• International Journal of Industrial Entomology and Biomaterials
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• v.19 no.1
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• pp.187-192
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• 2009

Silk filament progression study applying backcross breeding with recipient parent Jata and donor parent Daba ecoraces of tropical tasar silkworm, Antheraea mylitta Drury conducted during 2006 to 2008, revealed introgression of filament denier (10.2 d) superior to both parents at BC4 level. Also, the silk waste (0.35%) and filament breaks (2.6 nos) were reduced compared to both parents, while the filament length (973 m) and non break filament (296 m) improved over donor and could attain closer to recipient parent. The best performance of Jata $\times$ Daba at F1 level, with highest silk filament length (1646 m) of 12.5 d denier, denotes heterosis impact on silk trait with parental heterogenousity, an advantage to exploit silk filament yield. The progression of quality in terms of finer filament denier, less silk waste and least number of filament breaks over both parents and improvement in filament length and non break filament over donor parent except for a marginal shortage against recipient at BC4 level indicates the prospects of Jata and Daba ecoraces as source of breeding material for qualitative improvement of tasar silk filament. The study suggests that the commercially important finer denier of tasar silk filament can be attained with minor reduction in silk yield of wild Jata ecorace by adopting repeated backcrossing for four generations with semi domesticated Daba ecorace.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.43-49
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• 2004

Ten promising polyvoltine mulberry silkworm strains(SDMGl, SDMG2, SDMG3, SDMG4, SDMWl, SDMW2, RMWl, RMW2, RMW3 and RMW4) that are superior in quantitative and qualitative traits have been synthesized in the polyvoltine breeding laboratory of Andhra Pradesh State Sericulture Research ＆ Development Institute, Hindupur through systematic hybridization and appropriate selection methods. After the genotypes were found homozygous for the desired traits, they have been crossed with 3 bivoltine testers $(APS8, APS4 and {NB_2}{D_4})$ and thirty new hybrid combinations were developed for the assessment of their hybrid performance. Phenotypic expressions of economically important quantitative and qualitative traits of fist filial generation were measured and subjected for statistical analysis. Evaluation Index and Subordinate Function methods were employed for the assessment of hybrid performance since they are widely used in silkworm hybrid evaluation. Total of seven poly${\times}$bivoltine combinations, which ranked high in both the methods, were selected as potential combinations for further field test. These combinations also ranked significantly higher than the control hybrid (APMl${\times}$APS8).

• Journal of Life Science
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• v.29 no.2
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• pp.272-278
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• 2019

The silkworm performs sexual reproduction for the production of its healthy offsprings from generations to generations. Parthenogenesis in the silkworm, Bombyx mori acquires immense use in the development of outstanding homozygouse lines with higher viability, hybrid vigour, combining ability and less phenotypic variability, and it can serve as a powerful tool in controlling sex of the offsprings as well as a useful tool in selection of breeding schemes. However, naturally occuring parthenogenesis in silkworm could not be found so far. Fortunately, artificial induction of parthenogenesis is possible in silkworm. So, it is very important to find out novel methods for induction of parthenogenesis. We investigated to attempt to get a novel parthenogenetic method. Accordingly, parthenogenetic studies on between unfertilized in vivo ovarian eggs of live silkworm moth(novel) and unfertilized in vitro ovarian eggs(conventional) taken out from live silkworm moth were investigated by hot water ($46^{\circ}C$), hot air ($46^{\circ}C$) and low temperature ($0^{\circ}C$ and $-20^{\circ}C$) treatments. The best ratio of parthenogenetic eggs was obtained with in vivo ovarian eggs of live silkworm moth rather than with in vitro ovarian eggs taken out from live silkworm moth in all the treatments. The optimum exposure time absolutely depended upon the temperatures of treatments and the forms of in vivo or in vitro ovarian eggs. From these results, we expect that in vivo artificial parthenogenetic treatments on live silkworm moth will be useful for the higher induction of parthenogenesis in the silkworm, B. mori.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2002.10a
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• pp.33-33
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• 2002

No Abstract, See Full Text

• Journal of Sericultural and Entomological Science
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• v.49 no.2
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• pp.51-55
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• 2007

