the appliances used

are made from cheap and locally available materials. Hence, the appliances used

differ from place to place and also according to the system of rearing and system off'

mulberry harvest The most common method of rearing in India is the shelf rearing as

it facilitates the rearing of a large number of worms in a small space. Various types of

appliances used for this method of rearing are briefly explained here. With regard to

various appliances used in sericulture they should be observed, distinguished and


189

studied in a sericulture rearing station close your area. Here it is only possible to

enumerate and explain the usages of various types of appliances.

A. Appliances used for keeping the worms reared

Appliances for keeping the worms are listed out with brief explanations.

Table 5.5 : Appliances for keeping the worms

Sl. No.

Appliances Specifications and uses

1 Rearing stand It is used for supporting the rearing trays which are placed horizontally in vertical rows. It is made of locally available wood or bamboo. The standard sized stands has a height of 2.5 m, length of 1.5 m and a width of 0.65 m. It has cross bars with a distance of 0.15 m to accommodate 10-12 tiers of rearing trays.

2 Rearing trays These are placed one above the other in the rearing stand to accommodate large number of silkworms. The chopped leaves placed on the trays with worms are called the rearing bed.

3 Ant wells These are placed below the legs of the rearing stand and are filled with water to prevent ants creeping on to the trays

4 Paraffin paper Thick craft paper coated with paraffin wax is used to prevent evaporation of moisture and to maintain high humidity in the rearing trays of young silkworms.

5 Foam robber strips These are also used to maintain high humidity. Thick folding of newsprint paper on blotting paper-soaked in water may also be used.

6 Chop sticks These are two thin sticks of bamboo (17.5 cm and 20 cm) which taper to a point. At the thick end the two are connected by a small thread, and these are used like forceps for picking worms.

7 Feathers Bird's feathers are used for brushing newly hatched larvae from the egg card into the rearing tray


190

B. Appliances used for feeding

Feeding also needs some separate equipment which should be safe to use.

Table 5.6 : Appliances used for feeding

Sl. No.

Appliances Description

1 Leaf baskets These are bamboo baskets of convenient size used for collecting and transporting of leaves from the field to the rearing house.

2 Leaf chamber A chamber, the sides and bottom of which are made of strips of wooden reapers, is used to store harvested mulberry leaves. Wet gunny clothes is placed as a lining.

3 Chopping board This is a rectangular board made of soft wood used for cutting mulberry leaves.

4 Chopping knife Sickle like knives with broad and sharp blade are needed for chopping leaves.

5 Mats These are placed below the chopping boards prior to chopping and are used to collect cut leaves

6 Feeding stand A folding stand on which the trays removed from the stand are placed, one at a time for feeding and bed cleaning.

C. Appliances used for bed cleaning

Nets of different mesh size made of cotton or nylon are placed above the trays

for cleaning the rearing beds or trays. When the mesh is placed on the tray and some

leaves are put the worms pass through the mesh and climb on the mesh. When all the

worms have come up them the mesh is lifted and the tray is removed and cleaned.

D. Appliances used to support the spinning larvae

Mountages -These are contrivances used for supporting the larvae when they

spin the cocoons. Different types of mountages are used in different parts of India. In

addition to support the spinning worms, the mountages should satisfy the following

requirements.

1. Provide convenient space of suitable dimension for spinning good sized

cocoons.


191

2. Should not promote formation of double cocoons, malformed cocoons and

flimsy cocoons.

3. Should have provisions for drying up of the last excreta of the worm prior to

spinning and prevention of its falling on the cocoons of other worms.

4. Should be suitable for easy mounting and harvesting. The common mountages

used in India are briefly described here.

a) Dried grass and twigs spread in shallow bamboo baskets are used in

Assam.

b) Dried weeds, paddy straw and fresh weeds are used in Jammu and

Kashmir. In these two moulting and harvesting is difficult and require

more labour. Further, formation of double and deformed cocoons is high.

c) Chandrika which is formed by a bamboo spiral is the most common

mountage Used in South India and West Bengal. This consist of a

bamboo mat of size 1.8 m x 1.2 m supported by split bamboo reapers on

all sides. On this bamboo mat, a bamboo tape of 4 to 5 cm width is

wound in a spiral manner. The bamboo tape has V-shaped struts

supported by three long bamboo strips. About 1000 worms can be

mounted on this mountage.

