Gonometa postica

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Gonometa postica
Gonometa postica05.jpg
male and female
Scientific classification
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G. postica
Binomial name
Gonometa postica
Walker, 1855
Synonyms
  • Gonometa effusaWalker, 1865
  • Gonometa marginataWalker 1881
Gonometa postica00.jpg
Gonometa postica01.jpg

Gonometa postica (Walker, 1855), known commonly as the African wild silk moth, burn worm, and brandwurm, [1] is a large species of African moth belonging to the family Lasiocampidae. The genus Gonometa boasts some very large moths and larvae; Gonometa sjostedti from Africa has a larva 16 centimeters long, for example. Most of the Lasiocampidae are highly sexually dimorphic. In G. postica the forewing of the male measures 21–25 mm and of the female 35–42 mm.

Gonometa postica and Argema mimosae 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. [2]

The species has become notable for producing a fine quality wild silk in its cocoon. The cocoons are harvested commercially in Namibia, Botswana, Kenya and South Africa, and the species also occurs in Zimbabwe and Mozambique. An Oxford University research team found that the cocoon surfaces are covered with calcium oxalate, hindering their commercial utilisation. They discovered and patented a method known as demineralizing using a warm solution of EDTA (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. [3]

The larvae are quite variable in their patterning and, like many of the genus, are covered in irritating setae, or hairs. The larva is black with lateral tufts of white, yellow or orange. It has been recorded feeding on Acacia , Brachystegia , Elephantorrhiza , Pinus radiata , and Julbernardia . Another silk-producing member of the genus is Gonometa rufobrunnea (Aurivillius, 1927), which feeds almost exclusively on Colophospermum mopane . [4] [5] G. postica larvae and pupae are subject to parasitism by Diptera and Hymenoptera, the most common parasitoids being Palexorista species from the Tachinidae and Goryphus species from the Ichneumonidae. [6]

The cocoons have long been known to cause the death of cattle, antelope and other ruminants in the Kalahari. During drought periods, the cocoons are eaten, probably because they resemble acacia pods. The silk is indigestible and blocks the rumen of multiple-stomach animals, causing starvation. [7]

In Madagascar, wild silk has been harvested for centuries, and this expertise has been introduced to southern Africa. A feasibility study was funded by Oxfam and the Namibian Ministry of Agriculture, and a pilot project was started in Leonardville. [1] A number of other moth species suited to silk harvesting are Attacus atlas , Antheraea paphia , Antheraea pernyi , Cricula andrei , and Samia canningi .

Gonometa fibroin is rich in basic amino acids, making it a potentially useful biomaterial in cell and tissue culture. [8]

Related Research Articles

Silk Fine, lustrous, natural fiber produced by the larvae of various silk moths, especially the species Bombyx mori

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 cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture). The shimmering appearance of silk is due to the triangular prism-like structure of the silk fibre, which allows silk cloth to refract incoming light at different angles, thus producing different colors.

Moth Group of mostly-nocturnal insects in the order Lepidoptera

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 which have yet to be described. Most species of moth are nocturnal, but there are also crepuscular and diurnal species.

<i>Bombyx mori</i> Moth mainly used in the production of silk

Bombyx mori, the domestic silk moth, is an insect from the moth family Bombycidae. It is the closest relative of Bombyx mandarina, the wild silk moth. The silkworm is the larva or caterpillar of a silk moth. It is an economically important insect, being a primary producer of silk. A silkworm's preferred food are white mulberry leaves, though they may eat other mulberry species and even the osage orange. Domestic silk moths are entirely dependent on humans for reproduction, as a result of millennia of selective breeding. Wild silk moths are not as commercially viable in the production of silk.

Pupa Life stage of some insects undergoing transformation

A pupa is the life stage of some insects undergoing transformation between immature and mature stages. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, with four life stages: egg, larva, pupa, and imago. The processes of entering and completing the pupal stage are controlled by the insect's hormones, especially juvenile hormone, prothoracicotropic hormone, and ecdysone. The act of becoming a pupa is called pupation, and the act of emerging from the pupal case is called eclosion or emergence.

Luna moth Species of insect

The Luna moth is a Nearctic moth in the family Saturniidae, subfamily Saturniinae, a group commonly known as giant silk moths. It has lime-green colored wings and a white body. The larvae (caterpillars) are also green. Typically, it has a wingspan of roughly 114 mm (4.5 in), but can exceed 178 mm (7.0 in), making it one of the larger moths in North America. Across Canada, it has one generation per year, with the winged adults appearing in late May or early June, whereas farther south it will have two or even three generations per year, the first appearance as early as March in southern parts of the United States.

Saturniidae Family of moths

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 giant silk moths.

