Editing Bombyx mori

{{Short description|Moth mainly used in the production of silk}}
{{Redirect|Silkworm|other uses|Silkworm (disambiguation)}}
{{Use dmy dates|date=December 2020}}
{{Speciesbox
| image = Pairedmoths.jpg
| image_caption = Paired male (above) and female (below)
| image2 = Silkworms3000px.jpg
| image2_caption = Fifth [[instar]]
| image2_alt = Fifth [[instar]] worm
| status = DOM
| taxon = Bombyx mori
| authority = ([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])
| synonyms =
* ''Phalaena mori'' Linnaeus, 1758
* ''Bombyx arracanensis'' Moore & Hutton, 1862
* ''Bombyx brunnea'' Grünberg, 1911
* ''Bombyx croesi'' Moore & Hutton, 1862
* ''Bombyx fortunatus'' Moore & Hutton, 1862
* ''Bombyx meridionalis'' Wood-Mason, 1886
* ''Bombyx sinensis'' Moore & Hutton, 1862
* ''Bombyx textor'' Moore & Hutton, 1862
}}
'''''Bombyx mori''''', commonly known as the '''domestic silk moth''', is a [[moth]] species belonging to the [[family (biology)|family]] [[Bombycidae]]. It is the closest relative of ''[[Bombyx mandarina]]'', the wild [[silk]] moth. '''Silkworms''' are the [[larva]]e of silk moths. The silkworm is of particular economic value, being a primary producer of silk. The silkworm's preferred food are the [[leaves]] of [[white mulberry]], though they may eat other species of mulberry, and even leaves of other plants like the [[Osage orange]]. Domestic silk moths are entirely dependent on humans for reproduction, as a result of millennia of selective breeding. Wild silk moths, which are other species of ''Bombyx'', are not as commercially viable in the production of silk.

[[Sericulture]], the practice of breeding silkworms for the production of raw silk, has existed for at least 5,000 years in China,<ref>{{cite book |title=Prehistoric Textiles: the Development of Cloth in the Neolithic and Bronze Ages with Special Reference to the Aegean |last=Barber |first=E. J. W. |year=1992 |publisher=[[Princeton University Press]] |isbn=978-0-691-00224-8 |page=31 |url=https://books.google.com/books?id=HnSlynSfeEIC&pg=PA31}}</ref> whence it spread to India, Korea, Nepal, Japan, and then the West. The conventional process of sericulture kills the silkworm in the pupal stage.<ref>Sh. S.D. Pateriya. "Introduction to Sericulture". https://www.ignfa.gov.in/document/biodiversity-cell-ntfp-related-issues4.pdf</ref> The domestic silk moth was domesticated from the wild silk moth ''[[Bombyx mandarina]]'', which has a range from northern India to northern China, Korea, Japan, and the far eastern regions of Russia. The domestic silk moth derives from Chinese rather than Japanese or Korean stock.<ref>{{cite journal |author1=K. P. Arunkumar |author2=Muralidhar Metta |author3=J. Nagaraju |year=2006 |title=Molecular phylogeny of silkmoths reveals the origin of domesticated silkmoth, ''Bombyx mori'' from Chinese ''Bombyx mandarina'' and paternal inheritance of ''Antheraea proylei'' mitochondrial DNA |journal=[[Molecular Phylogenetics and Evolution]] |volume=40 |issue=2 |pages=419–427 |doi=10.1016/j.ympev.2006.02.023 |pmid=16644243 |bibcode=2006MolPE..40..419A |url=http://repository.ias.ac.in/24304/1/313.pdf }}</ref><ref name="Maekawa et al 1988">{{cite journal |author1=Hideaki Maekawa |author2=Naoko Takada |author3=Kenichi Mikitani |author4=Teru Ogura |author5=Naoko Miyajima |author6=Haruhiko Fujiwara |author7=Masahiko Kobayashi |author8=Osamu Ninaki |display-authors=3 |year=1988 |title=Nucleolus organizers in the wild silkworm ''Bombyx mandarina'' and the domesticated silkworm ''B. mori'' |journal=[[Chromosoma]] |volume=96 |issue=4 |pages=263–269 |doi=10.1007/BF00286912|s2cid=12870165 }}</ref>