Investigation of atmospheric data and rearing results was conducted to analyze the effects of atmospheric factors such as temperature and precipitation on silkworm in 8 rearing places in which local adaptation test was being conducted with different mulberry growth condition, soil and atmosphere during spring and autumn rearing season of 2006. The atmospheric characteristics of spring rearing time are as follows. The average temperatures of young silkworm, old silkworm, mounting were $17.7^{\circ}C$, $19.8^{\circ}C$, $21.5^{\circ}C$ respectively, and $1^{\circ}C$ higher than normal year. The precipitation of young silkworm, old silkworm, mounting were 15.1 mm, 6.9 mm, 7.0 mm, respectively, and 22.9 mm lower than normal year in old silkworm and mounting. The daylight hours in larval stage was 1.7 hour shorter than normal year, but no difference in mounting. Thus precipitation was lower and temperature was higher than normal year in 2006. The rearing results of 2006 were 1 kg lower than normal year in cocoon yields per 10,000 3 rd molted larvae, single cocoon weight and cocoon shell percentage were a little higher. The atmospheric characteristics of spring rearing season are as follows. The average temperatures of young silkworm, old silkworm, mounting were $25.1^{\circ}C$, $20.5^{\circ}C$ and $19.9^{\circ}C$ respectively, temperature in young silkworm was $1^{\circ}C$ higher than normal year, and temperature in old silkworm was $1.3^{\circ}C$ lower than normal year. The precipitation of young silkworm, old silkworm, mounting were 110.2 mm, 4.6 mm, 3.7 mm, respectively and there were little differences compared to normal year. The atmospheric condition of 2006 which was similar to normal year did not affect the autumn rearing results of 2006. Namely, the single cocoon weight and cocoon shell weight were not different from normal year, and the same was cocoon shell percentage.

• Journal of Sericultural and Entomological Science
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• v.29 no.2
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• pp.24-30
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• 1987

To investigate suitable breeding system for the improvement of economic characters of the sexlimited dark egg colour strains, the four kinds of breeding methods which are represented as sibmating, repeated backcrossing, multi-backcrossing every other generation, and repeated hybridization were detected from the P to the F6. 1. Pupation ratio was varied between the four kinds of breeding methods and decreased gradually in order of repeated hybridization, mult-backcrossing every other generation and sib-matinv, and repeated backcrossing. 2. Repeated backcrossing, multi-backcrossing every other generation, and repeated hybridization with the exception of sib-mating were consiered as available breeding methods to improve single cocoon weight, cocoon shell weight and cocoon shell ratio of the sex-limited dark egg colour strains. 3. As for the responses of the economic characters form the P to the F6, pupation ratio was fluctuant and unstable, on the other hand single cocoon weight, cocoon shell weight and cocoon shell ratio increased remarkably in the F2, but in the subsequant generatios the increasing rate of each characters were fluctuant irregularly. 4. After the original sex-limited dark egg colour strains were bred under the corresponding breeding methods, from the P to the F6 the economic characters were approached to the level of normal breeding silkworm lines'. 5. It came to the consideration that the autosomal fragment which was translocated on the W chromosome had no physiologically significant effect on the expression of the economic characters because the Expression index (E) of the sex-limited dark egg colour strains was similar to that of normal silkworm lines. 6. From the results, it comes to the conclusion that the useful breeding methods to improve the economic characters of the sex-limited dark egg colour strains will be a line separation including fixation of the characters.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.41-46
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• 2004

A breeding programme was initiated by utilizing a robust bivoltine breed CSR$_{18}$ and a polyvoltine breed Cambodge with the main objective of developing robust polyvoltine silkworm breeds/hybrids. At F$_1$ and F$_2$, parthenogenetic development was induced following warm water treatment of eggs at 46$^{\circ}C$ for 18 min followed by two backcrosses with Bl$_{67}$, an evolved polyvoltine breed. The newly developed breed was subjected for hybrid study using eight hybrid combinations in the laboratory at F$_{8}$ generation. F$_1$ hybrids between newly developed breed Bl$_{67}$ (Pg) and promising bivoltine breeds exhibited their superiority by expressing significant hybrid vigour for several economic characters like cocoon yield/10,000 larvae, cocoon weight, cocoon shell weight, cocoon shell ratio and denier. Study on cocoon shape variability revealed that cocoons of all the F$_1$ hybrids except BL$_{67}$ (Pg)${\times}$NB$_4$D$_2$ were found comparatively uniform in shape.pe.

