Sericulture is the term used for the culture of silkworms for silk production.

Using a rough figure of one kilometer of silk (about 3300 feet) per cocoon, ten unraveled cocoons could theoretically extend vertically to the height of Mt Everest. About 2,000 to 3,000 cocoons are required to make a pound of silk, or roughly 1,000 miles of filament (Palmer 1949).

Kraig Biocraft Laboratories[13] has used research from the Universities of Wyoming and Notre Dame in a collaborative effort to create a silkworm that is genetically altered to produce spider silk. In September 2010, the effort was announced as successful.[14]

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A number of commercially important diseases affect silkworms. Notable examples are:

Silkworms were first domesticated in China over 5000 years ago.[17][18] Since then, the silk production capacity of the species has increased nearly tenfold. The silkworm is one of the few organisms wherein the principles of genetics and breeding were applied to harvest maximum output. It is next only to maize in exploiting the principles of heterosis and cross breeding.[citation needed]

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Silkworm is the larva or caterpillar of various species of moths, in particular, Bombyx mori, the domesticated silkmoth, whose silk cocoons can be used in the production of silk.

Consequently, the two silkmoths have been united as subspecies of a single species; in this case the name Bombyx mori which was published first applies for both. However, today it is usually recognized that the domesticated silkmoth is entirely dependent on human care for its survival and thus has a level of reproductive isolation from its wild relatives.

Like many insect species, silkworm pupae are eaten in some cultures.

Silkworms are native to northern China. They are totally dependent on humans; there are no wild populations.

Researchers at the MIT Media Lab experimented with silkworms to see what they would weave when left on surfaces with different curvatures. They found that on particularly straight webs of lines, the worms would connect neighboring lines with silk, weaving directly onto the given shape. Using this knowledge they built a silk pavilion with 6,500 silkworms over a number of days.

At least 70 million pounds of raw silk are produced each year, requiring nearly ten billion pounds of mulberry leaves. The annual world production represents 70 billion miles of silk filament, a distance well over 300 round trips to the sun.

The eggs of the domesticated silkworm are very small and are initially lemon-yellow but later turn black (Grzimek et al. 2004). They take about ten days to hatch.

Silkworm is the source of the traditional Chinese medicine jiāngcán ("stiff silkworm," Simplified Chinese: 僵蚕; Traditional Chinese: 僵蠶, trade name "Bombyx batryticatus"). It is the dried body of the 4-5th instar larva which has died of the white muscardine disease. Its uses are to dispel flatulence, dissolve phlegm, and relieve spasms.

In traditional Chinese medicine, silkworm is the source of the "stiff silkworm", which is made from dried fourth- or fifth-instar larvae which have died of white muscardine disease (a lethal fungal infection). It is believed to dispel flatulence, dissolve phlegm, and relieve spasms.[citation needed]

B. mandarina is able to hybridize with B. mori. Both in the wild and in a domesticated environment, females release pheromones and wait for males to be attracted and fly to them. However, B. mori males cannot fly. Hybridisation, therefore, inevitably means breeding between domestic (B. mori) females and wild (B. mandarina) males.

The cocoon is made of a thread of raw silk from 300 to about 900 m (1,000 to 3,000 ft) long. The fibers are very fine and lustrous, about 10 μm (0.0004 in) in diameter. About 2,000 to 3,000 cocoons are required to make a pound of silk (0.4 kg). At least 70 million pounds of raw silk are produced each year, requiring nearly 10 billion pounds of cocoons. [10]

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The genome of the silkworm is mid-range with a genome size around 432 megabase pairs.

The caterpillars feed on leaves of mulberry trees, with the preferred food being the white mulberry. Adults in the Bombycidae family have reduced mouth parts and do not feed.

In the USA, teachers may sometimes introduce the insect lifecycle to their students by raising silkworms in the classroom as a science project. Students have a chance to observe complete lifecycles of insect from egg stage to larvae, pupa, moth.

The cocoon of the domesticated silkworm is made of a single continuous thread of raw silk from 300 to 900 meters (1000 to 3000 feet) long. The fibers are very fine and lustrous, about ten micrometers (1/2500th of an inch) in diameter. They are made mostly of an insoluble protein (fibroin), coated by a smaller amount of a water-soluble protective gum (sericin), as well as including small amounts of other substances.