Silk moths were unlikely to have been domestically bred before the [[Neolithic]] period. Before then, the tools to manufacture quantities of silk thread had not been developed. The domesticated ''Bombyx mori'' and the wild ''Bombyx mandarina'' can still breed and sometimes produce hybrids.<ref>{{Cite book |last=Hall |first=Brian K.  |url=https://books.google.com/books?id=V24EHUgEl5EC&pg=PA342 |title=Evolution: Principles and Processes |publisher=Jones & Bartlett |year=2010 |isbn=978-0-763-76039-7 |page=400}}</ref>{{rp|342}} It is unknown if ''B. mori'' can hybridize with other ''Bombyx'' species. Compared to most members in the genus ''Bombyx'', domestic silk moths have lost their [[Animal coloration|coloration]] as well as their ability to fly.<ref>{{Cite web|url=https://phys.org/news/2013-11-captive-thousands-years-impaired-olfactory.html|title=Captive breeding for thousands of years has impaired olfactory functions in silkmoths}}</ref>

== Types ==
Mulberry silkworms can be divided into three major categories based on seasonal brood frequency. Univoltine silkworms produce only one brood a season, and they are generally found in and around Europe. Univoltine eggs must hibernate through the winter, ultimately cross-fertilizing in spring. Bivoltine varieties are normally found in East Asia, and their accelerated breeding process is made possible by slightly warmer climates. In addition, there are polyvoltine silkworms found only in the tropics. Their eggs typically hatch within 9 to 12 days, meaning there can be up to eight generations of larvae throughout the year.<ref>{{cite web|last=Trevisan|first=Adrian|title=Cocoon Silk: A Natural Silk Architecture|url=http://www.senature.com/research/publications/cocoon-silk-a-natural-architecture|publisher=Sense of Nature|url-status=dead|archive-url=https://web.archive.org/web/20120507085636/http://www.senature.com/research/publications/cocoon-silk-a-natural-architecture|archive-date=7 May 2012}}</ref>

== Description and life cycle ==

=== Larvae ===
Eggs take about 14 days to hatch into larvae, which eat continuously. They have a preference for [[Morus alba|white mulberry]], having an attraction to the mulberry odorant [[Jasmone|cis-jasmone]]. They are not [[monophagous]], since they can eat other species of ''[[Morus (plant)|Morus]]'', as well as some other [[Moraceae]], mostly [[Osage orange]]. They are covered with tiny black hairs. When the color of their heads turns darker, it indicates they are about to [[Ecdysis|molt]]. After molting, the larval phase of the silkworms emerge white, naked, and with little horns on their backs.

=== Pupae (cocoon) ===
After they have molted four times, their bodies become slightly yellow, and the skin becomes tighter. The larvae then prepare to enter the pupal phase of their life cycle, and enclose themselves in a cocoon made up of raw silk produced by the [[salivary gland]]s. The final molt from larva to pupa takes place within the cocoon, which provides a layer of protection during the vulnerable, almost motionless pupal state. Many other [[Lepidoptera]] produce cocoons, but only a few&nbsp;— the Bombycidae, in particular the genus ''Bombyx'', and the [[Saturniidae]], in particular the genus ''[[Antheraea]]''&nbsp;— have been exploited for fabric production.

The cocoon is made of a thread of raw silk from {{convert|300|to about|900|m|ft|sigfig=1}} long. The fibers are fine and lustrous, about 10&nbsp;μm in diameter. The number of cocoons required to produce a final yield of silk is approximately {{convert|2000-3000|/lb|/kg|sigfig=1|order=flip}}; at least {{convert|70|e6lb|e6kg|order=flip|abbr=off}} of raw silk are produced each year, requiring nearly 10 billion cocoons.<ref>{{cite web|url=http://faostat.fao.org/site/603/DesktopDefault.aspx?PageID=603#ancor|title=faostat.fao.org}}</ref>{{Better source needed|reason=FAO link is vague|date=July 2023}}

If the animal survives through the pupal phase of its life cycle, it releases [[Protease|proteolytic enzymes]] 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 reduces the value of the silk [[Yarn|threads]], although these damaged silk cocoons are still used as "stuffing" available in China and elsewhere in the production of [[duvet]]s, jackets, and other purposes. To prevent this, silkworm cocoons are boiled in water. The heat kills the silkworms, and the water makes the cocoons easier to unravel. Often, the silkworm is eaten.

As the process of harvesting the silk from the cocoon kills the pupa, sericulture has been criticized by animal welfare and rights activists. [[Mahatma Gandhi]] was critical of silk production based on the ''[[ahimsa]]'' 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,<ref>{{cite book |editor=S. Radhakrishnan |title=Mahatma Gandhi: 100 Years |date=1968-01-01 |isbn=071892035X |page=349 |url=https://books.google.com/books?id=LGVuAAAAMAA |accessdate=2025-04-18}}</ref> and an extension of this principle has led to the modern production practice known as [[Ahimsa silk]], which is [[wild silk]] (from wild and semiwild silk moths) made from the cocoons of moths that are allowed to emerge before the silk is harvested.

