• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.1
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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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• 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 Sericultural and Entomological Science
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• v.37 no.1
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• pp.27-32
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• 1995

Studies were carried out to report breeding procedure and characteristics of Fb, a strain of silkworm with abnormal food habit polyphagous. Selection was continued up to the 14th generation toward higher incidence of cabbage leaves feeding variants. In the autumn of 1992(7th generation), selected strain were subjected to severe selection by feeding them on artificial diet that did not contain mulberry leaf powder. The results were clearly positive and reached to higher than 95% of cabbage feeding in the 14th generation. This strain was first discovered by feeding cabbage leaves, but later they were observed to eat some kind of plants like lettuce, Chinese cabbage, radish, beet, apple, persimmon, pear, etc. As described above the procedure, cabbage feeding trait was clearly heritable. The strain responsible for this traits was named Fb.

• Journal of Sericultural and Entomological Science
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• v.37 no.2
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• pp.235-243
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• 1995

Recently, the cocoon production is reducing very steeply in Japan. The main reason for this cocoon reduction is due to high labor cost and the production expense is apt to rise year by year. Accordingly, the improvement of cocoon productivity by retrenchment of the production expense is intensively required in my country. Therefore, the silkworm rearing on the artificial diet is largely expected as the innovation techniques of sericulture. Since rearing of the silkworm on artificial diets has first been achieved in 1960, and the silkworm larvae were reared throughout all the instars on artificial diets(Fukuda et al., 1960, Ito & Tanaka, 1960). The artificial diets used at this time contained 50% or more of dried, pulverized mulberyy leaves as one of the main ingredients, and the composition was rather simple. When reared on these diets, larval growth and development were retarded, small cocoons appeared, and the adults laid only a small number of eggs. At first, we would like to study about nutritional requirement of the silkworm, using the chemically defined diet which prepared artificially. Subsequently, attempts were made to improve the diets by replacement of crude ingredients with possibly purer compounds, as mentioned later. Before giving the details on individual nutrient, I would like to summarize about the outline of utilization flow of various nutrients through the larval-pupal development and these daily quantitative requirements per body weight in the silkworm when they were reared on mulberry leaves.

• Mycobiology
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• v.38 no.3
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• pp.180-183
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• 2010

This study was conducted out to select a silkworm variety suitable for synnemata production of Isaria tenuipes. Four kinds of the mulberry silkworm varieties, Bombyx mori, were hybridized using a Japanese parental line and a Chinese parental line, and used to test for synemata formation in I. tenuipes. The larval period of normal silkworms was 22 hr longer than the silkworms inoculated with this fungus. Among the silkworm varieties tested, Hachojam had the shortest larval period with 23.02 days. The non-cocooning silkworm had a shorter larval period than the cocoon producing silkworms. The pupation rate of normal silkworms was about 9% higher than that of silkworms sprayed with I. tenuipes. Hachojam had the highest infection rate at 99.8%, but no significant difference was observed for the infection rate by silkworm variety. The production of synnemata was the best in JS171 $\times$ CS188 with an incidence rate of 99.3%, followed by Hachojam, and Chugangjam. The synnemata produced from Hachojam were the heaviest and showed white or milky-white in color.

• International Journal of Industrial Entomology and Biomaterials
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• v.13 no.2
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• pp.109-112
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• 2006

The use of commercial silkworm hybrids resistant to important silkworm diseases is economical and better option particularly in tropical areas. This necessitated the evolution of productive bivoltine silkworm breeds non-susceptible to $BmDNV_1$. Non-susceptibility to $BmDNV_1$, infection was found to be controlled by a single recessive gene, nsd-l or a dominant gene, Nid-l. A major dominant/recessive gene confers resistance to $BmDNV_1$, from potent donor parents have been transferred to 10 productive but susceptible bivoltine silkworm strains through conventional breeding methods. By utilizing these breeds prepared 25 hybrids $(5{\times}5)$ and hybrid evaluation was carried out to identify most promising hybrids resistant to $BmDNV_1$. All these hybrids are inoculated with $BmDNV_1$ inoculum along with productive control hybrid $CSR2{\times}CSR4$ and reared under standard rearing procedure. Based on inoculated rearing and test reeling results, two most promising hybrids $(CSR18DR{\times}CSR29DR\;and\;CSR21DR{\times}CSR50DR)$ were selected for commercial exploitation. The selected hybrids have shown a survival rate of >85% with productive traits, where as control hybrid have shown 11.1% survival with inferior cocoon traits. The methodologies adopted were discussed.

• 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.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.377-385
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• 2022

Most pruning branches of mulberry, Korean raspberry (bokbunja), and blueberries are discarded without use. These discarded pruning branches were utilized as feed in the investigation of the development and oviposition characteristics of Protaetia brevitarsis with a focus on breeding possibilities. It was observed that the developmental period of P. brevitarsis larvae fed with berry fermented sawdust from mulberry, bokbunja, and blueberry was shortened to 157.3 130.3 days, and 140 days, respectively, compared to 169.3 days for those fed with oak fermented sawdust. The weight and survival rate of the larvae also increased. Under all three types of fermented sawdust feed, the percentage of larvae with weight ≧ 2.5 g during the group was over 60% between 6-8 weeks after hatching; however under oak fermented sawdust feed, it was within 10%, and the percentage only increased after 10 weeks. The average number of eggs laid per female was ≧ 80, with an average oviposition period of approximately 9 weeks; however, there was no significant difference owing to the large deviation per individual. Furthermore, mixed fermented sawdust from the three berries enhanced the growth rate of larvae, and there was no difference in the number of eggs laid compared to those fed with control oak fermented sawdust. Our study demonstrates berry fermentation sawdust is just as effective as oak fermentation sawdust in the breeding of P. brevitarsis.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.2
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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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• v.45 no.1
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• pp.22-28
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• 2022

Silkworms are very sensitive to changes in temperature and humidity, and unless it is a suitable temperature and humidity to grow, the productivity and quality of silkworms are greatly reduced. Therefore, it is very important to manage temperature and humidity for silkworm feeding facilities. In particular, it is essential to install heating facilities in Asian countries with distinct seasonal changes. During the feeding period, many farms manage the temperature and humidity of feeding facilities by installing and using electric heaters inside the facilities. However, it is very difficult to manage the room temperature stably by the heaters. In addition, unlike the temperature inside the facility, silkworms could undergo severe temperature changes as the inside of the rearing tray could not be warm enough. In this study, in order to improve the previous heating method, the new rearing method that directly heats the bottom of the rearing tray was developed. Compared to the previous room-heating system, the novel heater-installed tray (HIT) system significantly reduced the change in temperature during the experimental period. In addition, the number of days of silkworm growth up to harvest was shortened, which was effective in growth performance, and it was also found that silkworms grew more uniformly in HIT system than in previous system. Moreover, as the heater tubes were installed directly under the rearing tray, it quickly dried mulberry leaves and silkworm feces after feeding, and as a result, the environment in the tray was greatly improved with decrease the labor of breeder. In conclusion, these results suggest that the heater-installed rearing tray method greatly improves silkworm quality, increases weight of silkworms, and final profits compared to the previous room heating system with electric heaters.