Sericulture with Emphasis of Rejuvenation of Races at RSRS, Sahaspur

Larvae   Cocoon Silk

INTRODUCTIONSilk is known as the queen of all fabrics over thousands of years. It has become an inseparable part of Indian culture and tradition. Silk fiber in India is mostly considered to be as more traditional and used to wear in special occasions and events. There are number of other beliefs and mythological thoughts that are considered to be attached to silk fiber, therefore, the silk acquired the place of queen of fiber.

In India, it is a rural based agro industry providing employment to rural population, although sericulture is considered to be a subsidiary occupation and technical innovation made it possible to generate more employment. It is the most labor intensive section for the economy which provides livelihood to a large section of population.Sericulture, or silk farming, is the rearing of  silkworm for production of raw silk. Although there are several commercial species of silkworms, Bombyx mori is the most widely used and intensively studied. Silkworm larvae are fed mulberry leaves, and after the moulting, climb a twig placed near them and spin their silken cocoons. This process is achieved by the worm through a dense fluid secreted from its structural glands, resulting fiber of cocoon. The silk is a continuous-filament fiber consisting of fibroin protein, secreted from two salivary glands in the head of larva, and a gum called sericin, which cements the two filaments together. The sericin is removed by placing the cocoons in hot water, which frees the silk filaments and readies them for reeling. This is known as the degumming process. The immersion in hot water also kills the silkworm pupae.Single filaments are combined to form thread. This thread is drawn under tension through several guides and round into reels. The threads may be

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plied together to form yarn. After drying the raw silk is packed according to quality.

History of Sericulture

According to Confucian texts, the discovery of silk production B. mori dated about 2700 BC, although archaeological records point to silk cultivation as early as the Yangshao period (5000 – 3000 BC). About the first half of the 1st century AD it had reached ancient Khotan, and by AD 140 the practice had been established in India. Later it was introduced to Europe, the Mediterranean and other Asiatic countries.

Once upon a time long, long ago in an ancient kingdom of China there lived Queen Xi-Ling, wife of Emperor Huang-Di. She was interested in the arts and looming. One day she sat under her favorite mulberry tree in the garden sipping tea and admiring the beautiful spring flowers, something fell into her tea cup. She jumped up horrified and spilled the tea all over her lovely dress.  Her ladies-in-waiting rushed to wipe off the stains but lady Xi-Ling stopped them. On top of the tea stain on her dress she spotted a lovely web of the most exquisite threads she had not ever seen before. She carefully picked up the delicated threads. She felt soft and smooth to the touch. She understood that is the silk threads come from the silkworm’s cocoon where it fell from Mulberry tree. She sat on her loom and started working out a complicated pattern. It was the most exquisite piece she had ever woven. This discovery of silk was celebrated with great feasting and rejoicing throughout the land. Later when commercial relations were established between China, and rest of the world. Knowledge of Silk spread far and wide.Silkworm eggs and the technology of making silk, was brought to India by Buddhist monks from China. Also, the industry had said to spread in Tibet when a Chinese princess, carrying silkworm eggs and Mulberry seed in her dress, married with king of Kotan in Tibet.

About two and half centuries ago silk was introduced into Karnataka by Tipu Sultan, the ruler of the State. Today it is the biggest silk producing centre in India. Sericulture introduced in Tamilnadu from the border area of Karnataka during early 1960. Now Tamilnadu Stands number one in Bivoltine Silk production in India.

Moriculture, it is the important aspect of the sericulture in relation to the mulberry silk production. As the B. mori only feeds on the mulberry leaves, so we can say the quality and quantity of cocoon depends on the mulberry leaves. Moriculture can be defined as the culture of the mulberry

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plant. According to Western historians, mulberry-tree cultivation spread to India through Tibet during 140 BC and cultivation of mulberry trees. Rearing of silkworms began in the areas flanking the Brahmaputra and Ganges rivers. Mulberry plant is an important plant that can be useful in many ways.

It is widely used as feed for the mulberry silkworm, fuel, making baskets, preparing jam and jelly from its fruits.

There are mainly 4 types of silk that are mulberry silk, tasar silk, eri silk and muga silk in world. In India we produce all types of silk. Sericulture has become one of the most important cottage industries in a number of countries like China, Japan, India, Korea, Brazil, Russia, Italy and France. Today, China and India are the two main producers, together manufacturing more than 60% of the world production. Production of raw silk in India was 23,060 MT (matric ton) in 2011-12, of which, mulberry raw silkoutput aggregated to 18,272 MT (79.24%). The remaining 4,788 MT (20.76%) was tasar silk. Mulberry sericulture is mainly practiced in five states namely, Karnataka, Andhra Pradesh, West Bengal, Tamil Nadu and Jammu & Kashmir jointly account for about 97% of the total mulberry silk production in the country.India is the largest consumer of raw silk in the world. As the consumption of raw silk (around 28,733 MT) exceeds the production, the additional requirement of around 5,700 MT of silk (particularly bivoltine mulberry silk of international quality) is imported mainly from China. Moriculture

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AREA WITH MULBERRY IN INDIA

Mulberry foliage is the only food for the silkworm (Bombyx mori) and is grown under varied climatic conditions ranging from temperate to tropical. Mulberry leaf is a major economic component in sericulture since the quality and quantity of leaf produced per unit area have a direct bearing on cocoon harvest. In India, most states have taken up sericulture as an important agro- industry in different places of india with excellent results.

