Domestic Silk Moth

Appearance

Domestic silk moths are very different from most members in the genus ''Bombyx''; not only have they lost the ability to fly, but their color pigments have also been lost.

Behavior

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 is white mulberry leaves, though they may eat other mulberry species and even Osage orange. Domestic silk moths are closely dependent on humans for reproduction, as a result of millennia of selective breeding. Wild silk moths are different from their domestic cousins as they have not been selectively bred; they are thus not as commercially viable in the production of silk.

Sericulture, the practice of breeding silkworms for the production of raw silk, has been under way for at least 5,000 years in China, whence it spread to India, Korea, Japan, and the West. The domestic silk moth was domesticated from the wild silk moth ''Bombyx mandarina'', which has a range from northern India to northern China, Korea, Japan, and the far eastern regions of Russia. The domestic silk moth derives from Chinese rather than Japanese or Korean stock.

Silk moths were unlikely to have been domestically bred before the Neolithic Age. Before then, the tools to manufacture quantities of silk thread had not been developed. The domesticated ''B. mori'' and the wild ''B. mandarina'' can still breed and sometimes produce hybrids.:342

Reproduction

Silkworms were first domesticated in China over 5,000 years ago. Since then, the silk production capacity of the species has increased nearly tenfold. The silkworm is one of the few organisms wherein the principles of genetics and breeding were applied to harvest maximum output . It is second only to maize in exploiting the principles of heterosis and crossbreeding.



Silkworm breeding is aimed at the overall improvement of silkworms from a commercial point of view. The major objectives are improving fecundity , the health of larvae, quantity of cocoon and silk production, and disease resistance. Healthy larvae lead to a healthy cocoon crop. Health is dependent on factors such as better pupation rate, fewer dead larvae in the mountage, shorter larval duration and bluish-tinged fifth-instar larvae . Quantity of cocoon and silk produced are directly related to the pupation rate and larval weight. Healthier larvae have greater pupation rates and cocoon weights. Quality of cocoon and silk depends on a number of factors, including genetics.