INVESTIGATIONS ON THE QUANTITATIVE FEATURES RELATED TO LARVAL GROWTH AND DEVELOPMENT AS WELL AS GOOD HEALTH OF A COMMERCIAL BREED OF SILKWORM, Bombyx mori L.

Abstract

To evaluate quantitative parameters tied in growth and development mechanisms of 4^th and 5^th instar healthy larvae of a commercial breed of mulberry Silkworm (Nistari x NB₄D₂) reared on two varieties of mulberry leaves in an ambient condition. Distinctiveness of the voltinism or of moultinism and hibernation is related to some features such as the number of rearing days, nourishment level, and the body weight that has been considered for substantial productivity. These features change depending on the abiotic factors in the environment and from the physiological point of view; such features are ultimately associated to the good healthy status of the silkworm. Two varieties of mulberry leaves viz., S-1 and S-1635 were selected for the leaf quality and palatability through rearing experiments. Active healthy silkworms of 4^th and 5^th instars were sorted batch wise and measured. The larval growth in both stages showed difference on all 1 to 7 days of growth in their body weights and logarithmical increase was distinctly noted till the 7^th day of 5^th instar. Just during the beginning of 5^th instar larvae merged by moulting from the 4^th instar, the larval bodyweight does not increase and remained as stationary phase. The experiment concerned the quality of nourishment during mature stages and the growth thereafter. The maximum value of weight and length 4^th and 5^th instar silkworm larva was noted feeding on S-1635 mulberry leaf variety than S-1 variety. S-1635 variety can be considered for high yield of cocoon, better larval availability and better silk productions and hence are found favourable under these present climatic conditions for our farmers’ side.