• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.47-51
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• 2004

To evolve silkworm hybrids with higher survival and productivity and easy and effective seed cocoon production, three new evolved bivoltine hybrids of silkworm (Bombyx mori L.), created with participation of sex-limited lines at eggs and larva stage were evaluated with control Super$_1$${\times}$Hessa$_2$ hybrid at Plovdiv Agrarian University during 2000 - 2002. ANOVA analysis was employed and the performance of hybrids was observed in respect of main quantitative traits. The results obtained show significant superiority of new hybrids T$_{15}$ 4/${\times}$TBV$_{2}$24/, XT$_{215}$38/${\times}$TV$_{3}$2/, XT$_{215}$38/${\times}$B$_{2}$6/ and their reciprocal crosses over the control. They were characterized with 99% hatchability of eggs, 93-95% silkworm survival, 2.32- 2.42 g cocoon weight, 53.5-55.7 cg shell weight, 22.9-23.1% shell ratio, 1,307-1,326 m filament length, 3.08-3.17 denier, 95-96% reelability, 44.4-45.1% silk ratio, 569-593 number of normal eggs per lying and 347-364 mg weight of normal eggs per lying. Newly evolved hybrids were manifested high productivity, 41.0-43.6 kg cocoon yield and 7.33-7.78 kg raw silk yield per one box (20,000$\pm$200 viable eggs), which significant surpass the control Super$_1$${\times}$Hessa$_2$ hybrid with 7.6-14.4% and 10.8-17.6%, respectively. T$_{15}$ 4/${\times}$TBV$_{2}$24/ and XT$_{215}$38/${\times}$TV$_{3}$2/ were considered as highly productive hybrids to local conditions and found suitable to rear in spring season.n.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.27-32
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• 2004

With an objective of evolving quantitatively and qualitatively superior bivolitine silkworm hybrid of Bombyxmori L. for tropics with shorter larval duration without compromising on productivity traits, a breeding programme was initiated at this institute during 1997 by utilizing breeding resource material from the institutes Germplasm collection. The breed SD7 is characterized with plain larvae spinning white oval cocoons and SD12 is characterized by sex-limited larval markings spinning white dumb-bell cocoons. After fixation, these breeds along with other newly evolved breeds were subjected for hybrid evaluation in the laboratory. Based on the hybrid studies, the hybrid SD7${\times}$SD12 was selected and evaluated for one year comprising three major sea- sons (6 trials) of tropics viz., Pre-monsoon (characterized by high temperature, low humidity and without any rain fall), Monsoon (characterized by moderate temperature, heavy rain fall with high humidity) and post-monsoon season (characterized by low temperature and low humidity with frequent rain fall) to know the fluctuations in the larval duration. The evaluation studies indicated that the hybrid is having shorter larval duration with productive merits. The hybrid SD7${\times}$SD12 recorded survival percent of 92.74, shell weight of 46.7 cg, shell ratio % of 24.0 and filament length of 1,200 meters with a shorter larval duration of 24 hrs; when compared to productive hybrid CSR2${\times}$CSR5(control). The breeding methodologies and hybrids usefulness for tropics were discussed.