• International Journal of Industrial Entomology and Biomaterials
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• 제2권2호
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• pp.123-127
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• 2001

In order to introduce bivoltine races in a tropical country like India, it is necessary to have stability in cocoon crop under high temperature environments. Unlike any temperate country like Japan, the rearing conditions/environment, climatic conditions, quality of mulberry leaf and incidence of diseases are unpredictable in India. Geneticists and breeders of all the sericultural countries have experienced the influence of environment during the process of breeding. in order to select efficiently the breeds with high temperature tolerance, it is verb important to analyse clearly the heritability nature of high temperature tolerance. In light of the above, the present study was undertaken to determine the effect of high temperature treatment of (A) $35{\pm}1^{\circ}C$ and 85${\pm}$5% RH for 24 hrs continuously, (B) $35{\pm}1^{\circ}C$ and 85${\pm}$5% RH for 48 hrs continuously and (C) the control (25${\pm}1^{\circ}$ and 65${\pm}$5% RH in the normal rearing condition from the $3^{rd}of5^{th}$ instar on the pure races such as Moria, Nl37 and Cl46 as well as their Fl hybrids. The overall performance indicate that the hybrids are mare tolerant than the pure races. it was also observed that the overall performance declined in those batches where 48 hrs treatment was given. The most interesting observation noticed in this study was that there was maternal effect regarding temperature tolerance as evident from the better performance of those hybrids where the female parent used was more tolerant as pure race.

• International Journal of Industrial Entomology and Biomaterials
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• 제12권2호
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• pp.51-56
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• 2006

Use of products containing phytoecdysteroid (PE) as active principle has become popular in prominent sericultural areas of India for hastening larval maturation events and synchronizing cocoon spinning activities as an obvious advantage is assured. At times, the present recommendation of administering PE at the onset of spinning results in peak labour requirement at odd hrs. To enable making recommendation for the use of PE on $multi{\times}bivoltine$ silkworm hybrids based on the climatic conditions prevailing in different areas especially with regard to temperature, the experiment was taken up to determine proper treatment times so that the induced spinning will be more orderly and the labour can be leveraged more efficiently. Different brackets of low ($18-22^{\circ}C$), medium ($24-28^{\circ}C$) and high ($29-32^{\circ}C$) temperature were simulated during the latter half of V larval instar and cocoon spinning. PE was administered to $multi{\times}bivoltine$ silkworm ($BL67{\times}CSR101$) hybrid batches as per the recommended dose at three different times viz., 10 am, 4 pm and 10 pm. Three replicates of 100 larvae were maintained for each treatment. Absolute controls were also maintained in each temperature range to compare the results. Cumulative maturation percentage was recorded at 6 hrs interval to ascertain peak mounting span. The influence of the treatment on the cocoon traits also was studied. Based on the peak mounting span, it was evident that in low temperature 10 pm treatment would be better. In medium and high temperature, treatment at 4 pm proved to be a better option. The influence of the treatment times at different temperature range on labour management is discussed.

• International Journal of Industrial Entomology and Biomaterials
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• 제3권2호
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• pp.127-133
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• 2001

With an objective of evolving quantitatively and qualitatively superior bivoltine breeds/hybrids of silkworm Bombyx mori L. for tropical conditions, breeding work was initiated in Central Sericultural Research and Training Institute, Mysore during 1992 by utilizing two Japanese hybrids namely BNl8$\times$BCS25 and Shunrei$\times$Shogetsu along with Indian evolved breed, KA. The breed CSR12 which is characterized with sex-limited larval marking and white oval cocoons was evolved from the Japanese hybrid BNl8 ${\times}$ BCS25 by crossing with KA, while the breed CSR6 which is characterized with normal marking (marked larvae) and white dumbbell cocoons was extracted from the Japanese commercial hybrid Shunrei${\times}$Shogetsu through continuous inbreeding coupled with selection. After fixation, these breeds along with other newly evolved breeds were subjected to hybrid study under optimum environmental conditions in the laboratory for expression of full potential of the genotypes. These hybrids were evaluated by Multiple Trait Evaluation Index (Mano et al., 1993). The hybrid CSR12${\times}$CSR6 was selected based multiple trait evaluation index value. The hybrid CSR12$\times$CSR6 recorded survival of 96.0%, shell weight of 50.0 cg, shell ratio of 24.3%, raw silk percentage of 19.6, filament length of 1,216 m, boil off loss of 22.4% and renditta of 5.1. On the other hand, the control hybrid (KA ${\times}$ NB4D2) has recorded survival of 90.6%, shell weight of 42.1 cg, shell ratio of 20.4%, raw silk percentage of 15.9, filament length of 999 m, boil off loss of 24.8% and renditta of 6.3. The hybrid CSR12$\times$CSR6 was authorized during 1997 by Central Silk Board, Government of India for commercial exploitation during favourable months based on national level race authorization test.

