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The domestic silk moth (''Bombyx mori''), is an insect from the
moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Bombycidae The Bombycidae are a family of moths. The best-known species is ''Bombyx mori'' (Linnaeus) or silkworm, native to northern China and domesticated for millennia. Another well-known species is ''Bombyx mandarina'', also native to Asia. Taxonomy Th ...
. It is the closest relative of ''
Bombyx mandarina ''Bombyx mandarina'', the wild silk moth, is an insect from the moth family Bombycidae. It is the closest relative of ''Bombyx mori'', the domesticated silk moth. The silkworm is the larva or caterpillar of a silk moth. Unlike the domesticated r ...
'', the wild silk moth. The silkworm is the
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
or
caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...
of a silk moth. It is an economically important insect, being a primary producer of
silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...
. A silkworm's preferred food are white mulberry leaves, though they may eat other mulberry species and even the
osage orange ''Maclura pomifera'', commonly known as the Osage orange ( ), is a small deciduous tree or large shrub, native to the south-central United States. It typically grows about tall. The distinctive fruit, a multiple fruit, is roughly spherical, b ...
. Domestic silk moths are entirely dependent on humans for reproduction, as a result of millennia of selective breeding. Wild silk moths (other species of ''Bombyx'') are not as commercially viable in the production of silk.
Sericulture Sericulture, or silk farming, is the cultivation of silkworms to produce silk. Although there are several commercial species of silkworms, ''Bombyx mori'' (the caterpillar of the domestic silkmoth) is the most widely used and intensively studie ...
, the practice of breeding silkworms for the production of raw silk, has been under way for at least 5,000 years in China, whence it spread to
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
,
Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
,
Nepal Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is mai ...
,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
, and the
West West or Occident is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sunset, Sun sets on the Earth. Etymology The word "west" is a Germanic languages, German ...
. The domestic silk moth was domesticated from the wild silk moth ''
Bombyx mandarina ''Bombyx mandarina'', the wild silk moth, is an insect from the moth family Bombycidae. It is the closest relative of ''Bombyx mori'', the domesticated silk moth. The silkworm is the larva or caterpillar of a silk moth. Unlike the domesticated r ...
'', which has a range from northern India to northern
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, Korea, Japan, and the far eastern regions of
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
. The domestic silk moth derives from Chinese rather than Japanese or Korean stock. Silk moths were unlikely to have been domestically bred before the
Neolithic The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several parts ...
Age. Before then, the tools to manufacture quantities of silk thread had not been developed. The domesticated ''B. mori'' and the wild '' B. mandarina'' can still breed and sometimes produce hybrids. Domestic silk moths are very different from most members in the genus ''
Bombyx ''Bombyx'' is the genus of true silk moths or mulberry silk moths of the family Bombycidae, also known as silkworms, which are the larvae or caterpillars of silk moths. The genus was erected as a subgenus by Carl Linnaeus in his 10th edition of ...
''; not only have they lost the ability to fly, but their color pigments have also been lost.


Types

Mulberry silkworms can be categorized into three different but connected groups or types. The major groups of silkworms fall under the univoltine ("uni-"=one, "voltine"=brood frequency) and bivoltine categories. The univoltine type is generally linked with the geographical area within greater Europe. The eggs of this type hibernate during winter due to the cold climate, and cross-fertilize only by spring, generating silk only once annually. The second type is called bivoltine and is normally found in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
, and
Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
. The breeding process of this type takes place twice annually, a feat made possible by the slightly warmer climates and the resulting two life cycles. The polyvoltine type of mulberry silkworm can only be found in the tropics. The eggs are laid by female moths and hatch within nine to 12 days, so the resulting type can have up to eight separate life cycles throughout the year.


