An analysis of genetic variation and divergence in Indian tropical polyvoltine silkworm (Bombyx mori L.) genotypes

The genetic variation and diversity among fifty-eight polyvoltine silkworm genotypes was estimated by using ten economic traits. The results revealed that the single shell weight showed higher genetic variation such as PCV% (۱۷.۲۰%), GCV% (۱۲.۹۳%), and heritability (۵۶.۵%) followed by single cocoon weight, shell ratio and matured larval weight. The D۲ (Mahalonobis? distance) statistics revealed nine clusters with substantial inter and intra cluster distances. The genotypes included in different clusters varied from ۱ to ۱۶. The genotype Pure Mysore was included in isolated cluster indicates its longer adaptation. The genotypes included in cluster VIII and IX showed optimum genetic distance along with higher cluster mean emphasised for utilization in the silkworm breeding.   REFERENCES Anonymous (۱۹۹۷) Principles and techniques of silkworm breeding. ESCAP, Oxford & IBH Publishing Co. Pvt. Ltd., United Nations, New York, ۱۱۴ p. Arunachalam, S., Bandyopadhy, S.N., Nigam, R. W. and Gibbons (۱۹۸۴) Heterosis in relation to genetic divergence and specific combining ability in groundnut (Arachis hypgaea). Euphytica, ۳۳‚ ۳۳-۳۹. Chatterjee, S.N. and Mohandas, T.P. (۲۰۰۳) Identification of ISSR markers associated with productivity traits in silkworm Bombyx mori L. Genome, ۴۶: ۴۳۸-۴۴۷. Chatterjee, S.N., Ramamohana Rao, P., Ravindra Singh and Datta, R.K. (۱۹۹۳) Genetic variability in mulberry silkworm Bombyx mori L. breeds with low silk yield. Indian J. Seric. ۳۲‚ ۶۹- ۸۶. Dalton, D.C. (۱۹۸۷) An introduction to practical animal breeding. ۲nd Edition, English Language Book Society/Collins, ۱۸۲ p. Frankel, O.H. and Brown, A.H.D. (۱۹۸۳) Current plant genetic resources a critical appraisal. In: Genetics: New Frontiers, Volume IV Applied Genetics, Proceedings XV International Congress of Genetics, New Delhi, V.L. Chopra, B.C. Joshi, R.P. Sharma and H.C. Bansal, eds.) (New Delhi: Oxford and IBH Publishing Co) pp: ۳-۱۳. Jolly, M.S., Datta, R.K., Noamani, M.K.R., Iyengar, M.N.S., Nagaraj, C.S., Basavaraj, H.K., Kshamarani, G. and Ramamohana Rao, P. (۱۹۸۹) Studies on the genetic divergence in mulberry silkworm Bombyx mori L. Sericologia, ۲۹‚ ۵۴۵- ۵۵۹. Krishnaswamy, S. (۱۹۷۸) New technology of silkworm rearing. CSR&TI., Central Silk Board, Mysore, India, Bullettin No. ۲. Kumaresan, P., Sinha, R.K., Sahni, N.K. and Sekar, S. (۲۰۰۰) Genetic variability and selection indices for economic quantitative traits of multivoltine mulberry silkworm (Bombyx mori L.) genotypes. Sericologia, ۴۰‚ ۵۹۵-۶۰۵.  Kumaresan, P. and Sinha, R.K. (۲۰۰۲) Genetic divergence in multivoltine silkworm germplasm in relation to cocoon characters. Indian J. Genet. ۶۲‚ ۱۸۳-۱۸۴. Kumaresan, P., Sinha, R.K. and Thangavelu, K. (۲۰۰۳) Heterosis studies in some elite multivoltine silkworm (Bombyx mori L.) races with popular bivoltine NB۴D۲. Int. J. Indust. Entomol. ۷‚ ۲۲۱- ۲۲۹. Kumaresan, P., Mahadevamurthy, T.S., Thangavelu, K. and Sinha, R.K. (۲۰۰۳a ) Further studies on the genetic divergence of multivoltine silkworm (Bombyx mori L.) genotypes based on economic characters. Entomon, ۲۸‚ ۱۹۳-۱۹۸.  Kumaresan, P., Sinha, R.K., Mohan, B. and Thangavelu, K. (۲۰۰۴) Conservation of multivoltine silkworm (Bombyx mori L.) germplasm in IndiaAn Overview. Int. J. Indust. Entomol. ۹‚ ۱-۱۳. Kumaresan, P., Sinha, R.K. and Thangavelu, K. (۲۰۰۵) Phenotypic stability and G  E interaction in cocoon weight of multivoltine silkworm (Bombyx mori L.) genotypes. Indian J. Seric. ۴۴‚ ۱۳۶-۱۳۸. Murakami, A. (۱۹۹۴) Growth phenomena in Bombyx mori L. with a special reference to genetic factors responsible for growth acceleration and moultinism. Indian J. Seric. ۳۳‚ ۱۲-۱۴. Mukherjee, P., Mukherjee, S. and Kumaresan, P. (۱۹۹۹) An analysis of genetic divergence in Indian multivoltine silkworm (Bombyx mori L.) germplasm. Sericologia, ۳۹‚ ۳۳۷-۳۴۷. Narasimharaju, R., Govindan, R., Ashoka, J., Rayar, S.G. (۱۹۹۰) Genetic variability for quantitative traits in silkworm B. mori. Entomon, ۱۵‚ ۱۹۷-۲۰۱. Ramamohana Rao, P. and Nakada, T. (۱۹۹۸) Clustering of polyvoltine strains of the silkworm B. mori by image processing method: Significance of cocoon size and weight variables. Indian J. Seric. ۳۷‚ ۳۳-۳۹.

Keywords:

Polyvoltine silkworm genotypes , Genetic variation , divergence analysis