Abstract: 【Aim】The Eri-silkworm, Samia cynthia ricini, is a lepidopteran insect. Chymotrypsin inhibitors (CI) play important roles in the development and defense of the Eri-silkworm. The analysis of the polymorphism of CIs between different strains and the functional study of CIs in the Eri-silkworm could provide theoretical evidence for controlling Lepidoptera insects. 【Methods】 We investigated CIs in major tissues of 18 strains of S. cynthia ricini by using pH 8.3 and pH 4.0 native polyacrylamide gel electrophoresis. At the same time, the total protein content and CI activity in the hemolymph were determined. 【Results】 Seven CIs were found in the hemolymph of different strains of S. cynthia ricini in the pH 8.3 PAGE, and three CIs were found in the pH 4.0 PAGE. The CIs in the hemolymph maintained very high level from the 3rd day of the 5th instar larvae to the 1st day of the pupae. CIs had relative lower contents in the head, integument and fat body than in the hemolymph, and could not be detectedin the silkgland. 【Conclusion】 The expression level of CIs in S. cynthia ricini is higher than that in the silkworm, Bombyx mori. The polymorphism of CIs in S. cynthia ricini means that CIs vary in the same tissue of different stains and different tissues of the same strain.

Key words: Samia cynthia ricini, Bombyx mori; , tissue and organ, chymotrypsin inhibitor, specific activity