SPECIES AND VARIETIES UNDER CULTIVATION

There are about 68 species of the genus Morus. Majority of these species occur in Asia, especially in China 24 species and Japan 19 species. American continental also rich in Morus species. This genus shown low production in Africa, Europe and the Near East and poor in Australia.

In India, there are many species of Morus, of which Morus alba, M. indica. M. serrata and M.laevigata grow wild in the Himalayas. Several other varieties have been introduced that are M. multicaulis, M. nigra, M. sinensis and M. philippinensis. Most of the Indian varieties of mulberry belong to M. indica.

In China there are 15 species, of which four species, Morus alba, M. multicaulis, M. atropurpurea and M. mizuho are cultivated for sericulture. In the former Soviet Union M. multicaulis, M. alba, M. tartarica and M. nigra are present.

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GENERAL DESCRIPTION

Mulberry is a fast growing deciduous woody perennial plant. It has a deep root system. Their leaves are simple, alternate, stipulate, petiolate, entire or lobed. The number of lobes varies from one to five. Plants are generally deciduous. Inflorescence is catkin with pendent or drooping peduncle bearing unisexual flowers. Inflorescence is always auxiliary. Male catkins are usually longer than the female catkins. Male flowers are loosely arranged and after shedding the pollen, the inflorescence dries and falls off. These are four persistent parianth lobes and four stamens implexed in bud. Female inflorescence is usually short and the flowers are very compactly arranged. There are four persistent parianth lobes. The ovary is one-celled and the stigma is bifid. The chief pollinating agent in mulberry is wind. Mulberry fruit is a sorosis, mainly violet black in colour.

Most of the species of the genus Morus and cultivated varieties are diploid, with 28 chromosomes. However, triploids (2n= (3x) =42) are also extensively cultivated for their adaptability, vigorous growth and quality of leaves.

LEAF CHEMICAL COMPOSITION

Its differs according to variety and maturity. However, on the basis of the analysis carried out at CSRTI (Mysore), the chemical composition of the leaf is as follows:

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TABLE 2

Mulberry varieties in India

Variety Region Developed at OriginKanva-2 South India

IrrigatedCSRTI, Mysore Selection from natural

variabilityS-36 South India

IrrigatedCSRTI, Mysore Developed through EMS

treatment of Berhampore Local

S-54 South India Irrigated

CSRTI, Mysore Developed through EMS treatment of Berhampore Local

S-13 South India Rainfed CSRTI, Mysore Selection from polycross (mixed pollen) progeny

S-34 South India Rainfed CSRTI, Mysore Selection from polycross (mixed pollen) progeny

S-1 Eastern and NE India Irrigated

CSRTI, Berhampore

Introduction from (Mandalaya) Myanmar

S-1635 Eastern and NE India Irrigated

CSRTI, Berhampore

Triploid selection

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Component Range

Moisture 65 – 78 per cent

Protein 19 - 25 per cent

Minerals 10 – 15 per cent

Reducing sugars 1.2 - 1.9 per cent

Sugars 10 - 15 per cent

S-146 N. India and Hills of J and K Irrigated

CSRTI, Berhampore

Selection from open pollinated hybrids

Tr-10 Hills of Eastern India

CSRTI, Berhampore

Triploid of Ber. S1

Goshoerami Temperate CSRTI, Pampore

Introduction from Japan.

Climatic requirementsMulberry thrives under various climatic conditions ranging from temperate to tropical located north of the equator between 28° N and 55°N latitude. The ideal range of temperature is from 24 to 28°C. Mulberry grows well in places with an annual rainfall ranging from 600 to 2,500 mm. In areas with low rainfall, growth is limited through moisture stress, resulting in low yields. On average, mulberry requires 340m3/ha of water every ten days in case of loamy soils and 15 days in clay soils. Atmospheric humidity in the range of 65-80 percent is ideal for mulberry growth. Sunshine is one of the important factors controlling growth and leaf quality.

Soil condition

Mulberry flourishes well in soils that are flat, deep, fertile, well drained, loamy to clay, and porous with good moisture holding capacity. The ideal range of soil pH is 6.2 to 6.8, the optimum being 6.5 to 6.8. Soil amendments may be used to correct the soil to obtain the required pH.

Propagation of Mulberry:

Mulberry can be propagated in two ways. i. Sexual Propogation, ii. AsexualPropogation

i. Sexual Propagation:-In mulberry the sexual propagation is through seedlings, particularly seed propagation carries a varied population, For seed germination certain prerequisites are needed to be fulfilled such as selection of quality seed, preparation of land, and seed should be selected such that can definitely germinate. This is possible only when the seed is subjected to suitable environmental conditions, embryo of seed is alive, healthy, and internal conditions of seed are capable for germination.

ii. Asexual Propagation:-In asexual type of propagation vegetative plant parts are used. In mulberry the propagation is mainly of three types.

