Sericulture-agro based cottage industry

Sericulture is the art and science of silkworm breeding for producing silks. In Pakistan it is a village based industry and it is a source of employment for a large section of population.

Sericulture-agro based cottage industry

It is most labour-intensive sector that combines both agriculture and industry. This industry is great source of employment as it provides employment opportunities to many layers of people, including, seed producers, farmers, reelers, twisters, weavers, spinners of silk waste, traders and others.

Life cycle of silk worm

The silkworm pass through four developmental stages to complete its life cycle. These stages are eggs, larvae, pupae and adult (imago). The whole life cycle completed in five to seven weeks and it depends upon climatic conditions. The life cycle begins as the moth lays eggs which develop into silkworm larvae. The larvae feed on fresh mulberry leaves.

The 5th instar larvae feed heavily on leaves and it feed about 85% of their feeding during this instar and increased in size 10000 times. After that the caterpillar spins a cocoon for protection and it took 3 days to develop completely. The pupation takes place in that cocoon and the adult emerge from the cocoon. The adults don’t feed and their only work is to mate. They die after few days. The adults also cannot fly but they have strong smelling power.

Sericulture

Types of Silk 

There are two broad classifications of silk, wild silk and domesticated silk. Under ‘domesticated silk’ we have mulberry silk and non-mulberry silk.

Global Silk Perspective 

Globally, over 30 countries produce silk, 16 of which are in the Asian continent, accounting for about 90% of the total world silk production.

Sericulture and developing countries:

Sericulture includes the cultivation of mulberry, silkworm rearing and post cocoon activities leading to production of silk yarn. It provides;

  1. Employment,
  2. Economic development
  3. Improvement in the quality of life to the people in rural area
  4. Important role in anti poverty programme
  5. Prevents migration of rural people to urban area in search of employment.

Hence several developing countries have taken up sericulture to provide employment to the people in rural area.

Sericulture in Pakistan

In Pakistan the sericulture has been mostly practiced on small and medium sized land holdings. This cottage industry has potential to provide employment to 25 percent population of rural areas and it is only possible by the support of the government which can boost up this industry. This it can also a source of foreign exchange. Still 15000 families are involved and earning through sericulture.

 India is earning billions of foreign exchange by export of silk to demanding western countries but in Pakistan we still spending money on import of silk. One of basic unit for Sericulture silk industry is the packet of silkworm eggs, which contain 20,000 eggs and it is available at cost of Rs 200. The silk cocoons are ready in only 35 days and it can give earning of Rs 8000.

In Pakistan a species Bi-voltine is reared only in spring season while in India a modern silkworm species namely poly-voltine gives 4 crops in a year. Other obstruction is that twenty thousands silkworms eat out 600 kg mulberry leaves, while mulberry trees are rare in Punjab. However, new species of mulberry tree (bush sized mulberry) has been found, which is sowed like a crop but it is yet to be promoted in Punjab.

Climatic factors for sericulture

  1. Effect of carbon dioxide

In the rearing room the carbon dioxide is generally 0.03-0.04% but if it exceeds 2% concentration then the growth of the larvae is badly effected and results in retarded growth. So care should be taken and concentration of the fresh air should be checked regularly

  1. Effect of light

The larvae of silkworm are very photosensitive and they prefer dim light thus they move towards dim light. The larvae also avoids high light or too much darkness. For the survival of late age silkworm larvae 16 hours of light and 8 hours of darkness is preferred as they survive better in such conditions while for the young larvae survive and grow better in 16 hours of darkness and 8 hours of light period.

  1. Effect of temperature

Rate of eggs laying, cocoon production vary greatly with change in the temperature. The optimum range for eggs laying is 25 degree centigrade. The males when kept at 32 degree centigrade for four days then the males become sterile.

Silk production and process

  1. Hatching the Eggs

The principal phase of silk creation is the laying of silkworm eggs, in a controlled situation, for example, an aluminum box, which are then inspected to guarantee they are free from sickness.

The eggs are hatched with help of incubator. The eggs hatch into tiny larvae that have simple mouthparts and does not eat a lot.

The modest eggs of the silkworm moth are brooded (around 10 days) until they hatch and caterpillars come out.

  1. The Feeding Period

After hatching the larvae are placed on the chopped mulberry leaves and provided with optimum environment. The larvae shed four times it skin, during its feeding stage. The larvae can also be feed on Osage orange or lettuce. Mulberry leaves fed larvae produce very finest silk. The larva eats 50,000 times its initial weight in plant material.

For about six weeks the silkworm eats almost continually. It took six weeks of time period for growing its maximum size of three inches. Later the larvae stops eating and changes color is visible. At that time the larvae is about ten thousand times heavier as compared to when it was hatched.

During this stage of life cycle the larvae is ready to spin a silk cocoon.

  1. Spinning the Cocoon

The larvae search for a support and attaches to any support present or provided in the cages for example frame, twig, tree or shrub in a rearing house. It takes over a 3 to 8 days to spin a silk cocoon. This period is also known as pupating.

Silkworms have specialized structures known as sericteries which is a modified salivary gland. Their secretion is responsible for the production of fibroin.

These secretions on exposure to air become hard and make a twin filaments which in turn is made of fibroin, a protein material. The other pair of glands secretes a binding fluid called sericin which bonds the two filaments together.

After the next four days, the silkworm rotates its body in a figure-8 movement for approximately 300,000 times to construct a cocoon and produce silk filament which is about a kilometre.

  1. Reeling the Filament

Now the cocoon is treated with boiling water or hot air and steam. By softening the silk is unbound from the cocoon and later unwinding, or ‘reeling’ of the filaments from four to eight cocoons is done at same time.