The defects of this mountage are:

i. percentage of flimsy and soiled cocoons are high.

ii. drying is uneven.

iii. harvesting and cleaning is difficult.

To overcome these defects, chandrika with 12 mm holes provided in the

back mat have been introduced recently.

Other recently introduced modifications under trial are screen type of

bamboo mountage and plastic collapsible mountage. These are

convenient to handle and store.

d) Bottle brush mountage is introduced recently is not only cheap but can

be fabricated very quickly and occupies very little space compared to

Chandrika. It consists of a thick coconut or jute fibre-rope into which 6

to 9" sticks (midrib of coconut leaves) are inserted very closely. The

silkworms used the sticks as support and spin the cocoons in the space

between the sticks.


192

E. Appliances needed for disinfection

1. A sprayer, either hand operated or power operated is needed to spray 2%

formalin prior to rearing operation.

2. If fumigation is adopted for disinfection, a gas mask is used to protect the face

of the operator.

E. Appliances used for maintaining optimum conditions

1. Thermometer -to measure the temperature

2. Hygrometer -to measure the humidity

3. An oven (electrical) or stove (charcoal) to warm up the rearmg room.

4. Floor mat soaked in formalin. Kept at the door.

5. Wash basin.463

5.3 REARING OPERATIONS

The silkworm rearing involves the common operations such as disinfection,

hatching, brushing, maintenance of optimum temperature and humidity in rearing

beds, feeding, bed cleaning, spacing, care during moulting, mounting of mature

worms for spinning and harvesting of cocoons.

The details of the operation vary from place to place to suit local conditions of

environment and according to local tradition of rearing. These operations are briefly

explained one by one as follows.

A. Disinfection

It is a preliminary operation and the following points are kept in mind before

selecting the disinfectant and the method of its application.

1. The disinfectant must be effective against the pathogens of silkworm diseases.

2. Its application must be simple, easy and less time taking.

3. It must be harmless to man and domestic animals.

4. It must be cheap and easily available.

Physical methods of disinfection include, sun-drying, steaming and hot air

sterilization. Among the chemical methods, chemical like paraformaldehyde, sodium

hypobromide, iodine, idoform, alcohol have been tried for disinfection. The most

popular chemical disinfection methods used by commercial rearers are following.


193

a) spraying with 2% formalin.

b) spraying with chlorkalk solution.

c) fumigating with formaldihyde gas.

Different concentrations of formalin are used for different disinfection

purposes as given in Table 5.6.

Table 5.7 : Different concentrations of formalin used for different purposes

Sl.No Purpose % used Remarks

1 For routine disinfection 1-2 % Rearing room & appliances

2 After pebrine infection 4-5 % Rearing room & appliances

3 During muscardine infection 0.7-0.8 % Sprayed on the worms

Chlorkalk is a white powder containing Ca, CI and water. The advantage of

using chlorkalk is that it is cheap, harmless to man, his animals. 55 g of chlorkalk is

dissolved in 95 cc of water and left undisturbed. Clear supernatant solution is used for

disinfection. 220 cc. is needed for spraying 10 m2area.

Regarding fumigation by formaldihyde gas 35 gram of formalin gas is

obtained be evaporation of 92 cc of 35% formalin. The doors and windows are closed

at tight before fumigation and kept closed for 24 hours.

B. Hatching:

Hatching (coming out of the larvae from the egg after breaking the shell) is a

photoperiodic response and begins in the early morning with sunrise and continues till

noon. The newly hatched larvae are black and bristly and are called ants.

C. Brushing:

The process of separating the newly hatched larva from their egg shell and

transferring them to the rearing bed is called brushing. The best time for brushing is

10 A.M. when the peak of hatching has occurred. Unhatched eggs are transferred back

to the hal box and brushed the next day.

1. Brushing the loose eggs in egg boxes:

This is done when 75% of the eggs have reached the blue egg stage (blue eggs

are hatched eggs). The hatched larvae crawl up through the holes of perforated paper


194

spread over the box, to eat the chopped pieces of leaves which are spread over. When

a large number of larvae have crawled up, the larvae along with the chopped leaves

are tapped.

2. Brushing from egg cards:

The various brushing methods adopted are

i. Feather method:

This is a popular method in India. Egg card is held vertically above the rearing

bed and by gentle strokes of feathers the larvae are pulled out.

ii. Husk method:

Powdered husk is sprinkled over the freshly hatched larvae on the egg card.