Propagation by Cutting.

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Propagation by Grafting. Propagation by Budding.

Land preparation.-If the land has a gentle slope, it can be levelled by minor land shaping and providing suitable type of bunds across the slope. If the slope is greater, contour bunding terrace planting or contour line planting can be adopted. In more sloping areas, platforms for individual plants on contour lines are more suitable since this involves less soil cutting.

Application of fertilizers:-Fertilizers also must be used as per the recommended dosage mainly N.P.K. The recommended dosage of N.P.K will be in the ratio of varied from place to place. Generally N.P.K. will be in the ratio of 2.5:1:1 for irrigated conditions and 2:1:1 of N.P.K for rain fed conditions. In hilly areas the recommended N.P.K. are 100:40:40.

Spacing:-Spacing of tree depends on soil topography, the extent of land available for cultivation and training method. For gentle slopes, 3´ x 3´, 5’ x 5’ may be adopted. In sloping more land 10’ x 10’ can be adopted. Pits are to be prepared for plantation. In deep textured loose soils, 45 x 45 cm and in hard shallow soils 60 x 60 x 60 cm pits are to be prepared. For each pit, 5 kg (one iron pan) of FYM or compost must be applied.

Planting:-Saplings of five months age with five to six roots are suitable for planting during the regular onset of the monsoon. One sapling per pit should be planted. The saplings should be supported with a stick to ensure straight growth.Maintenance:-After one month, all the buds except the top five to six should be removed carefully without damaging the bark. Weeds around the plant should be removed and regular pot watering given. After three months of plantings second weeding should be done and 25 g of suphala/plant should be applied in a trench and should be covered with soil. A second dose of fertilizer (25 g urea/plant) should be applied before cessation of the monsoon. Plants must be protected from grazing.

Mulberry Cultivation and practices:- Mulberry can be cultivated in a wide range of soil. Favorable soils for mulberry growth are sandy loam, loam and clayey loam. The mulberry can be even grown on slopes of hilly areas, which are not prone to water logging. In case of slightly sloppy lands, proper drainage must be provided. No doubt the mulberry cultivation can be practiced in wide range of soils; however the leaf yield is the main factor. To increase the quality of leaf yield per hector all required favorable mulberry cultivation practices should be adopted, because the silkworm is fed by mulberry leaves only. The soil pH, water retaining capacity of field, quality of mulberry variety, temperature, environmental conditions fertilizer/manure

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application, irrigation practices and soil texture etc., all these factors very much influence on quantity and quality of leaf yield per acre per year. The land should be ploughed repeatedly to loosen the soil and all gravel, stones and weed should be removed making the soil fine. In irrigated land the recommended organic manure such as cattle dung compost @20 tonnes per hector or @ 10 tonnes per hectare in rainfed conditions must be applied and mixed with soil by ploughing 2-3 times. Land leveling is also important in case of plains. However, in hilly areas generally the land will be sloppy where pit system is adopted. In hilly areas June/July are the favorable where pit system is adopted in rainfed areas. In case of pit system the pits should be filled with loose soil and organic manure.

Inter Cultivation:-To eliminate the weeds and to loosen the soil for good aeration, around mulberry plant, light hoeing should be done two months after plantation. This will facilitate the plant to absorb the water freely and plant growth will not be restricted by weeds by competing with mulberry plant for food, nutrition and water.

Pruning:-Pruning of mulberry trees should be done after one year of plantation. By pruning the mulberry branches, leaf yield can be increased and production of leaf can be synchronized with silkworm rearing schedules all through the seasons. Pruning schedules controls the irregular growth of mulberry branches there by save wastage of nutrition and energy. Care should be taken during pruning; bark should not get peeled off since cut wounds do not heal, which leads infections and diseases.

Leaf Harvesting:-Along with leaf production, leaf utilization is also important. Leaf harvesting depends upon type of rearing practice. Leaf harvested by 1) leaf picking, 2) Branch cutting / shoot harvesting. Leaf harvesting in time is very essential as mature leaf contain low nutrient value & silk worms fed upon them become disease susceptible.

Leaf Picking:-In India mostly leaf picking is practiced. However, this is more labour intensive, as availability of labour is not a big problem. Presently this method is being followed by most of the rearers. In a year 5-6 harvests are possible. First leaf harvest takes place after (10) weeks of bottom pruning.

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DISEASES & INSECT PEST MANAGEMENT OF MULBERRY

There are following major diseases of the mulberry-

1. Leaf Spot Disease:-

Season of Occurrence- Rainy Season Causal Organism- Myrothecium rondum Cercospora moricola

Symptoms- Appearance of black irregular spots with yellow margins. Premature leaf fall.

Control measures- Pruning of plants during June end. Collection and burning of diseased leaves. Spray of 0.1-0.2 percent Carbandazim / Bavestine /

Bengard.