Process

Eggs take about 14 days to hatch into larvae, which eat continuously. They have a preference for white mulberry, having an attraction to the mulberry odorant
cis-jasmone Jasmone is an organic compound, which is a volatile portion of the oil from jasmine flowers. It is a colorless to pale yellow liquid. Jasmone can exist in two isomer In chemistry, isomers are molecules or polyatomic ions with identical mol ...
. They are not
monophagous A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of env ...
, since they can eat other species of '' Morus'', as well as some other
Moraceae The Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 38 genera and over 1100 species. Most are widespread in tropical and subtropical regions, less so in temperate climates; however ...
, mostly
Osage orange ''Maclura pomifera'', commonly known as the Osage orange ( ), is a small deciduous tree or large shrub, native to the south-central United States. It typically grows about tall. The distinctive fruit, a multiple fruit, is roughly spherical, b ...
. They are covered with tiny black hairs. When the color of their heads turns darker, it indicates they are about to
molt In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
. After molting, the
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
l phase of the silkworms emerge white, naked, and with little horns on their backs. After they have molted four times, their bodies become slightly yellow, and the skin becomes tighter. The larvae then prepare to enter the
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
l phase of their lifecycle, and enclose themselves in a cocoon made up of raw silk produced by the
salivary glands The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary gla ...
. The final molt from larva to pupa takes place within the cocoon, which provides a vital layer of protection during the vulnerable, almost motionless pupal state. Many other
Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
produce cocoons, but only a few—the
Bombycidae The Bombycidae are a family of moths. The best-known species is ''Bombyx mori'' (Linnaeus) or silkworm, native to northern China and domesticated for millennia. Another well-known species is ''Bombyx mandarina'', also native to Asia. Taxonomy Th ...
, in particular the genus ''
Bombyx ''Bombyx'' is the genus of true silk moths or mulberry silk moths of the family Bombycidae, also known as silkworms, which are the larvae or caterpillars of silk moths. The genus was erected as a subgenus by Carl Linnaeus in his 10th edition of ...
'', and the
Saturniidae Saturniidae, commonly known as saturniids, is a family of Lepidoptera with an estimated 2,300 described species. The family contains some of the largest species of moths in the world. Notable members include the emperor moths, royal moths, and gi ...
, in particular the genus ''
Antheraea ''Antheraea'' is a moth genus belonging to the family Saturniidae. The genus was erected by Jacob Hübner in 1819. Several species of this genus have caterpillars which produce wild silk of commercial importance. Commonly called "tussar silk", t ...
''—have been exploited for fabric production. If the animal is allowed to survive after spinning its cocoon and through the pupal phase of its lifecycle, it releases
proteolytic enzyme A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the for ...
s to make a hole in the cocoon so it can emerge as an adult moth. These enzymes are destructive to the silk and can cause the silk fibers to break down from over a mile in length to segments of random length, which seriously reduces the value of the silk threads, although these damaged silk cocoons are still used as "stuffing" available in China and elsewhere for doonas, jackets, etc. To prevent this, silkworm cocoons are boiled. The heat kills the silkworms and the water makes the cocoons easier to unravel. Often, the silkworm itself is eaten. As the process of harvesting the silk from the cocoon kills the larva, sericulture has been criticized by animal welfare and rights activists.
Mahatma Gandhi Mohandas Karamchand Gandhi (; ; 2 October 1869 – 30 January 1948), popularly known as Mahatma Gandhi, was an Indian lawyer, anti-colonial nationalist Quote: "... marks Gandhi as a hybrid cosmopolitan figure who transformed ... anti- ...
was critical of silk production based on the
Ahimsa Ahimsa (, IAST: ''ahiṃsā'', ) is the ancient Indian principle of nonviolence which applies to all living beings. It is a key virtue in most Indian religions: Jainism, Buddhism, and Hinduism.Bajpai, Shiva (2011). The History of India ...
philosophy "not to hurt any living thing". This led to Gandhi's promotion of cotton spinning machines, an example of which can be seen at the Gandhi Institute, and an extension of this principle has led to the modern production practice known as
Ahimsa silk Ahimsa silk (''ahiṃsā'': Sanskrit for 'nonviolence') is a method of nonviolent silk breeding and harvesting. Wild silk moths are bred, rather than the domestic variety. It allows the completion of the metamorphosis of the silkworm to its moth s ...
, which is
wild silk Wild silks have been known and used in many countries from early times, although the scale of production is far smaller than that from cultivated silkworms. Silk cocoons and nests often resemble paper or cloth, and their use has arisen independent ...
(from wild and semiwild silk moths) made from the cocoons of moths that are allowed to emerge before the silk is harvested. The moth – the adult phase of the lifecycle – is not capable of functional flight, in contrast to the wild ''B. mandarina'' and other ''Bombyx'' species, whose males fly to meet females and for evasion from predators. Some may emerge with the ability to lift off and stay airborne, but sustained flight cannot be achieved. This is because their bodies are too big and heavy for their small wings. Silk moths have a wingspan of and a white, hairy body. Females are about two to three times bulkier than males (for they are carrying many eggs), but are similarly colored. Adult
Bombycidae The Bombycidae are a family of moths. The best-known species is ''Bombyx mori'' (Linnaeus) or silkworm, native to northern China and domesticated for millennia. Another well-known species is ''Bombyx mandarina'', also native to Asia. Taxonomy Th ...
have reduced mouthparts and do not feed.