Cutworm Genus of moths

Cutworms are moth larvae that hide under litter or soil during the day, coming out in the dark to feed on plants. A larva typically attacks the first part of the plant it encounters, namely the stem, often of a seedling, and consequently cuts it down; hence the name cutworm. Cutworms are not worms, biologically speaking, but caterpillars.

<i>Orgyia antiqua</i> Species of moth

Orgyia antiqua, the rusty tussock moth or vapourer, is a moth in the family Erebidae.

Limacodidae Family of moths

The Limacodidae or Eucleidae are a family of moths in the superfamily Zygaenoidea or the Cossoidea; the placement is in dispute. They are often called slug moths because their caterpillars bear a distinct resemblance to slugs. They are also called cup moths because of the shape of their cocoons.

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, Samia and Gonometa. Silk in its raw state consists of two main proteins, sericin and fibroin, with a glue-like layer of sericin coating two singular filaments of fibroin called brins.

<i>Glyptapanteles</i> Genus of wasps

Glyptapanteles is a genus of endoparasitoid wasps found in Central and North America and New Zealand. The larvae of the members of Glyptapanteles sp. are distinguished by their ability to manipulate their hosts into serving as bodyguards.

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 independently in many societies.

<i>Antheraea assamensis</i> Moth of the family Saturniidae

Antheraea assamensis, known as the muga silkworm as a larva and Assam silk moth as an adult, is a moth of the family Saturniidae. The species was first described by T. W. Helfer in 1837. It is found in Assam in northeast India where 99% of its production occurs.

Demineralizing has the potential to be used in the silk sector enabling wet reeling of Wild Silk moth cocoons by removing the mineral layer present in these cocoons. This technique is not like degumming where the gum of the fibroin fibres is removed what would lead to a tangled cocoon. With "demineralizing" the gum and structure of the cocoon is kept intact enabling the cocoons to be wet reeled. This could allow a new silk industry in areas which have not the conditions or infrastructure for raising the domesticated silk worm Bombyx mori, possibly generating a revolutionary new income stream and alleviating poverty

<i>Cadra calidella</i> Species of moth

Cadra calidella, the dried fruit or date moth, is a species of snout moth in the genus Cadra and commonly mistaken for the species Cadra figulilella. It thrives in warmer conditions and is found primarily in Mediterranean countries, although it can also be found in Central Asia, Kazakhstan, Transcaucasia, Caucasus, and the western part of Russia. It feeds on dried fruits, carobs, nuts and seeds, hence earning its colloquial name. This diet damages the food industry, and it is a common storage pest. Because of this, much research has been done to study ways to limit its reproduction rate and population size. It was first described by Achille Guenée in 1845.

<i>Antheraea paphia</i> Species of moth

Antheraea paphia, known as the South India small tussore, the tasar silkworm and vanya silkworm is a species of moth of the family Saturniidae found in India and Sri Lanka. The bulk of the literature on this species uses a junior synonym, Antheraea mylitta, rather than the correct name, A. paphia. It is one of a number of tasar silkworms, species that produce Tussar silk, a kind of wild silk that is made from the products of saturniid silkworms instead of the domesticated silkworm.

<i>Lymantria dispar dispar</i> Species of moth (gypsy moth)

Lymantria dispar dispar, commonly known as the gypsy moth, European gypsy moth, or North American gypsy moth, is a species of moth in the family Erebidae that is of Eurasian origin. It has a range that extends over Europe, Africa, and North America.

Cotesia urabae is a small wasp, having a black body with yellow-brown legs, characterized by a solitary larval endoparasitoid stage. It is part of a large complex of 11 primary parasitoids of Uraba lugens Walker, many of which are polyphagous. The female inserts its ovipositor into the a U. lugens larva, depositing its eggs there, and it has been found that one female may carry up to 400 eggs. While C. urabae females are able to attack the same larva several times; only one single parasitoid completes its development in each larva.

<i>Hypera postica</i> Species of beetle

Hypera postica, commonly known as the alfalfa weevil, is a species of beetle in the superfamily Curculionoidea; it can be found in alfalfa fields throughout Europe. Considered a destructive threat to alfalfa production in North America, several accidental introductions have been successfully countered though the use of a variety of biological control species.

References

  1. 1 2 Bause, T. Beautiful silk scarves from a nasty pest. The Namibian June 24, 2005.
  2. http://www.insects.org/ced4/peigler.html
  3. 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.
  4. Gonometa postica: Kalahari Wild Silk. Anthropological Entomology: Silk Textiles. Mississippi Entomological Museum.
  5. 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.
  6. 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.
  7. Bafana, B. Going wild for silk in Zimbabwe. New Agriculturist. May, 2009.
  8. 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.