• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.2
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• pp.199-205
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• 2004

With the main objective to know the feasibility of exploitation of F$_1$ hybrids in semi arid and arid climatic conditions of India, the present study was carried out by utilising RD$_1$ as female parent and six bivoltine silkworm breeds viz., CSR$_2$, CSR$_4$, CSR$_{5}$, CSR$_{17}$, CSR$_{18}$ and CSR$_{19}$ along with NB$_4$D$_2$ as male parents. Different hybrids exhibited their superiority for various economic characters during different seasons. Among F$_1$ hybrids, RD$_1$${\times}$CSR$_{5}$ was adjudicated as the best hybrid in terms of expression of significant positive hybrid vigour over mid parental value for five economic characters namely hatching %, cocoon yield, cocoon weight, cocoon shell weight and filament size, highest multiple trait average evaluation index value of 56.77 and comparatively uniform cocoon size with coefficient of variation (CV%) of 3.80 and Standard Deviation (SD) of 7.99 during September - October 2003. Results of the present study revealed that the F$_1$ hybrid RD$_1$${\times}$CSR$_{5}$ can be successfully exploited on commercial in semi arid and arid climatic conditions in India. India.dia.

• International Journal of Industrial Entomology and Biomaterials
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• v.24 no.1
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• pp.7-16
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• 2012

To meet the local requirement i.e. the tropical stress of Andhra Pradesh and marginal farmers, twenty four new hybrid combinations were tested in Line x Tester method involving eight newly developed polyvoltine oval lines viz., MSO1, MSO2, MSO3, MSO4, MSO5, MSO6, MSO7 and MSO8 and three bivoltine silkworm breeds viz., APS12, APS45 and APS8 as testers. These hybrids were reared to evaluate their performance. Data for eight economically important metric traits viz., fecundity, cocoon yield per 10,000 larvae by number, cocoon yield per 10,000 larvae by weight, survival rate, cocoon weight, cocoon shell weight, cocoon shell ratio and filament length was recorded. General combining ability (gca), specific combining ability (sca) and heterosis were analyzed. Further, the relative merit of the hybrids for all the traits under study was also assessed adopting Evaluation Index method. Based on combining ability effects, heterosis and evaluation index, five hybrid combinations viz., MSO3 $\times$ APS45, MSO1 $\times$ APS12, MSO7 $\times$ APS8, MSO2 $\times$ APS45 and MSO1 $\times$ APS45 were selected for further evaluation in different seasons.

• International Journal of Industrial Entomology and Biomaterials
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• v.38 no.2
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• pp.31-37
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• 2019

Silkworm larval mortality specifically during spinning stage leading to non-spinning with specific morphological symptoms was frequently complained by sericulturists in Karnataka, India during 2015. Survey was conducted and information collected through questionnaire from the identified farmers who faced the problem of non-spinning in both traditional and non-traditional areas of Karnataka. Survey results indicate that the problem is specific to the silkworm crop of those farmers' who shifted from other crops of agriculture/ horticulture/olericulture/ floriculture to Sericulture. Silkworm rearing performance of the batches fed with these leaves confirmed that the pesticide sprayed to the crops previous to mulberry, remain in the soil and when mulberry plantation is taken up in these gardens, the pesticide is absorbed by the roots of mulberry plants and transported to the leaves. Silkworms that feed on these mulberry leaves, grow and ripen normally but during spinning stage, larvae die with external symptoms like regurgitation, body shrinkage, rectal protrusion later become hook shaped leading to non-spinning or partial metamorphosis into pupa and death or spin flimsy cocoons. Larval mortality ranged from a minimum of twenty five percent to a maximum of hundred percent. The problem was noticed from the first harvest of leaves and lasted for a maximum period of 36 months. Cocoon crop loss depends on the concentration, duration and type of pesticides used previously for other crops.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.1
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• pp.107-113
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• 2011

