Vol. 8, Issue 9, Part A (2022)

Abstract
Enzymes play a very significant role in growth and physiology of silkworm (Bombyx mori L.). The growth of the silkworm during larval stage is enormous, increase in growth by size and weight necessitates involvement of various enzymes. Amylase is a hydrolytic enzyme involved in digestion and metabolism of carbohydrates present in the mulberry leaves in the form of starch. Amylase activity is determined by calculating the reducing component volume being released from the soluble starch. The haemolymph amylase was selected for the present study, since it is the only carrier for transport of every substance including amylase and other enzymes. Three different breeds viz., Pure Mysore (Polyvoltine), APS45 (Bivoltine) and SLFC27 (Sex-limited breed for cocoon colour) were selected for estimation of amylase activity. The haemolymph of the selected strain at their 5th instar starting from first day to seventh day was considered to determine the amylase activity. The haemolymph of both the sexes was used for the assay. Increased trend of amylase activity was noted in the haemolymph of all the selected breeds from first day to fifth day which was from a low range of 127.35 µg/20 µL in SLFC27 on first day to a higher range of 427 µg/20 µL in APS45 on fourth day. Amylase activity of PM is highly significant on day 5 when compared to SLFC27 and Amylase activity of SLFC27 is significantly high on the 5th day when compared to APS45 (* p<0.05, ** p<0.01) indicating that there is a gradual decrease in the amylase activity on day six by 22-25% than fifth day in all the selected breeds as this may be due to maturation of silkworm larvae and leaf consumption getting reduced as they approach for spinning process. The study specifies that, all the breeds showed high enzyme activity during larval stage along with positive correlation with respect to cocoon parameters. The higher amylase activity was recorded during the larval stage of the silkworm and decreased gradually towards spinning stage.