Relations between the amylase activity of the larval digestive juice and several quantitative characters in ae strains of the silkworm, Bombyx mori

Abstract

Since there was a variation in the anylase activity of their larval digestive juice among ae strains the larvae of ae gene constitution were separated into two classes of the high and low amylase activities and its effect upon the several quantitative characters was examined by rearing the larvae of eight commercial inbred strains under three different nutritional conditions, normal leaves, hardened leaves and an artificial diet.
In all the rearing experiments, cocoon weight, cocoon shel weight, cocoon shell percentage, cocoon shell productivity per day in the 5th instar, and survival rate were higher in larvae of the high amylase activity than in thore of the low activity. Especially, these differences were remarkable when the larvae were reared on hardencd leaves or the artificical diet. In the rearing experiments of larvae of F₁ hybrids between Japanese and Chinese inbred strains, however, the differences in these quantitative characters were not remarkable on account of the heterosis.
From these results, it may be concluded that the high amylase activity is advantageous for the commercial breeds of ae gene constitution.