Infection effect of $Nosema$ $bombyics$ on the midgut of silkworm $Bombyx$ $mori$ and subsequent appearance of spores and the performance of larvae was studied. Autopsy of larvae showed white pustules on the surface of midgut at 5 days of post infection (pi). At later stage, important organs like midgut, silk gland and gonads reduced in size and all these organs showed white pustules. Light microscope observation of pustules revealed enormous spores. Spore multiplication was at a faster rate in young larvae. Infection of the adult larvae resulted in pebrinized pupa and moths. Larval weight, cocoon weight and cocoon shell ratio reduced as the post infection period increased. Transverse sections of midgut showed $N.$ $bombycis$ infection limited to a few columnar cells at 3-5 days of pi. At 7 days pi, cell volume increased, cells were swollen and elongated. Heavily infected cells looked like sacks filled with parasite and the apical region of certain cells were bulging into the gut lumen. Later at 8-9 days of pi, spores or its developing stages leaked into the lumen either freely or enclosed within the globules of host cytoplasm. Besides columnar cells, development of $N.$ $bombycis$ was observed in the regenerative cells and rarely in goblet cells. Development of $N.$ $bombycis$ was also observed in both longitudinal and circular muscles at the late pi period. The histopathological changes, deformities and spore production time in the host were all influenced by the spore dosage and age of the host.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.59-63
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• 2003

In the present study, hybrid vigour in terms of heterosis and over dominance of newly evolved bivoltine hybrids and their reciprocals raised from the promising newly evolved bivoltine breeds were calculated for the important parameters like pupation, cocoon yield, cocoon weight, shell weight, shell ratio, raw silk percentage, filament length and neatness. Through there was no significant difference among the hybrids for the characters pupation, cocoon yield and cocoon weight, the magnitude of heterosis and over dominance were varied significantly for these characters. However, significant differences were observed between new hybrids and control hybrid for the characters like cocoon shell weight, cocoon shell ratio, filament length and raw silk percentage. The results indicate that majority of new hybrids have shown higher heterosis and over dominance than control hybrid. The data also indicate that highest mean heterosis of all new hybrids was recorded for cocoon yield followed by filament length. Whereas highest mean over dominance was recorded for cocoon yield followed by cocoon weight. Negative mean heterosis and over dominance were recorded for the trait cocoon shell ratio. Based on the results, the importance of three hybrids viz., CSR2 ${\times}$ CSR4, CSR2 ${\times}$ CSR5 and CSR3 ${\times}$ CSR6 and their reciprocals (CSR4 ${\times}$ CSR2, CSR5 ${\times}$ CSR2 and CSR6 ${\times}$ CSR3) which exhibited significant heterosis and over dominance, for commercial exploitation was discussed.

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.127-131
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• 1974

Although several kinds of repellents or attractants have been used for mounting accelerators in the silkworm. Bembyx mori, more effective reagents still have not been developed. The authors developed a mounting accelerator with medical herb (Achyranthes bidentata Blume) and glutamic acid, an indispensable amino acid of silkworm, and experimented it's effects in both periods of spring and fall in 1972-1973. It was obtained that the mounting accelerator newly developed by authors shortened the economic periods by a half day, and did not have an bad effect on cocoon quality.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.33-41
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• 2004

The type of trichomes, their density and pattern of distribution on leaves of 16 genotypes of mulberry, belonging to both diploid and polyploid categories, were studied by scanning electron microscope. The present investigation was undertaken to find out the relationship of physical attributes, especially the density and trichome types with higher acceptability and better rearing performance by the silkworm Bombyx-mori L. Two types of trichomes glandular and non-glandular types were observed on both the leaf surfaces of all the mulberry genotypes studied. In general, greater densities of trichomes were observed on the abaxial surface than the adaxial surface of leaves in most of the genotypes. Distribution of glandular trichomes were more in abaxial surface and non-glandular trichomes were more in adaxial surface. Overall, distribution of glandular and non-glandular trichomes per unit area of leaf did not follow any regular pattern. When leaves of those genotypes were fed to silkworms, trichome density was found to be significantly negatively correlated with the survival of larvae i.e., effective rate of rearing, but trichome density did not influence the economic characters of rearing. As the distribution of glandular trichomes (GT) and non-glandular trichomes (NGT) did not follow any definite pattern, no relation could be established between the GT and NGT densities with silkworm rearing performance. However, the ratio of GT and NGT in a particular genotype influenced the rearing parameters, higher the ratios better the rearing performance. High GT and NGT ratio (＞1.00) was found positively significant when correlated with economic parameters viz., larval weight, single cocoon weight and single shell weight. The study is useful in screening different mulberry genotypes for their better acceptability to silk-worm and higher rearing performance at the early stage of selection without actually conducting the rearing.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.2
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• pp.151-159
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• 2004

