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The Indian Council of Agricultural Research has recently revised the syllabus of B.Sc. (Hons.) Horticulture which is uniform throughout the country. There are some Skill Enhancement Courses (SEC) in the syllabus, each of 2 (0+2) credits, aiming at developing skill. Sericulture is one of them. The present textbook “Sericulture: Skill Enhancement” is designed to be used in practical classes of one semester. It has 20 chapters for 32 practical classes. Simple and lucid language has been followed for easy understanding of the beginners. The information contained in the textbook has been gathered from various published sources and internet websites which are mentioned at the end of each chapter under references. Attempts have been made to provide latest information; still some valuable information might have been missed. Questions are set at the end of each chapter under outcomes assessment to assess the understanding of the students. The questions include true/false questions, one/two sentence answer questions, short notes, and multiplechoice questions (MCQs). We would like to thank Mr. Sai Suman, 3rd year B.Sc. (Ag) for his immensible efforts in helping in preparation of the book in stipulated time period.

1.1 Introduction Sericulture involves raising silkworms to produce silk. It is an agricultural industry that includes growing food plants for silkworms, raising them to produce cocoons, and then processing the cocoons to create yarn for weaving, resulting in value-added benefits. 1.2 Definition of Sericulture Sericulture (also known as ‘silk production’) involves breeding and caring for silk worms to produce silk on a large scale. This process includes raising the worms on mulberry plants, harvesting and processing their cocoons to extract raw silk fibres, and ultimately creating commercial silk products. The art of silk production is called sericulture that comprises cultivation of mulberry, silkworm rearing and post-cocoon activities leading to production of silk yarn (FAO). While there are many species of silk worms, only a few are commonly used for commercial purposes. 1.3 Silkworm The silkworm is the larval stage of the domesticated silk moth Bombyx mori, which is in latin also referred to as the “silkworm of the mulberry tree”. Being the main source of silk, it is a significant insect from an economic standpoint. White mulberry leaves are the primary meal of silkworms (monophagous). The generation of domestic silk moths is largely dependent on humans due to millennia of selective breeding. Because wild silk moths have not undergone selective breeding like their domestic cousins, they are not economically viable to produce silk.

2.1 Introduction Growing as a perennial tree or shrub, the genus Morus (Mulberry) is employed in sericulture and is the only food source for the tamed silkworm Bombyx mori L. It is also a valuable commercial plant. The mulberry attracts silkworms because it contains elements that cause biting and swallowing. People who live in Karnataka, Andhra Pradesh, the northeastern states and other parts of India rely heavily on sericulture, which grows exclusively mulberries and their variants for the purpose of raising silkworms. 2.2 Mulberry Plant Mulberry is a plant that belongs to the kingdom Plantae, order Rosales, family Moraceae and genus Morus. It grows quickly when young but eventually slows down and rarely reaches a height of 33 to 50 feet. The leaves are alternately arranged, simple often lobed and typically lobed on juvenile shoots rather than on mature trees. The plant can be monoecious or dioecious depending on the species. It produces multiple fruits that are 2-3 cm long and mature fruits that are white or green to pale yellow with pink edges. In most species, the fruits are red when ripened, turning dark purple to black and possessing a sweet flavour.

Non-mulberry plants, sometimes referred to as Vanya plants, are important to the sericulture sector because they give silkworms—which are normally fed mulberry leaves—an alternate source of nutrition. Many species, including castor (Ricinus communis), oak (Quercus spp.) and arjun (Terminalia arjuna), are among these non-mulberry plants. These plants are a food source for a distinct species of silkworm known as Eri, Tasar and Muga silk, which are distinct from the common mulberry silkworm, Bombyx mori. These silks are prized for their unique properties, hues and textures which add to the variety and depth of silk goods on the market. 3.2 Host Plants 3.2.1 Host Plants for Tasar Silkworms The traditional tasar and the oak tasar are now two separate entities within the Indian tasar culture. Terminalia and Shorea dominate the traditional tasar tract, with Quercus oaks (as the name suggests) dominating the latter. Although tasar silkworms are actually polyphagous, there is some specificity in terms of their affinity for a given feeding source. Taxonomy: A. mylitta feeds primarily on Asan (Terminalia tomentosa, Fig.3.1), Arjun (Terminalia arjuna, Fig.3.2) and Sal (Shorea robusta, Fig.3.3), while A. proylei is mainly reared on Uyung (Quercus serrata, Fig. 3.4), Banj (Quercus incana, Fig. 3.5), Sahi (Quercus dealbata, Fig. 3.6) and Moru (Quercus himalayana, Fig. 3.7). Being important for tasar industry, these three genera (Terminalia, Shorea and Quercus) the silkworm feeds on Phutuka (Melastoma, Fig. 3.8) and Bogori (Zizyphus jujuba, Fig. 3.9).

