• International Journal of Industrial Entomology and Biomaterials
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• v.14 no.1
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• pp.23-32
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• 2007

The nature of genetic variation and diversity among the 65 multivoltine silkworm genotypes was evaluated for 16 post cocoon characters. The components of genetic variation revealed higher PCV (60.487%) and GCV (44.56%) for evenness (variation 1) followed by cohesion (PCV=55.38%, GCV=40.36%) and non-broken filament length (PCV=32.05%, GCV=31.28%). The higher heritability ($h^2$ in broad sense) was observed for boil-off loss (95.6%) followed by non-broken filament length (95.22%). The both genotypic and phenotypic correlation indicated significant positive correlation of filament length with non-broken filament length, silk recovery, raw silk, neatness, and low neatness; and negative correlation with denier, renditta and silk waste. The principal component analysis (PCA) revealed 75.381 % of total variance from the five principal components extracted. On the basis of Mahalonobis' $D^2$ values (Ward's minimum variance), the sixty-five multivoltine silkworm genotypes were classified in to 9 clusters with substantial inter and intra cluster distances. Number of genotypes included in different clusters varied from 3 to 17. The results indicated that the optimum distance obtained in cluster VII (15.059) along with higher cluster mean values especially for filament length, non broken filament length, renditta, silk recovery, silk waste, and raw silk emphasized the utilization of these genotypes in the conventional silkworm breeding programme for improvement of multivoltine silk fibre quality. The possibility of exploiting genetic variation in post cocoon traits for efficient breeding programme is discussed.

• Journal of Sericultural and Entomological Science
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• v.24 no.1
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• pp.25-27
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• 1982

The use of fumigation of Neo-PPS was tested for the larval disinfection and at the same time for easy handling and effective chemicals for larval disinfection. The results obtained are as follows: 1. There was no decrease of cocoon yield in spring season due to chemical damage by application of Neo-PPS fumigation to the disinfection of the silkworm except 2,4 and 6 hours' treatment everyday and 6 hours'/ twice/instar treatment as compared with the control. 2. There was no significance in pupal percent between treatments and control in spring season except 6 hours' treatment everyday. 3. No chemical damage seemed to give rise to percentage of cocoon shell in all treatments.

• International Journal of Industrial Entomology and Biomaterials
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• v.28 no.2
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• pp.32-38
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• 2014

Food consumption and conversion efficiency of eri silkworm Samia ricini Donovan were studied during $4^{th}$ and $5^{th}$ larval instars by feeding castor leaves fortified with 100, 200, 300, 400 and 500 ppm concentrations of aqueous extracts of cyanobacteria Anabaena variabilis. The nutritional indices viz., ingesta, digesta, approximate digestibility (%), reference ratio and efficiency parameters like ECI and ECD were recorded which were significantly high at 400 ppm concentration treated batches of $4^{th}$ instar larvae over control batches. The decline in nutritional efficiency parameters of $5^{th}$ instar treated larvae might be due to higher utilization of the digested food for metabolic activities. Significant difference of ECI to cocoon % and non-significant difference of ECD to cocoon% and shell were observed between the treatments and control. Cyanabacteria feed supplement contains antibiotic and nutritions factors which has reflective effect on the biological parameters in eri silkworm and therefore has greater application in commercial eri silkworm rearing.

• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.2
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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.

• Journal of Sericultural and Entomological Science
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• v.37 no.2
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• pp.121-126
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• 1995

The effects of oral application of fenoxycarb, the commercial formulation Insegar, to the selected developmental stages of the silkworm, Bombyx mori, was investigated. An oral application of the chemical to the silkworm from the 2nd- to the 5th-instar larvae delayed the larval development upto more than 40 days and increased the larval body weight in the range of 1.1 to 1.7 folds. When the chemical was orally applied to the final instar larvae, spinning and pupation were prevented, and consequently permanent larvae occurred. The weight of a cocoon and its shell of silkworm(bombyx, mori, L) increased following the application of fenoxycarb to the 2nd- and the 3rd-instar larvae.

