Here is your notes on sericulture!
It is the art and science of silkworm breeding for producing silks. The sericulture is an important cottage industry, but is now the basis of large industries in China, Japan, India and some European countries, where the silkworm, Bombyx mori is reared on mulberry leaves on a mass scale to get raw silk from the cocoons of the caterpillars of the moth.
The eggs of the silkworm moth hatch out within 10 days into creamy white rapidly moving caterpillars. The latter feed voraciously on the fresh mulberry leaves and soon undergo a fast growth and are popularly referred to as silkworms.
The silk glands secrete a sticky secretion which is spun around the caterpillars to form a hard covering of silk fibres, known as the cocoon (= pupal case).
Now, each caterpillar gradually metamorphoses in about a fortnight, into a pupal stage called chrysalis. After one or two days of cocoon formation, the pupae are killed either by drying them in the sun or by boiling them. The raw silk fibres forming the cocoon are then reeled out into silk threads. The pupae are killed, because with the emergence of the adult silkworm moth, the long silk fibres will be broken and can only be spun like cotton and cannot be reeled into skeins. Each cocoon of silk moth has about 1000 metres of silk thread.
About 25,000 cocoons yield one pound of silk. A few cocoons, called the seeds, are kept and are allowed to develop into adults to continue the generation. Now-a-days, the intestine of the silk-moth is being utilized to form a substance, known as ‘gut’ which is useful in fishing and some surgical work.
(i) Pebrine. The silkworms are destroyed in large numbers by a severe hereditary disease, known as pebrine, which is caused by a parasite protozoan, Nosema bombycis. Nosema infects the eggs of the silkworm and transmits the disease from one generation to another. The symptoms of pebrine are that the caterpillars turn brownish or pale, shrivel up and finally die.
(ii) Grasserie. It is caused by a kind of virus which attacks the larva. The larva utimately dies,
(iii) Muscaridine. It is caused by a fungus,
(iv) Flacherie. It is an infectious viral disease marked by digestive disorders.