2. Powdery mildew:

Season of Occurrence- Winter – November to February Causal Organism- Phyllactina corylea

Symptoms- Appearance of white powdery patches in lower side with

slight yellowing on upper surface. White patches turn black in later stage.

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Control measures- Avoid dense planting. Regular irrigation & weeding. Collection and burning of diseased leaves. Lady bird beetle for biological control. Spray of 0.1-0.2 percent Carbandazim on new leaves.

3. Leaf Rust:-

Season of Occurrence- Rainy and Winter Season. Causal Organism- Cerotelium fici, Aecidium mori.

Symptoms- Appearance of small spots on lower surface which turns red

to brown later. Leaves turns yellow, margins becomes dry. Premature leaf fall.

Control measures- Avoid dense planting. Timely pruning, weeding, loosening of soil, regular

irrigation.11

Collection and burning of diseased leaves. Spray of 0.2 percent Carbandazim.

There are certain other diseases that my cause damage to the plant but these are not of much economic importance and does not cause severe damage to the plant.

I. Pests

Tukra Disease:-

Season of Occurrence- April to June. Causal Organism- Maconellicoccus hirsutus.Loss due to disease- 10-20 percent

Symptoms-Malformation of apical shoot.The mealy bugs suck the sap resulting in stunted growth of the plant and reduction in leaf yield.Control measures-Removal and burning of the affected portion of the plants. Collect them I polythene bags and dip them in 0.5% soap solution to destroy the pests.Spray of 0.15% DDVP.Release the predatory cryptolaemus montouzieri – Lady Bird beetle @ 125 adults/acre.

2. Stem Canker:-

Season of Occurrence- Through out the year. Causal Organism- Lasiodiplodia theobromae.

Symptoms-Sudden withring and death of sprout.Black eruption on the bark in the infected region.Death of plants.

Control measures-Removal and burning of the infected cuttings and saplings in nurseries.Field sanitation is essential.Cuttings should be dipped in 0.2 % Carbendazim solution for 30 minutes prior to planting.Use Biofungicide Tricoderma harzianum –Nursery guard.

3. Leaf Roller:-

Season of Occurrence- Rainy season. Causal Organism- Diaphania pulverulentalis.Loss due to disease- 5-45 percent

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Symptoms-The young caterpillar within the unopened young leaves secrete delicate white silky filaments which binds the leaf blades together and feed on the soft tissues on the leaf surface.

Control measures-Removal and burning of the affected apical portion of the plants to destroy the larvae. Spray of 0.75% DDVP on apical portion of the plant.

Along with these pests there are other minor pests which do less harm to plants but are not severe.

Sericulture

Silk worm rearing is started with production of egg that is also known as the grainage then followed by the Chawki rearing and late age rearing. Silk that is produced in india is mainly of 4 types as follows-

Mulberry:-

Bombyx mori is reared on the mulberry, considering the economical conditions, such as rainfall and the nature of soil, different systems of plantations for raising mulberry are practiced in India. The silkworm Bombyx mori are reared throughout the year. The total life span of this silkworm is 50 days, out of these egg stage is 10 days, larval stage is 25-30 days and the pupa stage is 10 days. It passes 4 moults during growth. At the end of the larval duration, the silkworm emits silk from its mouth and constructs a cocoon on a scaffolding. The average annual yield of cocoons in India is as low as 150 kg under rainfed conditions, and under irrigated conditions it is about 400 kg.

Eri:-

This silk produced by Philosamia ricini is called eri silk. It is mostly grown in Assam in eastern parts of India.The food plants of this silkworm is castor (Ricinus communis) The alternative food plants are Heteropanax fragans, Manihot utilissima, Earica papaya, Ailanthus sp., Plumeria acutifolia. This silkworm is multivoltine and is reared indoors. The worms moult four times during its larval period of 30-32 days. It is generally hardy and not susceptible to diseases.

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Tasar:-

For the extraction of tasar silk three species of Antherea are used in India. They are Antherea mylitta, A. perniyi and A. royeli. This silkworm is reared on trees of Terminalia tomentosa, Terminalia arjuna. Tasar silkworms are reared wild in nature. They are usually green in colour.

Muga:-

Antherea assama produce golden yellow silk. This process is found only in the Brahmaputra Valley of India. It is semidomescticated. The worms are raised on Machilus bombycina and Litsaea polyantha trees.

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Mulberry silk production

Silk production is an process as follows-

Egg Production (grainage)

Grainage is a process responsible for the providing egg for regular rearing of the silkworm. Ultimate production of silkworm seed is to produce cocoons to get silk yarn. Advance planning, quality production, timely supply of seed is the critical factors in silkworm seed production.

The silkworm seed is produced in "Grainages". Grainages play a vital role not only in production of seed but also in the entire seed organization. During the Grainage operation one must know the seed suitability for a particular area before releasing commercially.

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Silkworm Rearing: -

Silkworm is domesticated over thousands of years and the sole food for the growth of silkworm is mulberry leaf.