• Journal of Sericultural and Entomological Science
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• v.43 no.1
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• pp.9-15
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• 2001

New Mulberry Cultivar, Milsungppong, was selected from F1 seedlings obtained by crossing the female, 4X Keomseolppong, and the male, Kaeryangppong. Local adaptability test has been carried out at five places(Suwon, Chunchun, Cheongju, Kongju and Sangju) for four years since 1992. Leaf quality was tested by silkworm rearing for two silkworm rearing seasons(spring and autumn) at Suwon in 1995. From these tests, Milsungppong was found to be superior to control cultivar, cultivar, Kaeryangppong, in productivity, rootability and shoot cold injury. The new cultivar, Milsungppong, has following agronomic characteristics as compared with Kaeryangppong, the most prevailing cultivar, Milsungppong, has following agronomic characteristics as compared with Kaeryangppong, the most prevailing cultivar in Korea It is triploid cultivar belonging to Morus bombycis KOIDZ with the leaf shape of five lobes, sprouting in spring nearly the same to the Kaeryangppong (Morus alba L.), high leaf yielding of 25% compared to Kaeryangppong (Morus alba L.) and the medium degree of cold resistance. It is adaptable to every where in Korea except the area cold injury broken out habitually. Milsungppong is recommended to rear silkworms not only in spring but also in autumn besides for young silkworms.

• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.2
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• pp.121-126
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• 2002

Breeding programme was initiated during November, 1995 with the main objective to breed productive multivoltine breeds/ hybrids with suitable genetic constitution to suit the fluctuating tropical climate prevailed in India. Two multivoltine breeds viz., BL-24 and BL-27 selected were as breeding resource materials from the silkworm germplasm maintained at Central Sericul-tural Research and Training Institute, Mysore. By adopting hybridization, backcrossing inbreeding and selection, a new multivoltine breed namely BL-67. This breed spins light greenish yellow cocoons and cocoon shape is oval with medium to coarse grains. The evolved breed was crossed with five tropical bivoltine breeds viz., NB4D2, CSR2, CSR5, CSR18 and CSR101 to study the combining ability, and identified a superior hybrid, BL67 ${\times}$ CSR101, named as CAUVERY, The hybrid is characterized by high pupation rate (>95%), high shell weight (> 35 cg), high cocoon shell ratio (> 20%), longer filament length (> 900 m) and high neatness (93) with a renditta of 6.5 producing 2A-3A grade silk. The hybrid is selected for Race Autho-rization test of Central Silk Board.

• International Journal of Industrial Entomology and Biomaterials
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• v.10 no.2
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• pp.147-151
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• 2005

Serious attempt for the improvement of quality parameters in silkworm hybrids came rather very late in India. Realising the need for productive breeds to the field and reorientation in breeding methodology, the silkworm breeders of CSRTI, Mysore were able to develop silkworm breeds with fine denier namely, JPN7, CSR48, B63 and B65 of specific industrial requirement through directional selection. As the success of silkworm breeds mainly depends on their combining ability, the developed breeds were subjected for hybrid evaluation. Out of 42 bivoltine hybrids studied, one hybrid, $CSR48{\times}CSR5$ was identified for its superiority over the existing bivoltine hybrids namely $CSR2{\times}CSR4,\;CSR2{\times}CSR5\;and\;CSR18{\times}CSR19$ for majority of qualitative traits. Post cocoon testing of large quantity of cocoons of $CSR48{\times}CSR5$ resulted in the production of high quality '3A'grade silk. It is for the first time in the Indian Sericulture industry that high quality silk with longer filament length of 1474 m, denier of 2.47, standard size deviation of 0.983 d, maximum size deviation of 1.322, neatness of 96 p, reelability of $85\%$, tenacity of 3.87 g/d, elongation of $22.32\%$ and cohesion of 110 strokes was produced. The superiority of fine denier silkworm breeds and their hybrids are discussed.