Cocoon

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 1 pound of silk (0.4 kg). At least 70 million pounds (32 million kg) of raw silk are produced each year, requiring nearly 10 billion cocoons.


Research

Due to its small size and ease of culture, the silkworm has become a
model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...
in the study of lepidopteran and arthropod biology. Fundamental findings on
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s,
hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...
s, brain structures, and physiology have been made with the silkworm. One example of this was the molecular identification of the first known pheromone,
bombykol Bombykol is a pheromone released by the female silkworm moth to attract mates. It is also the sex pheromone in the wild silk moth (''Bombyx mandarina''). Discovered by Adolf Butenandt in 1959, it was the first pheromone to be characterized chemica ...
, which required extracts from 500,000 individuals, due to the very small quantities of pheromone produced by any individual silkworm. Many research works have focused on the genetics of silkworms and the possibility of genetic engineering. Many hundreds of strains are maintained, and over 400 Mendelian mutations have been described. Another source suggests 1,000 inbred domesticated strains are kept worldwide. One useful development for the silk industry is silkworms that can feed on food other than mulberry leaves, including an artificial diet. Research on the genome also raises the possibility of genetically engineering silkworms to produce proteins, including pharmacological drugs, in the place of silk proteins. ''Bombyx mori'' females are also one of the few organisms with homologous chromosomes held together only by the
synaptonemal complex The synaptonemal complex (SC) is a protein structure that forms between homologous chromosomes (two pairs of sister chromatids) during meiosis and is thought to mediate synapsis and recombination during meiosis I in eukaryotes. It is currentl ...
(and not crossovers) during
meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately resu ...
.
Kraig Biocraft Laboratories Kraig Biocraft Laboratories, Inc. is an American biotechnology company headquartered in Ann Arbor, Michigan. It develops and manufactures recombinant spider silks and other high-performance polymers using spider silk gene sequences. Their most ...
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. Researchers at
Tufts Tufts University is a private research university on the border of Medford and Somerville, Massachusetts. It was founded in 1852 as Tufts College by Christian universalists who sought to provide a nonsectarian institution of higher learning. ...
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. Researchers at the
MIT Media Lab The MIT Media Lab is a research laboratory at the Massachusetts Institute of Technology, growing out of MIT's Architecture Machine Group in the School of Architecture. Its research does not restrict to fixed academic disciplines, but draws from ...
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 silkworms 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. Silkworms have been used in antibiotics discovery, as they have several advantageous traits compared to other invertebrate models. Antibiotics such as lysocin E, a non-ribosomal peptide synthesized by Lysobacter sp. RH2180-5 and GPI0363 are among the notable antibiotics discovered using silkworms. In addition, antibiotics with appropriate pharmacokinetic parameters were selected that correlated with therapeutic activity in the silkworm infection model. Silkworms have also been used for the identification of novel virulence factors of pathogenic microorganisms. A first large-scale screening using transposon mutant library of Staphylococcus aureus USA300 strain was performed which identified 8 new genes with roles in full virulence of S. aureus. Another study by the same team of researchers revealed, for the first time, the role of YjbH in virulence and oxidative stress tolerance in vivo.