4.1 Introduction The yield of the mulberry crop is a significant component in determining productivity and consequently, profitability in sericulture. The two most crucial goals—increasing cocoon output per hectare and lowering production costs—will be achieved through optimizing mulberry leaf yield per unit area. Therefore, ensuring that he receives the highest leaf yield possible from his mulberry crop ought to be the main goal of every sericulturist. Furthermore, it should be understood that every action made to increase leaf production also serves to enhance leaf quality, so securing insurance against losses to the cocoon crop later on in the silkworm raising process. 4.2 Soil and Climate Except for extremely steep terrain, mulberry may be grown practically on any type of terrain. However, when it is grown on either level ground or gently sloping or undulating terrain, good growths are obtained. More sloping or steep terrain calls for careful consideration of appropriate soil conservation techniques including bench teracing, contour planting and contour drainage. Although mulberry thrives in a variety of soil types, loamy to clayey loamsoils are ideal for growth. Mulberry plants can withstand somewhat acidic soil conditions. However, if the pH of the soil is too low, lime or dolomite should be applied as a necessary corrective measure. When it comes to alkaline soil Gypsum application in the soil is the best option for adjusting the soil’s alkalinity. Given that mulberries have deep roots, the soil should be sufficiently deep—up to two feet, at the very least. Mulberries grow well up to an elevation of around 4,000 feet after which their growth will be slowed by the lower temperatures. 

5.1 Pruning One of the most crucial aspects of mulberry farming is pruning. It involves methodically cutting off some branches in order to give the mulberry plants a manageable size and form as well as to encourage the bud to sprout and develop new branches. The primary goal of pruning is to increase leaf output and quality. In addition, it is used to harvest the shoots for silkworm rearing and to do various inter-cultivation tasks including weeding, ploughing, applying manure and fertilizer and proper timing of the rearing of silkworms. To prune without breaking the bark or stem, use a sharp secateur, pruning saw or sickle. The plants in rainfed environments are only ever trimmed once a year, at a height of 10–20 cm above the ground level in June or July when the monsoon season begins. After that the plants are let to grow into bushes with many branches till the next year. Leaf harvesting is limited to the leaf picking method. a) Pruning Types: Pruning is categorized according to the height of the stem at which it is cut. Bottom pruning is the practice of cutting the main stem at ground level after each harvest so as not to allow a stump to emerge. When low-cut pruning is used, the main stump of the plant is developed by cutting it 10 to 30 centimetres above the ground. At around 60 and 100 centimetres above the ground, medium and high cut pruning is performed respectively.

6.1 Introduction India’s mulberry plants, which are vital to sericulture, are susceptible to a range of pests and diseases that can harm them and reduce their productivity. The Leaf Roller, Mealy Bug, Whitefly, and Stem Borer are important pests that harm leaves and stems and lower plant yield. Plant degradation and leaf discolouration are caused by common diseases such as Powdery Mildew, Leaf Spot, Root Rot, and Bacterial Blight. To preserve healthy mulberry harvests and continue to produce silk, effective management requires the application of Integrated Pest Management (IPM) techniques, which include biological, chemical, and cultural approaches. Mulberry is also prone to a number of illnesses brought on by bacteria, mycoplasma toxins, and fungi. It is simple for a perennial agricultural plant to become vulnerable to different diseases. Similar to this, pest insects have a plenty of food available to them all year round to aid in reproduction. Therefore, developing high-yielding types through plant breeding programs is just as vital as preserving mulberries from disease and insect attacks. The diseases listed below are accompanied with control methods. Adopting appropriate management techniques will help prevent pests and diseases while producing high-quality and productive mulberry leaf.