=== Moth ===
The moth is the adult phase of the silk worm's life cycle. Silk moths have a wingspan of {{convert|3|–|5|cm|in|frac=2|abbr=on}} and a white, hairy body. Females are about two to three times bulkier than males (due to carrying many eggs). All adult [[Bombycidae]] moths have reduced mouthparts and do not feed.

The wings of the silk moth develop from larval [[Imaginal disc|imaginal disks]].<ref name="Singh 169–176">{{Cite journal |last1=Singh |first1=Amit |last2=Kango-Singh |first2=Madhuri |last3=Parthasarathy |first3=R. |last4=Gopinathan |first4=K. P. |date=April 2007 |title=Larval legs of mulberry silkworm Bombyx mori are prototypes for the adult legs |url=https://pubmed.ncbi.nlm.nih.gov/17417803/ |journal=Genesis |volume=45 |issue=4 |pages=169–176 |doi=10.1002/dvg.20280 |issn=1526-954X |pmid=17417803|s2cid=7171141 }}</ref> The moth is not capable of functional flight, in contrast to the wild ''B. mandarina'' and other ''Bombyx'' species, whose males fly to meet females. Some may emerge with the ability to lift off and stay airborne, but sustained flight cannot be achieved as their bodies are too big and heavy for their small wings. 
[[File:Bombyx mori caterpillar tagged2.png|thumb|2- thoracic legs.]]
[[File:CSIRO ScienceImage 10746 An adult silkworm moth.jpg|thumb|left|Adult silk moth]]

The legs of the silk moth develop from the silkworm's larval (thoracic) legs. Developmental genes like Distalless and [[PBX1|extradenticle]] have been used to mark leg development. In addition, removing specific segments of the thoracic legs at different ages of the larva resulted in the adult silk moth not developing the corresponding adult leg segments.<ref name="Singh 169–176"/>[[File:Cocoon.jpg|thumb|right|Cocoon of ''B. mori'']]

== Research ==
[[File:Micrographia Schem 25 fig 2.jpg|thumb|A study of an egg of a silkworm from Hooke's ''[[Micrographia]]'', 1665]]
[[File:Maria_Sibylla_Merian_Maulbeerbaum_samt_Frucht_plate_1.png|thumb|right|1679 study of the silkworm metamorphosis by [[Maria Sibylla Merian]], it depicts the fruit and leaves of a [[mulberry]] tree and the eggs and larvae of the silkworm moth.]]
Due to its small size and ease of culture, the silkworm has become a [[model organism]] in the study of lepidopteran and general arthropod biology. Fundamental findings on genetics, pheromones, hormones, brain structures, and physiology have been made with the silkworm.<ref>{{Cite journal |last=Onaga |first=Lisa |date=2010-03-11 |orig-date= |title=Toyama Kametaro and Vernon Kellogg: Silkworm Inheritance Experiments in Japan, Siam, and the United States, 1900–1912 |url=http://link.springer.com/10.1007/s10739-010-9222-z |journal=Journal of the History of Biology |language=en |volume=43 |issue=2 |pages=215–264 |doi=10.1007/s10739-010-9222-z |pmid=20665229 |issn=0022-5010}}</ref>{{Citation needed|date=November 2010}} One example of this was the molecular identification of the first known pheromone, [[bombykol]], which required extracts from 500,000 individuals, due to the small quantities of pheromone produced by any individual silkworm.{{Citation needed|date=November 2010}}

