Selection indices for cocoon traits in six commercial silkworm (Bombyx mori L.) lines

Abstract

Genetic parameters and economic values of cocoon traits in six commercial silkworm varieties (110, 107, 101433, Xinhong1, Koming1 and Y) were analyzed and selection indices for these traits were constructed. Cocoon weight, shell weight and shell ratio for each silkworm were carried out for four generations. Heritability and correlation coefficients were estimated by the REML method. Heritability of cocoon weight and cocoon shell weight were higher than the heritability of cocoon shell ratio. Using a deterministic model, the economic weights of the traits were calculated. In each variety, two conventional indices (family and individual indices), two restricted indices (family and individual restricted indices) and two base indices (individual and phenotypic base indices) were constructed. The expected economic efficiency resulting from family index selection was the highest. Thus, family index is suggested for selection. The maximum and minimum selection accuracy, expected economic gain and relative efficiency of individual to family index belonged to Xinhong1 and 107, respectively