7.1 Introduction The three factors used to categorise silkworm races are: (1) origin, (2) voltinism and (3) moulting. In addition, they are categorised according to their shape and colour. For more than 2,000 years, people have tamed and raised the silkworm Bombyx mori. It is a monophagous insect that exclusively consumes the leaves of mulberries. As a result, mulberry silk is typically meant when the word “silk” is used. 7.2 Classification Based on the Place of Origin (a) Indian Races: Native to South East Asia and India; these races are indigenous. They have a longer larval stage and can withstand high humidity and temperatures. The larvae and cocoon are modest in size. The cocoon is often spindle-shaped and coloured in shades of green, yellow, or golden yellow. With a lower shell percentage, the cocoon shell is thin and most of them are multivoltine. (b) Japanese Races: Japan’s indigenous races comprise this group. The larvae are strong. The cocoon resembles a peanut. The majority of cocoons are white, while some are yellow in hue. There are more double cocoons in the ratio. The silk strand is thick and short and of poor quality and are bivoltine or univoltine.

8.1 Life Cycle As in the case of a typical Lepidopteran insect, the silkworm passes through four distinct stages, i.e., egg, larva, pupa and adult during its life cycle, the duration of which may last for six to eight weeks depending upon racial characteristics and climatic conditions. Multivoltine races found in tropical areas have the shortest life cycle with the egg, larval, pupal and adult stages lasting for 9-12 days, 20-24 days, 10-12 days and 3-6 days respectively. (Fig.8.1) In uni/bivoltine races, the egg period of the activated egg may last for 11-14 days, the larval period 24-28 days, the pupal period 12-15 days and the adult stage 6-10 days. In nature the univoltine races produce only one generation during the spring, and the second generation egg goes through a period of rest or hibernation till the next spring. In the case of the bivoltine races, however, the second generation egg does not hibernate and hatches within 11-12 days and produces the second generation normally during summer. But it is the third generation egg which undergoes hibernation and hatches only the next spring, thus producing only two generations in a year (bivoltine). In multivoltine races, the life cycle is the shortest because of the warmer ecological conditions where they are reared, and so they may yield as many as seven to eight generations in a year in tropical sericultural areas such as India, Thailand, etc. Silkworm rearing is, therefore, continuous in tropical areas whereas in sub-tropical and temperate zones it is mostly seasonal lasting from spring to early autumn.

9.1 Structure of Silk Gland The silk of silkworms is secreted by a pair of labial glands, known as silk glands. The silk glands lie ventral to the alimentary canal. In full grown larvae, these occupy most of the body cavity. The silk glands are tubular in shape with different diameters in different regions. Each gland has 3 distinct regions (Fig.9.1). (1) Posterior Region: Blunt, highly folded tubular posterior regions of both glands remain attached to tracheal bushes of silkworm. This part secretes fibroin as fibrinogen which converted to fibroin upon extrusion. (2) Middle Region: Most prominent and widest part of silk gland. It remains folded in a W-shaped structure and thus has 3 limbs posterior, middle and anterior limbs. The posterior arm secretes sericin-I. It gets surrounded by sericin-II secreted from the middle limb. This sericin again gets surrounded by sericin- III secreted from the anterior limb. The middle region of silk gland also acts as the reservoir of fibroin where the later gets mature during the storage period. (3) Anterior Region: The thin anterior region of silk gland has no secretory role and only transports the assembled silk to the spinneret.

