Artificial Diets for the Silkworm, Bombyx mori, with Special References to a Semi-synthetic Diet for Fifth-instar Larvae, Which Includes a Large Amount of Defatted Soybean Meal

Abstract

The present study was undertaken to improve the efficiency of the semi-synthetic diets for the fifth-instar larvae of the silkworm. Larvae were reared on artificial diets from hatching through the end of the fourth instar (diet-I, -II, and -III; Table I). Newly ecdysed fifth-instar larvae were divided into five groups, and fed the five different test diets (Table II), which were different in the levels of defatted soybean meal and of cellulose powder.
The dietary levels of soybean meal affected greatly not only larval growth during the fifth instar but also the cocoon quality and egg production (Fig. 1; Tables III and IV). Thus it was concluded that fifth-instar larvae must be reared on the high-protein diet including a large amount of meal in order to get a good cocoon yield. However, the larval growth was somewhat reduced according to an increase in the dietary level of the meal. This effect could be attributed to a repellent substance for the silkworm, which occurred in soybeans. Although the rate of feeding was somewhat reduced for the first one or two days on a so-called high-protein diet, containing the meal as a protein source, the larvae were eventually accustomed to feed the diet well. In the present study rearing throughout on artificial diets was carried out successfully, and four different diets were used according to the larval development. The diet containing mulberry leaf powder was used for younger larvae, while that without leaf powder for older larvae.