Evolution of a bivoltine breed 'DNB₁' of the silkworm, Bombyx mori L. through ameiotic parthenogenesis.

摘要

An attempt was made to evolve a bivoltine silkworm breed through application of artificial parthenogenesis. Two Chinese bivoltine breeds viz., CSR18 and CSR12 possessing higher ability towards parthenogenetic development were utilized as breeding resource materials. Artificial parthenogenesis was followed to improve the selection efficiency. Eggs were extracted from virgin female moths. Induction of ameiotic parthenogenesis was carried out by treating the excised unfertilised eggs with 46 degrees C hot water for 18 min. Crosses were adopted twice with CSR2 to improve the quantitative characters of the parthenoclones. One line, DNB1 with larval sex-limited character and white oval cocoons was evolved. The line was evaluated utilizing four productive bivoltine silkworm breeds. Laboratory evaluation showed superiority of the hybrid DNB1 x CSR4 exhibiting higher fecundity (586), pupation rate (96.67%), cocoon shell weight (0.387 g), cocoon shell percentage (21.50%), filament length (1050 m) and neatness (92 p). The possibility of application of artificial parthenogenesis in the evolution of superior silkworm breeds and hybrids has been discussed.