Biochemical analysis of defensive enzymes in the hemolymph of bivoltine silkworm breeds of Bombyx mori (Lepidoptera: Bombycidae).

To better cope with unfavorable climatic conditions and perform optimal physiological functions, the silkworm Bombyx mori secretes some of its defensive enzymes in the hemolymph. To understand the extent of enzyme secretion in the hemolymph, we studied the profiles of defense enzymes in different silkworm breeds. We collected and analyzed the hemolymph of 5th instar larvae of 21 different bivoltine silkworm breeds with different characteristics for protein content and activities of enzymes such as catalase, peroxidase, polyphenol oxidase, amylase, and protease. The results revealed significant differences between the breeds in terms of protein and defensive enzyme activities. The activity of catalase, peroxidase, polyphenol oxidase, amylase, and protease varied between silkworm breeds, with an average activity of 8.791 U mg−1, 0.203 U mg−1, 0.42 U mg−1, 0.264 mg ml−1 min−1 mg−1 and 0.193 µg ml−1 min−1, respectively. To understand the genetic relationship between the silkworm breeds in terms of the activity of defensive enzymes, we constructed a dendrogram using Euclidean distance. The 21 silkworm breeds were grouped into five different clusters with different enzyme activities, revealing sufficient diversity between the silkworm breeds that can be used for parental selection in silkworm breeding programs. This study is highly informative in enhancing knowledge on the role of defensive enzymes in the development of new silkworm breeds that can adapt to adverse environmental conditions. [ABSTRACT FROM AUTHOR]