• International Journal of Industrial Entomology and Biomaterials
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• 제12권1호
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• pp.29-34
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• 2006

A breeding programme was initiated during 2001 utilizing two polyvoltine silkworm breeds viz. $BL_{69}$, an evolved breed tolerant to high temperature and MAR, comparatively resistant to Bombyx mori nuclear polyhedrosis virus (BmNPV) with the objective to develop robust polyvoltine breeds and hybrids. The breed $NP_1$ was developed by exposing the fifth instar larvae to high temperature $(36{\pm}1^{\circ}C)$, high Relative Humidity ($85{\pm}5%$ R.H.) and inoculating third instar larvae with BmNPV inoculum. At $F_{12}$, the breed was tested for hybrid forming ability utilizing six bivoltine silkworm breeds viz. $CSR_2,\;CSR_4,\;CSR_{17},\;CSR_{18},\;CSR_{19}\;and\;NB_4D_2$. The hybrid $'NP_1{\times}CSR_{17}'$ exhibited its superiority by recording 97.2% survival, 1.892 g cocoon weight, 0.406 g cocoon shell weight, 21.5% cocoon shell ratio, 16.6% raw silk percentage and 890 m filament length whereas the control $(PM{\times}CSR_2)$ has recorded 90.2% survival, 1.599 g cocoon weight, 0.304 g cocoon shell weight, 18.9% cocoon shell ratio, 13.1 % raw silk percentage and 768 m filament length. Commercial exploitation of the new $polyvoltine{\times}bivoltine$ hybrid in sericulture industry has been discussed.

• International Journal of Industrial Entomology and Biomaterials
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• 제4권2호
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• pp.169-173
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• 2002

A practical technology for silkworm disease management at farmer\\`s level was suggested and test verified for its efficacy and adaptability. The technology consisted of disinfection of rearing house and appliances, early disease diagnosis, personal and rearing hygiene and silkworm body and rearing seat disinfection. Besides, the supportive techniques associated in disease management are cited. The validation trials of the technology involving 845 farmers crops with 147,530 disease free layings (dfls) of CSR bivoltine hybrids confirmed the effectiveness of the technology which resulted an average yield of 68.98 kg cocoons/100 dfls.

• International Journal of Industrial Entomology and Biomaterials
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• 제3권2호
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• pp.153-155
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• 2001

Eight new three-way cross heterozygotic hybrid genotypes of the mulberry silkworm Bombyx mori, resulted from hybridization of multivoltine as female and bivoltine Fl hybrid as male component, have been evaluated for the cumulative effect of nine traits of commercial economic importance with the objective of selecting out the most prospective ones for their exploitation as an intermediate technology during unfavorable season. Five of them namely, G(P5${\times}$NBl8) (E.I. =57.23); S(NB18${\times}$P5) (E.I. : 55.48); S(P5${\times}$NBl8) (E.I. = 52.44); S(KBN${\times}$B7) (E.I. = 50.42) and S(NB7${\times}$KB) (E.I. : 50.16) have scored higher values of the Evaluation Index (E.I.) and could be selected in the same order for exploitation during unfavorable seasons in tropical climates.