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 inheritance|Mendelian mutation]]s have been described.<ref name=Goldsmith1>{{cite journal |last1=Goldsmith |first1=Marian R. |last2=Shimada |first2=Toru |last3=Abe |first3=Hiroaki |date=2005 |title=The genetics and genomics of the silkworm, Bombyx mori |journal=Annual Review of Entomology |volume=50 |issue=1 |pages=71–100|doi=10.1146/annurev.ento.50.071803.130456 |pmid=15355234 |s2cid=44514698 |url=https://digitalcommons.uri.edu/bio_facpubs/337 }}</ref> Another source suggests 1,000 inbred domesticated strains are kept worldwide.<ref name="silkworm08"/> One useful development for the silk industry is silkworms that can feed on food other than mulberry leaves, including an artificial diet.<ref name=Goldsmith1 /> 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]] (and not crossovers) during [[meiosis]].<ref>{{cite journal|last1=Gerton and Hawley|title=Homologous Chromosome Interactions in Meiosis: Diversity Amidst Conservation|journal=Nature Reviews Genetics|date=2005|volume=6|issue=6|pages=477–487|doi=10.1038/nrg1614|pmid=15931171|s2cid=31929047}}</ref>  In the oocytes of ''B. mori'', meiosis is completely [[chiasma (genetics)|achiasmate]] (lacking crossovers).<ref>{{cite journal |vauthors=Xiang Y, Tsuchiya D, Guo F, Gardner J, McCroskey S, Price A, Tromer EC, Walters JR, Lake CM, Hawley RS |title=A molecular cell biology toolkit for the study of meiosis in the silkworm Bombyx mori |journal=G3 (Bethesda) |volume=13 |issue=5 |pages= |date=May 2023 |pmid=36911915 |pmc=10151401 |doi=10.1093/g3journal/jkad058 |url=}}</ref> Even though [[synaptonemal complex]]es are formed during the [[pachytene]] stage of meiosis in ''B. mori'', crossing-over [[homologous recombination]] does not occur between the paired [[chromosome]]s.<ref>{{cite journal |vauthors=Rasmussen SW |title=The transformation of the Synaptonemal Complex into the 'elimination chromatin' in Bombyx mori oocytes |journal=Chromosoma |volume=60 |issue=3 |pages=205–21 |date=April 1977 |pmid=870294 |doi=10.1007/BF00329771 |url=}}</ref>

[[Kraig Biocraft Laboratories]]<ref>{{cite web|title=Kraig Biocraft Laboratories|date=13 October 2014|url=http://www.kraiglabs.com/spider-silk/}}</ref>
has used research from the [[University of Wyoming|Universities of Wyoming]] and [[University of Notre Dame|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.<ref>{{cite web|title=University of Notre Dame|date=6 January 2012 |url=http://science.nd.edu/news/34100-hybrid-silkworms-spin-stronger-spider-silk/}}</ref>

Researchers at [[Tufts Medical Center|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.<ref>{{cite web|author=Wolchover, Natalie|title=The Silk Renaissance |publisher=Seed Magazine |url=http://seedmagazine.com/content/article/the_silk_renaissance/|access-date=1 May 2012|archive-url=https://web.archive.org/web/20170326051023/http://seedmagazine.com/content/article/the_silk_renaissance|archive-date=26 March 2017|url-status=unfit}}</ref>

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 silkworms would connect neighboring lines with silk, weaving directly onto the given shape. Using this knowledge they built a [[Neri Oxman#Silk Pavilion|silk pavilion]] with 6,500 silkworms over a number of days.

Silkworms have been used in antibiotic discovery, as they have several advantageous traits compared to other invertebrate models.<ref>{{cite journal | last1 = Panthee | first1 = S. | last2 = Paudel | first2 = A. | last3 = Hamamoto | first3 = H. | last4 = Sekimizu | first4 = K. | year = 2017 | title = Advantages of the silkworm as an animal model for developing novel antimicrobial agents | journal = Front Microbiol | volume = 8 | page = 373 | doi = 10.3389/fmicb.2017.00373 | pmid = 28326075 | pmc = 5339274 | doi-access = free }}</ref> Antibiotics such as [[lysocin E]],<ref>{{cite journal | last1 = Hamamoto | first1 = H. | last2 = Urai | first2 = M. | last3 = Ishii | first3 = K. | last4 = Yasukawa | first4 = J. | last5 = Paudel | first5 = A. | last6 = Murai | first6 = M. | last7 = Kaji | first7 = T. | last8 = Kuranaga | first8 = T. | last9 = Hamase | first9 = K. | last10 = Katsu | first10 = T. | last11 = Su | first11 = J. | last12 = Adachi | first12 = T. | last13 = Uchida | first13 = R. | last14 = Tomoda | first14 = H. | last15 = Yamada | first15 = M. | last16 = Souma | first16 = M. | last17 = Kurihara | first17 = H. | last18 = Inoue | first18 = M. | last19 = Sekimizu | first19 = K. |display-authors=3| year = 2015 | title = Lysocin E is a new antibiotic that targets menaquinone in the bacterial membrane. Nat | journal = Chem. Biol. | volume = 11 | issue = 2| pages = 127–133 | doi = 10.1038/nchembio.1710 | pmid = 25485686 }}</ref> a non-ribosomal peptide synthesized by ''Lysobacter'' sp. RH2180-5<ref>{{cite journal | last1 = Panthee | first1 = S. | last2 = Hamamoto | first2 = H. | last3 = Suzuki | first3 = Y. | last4 = Sekimizu | first4 = K. | year = 2017 | title = In silico identification of lysocin biosynthetic gene cluster from Lysobacter sp. RH2180-5 | journal = J. Antibiot. | volume = 70 | issue = 2| pages = 204–207 | doi = 10.1038/ja.2016.102 | pmid = 27553855 | s2cid = 40912719 }}</ref> and GPI0363<ref>{{cite journal | last1 = Paudel | first1 = A. | last2 = Hamamoto | first2 = H. | last3 = Panthee | first3 = S. | last4 = Kaneko | first4 = K. | last5 = Matsunaga | first5 = S. | last6 = Kanai | first6 = M. | last7 = Suzuki | first7 = Y. | last8 = Sekimizu | first8 = K. |display-authors=3| year = 2017 | title = A novel spiro-heterocyclic compound identified by the silkworm infection model inhibits transcription in ''Staphylococcus aureus'' | journal = Front Microbiol | volume = 8 | page = 712 | doi = 10.3389/fmicb.2017.00712 | pmid = 28487682 | pmc = 5403886 | doi-access = free }}</ref> 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.<ref>{{cite journal | last1 = Paudel | first1 = A. | last2 = Panthee | first2 = S. | last3 = Makoto | first3 = U. | last4 = Hamamoto | first4 = H. | last5 = Ohwada | first5 = T. | last6 = Sekimizu | first6 = K. |display-authors=3|year = 2018 | title = Pharmacokinetic parameters explain the therapeutic activity of antimicrobial agents in a silkworm infection model. | journal = Sci. Rep. | volume = 8 | issue = 1 | pages = 1578 | doi = 10.1038/s41598-018-19867-0 | pmid = 29371643 | pmc = 5785531 | bibcode = 2018NatSR...8.1578P | s2cid = 3328235 }}</ref>