Place few leaves on the centre of the husk sprinkled. The larvae crawl up the layer of

husk to reach the leaves which are placed over the centre of the husk. As the larvae

crawl up the layer of husk themselves and are brushed by feather along with husk, the

chances of injury are less.

iii. Cloth/paper/net method:

This is an adaptation from the method used for loose eggs. A cloth/paper/net

with meshes is placed above the egg card and fresh chopped leaves are spread over it.

After half an hour, larvae attached to the underside of net and those that have crawled

on to the leaves are transferred to the bed gently.

3. Maintenance of optimum conditions for rearing

The optimum temperature and humidity for different in star is given in table

5.7.

Table 5.8: Optimum temperature and humidity conditions for different instars

Sl.No Instars Temperature Humidity

1 1st instar 26-28o C 85%

2 2nd instar 26-280C 85%

3 3rd instar 24-260C 80%

4 4th instar 24-25oC 75%

5 5th instar 23-24oC 70%


195

Normal, commercial rears do not have sophisticated gad- gets for adjusting

humidity and temperature. They adopt certain remedial measures for such

adjustments, as per the weather conditions. However, placing a thermometer inside

the rearing room is beneficial to observe the temperature fluctuations.

D. Feeding:

The quality of the cocoons harvested, depends mainly on the quality of leaves

fed during rearing. Feeding must satisfy both the appetite of the larvae and its

nutritional requirements. The first deals with the amount and frequency of feeding of

each instar and the second with the quality of leaves.

a. Quality and frequency of feeding:

The appetite increases with the age of the larvae. Of the total ingestion during

the entire larval period, nearly 85% is taken during IV and V instars. The amount of

food given also depends on the races. Uni and bi voltine require more than

multivoltine. The amount of leaves to be supplied for 50 DFL'G or 20,000 loose eggs

is given in table 5.8.

Table 5.9: Amount of leaves required for different stages of larvae

Sl.No Age/ instar

Uni or bi voltine race

Multivoltine&bivoltine in tropics

1 1st 1-2 kg 1-2 kg

2 2nd 5-6 kg 2-3 kg

3 3rd 20-55 kg 15-20 kg

4 4th 80-90 kg 35-50 kg

5 5th 450-475 kg 300-325 kg

Matured /Final stage 550-600 kg 350-400 kg

Insufficient amount of leaves leads to unequals among the worms and

overfeeding is uneconomical.

b) Frequency of feeding:

This varies from time to time and from place to place. In shoot and floor

rearing three feedings per day are sufficient. The current practices is to maintain the

frequency of feeding to 4 feedings per day.


196

Maximum amount should be given during the active feeding stage and no

feeding during the moulting stage.

c) Quality of leaf:

Leaves should be placed from well-maintained mulberry plants which have

received adequate fertilizers and irrigation. Too coarse or too tender leaves are less

suitable. Young worms require tender leaves rich in water, sugar, protein and minerals

with little starch and coarse fibre while late age worms/require mature leaves with less

of water and more crude fibres.

d) Preparation of leaf for feeding:

To enable the larva to feed easily, young worms have to be given chopped

leaves. For mature worms entire leaf collected by leaf picking may be given. The

main advantage of chopped leaf feeding are :

• It facilitates the even distribution of leaves in the rearing bed or tray.

• It enables precise regulation of the amount of leaves supplied per feeding.

• It prevents the bed from getting too damp in wet weather.

• It is advantageous in hot weather as chopped leaves do not curl up as quickly

as entire leaf.

E. Bed cleaning:

It is necessary to remove the litter (which consists of remains of leaves, exuvia

of moulted larvae and faecal matter) periodically, and the process of its removal is

called bed cleaning. The frequency of clearing required is given as follows.

No. of cleanings:

• 1stinstar -once during the premoulting stage.

• 2ndinstar -twice -once after moult and the second before the next moult.

• 3rdinstar -thrice -first after the moult, second in the middle of the instarand

third just before the next moult.

• 4th&5thinstar -For shelf rearing -once a day. For floor rearing -once for each

instar.

Regarding methods of cleaning, three methods can be adopted

a) cleaning with husk


197

b) cleaning with net

c) Combined net and husk method.

a. Cleaning with husk:

A thin layer of husk is sprinkled evenly and completely over the bed just

before feeding in the morning. The first feeding of chopped mulberry leaves is

sprayed over the layer of husk. The worms crawl through the layer of husk to get the

fresh leaves. At the time of second feeding the food is spread on a second tray and the

worms on the leaves above the husk are gently swept by a brush to the second tray.