• Journal of Sericultural and Entomological Science
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• v.36 no.1
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• pp.8-25
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• 1994

The study was conducted to obtain the genetic information on heterosis and combining ability of the quantitative characters for F1 hybrid breeding in silkworms. Six parental varieties and each set of 30 diallel crosses in F1's were used as materials, and bred on the randomized complete block design with three replications. Fourteen characters were observed with the twenty samples in each tray. The data were analyzed for (1) heterosis and combining ability in F1 hybrid. The heterosis in the weight and the length of cocoon showed positively high at 24.51%, and 23.4%, respectively and the weight of the whole cocoon as well as the weight of the whole cocoon layer showed a siginificant heterosis ranging from 15.56% to 15.71% and from 17.14% to 19.01%, but the fifth and the total instar period showed negative heterosis. It was found that the combination between, C70XRomogua and N9 X Romogua showed highly a negative heterosis on the fifth instar period and for the cocoon weight. The female of N9+Sansuian and the male of Romogua X Sansurian have a high heterosis effect, on the cocoon shell weight, and Sansurian X Romogua(reciprocal) on the length and the weight of cocoon filament with no regard to sexuality. The significant maternal and cytoplasmic effect on heterosis of the cocoon weight and the cocoon shell weight were observed with the combinations, N9 X C5, N63 X C70 and on the length of the cocoon filament with the combinations, Sansurian X N63, Sansurian X C5, Sansurian X C70 and N9 X C70, N63 X C70 on the weight of cocoon filament. As mean squared of GCA, SCA and RCA were significant with these combining ability for all characters resulted from additive and non-additive altogether and there is a significant difference between reciprocals. Sansurian showed a negative GCA effect on the fifth and total larval duration, but the higher positive GCA effects took places with varieties N9 and C5 on the length, width, weight of cocoon, cocoon shell weight, percentage of cocoon shell weight, length and weight of cocoon filament, percentage of raw-silk with no regard to both generations and silkworm sexuality. The values of SCA between the cross combinations varied generation-wise and sex-wise. It was shown that SCA value for the fifth instar period was highly negative for Sansurian X C70, Romogua X C70, Sansurian X C5, Romogua X C5, but it was positive effect on the cocoon weight, cocoon shell weight with N9 X C5, and C70 X Sansurian, on the length of cocoon filament with N9 X C5, Romogua X Sansurian on the weight of cocoon filament between Romogua and N63 and on the percentage of raw-silk between the combination of Sansurian X Romoga.

• Journal of Sericultural and Entomological Science
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• v.32 no.1
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• pp.31-37
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• 1990

For fine-denier cocoon filament production, the precocious trimolting silkworms were induced by the treatments with both the imidazole compound "KK-42" hating anti-juvenile hormone activity and high temperature, and their growth, dietary efficiency, cocoon and cocoon filament qualities were compared with those of normal tetramolters as control. 1. The percentage of precocious trimolters was higher in the application of KK-42 than the treatment of high temperature. The effective concentration of KK-42 was 10$\mu\textrm{g}$/1arva. The high temperature treatment for 48 hour was more effective than 36 hour treatment, and silkworm larvae fed on mulberry leaves were more sensitive than artificial diet to induce trimolters. 2. The larval duration of the trimolters induced by KK-42 was 5.17 day shorter than that of normal tetramolters in mulberry leaves rearing, and the increasing pattern of body weight in the 4th inster larvae of trimotlers was similar to the 5th instar larvae of normal tetramolters. 3. The qualities such as cocoon weight, cocoon layer weight and cocoon layer ratio of precocious trimolter induced by KK-42 were much lower those of normal tetramolters: the cocoon weight and cocoon layer ratio were 0.78g, 14.2cg and 18.4% in mulberry leaves rearing, and 0.86 cg, 10.3cg and 12.3% in artificial diet rearing, respectively. 4. The size of cocoon and cocoon filament was smaller in the precocious trimolter, both KK-42 and high temperature, as compared with that of the normal tetramolters. 5. The efficiency of cocoon layer production of the precocious trimolters by the KK-42 was lower than that of the normal tetramolters: amount of the cocoon layer production per 1g of dry mulberry leaves ingested was 7.97cg in the precocious trimotors, while 9.20cg in the normal tetramolters.