10.1 Disinfection Disinfection is the destruction of disease carrying germs. Proper disinfection is one of the key factors in determining the success of sericulture and also essential in prevention and control of silkworm disease. The disease caused by virus, bacteria, fungi and protozoa are known to occur in almost all the silkworm rearing areas of the world. The disease, together with the damage caused by the pest, accounts for 20 to 25% of crop loss. 10.2 Qualities of an Ideal Disinfectant • It should be highly effective against wide variety of microorganism and non-toxic for animals and plants. • It should be non-injurious and non-staining to materials like fabrics, furniture or metal wares and non-offensive to odours and taste. • It should be specific for specific microorganisms. • It should have good surface tension. That is good wetting and penetrating properties. • It should be stable in storage. • It should be readily available in market and non-expensive. • It should be easily applied under household or other practical conditions of use.

11.1 Grainage Grainages are establishments where disease free and quality seeds are produced on scientific lines. 11.2 Grainage Activities • Procurement of seed cocoons Within the cocoon market, the government can buy the necessary number of multivoltine cocoons from the seed cocoon market. The purpose of a grainage is to produce attractive seeds. This method involves unique procedures, such as the manufacture of silkworm seeds for the market. Half of the bivoltine cocoons should also be obtained from bivoltine cocoon marketplaces to guide hybrid seeds. • The seed cocoons are packed Loosely in perforated packing containers or bamboo baskets in small portions and are transported all through cooler hours of the day. Initially the seed cocoons arriving on the grainages are subjected to inflexible selection. In selection only sound and uniform cocoons conforming to the characteristics of the race are selected and defective cocoons and so forth., are rejected. Strengthen detection of pebrine disease, if any before the commencement of operation of each batch enables in keeping off excellent loss to the grainages.

12.1 Introduction Mulberry silkworm is a domesticated insect which cannot live without sufficient human care. It is also sensitive to high temperature and relative humidity. Besides good feed, a temperature range of 23°C to 28°C and relative humidity of 75-80% is ideal for silkworm. Though, there are a number of modern gadgets to regulate the temperature and relative humidity, investment on them is uneconomical. Therefore, mulberry sericulture is practiced only in those areas where the climate is congenial and the crops schedule is so regulated to avoid seasons with extreme climate. Besides, the silkworm rearing house is constructed to provide sufficient ventilation and keep the ambiance sufficiently cool. Due to poverty, many farmers rear silkworms within their dwelling house which cannot be disinfected due to the pungent nature of the chemicals used. However, it will be ideal to have a separate rearing house or at least a separate room for rearing purpose. The present unit deals with different kinds of rearing houses required for silkworm rearing.

13.1 Incubation The silkworm eggs are to be incubated properly to avoid irregular hatching. An ideal incubation is to maintain a temperature of 25oC and 75-80% humidity continuously. In most of the places incubators are not available. In such cases, the eggs are kept spread in wooden trays provided with paraffin paper for base and the cover and foam pads kept wet all around inside the trays to maintain 70-80% humidity. In each chawki tray of 90 cm × 120 cm about 4 sheets of eggs can be kept for incubation. The room temperature is maintained at 25°C. On 9th day the egg sheets are rearranged. About 25 dfls (disease free layings) are kept in a chawki tray of 90 cm × 120 cm to enable brushing and proper spacing for young worms later. The egg sheets are covered with a sheet of black paper or paraffin paper. On the due date of hatching and when a few larvae have started hatching, black paper and the paraffin paper are removed and the eggs are exposed to dim light for about an hour. This facilitates the uniform hatching of larvae. 13.1.1 Methods of Incubation There are two methods, i.e., constant temperature incubation and raised temperature incubation

In sericulture it is the larval life that is of direct importance to the rearer since he has to take care of the worms very carefully. The larval life may last from 20-24 days in the case of the multivoltine species in tropical areas or 24-28 days in the case of uni- and bi-voltine races in temperate areas, being shorter under warmer summer and autumn conditions, and somewhat longer under cooler spring conditions. During the larval life the worm moults or casts off its skin four times to be able so as to grow. There are also varieties of worms which moult three and five times but they are not of importance economically. In view of the four intervening moults, the larval life is divided into five distinct stages or instars (Fig.14.2) which are referred to popularly as five different ages. The first three instars are referred to as young ages and the fourth and fifth instars as late ages. 14.2 Moulting Each larval instar can be broadly divided into two phases i.e., the feeding phase and the moulting phase. After feeding voraciously and having attained full growth for the particular instar the worm loses its appetite and the larvaprepares to moult and cast off its old skin. Prior to each moulting, the larva  stops feeding and rests with its head held up. The lustrous body skin gradually becomes translucent, loose and wrinkled and the worm becomes dull in appearance and wanders about in search of a resting place. It emits a silky substance with which it fixes itself to dry leaves. The moulting periods last for 20 hours being shortest in the second moult, followed by the first, third and fourth. This resting for moulting is often referred to as going to sleep and the coming out of the worm from moult as waking up. During the moulting period the worms should not be disturbed so that the process of moulting is not interfered with and uniform moulting is ensured.

