Online assignment
- 1. ONLINE ASSIGNMENT Topic : SERICULTURE Submitted By Chithra. S Natural Science Reg. No.: 14367006
- 2. INTRODUCTION Silk fibres are also animal fibres. Silk worms spin the “silk fibres”. The rearing of silkworms for obtaining silk is called sericulture. Sericulture or cultre of silk works, is a very old occupation in India. India produces plenty of silk on a commercial scale. The exact time of discovery of silk is perhaps unknown. According to an old Chinese legend, the empress Si-lung-Chi was asked by the emperor Huang-ti to find the cause of the damaged leaves of mulberry trees growing in their garden. The empress found white worms eating up mulberry leaves. She also noticed that they were spinning shiny cocoons around them. Accidentally a cocoon dropped into her cup of tea and a tangle of delicate threads separated from the cocoon. Silk industry began in China and was kept a closely guarded secret for hundreds of years. Later on, traders and travellers introduced silk to other countries. The route they travelled is still called the ‘silk route’.
- 3. DATA COLLECTIONS Sericulture is the production of raw silk by raising silk worms. The productivity and profitability of sericulture depends on the yield of mulberry crop. It is a cottage industry combining agriculture and industry. The end product of this agro-industry is silk. The production process of silk involves along chain of interdependent specialized operations such as mulberry cultivation, silkworm seed production, rearing of silk worm, reeling, twisting and weaving of silk, etc. which provide employment to about 60 lakhs people in the villages of India through family labour and is the second largest employer in the country. Sericulture is an export oriented agro - industry. Indian silks are exported to more than 50 countries and gains about 800 crores of rupees each year from it. We have a unique position among the silk producing countries, because India is the only country in the world producing all the four commercially important varieties of natural silk - Mulberry, Tasar, Eri, and Muga silk. The silk industry originated in China and was kept in secret by them for about 3000 years. The sericulture industry is well established in India since the 4th century. Major silk producing states in India are Karnataka, Andhra Pradesh, Tamil Nadu and West Bengal. Only recently Kerala has got a place in the sericulture map of India. The scope and potentiality of sericulture industry is not limited in the production of silk as a textile fibre. The silk fibre produced by the mulberry silkworm and its byproducts can be utilized for many other purposes. The special properties of silk fibre makes it a raw material for making electric insulations, tyre linings, artificial blood vessels, surgical sutures, etc. Hydrolized proteins, aminoacids and vit B2 (Riboflavin) are extracted from the silkworm pupa. The major by products in sericulture industry are rearing wastes, waste cocoons and silkworm faeces. Rearing wastes can be used for the productionof biogas and vermicompost. Waste cocoons are the raw material of cocoon handicraft which involve the production of garlands;
- 4. flowers, dolls, greeting cards etc. Chlorophyll and phytol can be extracted from the silkworm faeces. Phytol is a raw mater for manufacturing vitamin E and K. The faeces is also used in plastic industry and as feed for fish, pig, cattle, etc. All these sideline developments of sericulture provide further employment opportunities and economic growth. TYPES OF SILKWORMS There are four kinds of silk worms which are producing commercially important natural silk. They are the following : Mulberry silkworm It is a domesticated variety of silkworm and has been exploited for over 4000 years. All the strains of mulberry silkworm belong to the species Bombyx mori. The term silk generally refers to the silk of mulberry silkworm because it contributes about 95 percent of world's silk production. Bombyx mori produces cocoons with continuous silk filament and therefore, it can be industrially reeled to produce raw silk.
- 5. Eri silkworm It is a domesticated species and is reared on castor plants, so they are called castor silkworms. The castor silkworm belongs ,to the species Sarnia cynthia ricini. Eri silkworms produce a white or brick red silk known as Eri silk or Endi or Errandi silk. The silk filament produced by these worms is not continuous and uniform and cannot be reeled properly. So the moths are allowed to emerge from the cocoons in natural way and the pierced cocoons are used to produce Eri silk. In India, Assam is the home of the Eri silk industry. Tasar silkworm Antheraea myletta is the taser silkworm. It is bivoltine species having two crops in a year. Indian taser worm feeds on the leaves of Terminalia and other minor host plants. The cocoons are very hard because of a hard protective covering secreted by the worms. The cocoons can be reeled into raw silk like mulberry silkworm cocoons. The reeling mechanism is slightly different from mulberry silk cocoons. The hard protective covering must be softened before reeling, using certain special technique.
- 6. Muga silkworm Muga silkworms belong to the species, Antheraea assamensis. These worms produce strong and beautiful golden yellow silk threads. These are found only in Assam. The worms feed on the leaves of som and soalu and Indian enjoys the sole monopoly in the production of muga silk in the world. Life cycle of Bombyx mori Life cycle of mulberry silk worm involves four distinct stages, viz. egg, larva, pupa and adult. The duration of life cycle may vary from six to eight weeks depending on racial characteristics and climatic conditions. Multivoltine races in tropical areas have the shortest life cycle. So silkworm rearing is continuous in tropical areas whereas in sub-tropical and temperate areas it is seasonal.
- 7. Egg. Each female lays about 400 eggs in clusters up on the mulberry leaves. The eggs are tiny smooth and ovoid. The colour of the eggs may vary from white, yellow or brown, depending on the races. Around 2000 eggs weighs to a gramme. The female dies within four to five days. Larva. After 9 to 12 days the silk worm hatches from the egg. The newly hatched larva is black or dark brown in colour. It has a large head and the body is covered with dense black bristles and looks like black ants. So they are generally refered to as “ants” or “ant worms”. The body of the larva has 13 visible segments and is divisible into head, thorax and abdomen. The head consists of six body segments, which are fused together. It is provided with a pair of five jointed antennae which are sensory in function. Six pairs of light sensitive ocelli are present at the base of the antenna. Mouth parts consist of mandibles, maxillae and labium. The mandibles are adapted for mastication. The maxillae are used to detect the taste of food. The labium has a chitinized prementum which carries a median process, a spinneret through which silk is secreted from the silk gland. The labial plaps are present on either sides of the spinneret. The thorax consists of three segments. Each thoracic segment carries a pair of three jointed legs with distal sharp claws. All the larvae carry the charactristic larval markings called eye spots on the dorsal side of the mesothorax. The abdomen consists of eleven segments, although only nine can be distinguished because the last three segments are fused together to form the nineth segment, anal piate and a pair of caudal legs. In addition to the caudal legs, the abdomen is provided with four pairs of legs. All the five pairs of abdominal legs are fleshy unsegmented muscular protuberances called prolegs or pseudolegs. A short anal horn is present on the 8th segment.
- 8. The larval life lasts for 25 to 30 days. This is the most active period in the life cycle of Bombyx mori. The larva fees voraciously upon the mulberry leaves and grows very quickly about 10000 times its weight at the time of hatching.
- 9. CONCLUSION Sericulture biologically means that the cultivation of silkworm. Mulberry plants are typically used as cultivating plant. Bombix mori is the most important silkworm. Sericulture is the production of raw silk by raising silk worms. Sericulture is an export oriented agro - industry. Indian silks are exported to more than 50 countries and gains about 800 crores of rupees each year from it. In India women are significantly involved in various kinds of industries related to silk production. These are rearing of silk work, reeling of silk from cocoons and processing of raw silk in to fabries. By their enterprise, they contribute to the nation’s economy. China leads the world in silk production. India also ranks among the leading silk producing countries. REFERENCE Applied ecology & environmental biology – Engine P ondum NCERT biology text book in VIIth standard.