Comparison of the Effects of Different Selection Strategies on Performance of two Commercial Silkworm Lines

The aim of this research was to estimate the variance components and genetic parameters for silkworm cocoon traits using univariate and multivariate models, and comparison of average productivity and resistance traits among three different selection strategies in two commercial silkworm lines of 153 and 154. Genetic parameters of cocoon weight, cocoon shell weight and cocoon shell percentage were estimated after three generations of selection, using the REML algorithm of the WOMBAT software. Selection criteria were conventional three-trait index (A) and basal three-traits index (B) based on cocoon weight, cocoon shell weight and cocoon shell percentage. For these goals, data were collected for two commercial silkworm pure lines of 153 and 154 during 2006-2010 in the Iran Silkworm Research Center (ISRC). In general, the obtained results of mean comparisons showed that strategy A can be recommended for improving of all productive traits. Total genetic gain obtained from three generations of selection for all traits in strategy A in pure line 153 was higher than line 154. Regarding to the high values of heritability for studied traits in univariate and multivariate analyses, it can be concluded that additive genetic effects had more effect on the phenotypic values of these traits and consequently the improvement of these traits in breeding programs would be possible.