Silkworm

Introduction

It is at the stage of caterpillar that the Bombyx mori produces the invaluable fiber, it secretes an abundant dribble which, while hardening, is transformed into a single wire of rough Soie with which it manufactures its Cocon, this wire measures between 300 and 1.500 meters length. It is produced by specialized glands, said silk-producing .

History

In China, one allots the discovery of the silkworm to a former named Empress Xi Ling-Shi (Mandarin: 嫘祖, Pinyin: Léi Zǔ). It is told that she drank the under a Mûrier when a Cocon fell into its cup. While wanting to recover this Cocoon, a soft silk wire was detached some! The more it drew, and the more the wire lengthened. It rolled up it around its finger to be able to still draw, and felt a pleasant heat. It understood immediately that it was this cocoon which produced silk. The Empress spoke about it around it, and this discovery was propagated, the Sériciculture had been born. This legend, most known, is only one of many to explain the discovery of silk. Currently, in order to make profitable its sericiculture, China developed all the industrial die. China does not neglect the artifices of the Occident to make enter of the currencies.

Since 1850, because of its economic importance and its long story, the silkworm is used as biological model to the researchers. The Génome of the silkworm was the object of many studies and experiments. Today, it can be modified Génétique lies thanks to work of French scientists, Japanese and American, in the hope to produce a wire with new and astonishing qualities. To make a success of this modification, one naturally integrates into the genetic inheritance of the silkworm a Protéine Fluor escente.

Taxonomy

Other butterflies bear in French the name of Bombyx without to belong to the scientific kind Bombyx , it is the case of the Bombyx of the ailante ( Samia cynthia (Drury, 1773)) or that of the oak ( Lasiocampa quercus (Linnaeus, 1758)).

It would be relatively close to the Bombyx mandarina with which it is capable of hybrider and which is originating in the north of the India, of the north of China, Korea and the Japan.

Description

Like all the lépidoptères, the Bombyx presents during its development an alternation between the larval stage in the form of caterpillar and the adult stage or imago. However it presents a singular characteristic with regard to the diapause or stop of the development to spend the cold season. This diapause is carried out in the form egg and not in the form chrysalis like more the share of the cases for the butterflies. We will study initially the caterpillar then the butterflies.

The caterpillar

The caterpillar of the silkworm is composed of 12 segments presenting on each one of a their with dimensions line of stomata. The first three segments carry each one a pair of articulated legs which will be those of the perfect insect; 6th, 7th, 8th, and 9th are equipped with membranous legs armed with spurs allowing the larva to cling to the sheets. Before last segment present on its higher face a spur whose point is directed backwards.

The sheet of white Mûrier is the only food which is appropriate for the silk worm with that of the mulberry tree black; all the other plants tested such as Cudrania triloba or simply the lettuce gave poor results.

Growth

When the silkworm leaves egg it long of 2 Misters and is approximately covered with hairs. It will undergo four driven, then, after having woven its Cocon it will be transformed into Chrysalide inside the cocoon. Its growth is considerable and can be summarized in the following table:

These figures can vary according to the races, of the conditions of breeding etc

Digestive system and circulatory

The digestive system is consisted a long cylindrical channel with the esophagus, the stomach and the intestine. The blood circulation is ensured by a dorsal vessel presenting several bulges. Blood circulates of back ahead.

Silk-producing glands

Along the intestinal channel and of each with dimensions of the body of the caterpillar the producing apparatus of silk is. They are two glands out of tube made up of three quite distinct parts: First is consisted a very rolled up capillary tube measuring 15 to 25 cm. of length and 1 Misters diameter; it is in its interior that the silky matter is elaborate. This tube emerges in a kind of lengthened bag being used as tank and in which the silky matter is versed: at this stage the substance is gelatinous. Former end of each tank is born a second capillary tube which meets in its congeneric to form one that only one conduit low length: it is the die.

In its course the silk wire of each of two glands takes consistency more and more. The two wire are welded in the die and are covered with a varnish preserving them of moisture and giving them its brilliance.

From these silk-producing glands the hair of Florence was prepared. When the worms are about to manufacture their cocoon, they are soaked in an acidulated bath, the glands are extracted then stretched slightly to manufacture a wire of 30 with 40cm. of length. This wire known under the name of hair of Florence was used in surgery like wire of joining and was used to make lines for fishing.

The butterfly

The Bombyx mori is unknown in a wild state. It is a completely artificial product of selection by breeding called Sériciculture, with a large variety of lines and races which differ by the color and quality from silk, the dimension and the shape of the cocoon, the number of annual generations. Certain modern cocoons resulting from genetic research are so large and so hard that the butterflies cannot escape from it if they are not helped.

With the state domesticates where it was reduced, the butterfly of the worms with silk does not fly. The female appears with white wings, little developed antennas and a bulky belly. The male is smaller with gray wings than it agitates continuously, of the very developed antennas which are used for to him detecting the odor emitted by the female and thus supporting the coupling. The female awaits the approach of the male which only can move. Three days after fecundation, it lays from 300 to 700 eggs (or seeds).

The butterflies of the silkworm prennet no food nor drink in an adult state. The eggs are entirely developed when the female is at the stage of the chrysalis and they are préts with being emitted in a single and abundant laying at the time when la' adult fate of the chrysalis.

Diseases of the silkworm

Louis Pasteur, eminent French microbiologist, made research on several diseases of the silkworm, which at that time threatened the production of silk in Europe.

Among the diseases of the worms with silk, let us quote: the Muscardine, the Pébrine, the Flacherie.

the badly of segno : a mushroom Beauveria bassiana causes a white Muscardine silkworm while Beauveria effusa causes a red of it.

the pébrine owes its name with the fact that the worms reached were strewn with small black spots resembling peppercorns (pebre = pepper into of Provence).

the disease deaths-flats or flachery owes its name with the fact that the dead worms become soft, flask (flacs or flats = flask into of Provence).

Use

Production of silk

See also: Silk, History of silk, Sericiculture

Medical uses

The silkworm gives an element of Chinese traditional medicine, the " bombyx batryticatus " or " silkworm raide" (Chinese simplified: 僵蚕, traditional Chinese: 僵蠶, Pinyin: jiāngcán). It is the dried body of the 45e larval stage, which died infected by the Champignon Beauveria bassiana . The traditional doctors use it to dissipate the wind, to dissolve the Pituite and to relieve the Spasme S.

Food use

to see Beondegi

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