The litter in the old tray is removed.

For the first two instars, powdered husk is used instead of entire one. Recently

use of charred husk or formalinized husk is recommended as an anti-muscardine

measure.

b. Cleaning with net:

A nylon or cotton net with a mesh of suitable size is spread completely over

the rearing tray to be cleaned and fresh chopped mulberry leaves are spread over the

net. Worms crawl through the meshes and feed on the leaves. After the second

feeding the net is removed and worms and fresh leaves on it are transferred to the

fresh rearing tray. The recommended mesh size for the different instars is

• 1st and 2ndinstars 2 mm2

• 3rd instar 10 mm2

• 4th and 5thinstars 20 mm2

The advantage of this method is that it is simple and requires less labour.

G. Care during moulting:

Moulting occurs four times during the larval life. It is a sensitive period lasting

for 15-30 hours, during which the worm does not feed but wriggles out of the old skin

and comes out with a new and soft skin. Care during moulting is stopping and

resuming feeding at appropriate time that ensures uniformity in growth. So also

keeping the bed dry and taking antimuscardine measures during moulting reduces the

chance of contraction of diseases during this sensitive period.


198

H. Rearing methods:

The requirements of temperature, humidity and leaf quality are different for

young and later stage worms. So also the schedule of rearing operations like feeding,

bed cleaning spacing is different. Accordingly the method of rearing of young and

mature worms is also different.

1. Rearing of young worms:

The emphasise on chawaki rearing is the maintenance of a higher temperature

(27°C) and humidity (80-85%) within the bed and supply of tender leaves rich in

moisture sugar salts, and proteins and with less fibre content.

a. Paraffin paper rearing:

The bottom and the top of the rearing beds are covered with paraffin papers,

with the paraffin side facing the bed. This is done to maintain the succulence of the

leaves as well as higher temperature. The paraffin cover on the top is removed 30

minutes prior to each feeding for ventilation and also during moulting time to provide

a dry bed. The incidence of muscardine is very high in this method and hence

application of thin layer of lime powder over the bed is advised during rearing and

especially during moulting period.

b. Box rearing:

Boxes or deep trays of wood or plastic or galvanized iron of at least 10-15 cm

depth are used for this method of rearing. In boxes rearing with lid, the boxes are

closed with lids after placing a paraffin paper on top and boxes are arranged in rearing

shelf. In boxes without lids, the boxes are kept cross- wise so that ventilation is

provided.

Feeding, bed cleaning, spacing and antimuscardine measures are to be done as

in paraffin paper method.

2. Rearing of mature worms:

The three methods for rearing these stages are the following:

a. Shelf rearing:

This is the most popular method of rearing in India. The worms are reared in

circular bamboo tray (1-1.2 m diameter) which are placed one above the other in tiers


199

in shelves arranged parallel to the wall. Spacing is generally combined with bed

cleaning. The main advantage of this method is that a large number of worms can be

reared in a small place and the place can also be kept clean. The disadvantages

include labour involved in feeding and bed cleaning which have to be done tray by

tray and also initial investment is involved in the purchase of trays and shelves.

b. Floor rearing:

This is similar to shelf rearing except that instead of trays, fixed rearing seats

or beds are used to accommodate the worms. The rearing seats are made of wood or

bamboo strips and are about 1 to 1.5 m in width and as long as the room can

accommodate. The seats are arranged in two or three tiers at a distance of 0.6 to 0.8 m

in between. Feeding is given three to four times per day with entire leaves or cut

twigs. Bed cleaning is done with nets. As in shelf rearing, care should be taken to give

proper spacing.

c. Shoot rearing:

This Japanese method is similar to floor rearing that here also rearing is

carried out on fixed platforms or beds. Here entire branches or shoots are given for

feeding. The leaves are distributed in three dimensions and there is better aeration

within the room. Bed cleaning is reduced to minimum of once for each instar. In

Japan, with labour shortage this is a popular method but in India with a lot of

unemployed labour, shelf rearing is the most popular method

I. Mounting:

For providing optimum spinning condition, the ripe worms are transferred to

special devices called 'Mountage'. The process of transferring the ripe worms to the

mountages or cocoonages or encabanages is called mounting.