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''.<ref>{{cite journal | last1 = Paudel | first1 = A. | last2 = Hamamoto | first2 = H. | last3 = Panthee | first3 = S. | last4 = Matsumoto | first4 = Y. | last5 = Sekimizu | first5 = K. |display-authors=3 |year = 2020 | title = Large-Scale Screening and Identification of Novel Pathogenic Staphylococcus aureus Genes Using a Silkworm Infection Model. | journal = J. Infect. Dis. | volume = 221 | issue = 11 | pages = 1795–1804 | doi = 10.1093/infdis/jiaa004 | pmid = 31912866}}</ref> 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.<ref>{{cite journal | last1 = Paudel | first1 = A. | last2 = Panthee | first2 = S. | last3 = Hamamoto | first3 = H. | last4 = Grunert | first4 = T. | last5 = Sekimizu | first5 = K. |year = 2021 | title = YjbH regulates virulence genes expression and oxidative stress resistance in Staphylococcus aureus. | journal = Virulence | volume = 12 | issue = 1 | pages = 470–480 | doi = 10.1080/21505594.2021.1875683 |issn=2150-5594| pmid = 33487122| pmc = 7849776 | doi-access = free }}</ref>

== Domestication ==
[[File:Han Gold Silkworm (47425344012).jpg|thumb|left|Gold silkworm, [[Han dynasty]]]]
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 [[leucism|leucistic]], 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.<ref>{{cite journal |author=Marian R. Goldsmith |author2=Toru Shimada |author3=Hiroaki Abe |year=2005 |title=The genetics and genomics of the silkworm, ''Bombyx mori'' |journal=[[Annual Review of Entomology]] |volume=50 |pages=71–100 |pmid=15355234 |doi=10.1146/annurev.ento.50.071803.130456|s2cid=44514698 |url=https://digitalcommons.uri.edu/bio_facpubs/337 }}</ref> The eggs are kept in [[Incubator (egg)|incubators]] to aid in their hatching.

=== Breeding ===

[[File:Women placing silkworms on trays together with mulberry leaves (Sericulture by Liang Kai, 1200s).jpg|thumb|Silkworms and mulberry leaves placed on trays ([[Liang Kai]]'s ''Sericulture'' c. 13th century)]]

Silkworms were first domesticated in China more than 5,000 years ago.<ref>{{cite journal |author=Hong-Song Yu1 |author2=Yi-Hong Shen |author3=Gang-Xiang Yuan|display-authors=et al |title=Evidence of selection at melanin synthesis pathway loci during silkworm domestication |journal=Molecular Biology and Evolution |volume=28 |issue=6 |pages=1785–99 |year=2011 |pmid =21212153 |doi=10.1093/molbev/msr002 |doi-access= }}</ref><ref>{{cite journal |author=Dennis Normile |title=Sequencing 40 Silkworm Genomes Unravels History of Cultivation |journal=Science |volume=325 |issue=5944 |pages=1058–1059 |year=2009 |pmid=19713499 |doi=10.1126/science.325_1058a |bibcode = 2009Sci...325.1058N |doi-access=free }}</ref>