Domestication

The domestic species ''B. mori'', compared to the wild species (e.g., ''B. mandarina''), has increased cocoon size, body size, growth rate, and efficiency of its digestion. It has gained tolerance to human presence and handling, and also to living in crowded conditions. The domestic silk moths cannot fly, so the males need human assistance in finding a mate, and it lacks fear of potential predators. The native color pigments have also been lost, so the domestic silk moths are
leucistic Leucism () is a wide variety of conditions that result in the partial loss of pigmentation in an animal—causing white, pale, or patchy coloration of the skin, hair, feathers, scales, or cuticles, but not the eyes. It is occasionally spelled ' ...
, since camouflage is not useful when they only live in captivity. These changes have made ''B. mori'' entirely dependent upon humans for survival, and it does not exist in the wild. The eggs are kept in incubators to aid in their hatching.


Silkworm breeding

Silkworms were first domesticated in China more than 5,000 years ago. 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 second only to
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
in exploiting the principles of
heterosis Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of ...
and
crossbreeding A crossbreed is an organism with purebred parents of two different breeds, varieties, or populations. ''Crossbreeding'', sometimes called "designer crossbreeding", is the process of breeding such an organism, While crossbreeding is used to main ...
. Silkworm breeding is aimed at the overall improvement of silkworms from a commercial point of view. The major objectives are improving
fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...
(the egg-laying capacity of a breed), the health of larvae, quantity of cocoon and silk production, and disease resistance. Healthy larvae lead to a healthy cocoon crop. Health is dependent on factors such as better
pupation A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...
rate, fewer dead larvae in the mountage, shorter larval duration (this lessens the chance of infection) and bluish-tinged fifth-instar larvae (which are healthier than the reddish-brown ones). Quantity of cocoon and silk produced are directly related to the pupation rate and larval weight. Healthier larvae have greater pupation rates and cocoon weights. Quality of cocoon and silk depends on a number of factors, including genetics.


Hobby raising and school projects

In the U.S., teachers may sometimes introduce the insect life cycle to their students by raising domestic silk moths in the classroom as a science project. Students have a chance to observe complete life cycles of insects from eggs to larvae to pupae to moths. The domestic silk moth has been raised as a hobby in countries such as China, South Africa, Zimbabwe, and Iran. Children often pass on the eggs, creating a non-commercial population. The experience provides children with the opportunity to witness the life cycle of silk moths. The practice of raising silk moths by children as pets has, in non-silk farming South Africa, led to the development of extremely hardy
landrace A landrace is a domesticated, locally adapted, often traditional variety of a species of animal or plant that has developed over time, through adaptation to its natural and cultural environment of agriculture and pastoralism, and due to isolation ...
s of silk moths, because they are invariably subjected to hardships not encountered by commercially farmed members of the species. However, these worms, not being selectively bred as such, are possibly inferior in silk production and may exhibit other undesirable traits.


