''Gonometa postica'' (

Walker Walker or The Walker may refer to: People *Walker (given name) *Walker (surname) *Walker (Brazilian footballer) (born 1982), Brazilian footballer Places In the United States *Walker, Arizona, in Yavapai County *Walker, Mono County, California * ...

, 1855), known commonly as the African wild silk moth, burn worm, and brandwurm,Bause, T
Beautiful silk scarves from a nasty pest.
''The Namibian'' June 24, 2005. is a large species of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

n moth belonging to the family

Lasiocampidae The Lasiocampidae are a family of moths also known as eggars, tent caterpillars, snout moths (although this also refers to the Pyralidae), or lappet moths. Over 2,000 species occur worldwide, and probably not all have been named or studied. It i ...

. The genus ''Gonometa'' boasts some very large moths and larvae; ''

Gonometa sjostedti ''Gonometa'' is a genus of moths in the family Lasiocampidae. The genus was erected by Francis Walker in 1855."''Gonomet ...

'' from Africa has a larva 16 centimeters long, for example. Most of the Lasiocampidae are highly

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

. In ''G. postica'' the forewing of the male measures 21–25 mm and of the female 35–42 mm. ''Gonometa postica'' and ''

Argema mimosae ''Argema mimosae'', the African moon moth, is a giant silk moth of the family Saturniidae. Similar in appearance to the giant Madagascan moon moth ('' Argema mittrei''), but smaller, this moth can be found widely in Eastern Africa and more locall ...

'' cocoons are traditionally used as ankle rattles in southern Africa by San and Bantu tribes. They are filled with materials such as fine gravel, seeds, glass beads, broken sea shells, or pieces of ostrich eggshell. The species has become notable for producing a fine quality

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 independe ...

in its cocoon. The cocoons are harvested commercially in

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

and

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, and the species also occurs in

Zimbabwe file:Zimbabwe, relief map.jpg, upright=1.22, Zimbabwe, relief map Zimbabwe, officially the Republic of Zimbabwe, is a landlocked country in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Bots ...

and

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

. An

Oxford University The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the second-oldest continuously operating u ...

research team found that the cocoon surfaces are covered with

calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula or . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydr ...

, hindering their commercial utilisation. They discovered and patented a method known as demineralizing using a warm solution of

EDTA Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid, is an aminopolycarboxylic acid with the formula . This white, slightly water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-solubl ...

(ethylenediaminetetraacetic acid), softening the cocoons by dissolving the sericin, permitting the silk to be unravelled with no appreciable loss of strength. Cocoons are also sexually dimorphic, with those of females being roughly twice the size of those of males, thus yielding more silk. Sex ratios in natural populations will clearly play a large role in the harvesting of cocoons.Veldtman, R., et al. (2002)
Variability in cocoon size in southern African wild silk moths: implications for sustainable harvesting.
''African Entomology'' 10(1) 127-36. The larvae are quite variable in their patterning and, like many of the genus, are covered in irritating

seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...

e, or hairs. The larva is black with lateral tufts of white, yellow or orange. It has been recorded feeding on ''

Acacia ''Acacia'', commonly known as wattles or acacias, is a genus of about of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa, South America, and Austral ...

'', ''

Brachystegia ''Brachystegia'' is a genus of tree of the subfamily Detarioideae that is native to tropical Africa. Trees of the genus are commonly known as miombo, and are dominant in the miombo woodlands of central and southern tropical Africa. The Zambezia ...

'', '' Elephantorrhiza'', ''

Pinus radiata ''Pinus radiata'' ( syn. ''Pinus insignis''), the Monterey pine, insignis pine or radiata pine, is a species of pine native to the Central Coast of California and Mexico (on Guadalupe Island and Cedros island). It is an evergreen conifer in t ...

'', and '' Julbernardia''. Another silk-producing member of the genus is ''

Gonometa rufobrunnea ''Gonometa'' is a genus of moths in the family Lasiocampidae. The genus was erected by Francis Walker (entomologist), Francis Walker in 1855.

