Effect of dietary levels of protein and pyridoxine on growth of 5th instar larvae of the silkworm, Bombyx mori

Abstract

The effects of the dietary levels of protein and pyridoxine (B₆) on growth and survival of the 5th-instar larvae of the silkworm were studied under aseptic condition. The silkworms were reared with the twenty-four different diets containing 15 to 60% of protein in combination with 0 to 1mg B₆ per g of the dry diet. When the larvae reared on the diet containing 30, 45, and 60% protein, they grew well at B₆ levels of 10, 100μg, and 1mg, respectively. All the larvae died with the diet containing less than 0.1μg of B₆ before pupation. Mortality of larvae was very high when they fed on high protein and low B₆ diet. Mortality of larvae was lowered with the increase of protein content in the diet. When the dietary protein level was low, excess amounts of B₆ showed slightly an inhibitory effect on the larval growth. Female larvae required a higher amount of B₆ than male larvae throughout the development. Minimum quantity of B₆ for survival ranged from 6 to 8μg in female and from 4 to 6μg in male larvae. Larvae needed more amounts of protein and B₆ for the growth of silkgland, than those for the other tissues.