Genome

The full
genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
of the domestic silk moth was published in 2008 by the International Silkworm Genome Consortium. Draft sequences were published in 2004. The genome of the domestic silk moth is mid-range with a
genome size Genome size is the total amount of DNA contained within one copy of a single complete genome. It is typically measured in terms of mass in picograms (trillionths (10−12) of a gram, abbreviated pg) or less frequently in daltons, or as the total ...
around 432 megabase pairs. High genetic variability has been found in domestic lines of silk moths, though this is less than that among wild silk moths (about 83 percent of wild genetic variation). This suggests a single event of domestication, and that it happened over a short period of time, with a large number of wild silkworms having been collected for domestication. Major questions, however, remain unanswered, according to Jun Wang, co-author of a related study published in 2008, who stated: "Whether this event was in a single location or in a short period of time in several locations cannot be deciphered from the data", and research also has yet to identify the area in China where domestication arose.


As food

Silk moth pupae are
edible insects Insects as food or edible insects are insect species used for human consumption. More than 2,000 insects species worldwide are considered edible. However, a much smaller number is discussed for industrialized mass production and partly regiona ...
and are eaten in some cultures: * In
Assam, India Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur to ...
, they are boiled for extracting silk and the boiled pupae are eaten directly with salt or fried with chili pepper or herbs as a snack or dish. * In
Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
, they are boiled and seasoned to make a popular snack food known as ''
beondegi ''Beondegi'' (), literally "pupa", is a Korean insect-based street food made with silkworm pupae. The boiled or steamed snack food is served in paper cups with toothpick skewers. Its aroma has been described as "nutty, shrimp-like, and a bit ...
'' (번데기). * In
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, street vendors sell roasted silk moth pupae. * In
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
, silkworms are usually served as a ''
tsukudani is small seafood, meat or seaweed that has been simmered in soy sauce and mirin. As a flavorful accompaniment to plain rice, tsukudani is made salty enough to not go bad, allowing high osmotic pressure to preserve the ingredients from microbial ...
'' (佃煮), i.e., boiled in a sweet-sour sauce made with
soy sauce Soy sauce (also called simply soy in American English and soya sauce in British English) is a liquid condiment of Chinese origin, traditionally made from a fermented paste of soybeans, roasted grain, brine, and '' Aspergillus oryzae'' or ''Asp ...
and sugar. * In
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
, this is known as ', usually boiled, seasoned with fish sauce, then stir-fried and eaten as main dish with rice. * In
Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
, roasted silkworm is often sold at open markets. They are also sold as packaged snacks. Silkworms have also been proposed for cultivation by astronauts as
space food Space food is a type of food product created and processed for consumption by astronauts during missions to outer space. The food has specific requirements of providing balanced nutrition for individuals working in space while being easy and sa ...
on long-term missions.


Silkworm legends


China

In China, a legend indicates the discovery of the silkworm's silk was by an ancient empress named
Leizu Leizu (), also known as Xi Ling-shi (, Wade–Giles Hsi Ling-shih), was a legendary Chinese empress and wife of the Yellow Emperor. According to tradition, she discovered sericulture, and invented the silk loom, in the 27th century BC. Myths A ...
, the wife of the
Yellow Emperor The Yellow Emperor, also known as the Yellow Thearch or by his Chinese name Huangdi (), is a deity ('' shen'') in Chinese religion, one of the legendary Chinese sovereigns and culture heroes included among the mytho-historical Three Soverei ...
, also known as Xi Lingshi. She was drinking tea under a tree when a silk cocoon fell into her tea. As she picked it out and started to wrap the silk thread around her finger, she slowly felt a warm sensation. When the silk ran out, she saw a small larva. In an instant, she realized this caterpillar larva was the source of the silk. She taught this to the people and it became widespread. Many more legends about the silkworm are told. The Chinese guarded their knowledge of silk, but, according to one story, a Chinese princess given in marriage to a
Khotan Hotan (also known as Gosthana, Gaustana, Godana, Godaniya, Khotan, Hetian, Hotien) is a major oasis town in southwestern Xinjiang, an autonomous region in Western China. The city proper of Hotan broke off from the larger Hotan County to become ...
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 AD. About AD 550, Christian monks are said to have
smuggled Smuggling is the illegal transportation of objects, substances, information or people, such as out of a house or buildings, into a prison, or across an international border, in violation of applicable laws or other regulations. There are various ...
silkworms, in a hollow stick, out of China and sold the secret to the
Byzantine Empire The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...
.