• Journal of Sericultural and Entomological Science
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• v.5
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• pp.25-38
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• 1965

I. Breeding of tussah silkworm(preliminary report). The preliminary examination for bleeding has been carried out since 1963 in tussah silkworms. 1) The strain(l-MG-B)of the heaviest silk quantity was the green silkworm and brown cocoon in univoltine, and the strains(2-G-B, 2-MG-B) of the heaviest silk quantity were also the green silkwom and brown cocoon in bivoltine in both spring and fall in 1965. 2) It looks like the voltinism, the body color and the cocoon color have reached to pure line up to 1965. II. Best place for the winter of tussah pupa. This work was aimed to find out good ways for the winter of tussah pupa. 1) The hatch of bivoltine was better than that of univoltine. 2) The cocoons covered with the leaves were good in the emergence of moth. 3) The cocoons which were kept at natural temperature till the first emergence of moths would show bad in both hatch and emergence. 4) If some of the pupae kept under natural condition were controled at proper temperature for a few days, hatch and laying eggs were best. 5) The best places for the winter were the egg storage and the rearing room. III. Relation between incubation temperature and voltinism. 1) When the tussah pupa are kept at natural temperature during winter, the moths do not come out of the pupa. 2) There is no difference between about 18$^{\circ}C$ and about 25$^{\circ}C$ during incubation in hatching ratio. 3) The tussah silkworms of univoltine in mortality are stronger than that of bivoltine. 4) There is not any relation between voltinism and high or low temperature for pupa and eggs. IV. Induced mutation by gamma-ray and neutron in tussah silkworm. This work was carried out in order to induce the mutation by treating the pupa or the eggs of tussah silkworm with gamma my and neutron. The results obtained are as follows. 1. Though the whole pupa treated with neutron become moths, the moths have no ability to copulate each other. The only moths emerged from pupa treated with neutron, 4000${\gamma}$ are able to lay all un-fertilized eggs, some of which have a hole on the surface and nothing of contents. 2. The non-diapause eggs are treated with neutron in spring, but the hatching ratio is 50∼60 percent, but the whole eggs treated with gamma ray are never hatched. 3. The sensitivity of the pupa to neutron is weaker than that of the eggs. 4. The hatching ratio is in direct proportion to the gamma ray dose. 5. Author find out a new mutant which is excellent in the cocoon quality, so he will do the progeny test next hear.

• Journal of Sericultural and Entomological Science
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• v.52 no.2
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• pp.117-122
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• 2014

On previous studies, we constructed a transgenic silkworm which produces the chimeric silk fused green fluorescent protein (EGFP), but the transgenic silkworm has decreased commercial feasible traits such as convenience of breeding and productivity of silk. In this study, we performed cross fertilization between green fluorescent silk transgenic silkworm and colored cocoon silkworm descents to make the transgenic the transgenic silkworm producing improved fluorescence cocoon. In the result, we found out a bit valuable cross fertilization manners ($female{\times}male$) in respect of silk productivity such as $T59B{\times}Jam26$, $Jam329{\times}T59W$, $T59W{\times}Jam329$, and $T59W{\times}Jam178$. The color-difference of offspring cocoons were measured according to different cross manners using by CIE Lab-based formulae with a X-rite VS450. In the result, the depth of green color of cocoons was a little high at cross manners as $Jam329{\times}T59W$, $T59W{\times}Jam178$. Meanwhile, the depth of yellow clolor of cocoons was remarkable at cross manners as $Jam178{\times}T59W$, $T59W{\times}Jam178$, respectively.

• International Journal of Industrial Entomology and Biomaterials
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• v.22 no.2
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• pp.45-49
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• 2011

The performance of five newly evolved cross breeds were evaluated across seasons to understand the genotype and environment interactions and their stability under fluctuating tropical environmental conditions along with control hybrids $PM{\times}CSR2$ and $APM1{\times}APS8$. The data was collected on eight economic traits namely fecundity, yield per 10,000 larvae by number, yield per 10,000 larvae by weight, survival rate, cocoon weight, cocoon shell weight, cocoon shell ratio and filament length. The data was subjected for Analysis of Variance (ANOVA) and relevant statistical methods. The performance data obtained was further subjected for multiple trait evaluation index method. The ranks were adjudicated based on the index values. The two hybrids viz., $MSO3{\times}APS45$ and $MSO1{\times}APS12$ performed well under diversified environmental conditions indicating their overall stability and superiority. These hybrids revealed highly significant (p < 0.01) improvement for the majority of the traits over the control hybrids.