A detailed evaluation of relative toxicity of fluoride to die 5th instar larvae of PM and NB$_4$D$_2$ races of silkworm and the effects of lethal, sublethal and prevailing levels of fluoride in groundwater on the growth, economic characters and fecundity of the silkworm, Bombyx mori (Lepidoptera: Bombycidae) were studied. The feeding of mulberry, Morus alba leaves treated with lethal and sublethal doses of fluoride to PM and NB$_4$D$_2$ races of silkworms from the beginning of the 5th instar to the end of the feeding period resulted in significant reduction in growth, single cocoon weight, single shell weight, silk index, average filament length, and fecundity when compared to controls. These manges were more pronounced on exposure to lethal dose than sublethal dose and in general, the changes induced by fluoride were more striking in NB$_4$D$_2$ than PM, indicating the greater resistance of PM to higher fluoride levels. Groundwater quality in sericulturally important villages of Karnataka and Andhra Pradesh States has been studied with special reference to the presence of fluoride. On exposure to dose of prevailing levels in the waters of sericulturally important areas, die changes observed on growth, economic characters and fecundity were slightly lower when compared to controls and the decrease was found to be insignificant (P$\geq$0.05). It was concluded that, though minute dose (4.0 ppm) of fluoride did not have any toxic impact, it is toxic at higher concentrations to silkworms.

• Journal of Sericultural and Entomological Science
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• v.53 no.2
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• pp.97-100
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• 2015

Korean commercial Bombyx mori silkworm cocoon made by Kumokjam and Daesungjam was examined to characterize for application. Amino acid analysis showed that the main amino acid of Kumokjam and Daesungjam cocoon was glycine, alanine, serine, tyrosine, and aspartic acid. The content of three major amino acids was about 67% and the content of long chain amino acids was about 37%. Stress-strain curve showed that breaking stress of Kumokjam cocoon, 50 MPa, was higher than that of Daesungjam cocoon, 48 MPa. Breaking strain of Kumokjam cocoon, 37%, was also longer than that of Daesungjam cocoon, 30%. These results might be used as basic information for development of non-textile materials using Bombyx mori silkworm cocoon.

• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.2
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• pp.81-86
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• 2006

Of all factors that govern productivity in sericulture, the role of silkworm egg is of prime importance. The production of silkworm seed involves a long chain of interdependent and highly specialized conditions. Female moths of Bombyx mori L. commence egg deposition immediately when the moths were decoupled. More than 60% of eggs are deposited within 4 hrs after decoupling i.e. 62.33% in CSR-3, 61.67% in CSR-6, 62.50% in CSR-16 and 63.28% in CSR-17. Almost 90% of eggs were laid in the first 12 hrs (93.13% in CSR-3, 90.81% in CSR-6, 89.71% in CSR-16 and 93.17% eggs in CSR-17) after decoupling. Almost 8 to 10% of more eggs were laid when oviposition period was prolonged upto 48 hrs instead of 24 hrs. The present investigation showed that a significant increase of 45 (8.34%), 50 (9.98%), 41 (8.26%) and 45 (8.30%) (P < 0.01) numbers of more eggs were found between 24 to 48 hrs (T6 to T9) in CSR-3, CSR-6, CSR-16 and CSR-17 races respectively. The findings of present investigation is very important for sericulture industry while producing layings to keep for different hibernation schedule especially for autumn/late autumn crop, female may be allowed for prolonged oviposition to get 8 -10% more eggs and farmer may fetch 8 -10 kg. more cocoon yield/l00 dfls with more income.