Types of Rearing:

Rearing of silkworm is done in various methods in different areas. Mainly the rearing of silkworm is of two types

a. Chawki Rearing:

Rearing of young age silk worms is called Chawki rearing. Here worms are reared upto third moult and distributed to the rearers for late age rearing. Chawki rearing in mass at each CRC will not only control the attack of diseases but also facilitate the rearing on most scientific lines and cost wise it is most economical.

b. Late Age Rearing:

Late age rearing after third moult does not require high temperature and humidity compared to chawki rearing. Late age rearing is a little easier process than chawki rearing. During late age the quantity of mulberry leaf required is more than 90% of total larval period.

Climatic requirements: -

Under ideal conditions silkworm completes cocoon formation in 24-28 days from the day of hatching. The following required temperature/humidity/spacing should be provided:

S. No.

Stage Temper-ature0C

Humi-dity%

Spacing

(for 100dfl’s) in Sq. ft

1 1st Instar 26-28 85-90

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2 2nd

Instar26-28 85-

9015-45

3 3rd

Instar25-26 80-

8546-90

4 4th 24-25 70- 91-100

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Instar

75

55th

Instar

23-24

70

181-360

Rearing shed: -

Rearing shed must be constructed with East/West direction, preferably with the thatched roofing, mud walls or any roofing must not reflect heat on the biological body growth of silkworm. Keeping good number of windows, proper ventilation, light, using country tiles for roofing will serve the purpose of maintaining required atmospheric conditions in the rearing house with reduced cost.

Leaf quality: -

Quality of mulberry leaf in addition to proper maintenance of temperature/humidity plays significant role in the development of healthy silkworm.

Leaf quality plays an important role in the production of quality cocoons. The young age worms are fed with tender, succulent leaves which contain sugar, less amount of fiber, starch but, high moisture and protein that are suitable for chawki worms.

harvested leaf should be transported in wet gunny bags or baskets made up of bamboo. Such leaf should be preserved in a separate room or in a corner of rearing room or in specially designed leaf preservation chamber made up of wood with sufficient number of ventilators.

Leaf requirement:

Silkworm attains nearly 10,000 times of weight starting from hatching to spinning stage, therefore, feeding quality leaf plays an important role in the development of silkworm.

Leaf Requirement (about 400 eggs per DFL’s)

S.No.

Silkworm Stage

Quantity of mulberry leaf

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Required (approx.) (Kgs)

1 1st Instar 2-42 2nd Instar 4-83 3rd Instar 30-404 4th Instar 80-905 5th Instar 600-650

Rearing Equipments:

The following equipments are required for silkworm rearing.

1. Mesh 2) Formalin 3) Sprayer 4) Mats 5)Leaf preservation chamber

6. Chopping board 7) Chopping knife 8) Chop sticks 9) Feathers

10. Ant wells 11) Foam pads 12) Paraffin Paper 13) Hygrometer

14. Thermometer 15) Bed cleaning net 16) Wash basin

17. Plastic buckets/Mugs 18) Rearing stands 19) Rearing trays

20. Feeding stand 21) Mountages

Disinfection:

Disinfection is a process of destructing the disease casual organisms. There is a possibility of carrying the pathogens or germs through the rearing equipment if there is any disease attack in the previous crop. Therefore, disinfection is necessary to protect the crop from disease attack. Before taking up rearing all the rearing equipments including the rearing house should be disinfected thoroughly. There are various methods of disinfection like physical and chemical. Physical disinfections are Sun drying, Steaming. In chemical disinfection, all the rearing equipment as well as the rearing house should be thoroughly disinfected with 2% formolin and dried.

Incubation:

The eggs should be kept in cooler places at 250C temperature and 80% humidity, lesser the humidity poorer the hatching percentage or more the temperature weak the larva and poorer the hatch percentage.

For uniform hatching all the egg cards or loose eggs should be kept in dark and cooler atmosphere. On the day of pin head or blue egg stage all

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the eggs are covered with a black sheet or kept in black box and known as black boxing. On the day of hatching all the eggs are suddenly exposed to bright light in the early morning at around 8 A.M. so that 95% hatching can be achieved.

Brushing: -Brushing is transferring of newly hatched larvae into rearing trays. The newly hatched larvae after one hour of hatching get ready to feed on mulberry leaf. They are fed with finely chopped tender mulberry leaf.

Feeding of Leaf: -

st feeding to the newly hatched larvae should be given at 9 A.M. in the morning. During the 1st instar depending upon the silkworm strain and other factors (environmental conditions and leaf quality) the required mulberry leaf per 100 DFL will be around 2-2.5 kgs. The 1st instar stays for 3-31/2 days and undergo moult. The moulting period last for about a day. This will depend upon the environmental conditions.

Spacing: -

The number of trays and space required for each instar will increase.

