Four pure mulberry silkworm breeds viz., Pure Mysore, Nistari, NB4D2 & CSR2 and two hybrid (Pure Mysore x CSR2 and Nistari x NB4D2 ) silkworms were selected for the present study. The specific activity of alkaline phosphatase (ALKP) in midgut and fat body tissues were estimated. The qualitative analysis of ALKP was carried out by Native-PAGE. The commercial characters viz., fecundity, larval weight, larval duration, cocoon weight, shell weight, shell ratio, filament length, denier and renditta were selected. The activity levels of ALKP of midgut and fat body tissue showed statistically significant (P<0.001) changes in their activity levels during fifth instar. The results of quantitative analysis were subjected for regression analysis against selected commercial characters to know the correlation coefficient between them. The results of regression analysis clearly showed that midgut ALKP has positive correlation with fecundity, larval duration and renditta only. The activity levels of fat body ALKP showed positive correlation with fecundity, larval weight and renditta only. The zymograms of ALKP in midgut and fat body also exhibited variation among the selected silkworm varieties.
