• International Journal of Industrial Entomology and Biomaterials
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• v.16 no.1
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• pp.15-20
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• 2008

Under the all India programme of evaluation of mulberry and silkworm genotypes, twelve bivoltine silkworm breeds obtained from Central Silkworm Germplasm Resource Centre, Hosur (CSGRC) were evaluated at the bivoltine silkworm breeding laboratory, Central Sericultural Research & Training Institute, Mysore (CSR&TI). These breeds were tested during September-October 2003, August-September 2004 and February-March 2005. The average temperature and humidity during September-October 2003 was $26.5^{\circ}C$ and 72.6% RH, while during August-September 2004, it was $26.5^{\circ}C$ and 75.2% RH and during February-March 2005 it was $24^{\circ}C$ and 48% RH respectively. The performance of the breeds in respect of 21 traits was studied and statistically analyzed using analysis of variance (Singh and Choudhary, 1985). Silkworm breeds were short-listed using multiple trait evaluation index method as suggested by Mano et at., (1993). Evaluation Index values were calculated for all the 11 traits of economic importance and six breeds were short-listed based on average index value 50 and above 50. Two breed viz., BV 183 (SMGS-1) have recorded average E.I. >50 in 10 traits (except in neatness) and ranked first and the breed BV 262 (SMGS9) with E.I. value >50 in nine traits except in cocoon weight and neatness ranked second, in the order of merit. These two breeds may be selected as resource material for evolving region specific silkworm breeds.

• International Journal of Industrial Entomology and Biomaterials
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• v.26 no.1
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• pp.22-30
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• 2013

The reproductive performance of multivoltine breed 'Nistari' and bivoltine breeds as NB18, P5 and a bivoltine hybrid (NB18 ${\times}$ P5) of B. mori were studied in different seasons in terms of total number of eggs laid, unlaid and hatching efficiency of the laid eggs to critically assess the breeds / hybrid potentiality. The bivoltine hybrid showed better performance in all the seasons as compared to the breeds investigated, as expected due to possibility of hybrid vigour. Among the breeds, bivoltine P5 had a better egg laid performance in S1 (February - March), S2 (May - June) and S3 (September - October) seasons but with an increase in the number of unlaid eggs. The hatching percentage, although didn't show any definitive trend, still suggested a marginal better performance in the hybrid. Most importantly, egg laying rhythmicity was studied by mating the female moth at 6.00 a.m. for $3{\frac{1}{2}}$ hours, and subsequently allowing the laying of eggs both under BOD condition ($25{\pm}1^{\circ}C$ and $85{\pm}5%$ RH) and at ambient temperature ($23-28^{\circ}C$ and $74.7{\pm}5%$) separately. Maximum (90%) egg laid occurred from 3.30 to 7.30 pm (i.e. 4 - 6 h after decoupling). Similar laying patterns were observed when females where mated at 12 noon and decoupled at 3.30 pm, revealing that late photoperiod and early scotoperiod were favourable for egg laying in case of multivoltine breed and bivoltine prefers late photoperiod for egg laying.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.2
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• pp.187-191
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• 2011

An attempt was made to assess the potentiality of bivoltine double hybrids under simulated conditions of farmers to identify the suitable bivoltine double hybrid combination. Four bivoltine double hybrids developed at Central Sericultural Research and Training Institute (CSRTI), Mysore along with popular single hybrid, $CSR2{\times}CSR4$ as control was assessed for economic traits. The rearing results showed significant improvement of 20-24% in fecundity of the double hybrids studied over single hybrid. Among the double hybrids, $[D7{\times}S5]{\times}[D13{\times}S1]$ recorded significantly higher survival (89.58 %), cocoon yield (76.328 kg/ 50,000 eggs), cocoon price (Rs. 180.87/kg) and lower cocoon leaf ratio of 1: 21.80. The performance of the reeling traits were also found significantly superior in $[D7{\times}S5]{\times}[D13{\times}S1]$ with higher filament length (1100 m), reelability (88%), raw silk (18.55%) and neatness (92 points) compared to $CSR2{\times}CSR4$ and other double hybrids evaluated. Besides, the cocoons of $[D7{\times}S5]{\times}[D13{\times}S1]$ exhibit uniformity in size with a standard deviation of < 8. Overall data indicated the superiority of $[D7{\times}S5]{\times}[D13{\times}S1]$ compared to the other hybrids evaluated and it has profound influence in expressing the full potentiality in the field.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.2
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• pp.273-277
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• 2004

Variation in the size of the silk filament will determine the uniformity and quality of the silk reeled. In the present study, an attempt has been made to study the filament size variation in 6 multivoltine parental breeds and 9 multivoltine ${\times}$ bivoltine hybrids in all three seasons of a year. All multivoltine breeds and multivoltine ${\times}$ bivoltine hybrids showed variation in filament size throughout its length from the outer layer to inner layer. Results of the present study indicated that the size of the filament decreased from outer to inner layer. The decrease in filament size was sudden in some breeds/hybrids whereas it was gradual in other. Relationship between filament length to that of slope, average filament size to slope, and maximum filament size to slope was determined based on regression analysis. Regression analysis revealed significant positive correlation between slope vs average filament length (r=0.92$^{**}$) in multivoltine${\times}$bivoltine hybrids. Among parental breeds, 96C showed lowest slope of the curve (b-value: -0.00428) and 96A showed highest slope of the curve (b-value: -0.00269). Among 9 hybrids, PM${\times}$N $B_4$ $D_2$ recorded lowest slope value (b-value: -0.00328) and BL24${\times}$N $B_4$ $D_2$ showed highest value for slope of the curve (b-value: -0.00234). The breed 96C, which showed lowest slope value can be utilized for future breeding programmes to breed strains with less size deviation. Three multivoltine${\times}$bivoltine hybrids viz., PM${\times}$N $B_4$ $D_2$, 96E${\times}$CSR19 and BL67${\times}$CS $R_{101}$ , which showed less slope values (b-values: -0.00328, -0.00300 and -0.00297 respectively) can be utilized for commercial exploitation to produce uniform silk.k.

