Investigation on improvement possibility of resistance, production and reproduction traits in 3P, 2P and P generations in three Japanese pure lines of silkworm Bombyx mori L., using individual selection in 3P generation.

摘要

Studies were conducted to determine the improvement possibility of resistance, production and reproduction traits in 3P, 2P and P generations in 3 Japanese pure silkworm (Bombyx mori) using individual selection in the 3P generation parent level. In silk cocoon production process and silkworm breeding programmes, reproduction traits supplies silkworm egg producers, cocoon quantitative and resistance traits supplies farmers' benefits. Furthermore, selection systems were applied in 3P pure line levels. Reproduction, production and resistance characters have negative correlations probably in some varieties. At each pure line, including 31, 103 and 107, the male and female cocoon weight were recorded and then 16 sire and dam parents were selected accordingly for the most weight at each line. Furthermore, 16 sire and dam parents were selected by chance and without any selection at each line. These 3 pure lines were reared in 3P, 2P and P generations and their resistance, production and reproduction traits were investigated and compared separately. From the obtained results, it was shown that the phenotypic trend for cocoon weight was positive and significant. It was shown that parental selection based on the single cocoon weight in 3P generation had not decreased reproduction and resistance characters at the next generations of 3P, 2P and P significantly. Hatchability, defected eggs percentage and pupae vitality did not decline significantly in the studied pure lines. These results had non-negative correlations between these traits in the 3 studied pure lines. From the obtained results, parents should be selected based on the cocoon weight parameters in 3P generation. Also, it is recommended that economical coefficients and genetic parameters are noticed for reproductive, resistance and quantitative cocoon characters together.