Studies on the effect of certain host plants and their phylloplane microfungi on the growth and development of muga silkworm

Abstract

India has an ancient silk culture. Himalayan belt, particularly, the Eastern Himalayan region is believed to be the homeland of silk. Silk culture gradually spread to other Asian countries and many silk roads were established later in Asian countries which ultimately lead to Middle East countries and Europe for the purpose of export of silk. India is unique, in that, all the four varieties of silk are produced in India. Assam in general and the northeastern region in particular is famous for production of excellent variety of muga silk. The muga silk worm Antheraea assama is endemic to the northeastern India. There are several, types of host plants, on the leaves of which the muga silk worm feed. Of these, Som (Machilus bombycina) Soalu (Litsaea polyantha) and Mejankari (Litsaea citrata) are very popular among silk growers. Each of these types of plants has several morphotypes. Muga silkworms, depending upon climate and others factors often show preference to some of the morphotypes. These morphotypes are easily recognised by the local people for rearing of silkworms. The types of plants are considered to be crucial for production of quality silk. The nutrient contents of leaves also play important role in silk production. The climate of Assam is most suitable for growth of host plants of the muga silkworm. These host plants are found to grow in wild condition. But for the purpose of rearing of muga silkworm these plants are now cultivated commercially by the Government as well as by private farms. Although hill slops are most suitable for the growth of such host plants, these can be grown in the plain area also. Morphology of the leaves, their longevity and inclination, apart from physiology has profound bearing on the preference of the host plants by the silkworms. Duration of the year, rainfall, temperature, etc also influence the host plants and so also the activities of the silkworms. Microbiology of aerial plant surface particularly the leaves have received wide attention in recent years. The leaf surface...