Introduction of NUTRITIVE EFFECTS OF VITAMIN B-COMPLEX ENRICHED MULBERRY LEAVES ON THE SILKWORM, BOMBYX MORI L. (LEPIDOPTERA: BOMBYCIDAE)
Sericulture is an agro-based industry, which is suitable for developmental country as like as Bangladesh. The art and science of silk production is called sericulture. Silkworm is reared on an extensive scale in rearing house and their silk cocoons are utilized as fine materials for clothing.
The main goal of sericulture is the better quality silk production. It depends on cultivation of mulberry plants and rearing of silkworm. Sericulture plays an important role in our national economy.
The mulberry silkworm, Bombyx mori L is completely domesticated insect which was discovered in China as long as 2640 B.C. by Si - Ling-Chi, wife of the Emperor, Huang Ti (Copper, 1964). The silk industry has an adventurous course of evolution, becoming established from time to time in other parts of the world Jolly et al.,( 1979).
The secret of this silk production is zealously guarded by the Chinese for about 3000 years Krishnaswami et al.,( 1973) From China the secret of silk technology transferred first to Korea with the immigration of Chinese.
According to western historians, the practice of sericulture i.e mulberry cultivation and silkworm rearing had spread to India via Tibet about 140 B.C and it began in the areas flanking the Brahmaputra and Ganges rivers (Krisshnaswa et al., 1973; Ganga and Chetty, 1999). Some are the opinion that the Hindus discovered it in the sub Himalayan region independently of the Chinese (Sarkar, 1958 and Rao, 1997).
The Silk industry developed in our country in the beginning of the seventeenth century. At the time Bengal was known as the ''Store house '' of the silk (Sarkar, 1958). Now day sericulture is a practiced in industrially advanced countries such as Japan, China, South Korea and Brazil. Silkworm is reared in Bangladesh particularly in the district of Rajshahi and Nawabgong where silkworm is cultivated extensively as a major source of rearing for the rural people.
There about 6500 areas in Bangladesh of them, 57% belong to Rajshahi, 19% to Rangpur, 11% to Jessore and the rest 12% in Dhaka region.
According to Barnett (1963) nearly 1000 varieties silkworm are reared in the world. Some varieties or races are named on the basis of the number of generations in a year. Such races are called uni, bi or multivoltine. It is supposed to be genetically controlled and also influenced by environmental
factors. However multivoltine silkworm breeds are suitable for tropical regions Sidhu et al.,( 1968).
Mulberry silkworm is monophagous insect and the main food of silkworm is mulberry plants Morus alba L. Quality food is one of the important factors in determining the successful rearing and good harvest of silkworm cocoon crop. The resistances to the developmental stages silkworm are strongly influenced by nutrition (Yokoyama, 1964).
Nutrition plays a pivotal role in sericulture by improving the commercial characters of silkworm, Bombyx mori. L. The silkworm natural food is the foliage of mulberry plants. Legay (1958) stated that silk production is dependent on the larval nutrition, and the nutritive value of mulberry leaves plays a very effective larval nutrition and the nutritive value of mulberry leaves plays a very effective role in producing good quality cocoons. Sengupta et al., (1972) reported that B. mori requires certain essential sugars proteins, amino acids and vitamins for its normal growth, survival and also for the growth of its silk glands and higher production of good quality silk.
The optimal levels of essential vitamins such as biotin, choline, folic acid, inositolnicotinic acid, pantothinate riboflavin and thiamin had been determined by Horie and Ito (1963, 1965) and Horie et al., (1966) in the growth and development of B. mori larvae. Feeding of nutritionally enriched leaves showed better growth and development of silkworms as well as gain in economic characters of cocoons Krishnaswami el al., (1971). Vishwanath and Krishnamurthy (1981) also studied influence of micronutrients on larval development and cocoon characters of silkworm.
Ito and Tanaka (1959) tested nutritional effect of various carbohydrates by means of oral administration in the form of solution and observed better results with glucose. The nutritional effects of B. mori biology have been carried out by many workers, (Ito, 1961; Ito and Arai, 1965a; Yasuhiro and Sholchi, 1971; Kumararaj et al., 1972; Khalequzzaman and Ansary, 1982and Khalequzzaman and Mannan, 1982).
Significant developments in the research on silkworm nutrition started with the formulation of artificial diets of proteins, Amino acids, Carbohydrates, Hormones, Vitamins minerals etc. Artificial diets with different nutrients on better production of cocoon crops was investigated by many workers likes Fukuda and Higuchiy ( 1963) Yokoyama ( 1964)and Hamamura ( 1964).
The requirements of vitamin in silkworm, B mori confirmed by different deletion experiments ( Faruki & Khan, 1992; Faruki, 1998 and Kumarilalita el al ., 1992).
It is obvious that the study of larval growth is an important aspect of research for the insect, which are economically important. Successful cocoon crops in sericulture depend mostly on a healthy larval growth.
It is well known that larval growth of silkworms is depended on the nutrition of mulberry plant leaves. Vitamins can be changes during larval development have been described in Bombyx mori (Lalvez et al ., 1976; Hua, 1986and Wang et al., 1987).
Vitamin B- complex plays a very effective role in the larval pupal and cocoon development. Small larva do not formed good quality cocoon. So, the production of better quality cocoon depends on the supplementary food.
The present work aimed to determine the growth and development of silkworm, Bombyx mori L. variety BSRI-95 due to oral administration of vitamin B- complex treated mulberry leaves.