[[File:Pupa of Silk worm nepal.jpg|thumb|left|Pupae]]

[[File:Weighing and sorting the cocoons (Sericulture by Liang Kai, 1200s).jpg|thumb|right|Silkworm cocoons weighed and sorted (Liang Kai's ''Sericulture'')]]

Silkworm breeding is aimed at the overall improvement of silkworms from a commercial point of view. The major objectives are improving [[fecundity]], 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 rate, fewer dead larvae in the mountage,<ref>{{cite web|title=Mountage: Meaning and Types {{!}} Sericulture|url=http://www.notesonzoology.com/sericulture/mountage-meaning-and-types-sericulture/200|website=Zoology Notes|date=21 July 2016}}</ref> 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.<ref>{{Cite web |title=Bombyx mori (Linnaeus, 1758) |url=https://www.gbif.org/species/112871225/verbatim |access-date=2025-04-06 |website=www.gbif.org |language=en}}</ref> Other than the U.S.,  this domestic silk moth is utilized in educational settings in several countries, including China, South Africa, Zimbabwe, Iran, and Taiwan.<ref>{{Cite web |date=2018-05-13 |title=Researchers develop silkworm for children to raise - Taipei Times |url=https://www.taipeitimes.com/News/taiwan/archives/2018/05/13/2003693004?utm |access-date=2025-04-06 |website=www.taipeitimes.com}}</ref>

== Genome ==
The full [[genome]] of the domestic silk moth was published in 2008 by the International Silkworm Genome Consortium.<ref name="silkworm08">{{cite journal |author=The International Silkworm Genome Consortium |year=2008 |title=The genome of a lepidopteran model insect, the silkworm ''Bombyx mori'' |journal=Insect Biochemistry and Molecular Biology |volume=38 |issue=12 |pages=1036–1045 |doi=10.1016/j.ibmb.2008.11.004 |pmid=19121390|bibcode=2008IBMB...38.1036T }}</ref> Draft sequences were published in 2004.<ref>{{cite journal |author1=Kazuei Mita |author2=Masahiro Kasahara |author3=Shin Sasaki |display-authors=et al |year=2004 |title=The genome sequence of silkworm, ''Bombyx mori'' |journal=[[DNA Research]] |volume=11 |issue=1 |pages=27–35 |pmid=15141943 |doi=10.1093/dnares/11.1.27|doi-access=free }}</ref><ref>{{cite journal |author=Xia Q |author2=Zhou Z |author3=Lu C|s2cid=7227719 |display-authors=et al |name-list-style=amp |year=2004 |title=A draft sequence for the genome of the domesticated silkworm (Bombyx mori) |journal=[[Science (journal)|Science]] |volume=306 |issue=5703 |pages=1937–40 |pmid=15591204 |doi=10.1126/science.1102210|bibcode = 2004Sci...306.1937X }}</ref>

The genome of the domestic silk moth is mid-range with a [[genome size]] around 432 million base pairs. A notable feature is that 43.6% of the genome are [[Repeated sequence (DNA)|repetitive sequences]], most of which are transposable elements. At least 3,000 silkworm genes are unique, and have no homologous equivalents in other genomes. The silkworm's ability to produce large amounts of silk correlates with the presence of specific tRNA clusters, as well as some clustered [[sericin]] genes. Additionally, the silkworm's ability to consume toxic mulberry leaves is linked to specialized sucrase genes, which appear to have been acquired from bacterial genes.<ref name="silkworm08" />