15.1 Silkworm Bed Cleaning Bed cleaning is an important silkworm rearing process to ensure the hygiene in the immediate vicinity of silkworms in order to protect from disease infection and to ensure them good feeding appetite. Hence, timely bed cleaning is critical to maintain the worm In a study observation on larval mortality, larval period, single cocoon weight, shell weight, length of silk thread and silk ratio were carefully noted for each treatment and replication. Three replications were used for each treatment of different eri silkworm races. Treatments were once bed cleaning frequency per day, twice bed cleaning frequency per day, and three times bed cleaning frequency per instar of Vietnamese eri-silkworm races, Indian eri silkworm races, Kenyan bivoltine silkworm races, Korean bivoltine silkworm races, and Vietnamese multivoltine silkworm races. Long spinning silk thread, robust silk cocoon and shell weight and higher percentage of silk ratio of silkworm races were registered from one time bed cleaning frequency per day and two times bed cleaning frequency per day. The rearing tray of silkworms accumulates some unconsumed leaves after each feeding, exuviae after moulting, excreta, dead or diseased larvae, etc. All these if not cleaned, combine to form a thick and damp litter which promotes the growth of different micro-organisms, generation of heat and injurious gases and depletion of oxygen. Hence, it is very necessary to remove the litter periodically and the process of its removal is called bed cleaning.

16.1 Process of Ripening of Worms Closer to the end of the fifth stage, the silkworm stops ingesting and turns into the so-called mature larva and starts spinning the cocoon. Properly reared worms, when ripe, will attempt to spin true cocoons even below incorrect conditions. However, it needs to be remembered that the worm spinning the cocoon is to defend itself from outside disturbances and enemies all through the maximum crucial period of its metamorphosis. The rearer can get the reward for his labour most effective, if he cooperates by making the situations such that, through spinning a commercially good cocoon it also most correctly protects itself. This cooperation is composed in imparting the ripe silkworm with appropriate mountages to facilitate its spinning of suitable cocoons. The eating duration throughout the fifth instar may close for 5 to 7 days in the case of multivoltine and bivoltine races in the tropical regions and 7 to 9 days in the case of bivoltine and univoltine races in sub-tropical areas. The mature worm is effectively distinguishable by its translucent colour. The frame also shrinks with duration; there is also a constriction seen on the 4th and 5th segments. The worm loses appetite and begins to look approximately as although on the lookout for a appropriate area to which to attach itself. Generally, the ripening worms circulate in the direction of the periphery of the rearing trays in search of anchorage to begin spinning of cocoons. This is the time for selecting the ripe worms and putting them on mountages. This process is known as ‘mounting’. It has to be remembered that all the worms in a tray do not ripen simultaneously. It commonly happens that by the time all the worms in a tray are ripe, a number of the early worms can be over-ripe. They could have misplaced a quantity of silk by the point they are picked up, and they are furthermore in a hurry to spin their cocoons that they continue to do it anyways, without ready to select a right location, and as a consequence produce irregularly formed and flattened or sticky cocoons causing loss to the rearer.