Vietnam

According to a Vietnamese folk tale, silkworms were originally a beautiful housemaid running away from her gruesome masters and living in the mountain, where she was protected by the mountain god. One day, a lecherous god from the heaven came down to Earth to seduce women. When he saw her, he tried to rape her but she was able to escape and hidden by the mountain god. The lecherous god then tried to find and capture her by setting a net trap around the mountain. With the blessing of
Guanyin Guanyin () is a Bodhisattva associated with compassion. She is the East Asian representation of Avalokiteśvara ( sa, अवलोकितेश्वर) and has been adopted by other Eastern religions, including Chinese folk religion. She ...
, the girl was able to safely swallow that net into her stomach. Finally, the evil god summons his fellow thunder and rain gods to attack and burn away her clothes, forcing her to hide in a cave. Naked and cold, she spit out the net and used it as a blanket to sleep. The girl died in her sleep, and as she wished to continue to help other people, her soul turned into silkworms.


Silkworm nutrition

''Bombyx mori'' is essentially monophagous, exclusively eating mulberry leaves (''Morus'' spp.). By developing techniques for using artificial diets, the amino acids needed for development are known.Hamed Kioumarsi, Nazanin Amani ''Silkworm/''Bombyx mori'': An Overview of What You Need to Know ''. AREEO, 2021. . Page 27. The various amino acids can be classified into five categories: *Those which, when removed, cause larval development to stop entirely: Lysine, Leucine, Isoleucine, Histidine, Arginine, Valine, Tryptophan, Threonine, Phenylalanine, Methionine *Those which, when removed, impede later stages of larval development: Glutamate and Aspartate *Semi-essential amino acids, with negative effects that can be eliminated by supplementing with other amino acids: Proline (Ornithine can be substituted) *Non-essential amino acids that can by replaced through biosynthesis by the larvae: Alanine, Glycine, Serine *Non-essential amino acids that can be removed with no effect at all: Tyrosine


Silkworm diseases

*''
Beauveria bassiana ''Beauveria bassiana'' is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is used as a biological ...
'', a fungus, destroys the entire silkworm body. This fungus usually appears when silkworms are raised under cold conditions with high humidity. This disease is not passed on to the eggs from moths, as the infected silkworms cannot survive to the moth stage. This fungus, however, can spread to other insects. * Grasserie, also known as nuclear polyhedrosis, milky disease, or hanging disease, is caused by infection with the ''Bombyx mori nucleopolyhedrovirus'' (aka ''Bombyx mori nuclear polyhedrosis virus'', genus ''
Alphabaculovirus ''Alphabaculovirus'' is a genus of viruses in the family ''Baculoviridae''. The natural hosts of species in this family are invertebrates, among them winged insects (Lepidopterans, Hymenopterans, Dipterans), and decapods. However, species in thi ...
''). If grasserie is observed in the chawkie stage, then the chawkie larvae must have been infected while hatching or during chawkie rearing. Infected eggs can be disinfected by cleaning their surfaces prior to hatching. Infections can occur as a result of improper hygiene in the chawkie rearing house. This disease develops faster in early instar rearing. *
Pébrine Pébrine, or "pepper disease," is a disease of silkworms, which is caused by protozoan microsporidian parasites, mainly '' Nosema bombycis'' and, to a lesser extent, '' Vairimorpha'', '' Pleistophora'' and '' Thelohania'' species. The parasites i ...
is a disease caused by a parasitic microsporidian, ''
Nosema bombycis Nosema bombycis is a species of Microsporidia of the genus '' Nosema'' infecting silkworms, responsible for pébrine. This species was the first microsporidium described, when pebrine decimated silkworms in farms in the mid-19th century. This des ...
''. Diseased larvae show slow growth, undersized, pale and flaccid bodies, and poor appetite. Tiny black spots appear on larval integument. Additionally, dead larvae remain rubbery and do not undergo putrefaction after death. ''N. bombycis'' kills 100% of silkworms hatched from infected eggs. This disease can be carried over from worms to moths, then to eggs and worms again. This microsporidium comes from the food that the silkworms eat. Female moths pass the disease to the eggs, and 100% of silkworms hatching from the diseased eggs will die in their worm stage. To prevent this disease, it is extremely important to rule out all eggs from infected moths by checking the moth's body fluid under a microscope. *
Flacherie Flacherie (literally: "flaccidness") is a disease of silkworms, caused by silkworms eating infected or contaminated mulberry leaves. Flacherie infected silkworms look weak and can die from this disease. Silkworm larvae that are about to die from ...
infected silkworms look weak and are colored dark brown before they die. The disease destroys the larva's gut and is caused by viruses or poisonous food. *Several diseases caused by a variety of funguses are collectively named
Muscardine Muscardine is a disease of insects. It is caused by many species of entomopathogenic fungus. Many muscardines are known for affecting silkworms.Singh, T. ''Principles And Techniques Of Silkworm Seed Production''. Discovery Publishing House. 2004. ...
.