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.1
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• pp.34-43
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• 2023

The eighteen (18) F₁ hybrid combinations were tested to identify potential combinations adaptable to type 1 climatic conditions in the Philippines. The six (6) bivoltine purelines (DMMMSU 108, DMMMSU 109, DMMMSU 110, DMMMSU 111, DMMMSU 113, and DMMMSU 119); and three (3) multivoltine purelines (DMMMSU 1000, DMMMSU 1007, and DMMMSU 1014), were crossed (multivoltine x bivoltine) in a mating plan. These were arranged in a Completely Randomized Design (CRD), replicated three times, and analyzed using Analysis of Variance (ANOVA). A test of significance was done using ANOVA across years and Tukey's Honest Significant Difference Test (HSD). The multiple trait evaluation index (EI) method was also used in the identification of potential F₁ hybrids. Three major phases were done: (1) parental rearing of multivoltine and bivoltine pure lines for breed multiplication; (2) hybridization process; and (3) evaluation of F₁ hybrids. Rearing evaluations were conducted for three consecutive years. Based from the three evaluations, 10 potential crosses were identified: DMMMSU MV-12, DMMMSU MV-11, DMMMSU MV-13, DMMMSU MV-16, DMMMSU MV-07, DMMMSU MV-14, DMMMSU MV-05, DMMMSU MV-09, DMMMSU MV-03, and DMMSU MV-10. The topmost combinations with the best economic and commercial characters and are consistently adaptable during two (2) cropping seasons were DMMMSU MV-07, DMMMSU MV-12, DMMMSU MV-05, DMMMSU MV-09 and DMMMSU MV-11. These newly-identified F₁ hybrids are considered potential breeds that could improve cocoon production.

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.2
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• pp.213-216
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• 2002

Food consumption and conversion efficiency of new bivoltine hybrids (CSR2$\times$CSR4 and CSR2$\times$CSR5) were studied under restricted feeding levels (10, 20 and 30% less quantity of mulberry leaves). The data were compared with a control fed with standard quantum of feed as per the recommendation. The nutritional indices parameters i. e. ingests, digesta, approximate digestibility (%) and reference ratio were recorded higher in control batches compared to less feed batches while nutritional efficiency parameters i. e., ECI and ECD to cocoon and shell were recorded significantly higher in restricted feeding level batches. This increase is attributed due to the physiological adaptation under nutritional stress condition.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.15-19
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• 2003

The study evaluated the influence of feeding different maturity leaves i.e., tender, medium, coarse and mixed leaves of three different maturity during late larval stages of new bivoltine race $(CSR_{3} {\times} CSR_{6})$. The data were compared with shoot feeding and control batches in which conventional feeding method was followed. The most of the larval and cocoon characters were recorded significantly higher in tender leaves fed batches followed by T4 batch (2 times tender and 1 time coarse leaves). Lowest melting percentage (1.494%) was recorded in T4 and highest (4.69%) was recorded in coarse leaf (T3) fed batches. Significantly higher post cocoon parameters viz., average filament length, non-breakable filament length, renditta and raw silk percentage were recorded in tender loaves fed batches.

• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.1
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• pp.37-41
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• 2002

Heterosis studies on rearing performance of 25 Fl Polyvoltine $\times$ bivoltine (sex-limited cocoon colour) hybrids revealed that manifestation of heterosis was highly significant for majority of the economic traits contributing to more silk yield. Five hybrids namely BL24${\times}$ CSR 19 (SL), BL24${\times}$${\times}$${\times}$${\times}$${\times}$

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.37-43
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• 2002

Eighteen new bivoltine silkworm (Bombyx mori L.) hybrids developed at Andhra Pradesh State Sericul-ture Research and Development Institute, Hindupur are evaluated for 10 economic traits by following two multiple trait index methods, i.e., Subordinate Function and Evaluation Index for their economic merit. The hybrid genotype, APS6${\times}$APS11 with highest Subordinate function value of 8.2432 and highest average Evaluation Index of 61.67 ranked first. This hybrid is adjudicated as most promising hybrid and recommended for commercial use. Further, applicability of Subordinate Function Index Method is tested and recommended for application of multiple trait evaluation similar to Evaluation Index Method as the results obtained are comparable. Further, both these methods can be applied for confirmation of results.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.2
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• pp.239-243
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• 2011

Thirty five bivoltine breeds were acclimatized under controlled condition for three years during two seasons to evaluate their efficiency in Seri industry of tropical region. Out of thirty five ten breeds had been short listed based on ranking for individual trait. Three breeds out of those ten selected breeds viz. SK6, NB18 and B.Con.4 ranked top in respect of overall performance. The ten breeds based on average Evaluation Index value > 50 considering twelve economically important traits are the resource material for future course of breeding program in West Bengal.