• International Journal of Industrial Entomology and Biomaterials
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• 제5권2호
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• pp.153-162
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• 2002

Earlier breeding experiments undertaken at Central Sericultural Research and Training Institute, Mysore, India since a decade had resulted in the development of many productive and qualitatively superior bivoltine hybrids. However, the hot climatic conditions of tropics prevailing particularly in summer are not conducive to rear these high yielding bivoltine hybrids. This has necessitated breeding of compatible bivoltine hybrids for year-round rearing. Accordingly, the Japanese hybrid, B2Ol ${\times}$ BCS12 which was found to be tolerant to high temperature was used as breeding resource material. Following hybridization and selection rearing of silkworms was taken up in SERICATRON (Environmental chamber with precise and automatic control facilities for uniform maintenance of temperature and humidity) at high temperature of $36{\times}1^{\circ}C$ and 85${\times}$5% RH in fifth instar and the control batches at $25{\times}1^{\circ}C$ and 65{\times}$5% RH. Directional selection was resorted to the batches reared at 36$\pm$1$^{\circ}C$ till F$_{5}$ keeping pupation rate as important selection criteria. From $F_{2}% onwards the experiment was modified in such a way as to conduct normal rearing every alternate generation to regain the lost vitality due to continuous exposure to high temperature and high humidity stress. At $F_{2}$ , Oval and dumb-bell cocoons were separated out and designated as CSR18 and CSR19, respectively. By utilizing these lines at $F_{12}$, the hybrid CSR18$\times$CSR19 was prepared and studied for the thermotolerance by subjecting to stress condition at high temperature of 36$\pm$1$^{\circ}C$ and 85$\pm$5% RH in fifth instar and the control batches at $25{\times}1^{\circ}C$ and 65${\times}$5% RH. The better performance of CSR18${\times}$CSR19 (survival > 88%) at $36{\times}1^{\circ}C$ clearly indicates the general superiority of CSR18${\times}$CSR19 with regard to high temperature tolerance over the productive hybrids and CSR18$\times$CSR19 can perform well in varied agro-climatic conditions of the tropics with optimum qualitative and quantitative characteristics.s.

• International Journal of Industrial Entomology and Biomaterials
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• 제4권1호
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• pp.23-30
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• 2002

The general and specific combining abilities and hybrid vigour of seven polyvoltine breeds [BL24, BL62, BL6S, BL67, BL68, BL69, and Pure Mysore (PM)] with five bivoltine breeds (NB4D2, CSR2, CSR5, CSR18 and CSR19) were evaluated in a line ${times}$ tester design by analysing six quantitative traits viz., fecundity, yield 110,000 larvae both by number and weight, cocoon weight, shell weight and cocoon shell ratio. ANOVA estimates showed significant effects for all the traits indicating the role of both additive and non- additive gene actions. Estimation of GCA revealed that the breed BL67 exhibited significant positive effects toy all the six traits followed by BL68 for four important economic traits viz., fecundity, cocoon weight, shell weight and cocoon shell ratio. Among testers, CSR5 showed significant GCA effects for five traits whereas CSR2 exhibited for shell weight and shell ratio. Three hybrids viz., BL67${times}$ NB4D2, BL67 ${times}$CSR5 and BL67${times}$ CSR19 excelled in four quantitative traits for SCA. Majority of the hybrids expressed positive hybrid vigour for cocoon yield/10,000 larvae by weight, cocoon weight and shell weight. Four hybrids namely PM ${times}$ NB4D2, BL67 ${times}$NB4D2, BL67${times}$ CSR5 and BL67${times}$ CSR19 manifesting positive hybrid vigour for five economic traits were adjudicated as best Heterotic hybrids and recommended for commercial exploitation to increase the silk yield.

• International Journal of Industrial Entomology and Biomaterials
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• 제8권2호
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• pp.129-133
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• 2004

The breeding work was initiated by utilizing two Japanese hybrids namely C135${\times}$N134 and N137${\times}$C146 along with two evolved Indian breeds, J14 and A24. The breed CSR16 which is characterized with marked larvae and white dumbbell cocoons was evolved from the Japanese hybrid C135${\times}$N134 by crossing with J14, while the breed CSR17 which is characterized with plain larvae and white oval cocoons was evolved from the Japanese hybrid N137${\times}$C146 by crossing with A24. The hybrid of these evolved breeds i.e., CSR16${\times}$CSR17 has shown superior over control hybrid $KA{\times}{NB_4}{D_2}$ and on par with the ruling hybrid of CSR2${\times}$CSR4. The hybrid CSR16${\times}$CSR17 was authorized during 1999 by Central Silk Board, Bangalore, Government of India for commercial exploitation during favourable months based on national level race authorization test.

• International Journal of Industrial Entomology and Biomaterials
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• 제4권2호
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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.