Study of resistance and vitality responses in six silkworm (Bombyx mori L.) hybrids under individual selection for parental lines

Abstract

Sericulture has been an important agricultural industry since 2650 BC (Seidavi et al. 2006). There are about 10 million farmers and 0.5 million related industrial workers in the world. The present capacity of silkworm eggs production in Iran is about 70000 boxes per year which are distributed among 40000 silkworm house holders. Annual cocoon production in Iran is about 6000 metric tons which is small in comparison with production in previous centuries. Silkworm breeding using selection systems can improve line and hybrid performance. Individual selection based on cocoon weight in GGP generation (great grandparent) improved GP (grandparent) and P (parent) parental line generation (Seidavi et al. 2007), but it did not consider the effects on resistance performance of hybrid generation. In this experiment, the effects of two phenotypic selections of GGP parents on vitality (percentage of survival pupae) and resistance properties in six of their hybrids (including 31×32, 32×31, 103×104, 104×103, 107×110 and 110×107) were studied.