Sericulture

Under silk culture or sericulture one understands the whole process of silk production and its components sericulture, mulberry cultivation and care of crops and processing of raw silk cocoons.

History

The silk culture has its origins in China, where silk should already have been produced around 2800 BC. Today, China is the world's largest producer of raw silk. The most important among the silk spinning insect comes to the rights silkworm ( Bombyx mori L.). 95% of natural silk are obtained by this. When silk fibers are referred to from the middle layer of the cocoons of the larvae of Bombyx mori L..

Sericulture

Food

The silkworms are monophagous and eat only leaves of the mulberry trees (Morus alba and other varieties ). At the start of silk production first is the cultivation of the mulberry culture.

Different kinds of the mulberry tree are found on all continents. The occurring in tropical evergreen species are relatively fast growing. The cuttings of new cultures are set in the rainy season. Usually they are found mulberry plantations in monoculture, but there is also the possibility of mixed culture, for example, with legume or maize. For the silkworm production, it is necessary to keep the trees that can reach a height of 20-25 m on shrub height.

The leaf yields of the different kinds of the mulberry tree exhibit, depending on site conditions, species and production system, a range of 5-30 tonnes per hectare and year.

Development

The silkworm belongs to the group of insects with complete metamorphosis. The life cycle of the silkworm, which lasts depending on the breed and the influence of environmental factors, about six to eight weeks, has four distinct stages: egg, larva (caterpillar ), pupa and imago. The eggs are produced by special breeding of the silkworm.

The weight of the newly hatched caterpillar is not more than 0.45 mg. Due to their enormous weight gain around 10,000 times the chitinisierte body blanket must be dropped four times and renewed. The time period between the hatching of the caterpillar to the first molt or between the individual molts is called instar ( larval stage ). With the end of the fifth instars the filled silk gland makes up about 40 % of total body weight, the caterpillar is now ripe spin.

Spinning of the cocoon

In two glands on the lower jaw of the caterpillar, the protein fibroin is formed. These two Fibroinstränge are linked by sericin ( silk gum ), which is formed by two other glands in the lower jaw. Thereafter, the silk yarn is pushed out of the silk gland at the end of the head. With this ongoing thread then the caterpillar forms the cocoon by moving its head from side to side. The cocoon hardens when sericin reacts with the air. Subsequently, the pupation takes place.

Extraction of raw silk

The extraction of raw silk is made up of various operations, such as harvesting the cocoons, killing the pupae by heat, drying, deflocculation, sorting and cooking the cocoons to soften the sericin and the unwinding ( winding the silk threads ) together.

There are zusammengehaspelt eight to ten Kokonfilamente, then form a single thread of silk. Single Kokonfilamente have a length of about 800 m. For the production of one kilogram of raw silk average 10-11 kg of cocoons are needed.

Yield and by-products

Depending on the breed have 100 silkworms in their lifetime 180-450 kg of mulberry leaves eaten. Since silkworms are monophagous, it is possible to relate the cocoon yield on the surface. However, this depends on the breed silkworms, the leaf yield of the mulberry tree, the number of leaf crops, the rearing cycles of silkworms each year, the unused Eimenge and the yield per Eibox. Under favorable conditions up to ten breeding cycles are possible in the tropics with year-round growth and prosperity of the mulberry trees.

In the silk production, large quantities of waste and by- products with very good nutrient content. These can be used in integrated production systems, such as animal feed.

Literature Note

• Hans Rich Mart: A Practical Guide to Successful of silk, silk culture German publishing house, Martin Salzmann, Dessau, 1920