Sometimes, the wild silkmoth is considered a subspecies of Bombyx mori as they are theoretically capable of full hybridization. However, due to the domesticated moth's requirement for human care to survive, gene flow is all but nonexistent and thus, despite its apparently recent origin, the domestic animal is generally treated as a distinct monotypic species today.

While other Lepidoptera produce cocoons, only a few large Bombycidae and Saturniidae have been exploited for fabric production.

Researchers at Tufts developed scaffolds made of spongy silk that feel and look similar to human tissue. They are implanted during reconstructive surgery to support or restructure damaged ligaments, tendons, and other tissue. They also created implants made of silk and drug compounds which can be implanted under the skin for steady and gradual time release of medications. [15]

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Silkworms were unlikely to have been domestically bred before the Neolithic age; before then, the tools required to facilitate the manufacturing of larger quantities of silk thread had not been developed. The domesticated B. mori and the wild B. mandarina can still breed and sometimes produce hybrids.[4]:342

The domesticated variety, compared to the wild form, has increased cocoon size, growth rate, and efficiency of its digestion. It has also gained tolerance to human presence and handling and living in crowded conditions; it cannot fly, so needs human assistance in finding a mate, and it lacks fear of potential predators. These changes have made it entirely dependent upon humans for survival.[16] The eggs are kept in incubators to aid in their hatching.

The Chinese guarded their knowledge of silk. It is said that a Chinese woman smuggled eggs to Japan, hidden in her hair. The Japanese thus began their love affair with silk. Making a single kimono requires the silk from 2100 silkworm moths.

Adults emerge from the cocoon after about three weeks, reproduce, and then die within five days (Grzimek et al. 2004). The adult phase (the moth) cannot fly. Under natural conditions, they have one generation per year, with the females laying 200 to 500 eggs (Grzimek et al. 2004).

Sericulture, the practice of breeding silkworms for the production of raw silk, has been under way for at least 5,000 years in China,[1] from where it spread to Korea and Japan, India and later the West. The silkworm was domesticated from the wild silkmoth Bombyx mandarina, which has a range from northern India to northern China, Korea, Japan, and the far eastern regions of Russia. The domesticated silkworm derives from Chinese rather than Japanese or Korean stock.[2][3]

Domestic Silkmoth

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The full genome of the silkworm was published in 2008 by the International Silkworm Genome Consortium.[11] Draft sequences were published in 2004.[21][22]

Due to its large size and ease of culture, Bombyx mori has long been a model organism in the study of Lepidopteran and arthropod biology (Goldsmith et al. 2004). Fundamental findings on pheromones, hormones, brain structures, and physiology were made with the silkworm (Grimaldi and Engel 2005). To characterize the first known pheromone, bombykol, extracts were needed from 500,000 individuals because only very small quantities are produced (Scoble 1995).

The Chinese guarded their knowledge of silk, but, according to one story, a Chinese princess given in marriage to a Khotan prince brought to the oasis the secret of silk manufacture, "hiding silkworms in her hair as part of her dowry", probably in the first half of the first century CE.[27] About 550 AD, Christian monks are said to have smuggled silkworms, in a hollow stick, out of China and sold the secret to the Byzantine Empire.

The nearest wild relative of Bombyx mori is Bombyx mandarina, the wild silkmoth, which is able to hybridize with the domestic taxon (Goldsmith et al. 2004). It ranges from northern India to northern China, Korea, and Japan. It is not known when the domestic silkmoth diverged from its wild relatives, only that the domestic population originated from inland Chinese rather than Japanese or Korean stock (Maekawa et al. 1988; Arunkumar et al. 2006).

Like many insect species, silkworm pupae are eaten in some cultures. In Korea they are boiled and seasoned to make a popular snack food known as beondegi. In China, street vendors sell roasted silkworm pupae.

Specific purposes apart from commercial purpose are given attention by advanced countries to breed development for specific purposes like sericin production, sex-limited breeds, thin/thick filament production, etc. Disease-resistance breeding is important, as the major reason for crop losses is pathogen infection. Efforts are being made to select breeds which are tolerant or resistant to various pathogens.[19][unreliable source?]

After they have molted four times (i.e., in the fifth instar), their bodies turn slightly yellow and their skin becomes tighter. The larvae enclose themselves in a cocoon of raw silk produced in the salivary glands that provides protection during the vulnerable, almost motionless pupal state. Spinning a cocoon takes three or more days. The filament is secreted in a slow, circular, figure-eight motion from glands called spinnerets located under the jaws.