Mounting is the final and most important busy operation in silkworm rearing.

The final instar larva after attaining full growth, selects a suitable place exudes silk

through its spinneret and spins a cocoon around itself and transforms into a pupa

inside it. The pupa after metamorphasing into a moth comes out by piercing open the

cocoon. The aim of sericulture is to rear silkworms and provide them with optimum

conditions so that they spin a good cocoon with high silk content and to harvest them

before moth emergence.


200

1. Characteristic features of a ripe worms:

The final instar larva after full growth stops feeding and is ready to spin the

cocoon. At this stage it is called the ripe worm. This stage is attained after 5-7 days of

feeding in 5th instar for multivoltine and bivoltine in subtropical regions. The ripe

worm is readily distinguishable by its translucent colour as it does not feed and gut

does not have any green colour in it. The body shrinks in length.

2. Process of spinning:

This process takes place about one to two days in multivoltine and two to three

days in uni/bivoltines. The fibre from the two silk glands come out through the

spinneret independently and is called brins. The serecin of the two glands cements the

two brinsinto a single threads called bave.

3. Methods of mounting:

a. Hand picking:

This method has an advantage that only ripe worms will be picked the worms

will be more uniformly distributed in the mountages and injured and diseased worms

can be easily recognized and removed.

b. Net method:

Nets are spread over the rearing beds and ripe worms alone crawl on the nets,

and the nets along with the ripe worms are removed and shaken on the mountages,

Handling is avoided in this method and it requires less labour.

c. Branch method:

This is similar to net method and here small branches are spread above the

rearing bed. In shoot rearing, the early ripening larvae (10-20%) are handpicked and

the rest are shaken off the shoot and transferred to mountage.

d. Free mounting:

This method is not popular in India. The early ripening larvae are handpicked

but the majority are allowed to crawl themselves on to the mountage which are placed

above the rearing bed.


201

Free mounting undoubtedly saves labor and causes minimum injury to the

worms but has the disadvantage that uniform distribution is not achieved on the

mountages.

4. Population density in mounting:

The ripe worm ordinarily requires an area which is the square of its body

length for spinning its cocoon. Too wide a spacing is uneconomical for the following

reason.

a) the silkworm wastes too much silk for spinning the preliminary web.

b) extramountages and extra labour are required.

c) too close a spacing is also uneconomical and results in the formation of double

cocoons (which are unreliable) are very high.

d) soiling and staining of the cocoons with excreta is very high. Overcrowding

condition lead to poor ventilation which winders the drying up of cocoons. As

a result more of damp, stained and inferior cocoons are formed.

The optimum density for chandrika, the popular Indian mountage is 50 worms

per 0.1 m2.

5. Precautions to be taken during mounting:

a) Only ripe worms should be mounted. As all worms do not ripe uniformly, they

must be picked and mounted.

b) Temperature around 24°C is optimum for spinning. Violent fluctuations of

temperature during spinning leads to uniformity of the filaments spun and

flaccid cocoon.

c) A humidity range of 60-70% is ideal for spinning. By adequate ventilation,

extra moisture must be dried. Too high a dryness prevents the worms from

spinning.

d) The worms must be disturbed during spinning as it causes suspension of

spinning and braking of thread.

6. Harvesting:

The aim of silkworm rearing is to harvest the cocoons produced and sell them

to the reeling agencies.


202

(a) Timing of harvesting:

Harvesting must be done after the pupal cuticle hardens and before the adult

emerges. Tropical multivoltine and bivoltine races pupate on the 3rd and 4th day and

temperature uni and bivoltines on the fourth or 5th day of spinning. The

recommended time of harvesting is 5th day of spinning for tropical races and 7th or

8th day for temperate races. Delay in harvesting beyond the recommended day may

lead to the formation of pierced cocoons by the emergence of parasitic uzifiy maggots

or by moth emergence. Too early harvesting leads to inside soiled cocoons due to

putrefaction of pupa injured by harvesting.

(b) Method of harvesting:

Normally cocoons are harvested by hands. Harvested Cocoons are cleaned by

removing any faecal pellets on them and sorted according to sizes. Defective cocoons

are separated.466

5.4 EXPERIMENT

Commercial silkworm hybrids selected for the present study were: Kolar gold,

CSR18 xCSR19, CSR2, CSR4, and CSR2xCSR4 developed by CSRTI Mysore, for

south Indian climatic conditions.

