eChapters

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).

Protozoa are considered as unicellular eukaryotic organisms and evolved after bacteria and thousands years early to multi-cellular organisms as well as animals. This unicellular eukaryotic organism contains all the organelles or structures like multi-cellular organisms but in single cells. Similar to multicellular, the genetic information of protozoa is also stored in chromosomes. The protozoa differ from bacteria in different manners. The differentiating features of bacteria and protozoa are given in Table 1.
1. General Structures of Protozoa
Protozoa, like other eukaryotic cells, contain a nucleus, endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes. Beyond these common organelles, protozoa feature a range of unique structures with specific functions that enable them to operate independently. Protozoan cells can be categorized into two primary components: the cytoplasm and the nucleus.

Theileriosis is a tick-borne protozoan disease that affects a wide range of domestic and wild animals, particularly cattle. While multiple species of Theileria exist, Theileria parva and Theileria annulata are the most important pathogens in terms of their impact on domestic cattle. This disease is transmitted by ixodid ticks and has a significant impact on cattle populations in tropical and subtropical regions. Theileriosis poses a substantial threat to livestock productivity, affecting economic stability in many countries, especially those that rely heavily on agriculture and cattle farming.
The disease has two primary forms: East Coast fever (ECF), caused by T. parva, which predominantly affects cattle in eastern, central, and southern Africa; and tropical theileriosis, caused by T. annulata, which affects cattle across northern Africa, the Middle East, and parts of Asia. Both diseases are highly pathogenic and, if left untreated, can lead to high morbidity and mortality rates, significantly impacting livestock production.

Bovine babesiosis is a significant febrile disease, primarily affecting cattle and buffalo, transmitted by ticks. The disease is marked by the rapid proliferation of parasites within the bloodstream, leading to the extensive destruction of red blood cells. This results in a cascade of clinical symptoms, including anemia, jaundice, hemoglobinuria, and splenomegaly, with the potential for severe cases to culminate in death. The acute form of bovine babesiosis is particularly severe, often characterized by these pronounced symptoms, which can lead to rapid deterioration in the affected animals. Babesiosis is not merely an acute illness but can also persist as a chronic infection. Chronic bovine babesiosis is typified by ongoing anemia and varying degrees of weight loss, reflecting the enduring impact of the parasite within the host. Economically, this disease poses a formidable challenge, especially in regions where cattle are most susceptible. Since the first description of Babesia bovis by Victor Babes in Romania in 1888, numerous distinct species have been identified, each contributing to the global burden of this disease (Hunfeld et al., 2008). The impact of bovine babesiosis on livestock improvement efforts in endemic regions is profound. The introduction of susceptible, naive animals into these areas often leads to significant losses, as these animals are highly vulnerable to the disease.

The reclassification of the order Rickettsiales was predicated upon comprehensive genetic analyses of 16S rRNA, groESL, and surface protein genes. Consequently, organisms within this order were systematically assigned to one of two families: Anaplasmataceae and Rickettsiaceae. Within the Anaplasmataceae family, phylogenetic analyses consistently delineated four genetically distinct clades: (1) Anaplasma, (2) Ehrlichia, (3) Wolbachia, and (4) Neorickettsia. Despite the obligate intracellular nature of rickettsial organisms in both families, those classified under Rickettsiaceae proliferate freely within
the host cell cytoplasm, whereas members of the Anaplasmataceae family are confined exclusively to membrane-bound vacuoles within the cytoplasm of host cells.
The first documented cases of anaplasmosis trace back to the late 19th century in South Africa. However, it wasn’t until 1910 that the causative agent of the disease was conclusively identified morphologically as “marginal points” within red blood cells by Max Theiler, later named it Anaplasma marginale. A year later, he identified another species, A. centrale, which caused a milder form of the disease in cattle. During the 1930s, Sanborn, Stiles, and Moc demonstrated the mechanical transmission of A. marginale by horse flies and stable flies. In the late 1980s, the life cycle of A. marginale was fully elucidated in ticks belonging to the genus Dermacentor.

Haemoprotozoan parasites are responsible for causing severe infections in humans as well as animals across the world. The important hemoprotozoan diseases of livestock are trypanosomosis, theileriosis, babesiosis, and
anaplasmosis, which are caused by several species of Trypanosoma, Theileria, Babesia, and Anaplasma, respectively, in several species of livestock. These diseases caused huge impact on health and productivity of livestock as well as human beings and causes great economic losses to the livestock production n terms of morbidity and mortality worldwide. In India, the annual economic loss has been esteemed in the livestock due to theileriosis, babesiosis and trypanosomosis of Rs 8426 crore, Rs 4000 crore and Rs 4474 core, respectively. The major clinical signs of the haemoprotozoan disease varies from fever, anorexia, anaemia, abortion, and even death in the acute form of infections. The symptomatological treatment is a quite common practice in the field condition to treat the animals suspected with haemoprotozon infection leading to the development of resistance in animals to currently available drugs against haemoprotozoans. The accurate and prompt diagnosis of haemoprotozoan infection is a key to control these diseases. Routine diagnosis of haemoprotozoan infection has been rely on clinical findings and microscopical demonstration of the infective parasitic stages in the blood or tissue fluid smear. Conventional diagnostic techniques such as Microscopical examination techniques and Immunological assay provide the definite clues about parasitic infections in general, but these tests have some limitations.

Livestock has been essential for Indian agriculture since prehistoric times. Livestock is crucial for tripling farmers’ revenue, for bovines—particularly cattle and buffaloes—play a crucial role in the economy. India has the
largest number of livestock owners, with a wide variety of livestock and poultry breeds that are essential to the socioeconomic advancement of rural communities. The production of consumables and maintaining the country’s food security are inextricably related to the livestock and agricultural sectors. Numerous illnesses have a detrimental effect on the health and productivity of livestock and are highly significant economically. Livestock illnesses have negative effects on producers, costing them money in upkeep, resources, and production.
Protozoal infections are a major contributor to the global burden of infectious diseases and have a profound effect on health, society, and the economy. Nearly one-sixth of the world’s population is at risk of dying from serious diseases like malaria (Plasmodium spp.), African sleeping sickness (Trypanosoma brucei), Chagas’ disease (Trypanosoma cruzi) and various forms of cutaneous and visceral leishmaniasis (Leishmania spp.). Although the burden of protozoal diseases primarily affects tropical and subtropical regions, environmental changes and ecological modifications brought about by both natural and manmade factors have had and are likely to continue to have a significant impact on the emergence and spread of these infections in high-income nations.

There are number of internal and external factors that affect the production performance of animals, among which parasites and parasitism are major of concern constraints to animal’s productivity especially in tropical countries. Feed intake and nutrient requirements have been recognized for long time as an important parameter for determining the efficiency of animal production. Most of the parasitic infection in domestic animals is caused by gastrointestinal nematode, which may result in depression in appetite, impairment in GI functions, alteration in protein, energy and mineral metabolism and changes in water balance. Nutrition can affect the ability of the host to cope with the consequences of parasitism and to contain and eventually to overcome parasitism. Since it is proposed that the host gives priority to the reversal of the pathophysiological consequences of parasitism over other body functions, it is to be expected that improved nutrition will always lead to improved resilience. On the other hand, it is proposed that the function of growth, pregnancy and lactation are prioritized over the expression of immunity. Improved nutrition may affect the degree of expression of immunity during these phases and can thus influence the resilience and resistance of host to parasite infection.