Multivoltine Silkworm (Bombyx Mori L.) Strains for Rearing Exclusively On Artificial Diet During Young Stage, Developed Through Directional Breeding Strategy

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Year:
2013
Type of Publication:
Article
Keywords:
Artificial Diet, Cocoon Traits, Feeding Response, Multivoltine Strains, Silkworm
Authors:
Jula S. Nair; S. Nirmal Kumar; K. Sashindran Nair
Journal:
IJISM
Volume:
1
Number:
1
Pages:
4-8
Month:
November
Abstract:
Rearing young stage silkworms on artificial diet for commercial purpose is a relatively new development. Silkworm is a typical monophagous lepidopteran raised on mulberry leaves. As component multivoltine pure strains of existing popular multivoltine x bivoltine silkworm hybrids did not accept the artificial diet, the study was taken up to create a pool of such strains which would feed on the artificial diet. Four strains viz., Moria, MAD, 2000K and LMO were short-listed based on the results of an initial screening which recorded feeding response percentage of more than 40. These four strains were further subjected to continuous inbreeding and directional selection for 11 generations for improving the feeding response over the generations and stabilizing it at more than 85 % so that they would form suitable breeding resource materials for preparation of commercial multi x bivoltine hybrids for exclusively rearing on artificial diet during young instar. Care was taken so that breed characters in terms of economic traits were not adversely affected. At the end of eighth generation, the feeding response reached above 88 % and further stabilized at the higher level and thus forming prospective parents for the hybrid combinations with bivoltine parents developed similarly. Data pertaining to G8~G11 were analyzed to check the stability in performance. The traits with particular reference to the diet phase such as feeding response, young instar larval duration and young instar larval weight have reflected non-significant differences in the last four generations indicating the stability in these traits. Other traits such as cocoon weight, cocoon shell weight, survival and cocoon yield also did not vary significantly among the generations in three out of four races. After the strains were stabilized for rearing on artificial diet, they were designated as Moria(A), MAD(A), 2000K(A) and LMO(A) as these strains are different from the normal strains, Moria, MAD, 2000K and LMO. The implications of the improved feeding response and stabilized economic traits in the context of this study are discussed.
Full text: IJISM_02.pdf