See also

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Cocoonase Cocoonase is a trypsin-like proteolytic enzyme produced by silkworms (of both ''Bombyx'' and ''Antheraea'' species) as they near the final stages of their metamorphosis. It is produced by cells in the proboscis and exuded onto the galeae. Its f ...
*
History of silk The production of silk originated in Neolithic China within the Yangshao culture (4th millennium BCE). Though it would later reach other places in the world, the art of silk production remained confined to China until the Silk Road opened at 114 B ...
*
Silk Road The Silk Road () was a network of Eurasian trade routes active from the second century BCE until the mid-15th century. Spanning over 6,400 kilometers (4,000 miles), it played a central role in facilitating economic, cultural, political, and reli ...
*
List of animals that produce silk Silk is produced by a variety of animals, for different purposes, with various types being produced. Insects *Silkworms produce silk when undergoing larval to adult metamorphosis. This includes not only the domesticated ''Bombyx mori'', but a wide ...
* ''
Samia cynthia ''Samia cynthia'', the ailanthus silkmoth, is a saturniid moth, used to produce silk fabric but not as domesticated as the silkworm, ''Bombyx mori''. The moth has very large wings of , with a quarter-moon shaped spot on both the upper and lower ...
'' *
Thai silk Thai silk ( th, ผ้าไหมไทย, , ) is produced from the cocoons of Thai silkworms. Thailand's silkworm farmers cultivate both types of the domesticated silkworms that produce commercial silk: ''Samia ricini'', commonly known as the ...
* Lao silk *
Japanese silk Japanese silk is silk harvested in Japan. Archaeological evidence indicates that sericulture has been practiced since the Yayoi period. The silk industry was dominant from the 1930s to 1950s, but is less common now. History Silk from East Asia h ...
*
List of domesticated animals This page gives a list of domesticated animals, also including a list of animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includ ...


References


Further reading

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External links


Student page on silkworm




* ttps://web.archive.org/web/20070626074209/http://morus.ab.a.u-tokyo.ac.jp/ SilkBase Silkworm full length cDNA Database
Silk worm Life cycle photos

Silkworm School Science Project Instruction

Life Cycle Of A Silkworm
1943 article with first photographic study of subject {{DEFAULTSORT:Bombyx Mori Moths described in 1758 Bombycidae Domesticated animals Edible insects Moths of Asia Moths of Japan Moths of Africa Moths of North America Silk Sericulture Traditional Chinese medicine Moths of New Zealand Insects of Turkey Taxa named by Carl Linnaeus Insects in culture Animal models