In 2018, [[Illumina, Inc.|Illumina]]'s short reads for 137 strain genomes were published.<ref>{{Cite journal |last1=Xiang |first1=Hui |last2=Liu |first2=Xiaojing |last3=Li |first3=Muwang |last4=Zhu |first4=Ya’nan |last5=Wang |first5=Lizhi |last6=Cui |first6=Yong |last7=Liu |first7=Liyuan |last8=Fang |first8=Gangqi |last9=Qian |first9=Heying |last10=Xu |first10=Anying |last11=Wang |first11=Wen |last12=Zhan |first12=Shuai |date=2018-07-02 |title=The evolutionary road from wild moth to domestic silkworm |url=https://www.nature.com/articles/s41559-018-0593-4 |journal=Nature Ecology & Evolution |language=en |volume=2 |issue=8 |pages=1268–1279 |doi=10.1038/s41559-018-0593-4 |pmid=29967484 |bibcode=2018NatEE...2.1268X |issn=2397-334X}}</ref> In 2022, [[Oxford Nanopore Technologies|Nanopore]]'s long reads for 545 strain genomes were published.<ref>{{Cite journal |last1=Tong |first1=Xiaoling |last2=Han |first2=Min-Jin |last3=Lu |first3=Kunpeng |last4=Tai |first4=Shuaishuai |last5=Liang |first5=Shubo |last6=Liu |first6=Yucheng |last7=Hu |first7=Hai |last8=Shen |first8=Jianghong |last9=Long |first9=Anxing |last10=Zhan |first10=Chengyu |last11=Ding |first11=Xin |last12=Liu |first12=Shuo |last13=Gao |first13=Qiang |last14=Zhang |first14=Bili |last15=Zhou |first15=Linli |date=2022-09-24 |title=High-resolution silkworm pan-genome provides genetic insights into artificial selection and ecological adaptation |journal=Nature Communications |language=en |volume=13 |issue=1 |page=5619 |doi=10.1038/s41467-022-33366-x |issn=2041-1723 |pmc=9509368 |pmid=36153338|bibcode=2022NatCo..13.5619T }}</ref>

== As food ==
[[File:Silkworm pupae to eat.jpg|thumb|Silkworm pupae dishes]] 
Silk moth pupae are [[edible insects]] and are [[Entomophagy|eaten in some cultures]]:
* In [[Assam, India]], 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.  Live pupae may be eaten raw, boiled or fried.<ref>{{Cite news |last=Akhtar |first=M. |date=16 July 2020 |title=In India's Northeast, a Rich Tradition of Insect Foods |url=https://science.thewire.in/environment/assam-entomophagy-silkworms-proteins-silk/ |access-date=30 October 2024 |work=[[The Wire (India)]]}}</ref>
* In [[Korea]], they are boiled and seasoned to make a popular snack food known as ''[[beondegi]]'' (번데기).<ref>{{Cite web |title=Have You Tried Steamed Silkworm Pupae? |url=https://www.atlasobscura.com/foods/beondegi-silkworm-pupae-korea |access-date=2022-08-06 |website=Atlas Obscura |language=en}}</ref>
* In [[China]], street vendors sell roasted silk moth pupae.
* In [[Japan]], silkworms are usually served as a ''[[tsukudani]]'' (佃煮), i.e., boiled in a sweet-sour sauce made with [[soy sauce]] and sugar.
* In [[Vietnam]], this is known as ''{{lang|vi|nhộng tằm}}'', usually boiled, seasoned with fish sauce, then stir-fried and eaten as main dish with rice.
* In [[Thailand]], 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]] on long-term missions.<ref>{{cite news |url=http://news.sciencemag.org/sciencenow/2009/01/13-02.html |title=Care for a Silkworm With Your Tang? |last=Choi |first=Charles Q. |date=13 January 2009 |work=ScienceNOW Daily News |access-date=14 January 2009 |url-status=dead |archive-url=https://web.archive.org/web/20110225234236/http://news.sciencemag.org/sciencenow/2009/01/13-02.html |archive-date=25 February 2011}}</ref>

== In culture ==
=== China ===
{{See also|Horse in Chinese mythology#Origins of sericulture}}
In China, a legend indicates the discovery of the silkworm's silk was by an ancient empress named [[Leizu]], the wife of the [[Yellow Emperor]], 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 [[Kingdom of Khotan|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 AD.<ref>Sarah Underhill Wisseman, Wendell S. Williams. ''Ancient Technologies and Archaeological Materials ''. Routledge, 1994. {{ISBN|2-88124-632-X}}. Page 131.</ref> About AD 550, Christian monks are said to have [[Smuggling of silkworm eggs into the Byzantine Empire|smuggled]] silkworms hidden in a hollow stick out of China, selling the secret to the eastern Romans.