 

Stage of silkworm

No.of trays required for 100 DFL’s(Diameter of tray 3 ½’)

Space required(Bi and Multi x Bi hybrids)

Beginning End of stage Begin End 1st instar 2 2 4 to 15 Sq.ft2nd instar 2 5-6 15 to 45 Sq.ft3rd instar 5-6 10-12 46 to 90 Sq.ft4th instar 10-12 20 91 to 180 Sq.ft.5th instar 20 40 181 to 360 Sq.ft

Bed Cleaning: -

Bed cleaning in silkworm rearing tray is done by various methods like using of paddy husk, straw, and bed cleaning net. During 1st instar bed clearing should be done once during pre-moulting, during 2nd instar – twice, once after moult and before next moult. During 3rd instar thrice i.e. after moult, before next moult and once in the middle. During 4 th and 5th

stage once in a day in case of shelf rearing.

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Feeding:

It is estimated that 50% of the total weight will be increased in the 5 th

instar itself. The feeding schedule is: -

S.No. 1st feeding 2nd feeding 3rd

feeding4th

feeding5th feeding

1 6 A.M.-6.30 A.M

11-11.30 AM

3-3.30 PM 7-7.30 PM  

2 7 AM – 7.30 AM

11-11.30 AM

2-2.30 PM 5-5.30 PM  

3 6 AM – 6.30 AM

10-10.30 AM

2-2.30 PM 6-6.30 PM 10-10.30 PM

Mounting:

Transferring of matured silkworm on to the mountage or cocoon frames is called "mounting". This is an important and skilled operation. Any deviation in identification of maturity of worms adversely affect on cocooning.

For the purpose the density of worms in the mountage should be limited to 40-50 worms per sq.ft.to avoid formation of double cocoon, stained

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cocoon. The matured worms picked up in any of the methods mentioned above are transferred to the mountages. In an area of 1 mt 800-900 worms can be mounted to avoid too much density in the mountage. In certain strains of silk worms around 250-300 worms can be conveniently mounted in a standard mountage of 90 x 60 cm size.

During mounting care should be taken to use the right type of chandrike in convenient size and shape. There are different types of chandrike that are used for the purpose of mounting.

a. Plastic Mountage

b. Bamboo made Chandrike

c. Straw Mountage

d. Bottle Brush

e. Revolving Mountage

Cocooning:

The matured silkworm spins the outer protective covering called cocoon and remains in dormant stage inside as pupa.

After mounting the ripen worms in chandrike the larvae sticks on to the mountage by oozing out the silk fluid which will harden immediately after coming in contact with air and sticks itself to the mountage. It starts to ooz out the silk by continuous movement of its head in a very specific manner to form the silk filament in the shape of arithmetic figure `8’.

Larvae moves its head continuously about 70-80 times per minute till the compact shell called cocoon is formed and detaches itself from the last layer of silk of then transforming into pupa.

Silkworm completes the spinning in 2-4 days depending upon the silkworm strain and climatic conditions provided.

Harvesting of Cocoons:

Harvesting of cocoons is done on the fifth day of spinning. Whereas seed cocoons should be harvested on eighth day or ninth day of spinning depending upon atmospheric temperature.

Harvesting should not be done immediately after pupation. Further, harvesting should be done before the moth emerges out.

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Cocoons are harvested generally with hand. In advanced temperate countries like Japan simple devices are used to harvest the cocoons from rotatory mountage.

Reeling

Reeling is a process of unwinding of silk filament from the cocoon. Reeling process is an important activity. Depending upon the required thickness (denier) of silk thread filaments from number of cocoons are combined together and reeled. An efficient reeler will maintain the fixed number of cocoons per end to produce uniform denier silk. Reeling is carried out by distinctive methods.

Types

Charka

It is about 50% of total raw silk production is contributed by charka. Reeling machine is traditionally home built by using wooden material with the assistance of black smith and corpenter hence,

Cottage Basin

In cottage basin, the cocoons are cooked separately and re-reeling is done separately to increase the quality of silk. In cottage basin cooking is done separately and the reeling basins are fixed to a reel bench. There will be 6-10 ends in each basin. Arrangement to supply hot water to each basin and to drain out the dirt water accumulated due to floss and sericin is made.

Filature

Filature or multi-end reeling machine works on the principle of slow motion reeling and thread production on small reels at a large number of ends per basin.

Automatic reeling machine

Bi-voltine cocoons are best suited to automatic reeling machines. This machinery requires superior quality cocoons and uniform size of cocoons with less floss. Generally the multi-voltine cocoons are not fit for automatic reeling. This is particularly due to inferior quality. The silk produced from automatic reeling machine will be superior.

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Different diseases of silkworm and their management

Life cycle of a mulberry silkworm-

Mulberry silkworm reared in north india are mainly bivoltine.Disease that may cause severe harm to the worms are as follows-

A. Protozoan diseasesThe protozoan diseases of silk worm is called pebrine because of the

characteristic pepper -like black spots appearing on the infected silk worm.This disease is caused by the infection of the protozoan Nosema bombycis Nageli.

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Symptoms

All stages of mulberry silk worm are affected by the pebrine spore.

Control measures

a. Rearing only disease free laying prepared in grainage after mother moth examination.

b. Removing disease larvae from the rearing tray and burning them.

c. Disinfecting rearing room and rearing appliances with 4 to 5% formalin or bleaching powder after pebrine infection to kill any spore that may be present.

