IJSR - INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH 535 Volume : 2 | Issue : 7 | July 2013 • ISSN No 2277 - 8179 Research Paper Zoology G. SAVITHRI Department of Sericulture, S.P. Mahila Visvavidyalayam, (Women’s University) Tirupati -517502,Andhra Pradesh, INDIA P. SUJATHAMMA Department of Sericulture, S.P. Mahila Visvavidyalayam, (Women’s University) Tirupati -517502,Andhra Pradesh, INDIA V.Asha Krishna Department of Sericulture, S.P. Mahila Visvavidyalayam, (Women’s University) Tirupati -517502,Andhra Pradesh, INDIA ABSTRACT The historical links between the United States and India can be traced to the year 1492, the year when Christopher Columbus discovered America in the course of his search for a new route to India. But the official and formal links began after India gained independence. American contacts with India had started before the American Revolution through soldiers and seamen who had lived both in the American colonies and in India later both countries had mutual contacts through various agencies such as missionaries, tourists, intellectuals and Indian freedom fighters Silkworm Bombyx Mori – An Economic Insect KEYWORDS : Silkworm. Bombyx mori, Economic insect, Silk Introduction Silk, considered as the queen of fibres, is proteinaceous in na- ture. The bulk of commercial silk is produced from the mulberry silkworm Bombyx mori, of which there are many strains rang- ing from the exotic high-yielding bivoltines to the sturdier, na- tive multivoltines. The other silkworms commercially exploited for silk production are eri (Philosamia species), and tasar and muga (Antheraea species) India is unique in producing all these varieties of silk. India is home to vast variety of silk secreting fauna which also includes an amazing diversity of silkmoths. This has enabled India to achieve the unique distinction of being a producer of all the commercial exploited varieties of natural silks namely mulberry and non-mulberry (tasar, oak tasar, eri and muga). Non-mulber- ry silkworms are known as “Vanya silkworms”. Mulberry The bulk of commercial silk produced in the world is mulberry silk that comes from the domesticated silkworm, Bombyx mori L. which feeds solely on the leaves of the mulberry plant. Tasar: Tasar (Tussah) is copperish colour, coarse silk mainly used for furnishings and interiors. Tasar silk is less lustrous than mulberry silk, but has its own feel and appeal. Tasar silk is generated by the silkworm, Antheraea mylitta which mainly thrive on the food plants Asan and Arjun. The rearings are con- ducted in nature on the trees in the open. Oak Tasar: It is a finer variety of tasar generated by the silk- worm, Antheraea proyeli J. in India which feed on natural food plants of oak. China is the major producer of oak tasar in the world and this comes from another silkworm which is known as Antheraea pernyi. Eri: Eri silk is the product of the domesticated silkworm, Philosamia ricini that feeds mainly on castor leaves. A multivol- tine silkworm known for its white or brick red silk. Eri cocoons are open-mouthed and are spun. The silk is used indigenously for preparation of chaddars (wraps) for own use by these trib- als. Eri culture is a household activity practiced mainly for pro- tein rich pupae, a delicacy for the tribal. Muga: This golden yellow colour silk is prerogative of India and the pride of Assam state. It is obtained from semi-domesticat- ed multivoltine silkworm, Antheraea assamensis confined to north-eastern states of India, is the least understood and unique species among saturnid moths. The silk proteins of these spe- cies have not been studied so far despite their unique properties of providing golden luster to the silk thread. These silkworms feed on the aromatic leaves of Som and Soalu plants and are reared on trees similar to that of tasar. Muga culture is specific to the state of Assam and an integral part of the tradition and culture of that state. The muga silk, a high value product is used in products like sarees, mekhalas, chaddars, etc. The domesticated silkworm Bombyx mori L., a member of the family Bombycidae, is a well-studied lepidopteran model sys- tem with rich repertoire of genetic information on mutations affecting morphology, development, and behavior (Arunkumar et al., 2006). This species has been used as a source of silk, and has lost some characteristics due to long-term breeding under artificial conditions. Though there are many types of silkworms, only mulberry silkworm has enjoyed a large share of the patron- age of the global scientific community. As a result the mulberry silkworm has achieved the distinction of being a “lepidoteran model system”. As an insect scientific research resource, it is next only to the most well studied insect, Drosophila. The wild silkmoth, Bombyx mandarina M., is believed to be the ancestor of B. mori (Banno et al., 2004), as these two species can cross-breed and yield fertile hybrid offspring. B. manda- rina includes significant variation within species (Yukuhiro et al., 2002). From the aspect of morphological and physiological characteristics, B. mandarina was very similar to B. mori (As- taurov et al., 1959; Yoshitake, 1968). The mulberry silkworm belongs to Phylum: Arthropoda, Class: Insect, Order Lepidop- tera, Family: Bombycidae, Genus: Bombyx and Species: mori . The domestic silkmoth, Bombyx mori, is a member of the family Bombycidae of about 300 moth species under the order Lepi- doptera. Vanya silkworms belong to family Saturnidae. Life Stages of Silkworm Bombyx mori Silkworms are lepidopteron insects. The larvae are caterpillars, which, at the end of the larval stage, spin a cocoon of silk, and transform into pupae and finally into adult moths. The silk pro- teins are synthesized in the silk glands. Larvae possess a pair of silk glands, which are long complexly folded tubular struc- tures located parallel to the gut, extending nearly throughout the entire length of the larvae, but much longer, may be up to seven times the length of the caterpillar itself! being coiled in the posterior silkglands are divided into anterior, middle and posterior silkglands. The gland is a tube made of glanular epi- thelium with two rows of cells surrounding the lumen. The silk fibre protein, fibrion, is synthesized in cells of the posterior silk glands, and secreted into the lumen and transported to the mid- dle silk gland for storage. The middle region acts as a reservoir of fibroin and the fibroin matures in this region during the stor- age period. Further, this region synthesizes the glue proteins called sericins and coat the fibroin in three layers accumulating there. The sericin is sub-divided into 1. Sericin –I (inner most layer) secretion of posterior part of middle region, 2. Sericin –II