Application of Biometrical Genetics in Mulberry Silkworm Breeding: A Review

The silkworm, Bombyx mori is a lepidopteron insect by virtue of its economic importance for over a century has been used in many genetical experiments in several countries, especially China, India, Japan, Soviet Russia, Korea and many Southeast Asian and European countries. Many of the economic traits of this insect are known to be controlled by large number of polygenes. The silkworm varieties include univoltines, bivoltine and polyvoltines races. These races are utilized by silkworm geneticists to programme crossing and selection experiments. Since, silkworm races are open genetic system crossing and hybridization experiment through out the world resulted in the evolution of new breeds and hybrids. However, the gene expression in Bombyx mori is known to be greatly influenced by environmental factors because of long course of domestication. It is important that the estimates of genetic variability in the breeding materials and the magnitude of genetic effects governing the yield and other economically important attributes and unbiased estimates of other genetic parameters are highly useful for a successful breeding programme. Thus understanding of genetic components through biometrical genetics is very necessary for breeders.