'' ( Aurivillius, 1927), which feeds almost exclusively on '' Colophospermum mopane''.''Gonometa postica'': Kalahari Wild Silk.
Anthropological Entomology: Silk Textiles. Mississippi Entomological Museum.Fening, K. O., et al. (2010)
Effect of seasons and larval food plants on the quality of ''Gonometa postica'' cocoons.
''Phytoparasitica'' 38(2) 111-19. ''G. postica'' larvae and pupae are subject to

parasitism Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...

and

Hymenoptera Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typi ...

, the most common

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

s being '' Palexorista'' species from the

Tachinidae The Tachinidae are a large and variable family of true fly, flies within the insect order Fly, Diptera, with more than 8,200 known species and many more to be discovered. Over 1,300 species have been described in North America alone. Insects in t ...

and ''Goryphus'' species from the

Ichneumonidae The Ichneumonidae, also known as ichneumon wasps, ichneumonid wasps, ichneumonids, or Darwin wasps, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25 ...

.Fening, K. O., et al. (2008)
Parasitoids of the African wild silkmoth, ''Gonometa postica'' (Lepidoptera: Lasiocampidae) in the Mwingi forests, Kenya.
''Journal of Applied Entomology'' 133(6) 411-15. The cocoons have long been known to cause the death of cattle, antelope and other ruminants in the

Kalahari The Kalahari Desert is a large semiarid sandy savanna in Southern Africa covering including much of Botswana as well as parts of Namibia and South Africa. It is not to be confused with the Angolan, Namibian, and South African Namib coastal d ...

. During drought periods, the cocoons are eaten, probably because they resemble acacia pods. The silk is indigestible and blocks the

rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary si ...

of multiple-stomach animals, causing starvation.Bafana, B
Going wild for silk in Zimbabwe.
''New Agriculturist''. May, 2009. In

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

, wild silk has been harvested for centuries, and this expertise has been introduced to southern Africa. A feasibility study was funded by

Oxfam Oxfam is a British-founded confederation of 21 independent non-governmental organizations (NGOs), focusing on the alleviation of global poverty, founded in 1942 and led by Oxfam International. It began as the Oxford Committee for Famine Relief ...

and the Namibian Ministry of Agriculture, and a pilot project was started in Leonardville. A number of other moth species suited to silk harvesting are ''

Attacus atlas ''Attacus atlas'', the Atlas moth, is a large Saturniidae, saturniid moth endemic to the forests of Asia. The species was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, 10th edition of ''Systema Naturae''. The Atlas mo ...

'', ''

Antheraea paphia ''Antheraea paphia'', known as the South India small tussore, the tasar silkworm and vanya silkwormKavane, R. P. (2014)''Syzygium cumini'' L. – A potential new host of tropical tasar silkworm, ''Antheraea mylitta'' Drury (Lepidoptera: Satur ...

'', ''

Antheraea pernyi ''Antheraea pernyi'', the Chinese oak tussar moth, Chinese tasar moth, or temperate tussar moth, is a large moth in the family Saturniidae. The species was first described by Félix Édouard Guérin-Méneville in 1855. '' Antheraea roylei'' is an ...

'', '' Cricula andrei'', and ''

Samia canningi ''Samia canningi'', the wild eri silk moth, is a moth of the family Saturniidae. It is found in south-eastern Asia and China. The wingspan is . The larvae mainly feed on ''Ailanthus altissima'', '' Prunus laurocerasus'', ''Ligustrum'' and ''Syr ...

''. ''Gonometa''

fibroin Fibroin is an insoluble protein present in silk produced by numerous insects, such as the larvae of ''Bombyx mori'', and other moth genera such as ''Antheraea'', ''Cricula trifenestrata, Cricula'', ''Samia (moth), Samia'' and ''Gonometa''. Sil ...

is rich in basic amino acids, making it a potentially useful

biomaterial A biomaterial is a substance that has been Biological engineering, engineered to interact with biological systems for a medical purpose – either a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a Medical diag ...

in cell and tissue culture.Mhuka, V., et al. (2013)
Chemical, structural and thermal properties of ''Gonometa postica'' silk fibroin, a potential biomaterial.
''Int J Biol Macromol.'' 52 305-11.

References

External links

University of Oxford. 20 May 2011.
Setae of Larva.
GEO-Reisecommunity.
Cocoon of ''Gonometa postica'''Nonmulberry silk biopolymers'
{{Taxonbar, from=Q5438065 Gonometa Silk production Moths described in 1855 Moths of Africa