As it was found that V-1 and M-5 variety of mulberry was comparatively rich

in nutritive quality, the author selected these two varieties for the present investigation

to study the influence of V-1 and M-5 mulberry plant leaves cultivated by irrigating

with different proportions of spentwash on the yields of silkworm cocoons hybrids of

Kolar gold, CSR18xCSR19, CSR2, CSR4, and CSR2xCSR4 reared using V-1 and M-

5 mulberry plant leaves.

5.5RESULTS

Cocoon weight of all the 5 hybrids fed with spentwash irrigated M-5 variety:

The total yields of all the cocoon hybrids fed with M-5 variety cultivated by

raw water and spentwash irrigation is presented in the table5.9. The yields were very

high in all the five types of cocoons reared using M-5 variety mulberry plant leaves


203

cultivated by 33% SW irrigation and moderate in 50% while comparatively poor in

raw water. (Fig-5.5). from the results it appears that the cocoon yield can be

obtainable for a maximum profit by feeding spentwash irrigated mulberry plant leaves

than raw water irrigated plants. Out of five variety, the yield (Average weight was

taken from 100 cocoons)was very high in Kolar Gold hybrid with weight of 0.226 kg,

followed by CSR2, CSR4, CSR2 x CSR4and CSR18 x CSR19 hybrid with weight

being 0.221, 0.209 ,0.195, and 0.190 kg respectively for 33% spentwash irrigation.

Whereas 50% spentwash irrigated M-5 variety fed cocoon showed comparatively less

yield than that of 33% spentwash irrigated M-5 variety with the decreasing order

cocoon weight being 0.210, 0.202, 0.189, 0.180, and 0.174 for CSR2, Kolar gold,

CSR4, CSR2XCSR4 and CSR18xCSR19 respectively. Whereas the raw water

irrigated M-5 variety fed cocoons provided comparatively low yield than that of

spentwash treated sample fed M-5 variety with weight of 0.155 and 0.160 kg for

CSR18xCSR19andCSR2xCSR4respectively, while the CSR2 and Kolar gold hybrid

showed same weight of 0.180 kg.

Cocoon weight of all the 5 hybrids fed with spentwash irrigated V-1 variety:

The total yields of all the cocoons species fed with V-1 variety cultivated by

raw water and spentwash irrigation is presented in the table-5.10. The yields were

very high in all the five types of cocoons reared using V-1 variety mulberry plant

leaves cultivated by 33% SW irrigation and moderate in 50%, while comparatively

poor in raw water(Fig.5.6). From the results it appears that the cocoon yield can be

obtainable for a maximum profit by feeding spentwash irrigated mulberry plant leaves

than raw water irrigated plants. Out of five variety, the yield (Average weight was

taken from 100 cocoons) was very high in CSR4, hybrid with weight of 0.230 kg,

followed by CSR2 with weight being 0.228kg. and Kolar gold hybrid showed

maximum weight next to CSR2 with weight being 0.199 kg. CSR2xCSR4, showed 0.

191kg whereas CSR18xCSR19 cocoon weight was 0.188 kg. Whereas 50%

spentwash irrigated V-1 variety fed cocoon showed comparatively less yield than that

of 33% spentwash irrigated V-1 variety with the decreasing order cocoons weight

being 0.210, 0.205, 0.189, 0.169 and 0.166 for CSR4, CSR2, Kolar gold,

CSR18xCSR19 and CSR2xCSR4 respectively. Whereas the raw water irrigated V-1

variety fed cocoons showed comparatively low yield than that of spentwash treated

sample fed V-1 variety with weight of 0.149 and 0.151 kg for


204

CSR2xCSR4andCSR18xCSR19 respectively, while the CSR2 and CSR4 hybrid

showed maximum weight of 0.188 and 0.181 kg. respectively.

5.6 DISCUSSION

It was observed that the yields of all the five varieties of cocoons produced by

rearing the silk worms using M-5 and V-1 variety of mulberryplant leaves cultivated

by irrigation in 33% SW were maximum and moderate in 50% SW and minimum in

raw water irrigations. It concludes that, in 33% SW irrigation the plants are able to

absorb maximum amounts of nutrients (NPK) both from the soil and the spentwash

resulting high yield and enhance the nutrients in plants leaves which in turn influence

the better growth of silk worms containing higher proportion of silk proteins yields

spinning of long silk threads in cocoons resulting in increased weight of cocoons. The

current study involved the spentwash as sources of organic manures and inorganic

fertilizers when applied to mulberry might have increased the crude protein content,

potassium and sulphur content in leaves which in turn influenced the cocoon and post

cocoon parameters. These results are in agreement with results obtained467 who

reported that, application of nitrogen to mulberry significantly influenced the cocoon

production, since it has profound influence on larval, cocoon and shell weights, shell

percentage and cocoon yield as nitrogen promotes protein content in mulberry leaf.

