Identifying parents and generating hybrids with high combining ability for yielding fresh cocoon and raw silk in silkworm (Bombxy mori L.)

Abstract

This study was carried out to identify parents and hybrids by determination of general combining ability (GCA), specific combining ability (SCA), and heterosis in pure lines and their hybrids, which were selected from our gene sources, to determine new hybrid combinations that could be alternative or higher in yielding compared with M × N hybrid used in production. Combining ability and heterosis effects were studied for the eight quantitative characters through line × tester mating design. Chinese origin lines (KZ, ZF) were identified as females and Japanese origin lines (BR, ZB) as males, and by these, four hybrids were derived. M, N, and their hybrid were both used as control genotypes and to calculate the heterosis and commercial heterosis as well. All the genotypes were reared in standard conditions, in three replications. ZF (for pupa survival rate) and ZB (for hatching and filament length) presented significantly higher and positive GCA effects. In addition, ZB had negative GCA effect for infertile egg rate. Effects of SCA were not significant for all the characters. In conclusion, ZF × ZB hybrid could have a potential for the higher cocoon and silk production in Turkey.

Identifying Hybrid Genotypes of Mulberry Silkworm (Bombyx mori) Using Heterosis for Biological and Silk Yielding Traits

“…Apart from improving productivity, hybridization is necessary to set aside the degenerating effect of recurrent rearing and protecting gene erosion. The superior strains/ hybrids are identified using either of the three genetic parameters: general combining ability, special combining ability or heterosis for important biological and silk yielding traits (Sahan, 2020). Biological and silk yielding traits are under multiple gene control and are also affected by nutrition and rearing conditions (Mirhosseini et al, 2005;Zhao et al, 2007;Hemmatabadi et al, 2016).…”

“…The primary objective of silkworm hybridization is to evolve robust strains to replace the old ones. The new strains are resistant to diseases, and have high productivity potential and environment adaptive compared to earlier strains (Kang et al, 2004;Sahan, 2020). Scores of hybrids have been synthesized with superior biological traits like fecundity, egg hatchability, larval development, pupation rate and silk yielding traits including cocoon weight, cocoon silk percentage, silk yield, silk filament (Talebi et al, 2010;Ghazy, 2012;Ghazy et al, 2017;Fouad, 2020;Sahan, 2020).…”