B. Bacterial diseases ('Flacherie')

Formerly, all diseases with the symptoms of diarrhoea and vomiting were collectively called 'Flacherie' and were believed to be caused by bacterial infection. Later on it was found that infections of bacteria were not always associated with flacherie.

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Bacterial Oacherie or Gastric injury flacherie

This disease considered to be caused by multiplication of bacteria in the alimentary canal which has become weakened due to bad environmental condition.

Causative organism

Various pathogens have been suspected to be the causative organism. In the initial stages of the disease Streptococci, in the advanced stage approaching death, coliform bacteria and in dead worms Proteus group of bacteria have been isolated from the diseased larvae.

c. Symptoms

The diseased larvae show the following general symptoms of flacherie are loss of appetite, sluggishness and retardation of growth and softening and inelasticity of the skin.

d. Control measures

This control measures consists of the following.

i. Provision of optimum environmental conditions and providing good quality leaves during rearing.

ii. Avoidance of unhealthy larvae by incubating eggs at uniform optimum temperature (22-25°C) and humidity (80-85% RH).

iii. Disinfection of rearing house and appliances with 2% formalin.

3. Grasserie disease

This viral disease is called jaundice as the infected larvae appear yellow in colour and excrete white faeces filled with viral polyhedra.

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There are three different kinds of polyhedrosis disease nuclear polyhedrosis, midgut cytoplasmic polyhedrosis and mid gut nuclear polyhedrosis

a. Control measures

Hygienic rearing, avoidance of unsuitable leaves, giving proper ventilation, removal of dead and sick larvae and sterilization of rearing room with steam or 2% formalin or bleaching powder.

This disease is controlled by oral administration of nalidxic acid, p-propiolactone, p-aminobutyric acid and tropical application of Imanine.

D. Fungal diseasesFungal diseases of silkworm are called muscardine. The

characteristic feature of this disease is the mummification of the infected larvae till and after death by deposition of calcium oxalate salts. Hence, this disease is also called calcino.

Table 2: distinguishing characters of different muscardine diseases

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Sl.No

Type Casual organism

Size Conidia shape

Colour

Tissue affected

Symptoms

1 Yellow muscardine

Paecilomyces

Farinosus

2.5-3.5-4.5x

2.3-3.3-4.00u

Generally oval in shape but rarely spherical or bellshaped

Individually colourless but collectively appear yellow in colour

Gut The body becomes hard and covered with yellow mycelia

2 Aspergillosis or brown muscardine

Aspergillus falvus link

Spherodial or oval

Very serious on chawki worms, infection is almost similar to other muscardine fungi but the infection is localized and it does not

Infected young worm become lustrous and die soon. Generally in the young worm the body will not rot but in late age worms, the area which is not covered by

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extend to the body fluid

mycelial mat will not due to secondary infections

3 Red muscardine

Sorosperella uvella

Fungus completes its development within the wall of its host without appearing externally

Infected worms occasionally show red-coloured before death; when the insect is cut open, brick red powdery mass of spores escapes. The spores germinate upon exposure to moisture. The parasite destroys the functional organs complet

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ely

4 White muscardine

Beauveria

Bassiana

2.5-3.5-4.5x

2.3-3.3-4.00u

Spherical or oval

The infection is mainly through cuticle. Conodia deposited on cuticle germinate under favourable conditions and the germ tubes at once pierce through the cuticle and invade into body within 24 hrs by mechanical force or enzym

In early stage of the disease the larvae lose appetite and becomes inactive. On progress of the disease moist specks/oily specks oil stain appears on different parts of the larval body. The specks do not exhibit marked colour unlike green muscardine. Larva shows negative

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atic action or both and from hyphal bodies in the body fluid

response to external stimuli and losses spontaneous movement. Due to delayed infection some worms may spin flimsy cocoons but many will fail to do so

5 Green muscardine

Spicaria

prasina

3.5-4.0-5.2x

2.00-2.5-3.2u

Round or oval

Light green in colour

The germ tube penetrated into the body, and reach body fluid and organizes the hyphal body

Large moist blackish specks appear all over the body without definite circumference

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6 Black or green muscardine

Metarrhizium arisopliae

5.9x

2.35u

Non-septate, cylindrical and ends rounded with a characteristic bend. They are produced in compact chains

Dark green

The infection process is similar to that of Beauveria

Symptoms

The common symptoms are the following:

i. loss of appetite, lag in growth resulting in 'unequals' in the rearing bed,

ii. oily specks and spots on the skin which may have black or green margin,

iii. diarrhoea, vomiting, shrinkage of body and inelasticity of the skin,

Control measures

If muscardine attack is noticed, control measure have to be taken both during rearing and in between successive rearing.

i. Infected larvae and litter must be removed immediately before formation of conidiospores on them and burnt. Infected and healthy larvae can be separated froin each other by spreading a net with fresh leaves over the rearing bed, when healthy ones alone crawl up to the net.

ii. Provision of good ventilation and low moisture in the rearing room.