17.1 Introduction The most important device that helps or supports the silkworms (larvae) for comfortable spinning their cocoon is called cocoonage or mountage. It determines both the quality and quantity of the cocoons. Different types of cocoonages are used in different parts of India. In general, these are made of wood, bamboo, cardboard, plastic, grass, dry leaves, twigs, etc. Mounting is an essential step in the rearing of silkworm. Mounting indicates the transition of silkworm from larval stage to pupal stage where it prepares to spin cocoons. Mounting is a process where fully grown (specifically 5th instar) silkworm larvae are picked and mounted in a suitable place (mountage) where it is about to spin. Mounting is a pivotal phase in silkworm rearing. The following are the objectives of mounting: 1. To provide an ideal space for silkworm larvae to spin, 2. To ensure good quality cocoons, 3. To minimize mortality among silkworm by avoiding overcrowding, 4. To ensure a maximum silk production.

18.1 Introduction The cocoons are harvested and sold to the reeling agencies. Harvesting has to be done after the sclerotization of the pupal cuticle and before the emergence of adult moth. It has been recommended to harvest at the fifth day of spinning for tropical races and seventh or eighth day for temperate races. Delay in harvesting leads to pierced cocoon by the emerging moth and early harvesting causes injury to the unsclerotized pupa and thereby soiling the cocoon. The cocoons are normally harvested by hand or by simple devices. Faecal pellets if any on them must be removed and cleaned. Healthy cocoons must be separated from the defective ones and sorted out based on their size. 18.2 Harvesting of Cocoon After completion of spinning of cocoon, the larval skin is cast off and pupation takes place. This generally occurs on the 3rd/4th day of spinning in the case of multivoltines and 4th/5th day of spinning in bivoltines and univoltines in the temperate regions. The pupa when formed has a thin cuticular skin which is soft to touch and may get ruptured easily, if disturbed. Too much delay in harvest is also not desirable, as it reduces the weight of cocoons. Harvesting of cocoons is normally done by hand. Only in the case of revolving mountages simple devices are used. The harvesting process is the best time for sorting cocoons according to the quality as good cocoons are easily distinguishable from double and defective cocoons.

19.1 Introduction Mulberry silkworm, Bombyx mori, is affected by a number of diseases caused by viruses, bacteria, fungi and protozoa. These illnesses are recognized to occur in practically every region where silkworms are raised in the world seriously harming the harvest of silkworm cocoons. Several actions have been proposed as a means of preventing and managing the illnesses, but none of them had shown signs of foolproof with the outcome that one must consistently be cautious to eradicate the core infection’s source in addition to avoiding crossinfection. Additionally, care has to be taken in order to ensure that they are not exposed to stressful circumstances such as low temperature and inadequate nourishment, poor ventilation, and humidity which could lead them easily susceptible to various diseases. 19.2 Diseases of Mulberry Silkworm and Their Control 19.2.1 Protozoan Diseases The protozoa that harm silkworms are the parasitic ones from the genera Nosema, Pleistophora, and Thelohania and class Microsporidia. In addition to this, reports of Leptomonas and Trypanosoma infections in the silkworm Bombyx mori L. have been made. However, the pebrine disease is the main protozoan illness of the silkworm. It is also known as ‘pepper disease’ because of the development of areas of black pepper after infection.

20.1 Introduction The technique of reeling several cocoon baves together to create a single thread is known as silk reeling. This is accomplished by winding the resulting thread onto a rapidly spinning reel after collectively unwinding filaments from a collection of cooked cocoons at one end in a heated water bath. There are three different ways to reel in raw silk: (1) directly on a standard-sized reel, (2) indirectly on small reels, and (3) by using a re-reeling machine to transfer the reeled silk from small reels onto standard-sized reels. An efficient reeler willhold onto the predefined number of cocoons per end in order to produce silk with a consistent denier Some techniques are used in reeling. Different reeling mechanisms are used for different purposes. 20.2 Various Silk Reeling Devices 20.2.1 Hand Spinning Wheel Using a simple spinning method, two hands run the apparatus to remove silk thread from cocoons: one hand turns the wheel while the other feeds the cocoons. In one of the devices, the cocoons are cooked, while in the other, reeling thread is wound onto each wheel. A more tactile and artisanal method of silk reeling is available with hand spinning wheel reeling. A great degree of expertise and experience are needed to provide consistent outcomes and the appropriate silk characteristics (Fig.20.1).