The present report shows significantly higher values of cocoon weight, for

kolar gold fed on M-5 than the other tested cocoon species. However the productivity

depends on fifth instar larval duration as well as digestion capacity which were

significantly better in desired direction in hybrids fed with the leaves of these

genotypes which were nutritionally superior with regard to moisture content, total

sugar and crude protein. From the present study it is obvious that, spentwash, rich in

nutritive components is having strong hold not only on the growth and development

of silkworm, but also has a direct effect on the cocoon, pupal and silk weight and

quality.

Chapter – V

Table 5

different

Cocoon va

KOLAR GO

CSR2 x CSR

CSR2

CSR4

CSR18x CS

RW - Raw w

Fig: 5.

0

0.05

0.1

0.15

0.2

0.25

Weight in Kg

V

5.10: Weig

t proportions

arieties

OLD 0

R4 0

0

0

SR19 0

water: PTSW

.5: Yield of c

0

5

1

5

2

5

KOLAR G

Rearing

ght of cocoo

s of spentwa

RW

.180±0.0049

.160 ±0.001

.180±0.008

.165±0.008

.155±0.003

W- Primary

cocoons rea

OLD CSR2 x

RW

g of Silk Wor

205

ons upon fee

ash: (Avera

9 0

7 0

86 0

88 0

33 0

treated spen

ared with M-

spentwa

x CSR4

Coco

50%PT

rms Fed with

5

eding with M

age weight i

50%PT

0.202 ±0.000

0.180±0.0025

0.210±0.002

0.189±0.001

0.174±0.002

ntwash

-5cultivated

ash.

CSR2

oon hybrids

TSW

h Spentwash

M-5 variety

is taken fro

SW

07 0

5 0

22 0

14 0

25 0

by different

CSR4

33%PTSW

h Irrigated M

y irrigated w

om 100 Coc

33%PT

0.226±0.0029

0.195±0.0036

0.221±0.001

0.209±0.002

0.190±0.003

t proportions

CSR18x CSR

Mulberry

with

coons)

TSW

9

6

17

26

37

s of

19

Chapter – V

Table 5

differen

Cocoon va

KOLAR GO

CSR2 x CSR

CSR2

CSR4

CSR18 x CS

RW - Raw w

Fig: 5.

0

0.05

0.1

0.15

0.2

0.25

Weight in Kg

V

5.11: Weig

nt proportion

arieties

OLD 0

R4 0

0

0

SR19 0

water: PTSW

.6: Yield of c

KOLAR GO

Rearing

ght of cocoo

nsspentwas

RW

.160±0.0049

.149 ±0.001

.188±0.008

.181±0.008

.151±0.003

W- Primary

cocoons rea

LD CSR2 x

RW

g of Silk Wor

206

ons upon fe

sh :( Averag

9 0

7 0

86 0

88 0

33 0

treated spen

ared with V-1

spentwa

CSR4

Cocoo

50

rms Fed with

6

eeding with

ge weight is

50%PT

0.189 ±0.000

0.166±0.0025

0.205±0.002

0.210±0.001

0.169±0.002

ntwash

1 cultivated

ash.

CSR2

on hybrids

0%PTSW

h Spentwash

V-1 variety

s taken from

SW

07 0

5 0

22 0

14 0

25 0

by different

CSR4

33%PT

h Irrigated M

y irrigated w

m 100 Coco

33%PT

0.199±0.0029

0.191±0.0036

0.228±0.001

0.230±0.002

0.188±0.003

t proportions

CSR18 x CSR

TSW

Mulberry

with

ons)

TSW

9

6

17

26

37

s of

R19


207

Fig 5.7: SILK WORM REARING


208

Fig. 5.8: GROWTH OF DIFFERENT STAGES OF SILKWORMS


209


210


211

Fig. 5.9 : Silkworms Hybrids (Larvae & Cocoons)


212

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