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iii 0.4% to 0.8% formalin is mixed with burnt paddy husk in the ratio of 1:10 and spread over the rearing tray form 30 minutes for one or two days particularly after the molt.

iv. High grade chlorinated lime (containing 0.1 % chlorine) is sprayed till the larvae are wet. After half an hour fresh food is supplied on a net and healthy larvae come out to feed and by this treatment any spore on their body is prevented from growing.v. A number of chemicals have been newly evolved for surface disinfection of the larva to prevent muscardine growth. These include, Dithane M -45 with lime, aliband, sunace, kinuban, pafsol, kabinuron, chemichlon, shinsha dust, benzoic acid and benzoal knonium chloride. Central Silk Board (CSB) has evolved resham keet ooshash for this purpose.

Introduction of sericulture at RSRS,Sahaspur

Regional sericulture research Station(RSRS), Sahaspur is a research station which works for te improvement of the sericulture in India. Its nodal centre is at Mysoore. Area under mulberry plantation is about 9.824 acres along with other buildings such as rearing house, administrative, seed house etc. include 3.664 acres. the total area of the station is about 15.62 acres. It runs many research programs as well as many training programmes are also conducted here. some of the projects running over here are as follows-

1. Silkworm breeds to evolve viable and productive silkworm genotypes/hybrid for sustainable bivoltine sericulture

2. Evaluation of elite bivoltine silkworm germplasm under different agroclimatic conditions

3. All India silkworm germplasm evaluation programme

4. Maintainance of GPB

5. Maintenance of parental line and breeder stock

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Rearing performance of GBP Rejuvenation during Spring 2013

Race

Rep.no.

Fecundity

Hatching %

Larval period days:hours

Wt of 10 mature larvae

Yd. of 1000 larvae retained/brushed

PER (litre)

Single cocoon wt(gms)

Single shell wt(gms)

Shell%

Cocoon /ltr

Pupation rate

Mount Cocoons %

Wt no.

C108

1B 488 97.13

28:00

35.00

11.714

9057

76

1.213

0.190

15.82

7.00

89.71

0.9

J112

2B 559 97.32

28:00

35.00

12.857

9028

92

1.448

0.220

15.26

7.00

88.28

0.6

J122

3A 527 96.02

28:00

35.00

12.286

9314

92

1.283

0.207

16.31

7.00

92.28

0.9

NB7

4A 497 95.17

27:00

40.00

11.857

7943

79

1.440

0.220

15.37

6.00

75.14

2.1

NB4D2

5B 428 94.86

28:00

35.00

7.428

5371

54

1.693

0.312

18.60

7.00

50.28

4.4

CC1

6A 545 96.33

28:00

42.00

12.714

9143

64

1.439

0.224

15.54

7.00

90.28

1.3

Fecundity-total eggs laid by one female

Hatching %-while brushing is taken some larvae remain unbrushed because they are late borns .Beside some eggs remain unfertilized, some dead eggs ,some unhatched egss also found on egg sheets. from no. of larvae brushed late born larve are deducted and divided by total no. of eggs. Its percentage is called hatching

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percentage. In total no. of eggs i.e. fecundity, fertilized eggs ,dead eggs ,unhatched eggs and hatched egg shells are counted.

Larval period-it is counted from brushing time to first moult time for first instar larvae, molt out time to again moult in time is counted for LP of second , third and fourth stages. In fifth age period from moult out to spinning is counted. Total larval period is counted by respective LP of fifth stage of the silkworm and four moulting times.

Yield- Yield /10000 larvae brushed. This parameter for wt. is counted on the basis of the good cocoons weight of area retained (300 or 350) divided by no of larvae retained and multiplied by 10000. For number this parameter is counted on the basis of no. of good cocoons (including double cocoons and the cocoons in which pupae are formed divided by the no. of larvae.

Good cocoons- After harvest dead larvae, stained cocoons, flimsy cocoons, and good cocoons are sorted out from the harvested lot in same chronological order. Normally cocoons confirming their parents are hybrid characters with live pupa are called good cocoons.

Pupation percentage- Every good cocoon is gently shaken holding it between index finger and thumb near our ears. If a clear sound comes , it shows live pupa inside. Live pupa divided by larvae retained and multiplied by 100 is called pupation percentage.

SCW (Single cocoon weight)-SCW ,SSW,SR% normally 10 males *10 females pupa are selected from a lot of 300 larvae retained for evaluation of these on an electronic balance. 10 male or female cocoons with their pupae inside are weighted for SCW pupa and exuviate are taken out empty cocoons shells are weighted again, this is called SCW. SSW divided by SCW and multiplied by 100 is called SR percentage.

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Conclusion

As per the practical experience gained let me made a conclusion that sericulture is a vast field of great economic importance and having a lot of potential. It has the capacity to provide employment to the landless as well as the small farmers which may improve the living standard of the peoples.

Along with that silk that is produced is have more value than any other fiber and have capability to provide good returns to the national economy.

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