=== 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 was 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]], 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.{{citation needed|date=September 2022}}

== Feeding ==
''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.<ref>Hamed Kioumarsi, Nazanin Amani ''Silkworm/''Bombyx mori'': An Overview of What You Need to Know ''. AREEO, 2021. {{ISBN|978-600-91994-0-2}}. Page 27.</ref> 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

== Diseases ==
*''[[Beauveria bassiana]]'', 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.
*[[Nuclear Polyhedrosis Virus|Grasserie]], also known as nuclear polyhedrosis, milky disease, or hanging disease, is caused by infection with the ''Bombyx mori nucleopolyhedrovirus''<!--ICTV MSL 2018b.v2--> (aka ''Bombyx mori nuclear polyhedrosis virus'', genus ''[[Alphabaculovirus]]''). 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]] is a disease caused by a parasitic microsporidian, ''[[Nosema bombycis]]''. 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 die in their worm stage. To prevent this disease, eggs from infected moths are ruled out by checking the moth's body fluid under a microscope.
*[[Flacherie]] 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]].

== See also ==
* [[Cocoonase]]
* [[History of silk]]
* [[Silk Road]]
* [[List of animals that produce silk]]
* ''[[Samia cynthia]]''
* [[Thai silk]]
* [[Lao silk]]
* [[Japanese silk]]
* [[List of domesticated animals]]

== References ==
{{Reflist}}

== Further reading ==
* {{cite book |url=https://books.google.com/books?id=_4waAAAAYAAJ&pg=PA1 |title=The culture of the mulberry silkworm |first1=Henrietta Aiken |last1=Kelly |place=Washington DC |publisher=[[U.S. Department of Agriculture]], [[United States Government Publishing Office|Government Printing Office]] |year=1903 |access-date=17 January 2012}}
* {{cite book |last1=Grimaldi |last2=Engel |first1=David A. |first2=Michael S. |author-link1=David A. Grimaldi |author-link2=Michael S. Engel |year=2005 |title=Evolution of the Insects |publisher=[[Cambridge University Press]] |isbn=978-0-521-82149-0}}
* {{cite book |last=Johnson |first=Sylvia |year=1989 |title=Silkworms |publisher=[[Lerner Publications]] |isbn=978-0-8225-9557-1 |url-access=registration |url=https://archive.org/details/silkworms00john }}
* {{cite book |last=Scoble |first=M. J. |year=1995 |title=The Lepidoptera: Form, Function and Diversity |publisher=[[Princeton University Press]] |isbn=978-0-19-854952-9}}
* {{cite journal |author=Yoshitake, N. |year=1968 |title=Phylogenetic aspects on the origin of Japanese race of the silkworm, ''Bombyx mori'' L. |journal=Journal of Sericological Sciences of Japan |volume=37 |pages=83–87}}
* {{cite web|last=Trevisan|first=Adrian|title=Cocoon Silk: A Natural Silk Architecture|url=http://www.senature.com/research/publications/cocoon-silk-a-natural-architecture|publisher=Sense of Nature|url-status=dead|archive-url=https://web.archive.org/web/20120507085636/http://www.senature.com/research/publications/cocoon-silk-a-natural-architecture|archive-date=7 May 2012}}

== External links ==
{{Commons category|Bombyx mori}}
* [http://animaldiversity.ummz.umich.edu/site/accounts/information/Bombyx_mori.html Student page on silkworm]
* [https://web.archive.org/web/20060412215344/http://www.wormspit.com/index.htm WormSpit, a site about silkworms, silk moths, and silk]
* [http://www.suekayton.com/silk.htm Information about silkworms for classroom teachers with many photos]
* [https://web.archive.org/web/20070626074209/http://morus.ab.a.u-tokyo.ac.jp/ SilkBase Silkworm full length cDNA Database]
* [https://archive.today/20121108172719/http://picasaweb.google.com/srither240255/CycleOfSilkworm Silk worm Life cycle photos]
* [https://web.archive.org/web/20120314044223/http://www.silkwormeggs.net/resources/Silkworm-School-Science-Project-Instruction.pdf Silkworm School Science Project Instruction]
* [https://books.google.com/books?id=pCcDAAAAMBAJ&pg=PA136 Life Cycle Of A Silkworm] 1943 article with first photographic study of subject

{{Insects in culture}}
{{Silk fibre}}

{{Taxonbar|from=Q134747}}
{{Authority control}}

{{DEFAULTSORT:Bombyx Mori}}
[[Category:Moths described in 1758]]
[[Category:Bombycidae]]
[[Category:Domesticated animals]]
[[Category:Edible insects]]
[[Category:Moths of Asia]]
[[Category:Moths of Japan]]
[[Category:Moths of Africa]]
[[Category:Moths of North America]]
[[Category:Silk]]
[[Category:Sericulture]]
[[Category:Traditional Chinese medicine]]
[[Category:Moths of New Zealand]]
[[Category:Insects of Turkey]]
[[Category:Taxa named by Carl Linnaeus]]
[[Category:Insects in culture]]
[[Category:Animal models]]