• Journal of Sericultural and Entomological Science
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• v.39 no.2
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• pp.140-145
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• 1997

Silkworm fed on mulgerry leaves with 1000 times diluted Insegar(main component : Fenoxycarb, ethyl-2-(4-phenoxyphenoxy)ethylcarbmate) and its effects was investigated on increase of the 5th larval silkgland weight and silk quality. The oral application of fenoxycarb showed increase of the silkgland weight. The whole period of the silkgland weight falls on the 2nd instar treatment by 13%, the 3rd day of the 4th instar by 111%(3100 mg) and the whole period of the 5th instar treatment rather decreased it by 66%(497 mg), as compared to 1470mg of the control. Female and male both increased 15%(1779mg) and 12%(1554mg) of the silkgland weight with the 2nd instar treatment, as compared to 1548mg and 1391mg in control, respectively. 118%(3368mg) and 104%(2832mg) of increase in the silkgland weight were also showed with the 3rd day of the 4th instar treatment but 70%(463mg) and 61%(539mg) of decrease were shown with the 5th instar treatment. The maximum weight of the middle silkgland weight increased by 6%(1248mg) and 127%(2673mg) with the 2nd instar and with the 3rd day of the 4th instar, respectively but 67%(393mg) of decrease took place, as compared to 1175mg of the control. The maximum increase of the posterior silkgland weight with whole peried of the 2nd instar treatment increased 12%(419mg) and 75%(656mg) and 64%(135mg) of decrease was shown, as compared to 374mg of the control. The oral application of Insegar at the 2nd instar increased 26 m of cocoon length, 4.0 cg of the cocoon filament weight and 0.21d of the silk denier, as compared to 1147 m of the cocoon length, 38 cg of the cocoon filament, 2.99d of the silk denier, weight of cocoon filament and silk denier, respectively but denier variance narrowed to 0.33d, as compared to that of the control.

• 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.

• Journal of Sericultural and Entomological Science
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• v.21 no.2
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• pp.1-6
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• 1979

Diallel crosses among six silkworm varieties were used as the materials. by the randomized block design, and diallel cross analyse were conducted to determine the relationships between parents and their F$_1$hybrids. The six parents and their 30 F$_1$crosses were evaluated for five quantitative characters in each female and male silkworms. All methods utilized were similar in detecting lines giving unexpected performance in the F$_1$generation. Mean values of total cocoon weight and weight of cocoon layer of female silkworms were more than those of male silkworms, but mean values of cocoon layer ratio of female silkworms were less than those of male silkworms in both parents and 30 F$_1$hybrids. Over dominance was exhibited by total cocoon weight and weight of cocoon layer, and partial dominance was exhibited by periods (days) of larval stage, periods (days) of 5th instar and cocoon layer ratio (weight of cocoon layer/total cocoon weight). Furthermore, it was recognized that varieties F (Yunil) and E (Kyung-choo) were recommendable varieties as the parents in breeding of silkworms for increasing the total cocoon weight and weight of cocoon layer, etc.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.53-58
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• 2004

Studies on heterotic expression in the silk productivity of 66 thermo-tolerant bivoltine hybrids reared under high temperature $(36{\times}1^{\circ}C)$ and low humidity (60${\times}$5%) conditions revealed that manifestation of heterosis was highly significant for majority of the quantitative traits contributing to more cocoon productivity. Observations were made on 8 economically important traits such as fecundity, pupation rate, cocoon yield, cocoon weight, cocoon shell weight, cocoon shell ratio, cocoon filament length and raw silk. Analysis of variance results revealed great deal of variability indicating significant (P < 0.001) variations. Out of 66 hybrids, 7 hybrids exhibited positive heterosis for seven traits and 4 hybrids expressed significant hetero-beltiosis for 6 traits, out of 8 traits evaluated. Based on results, the hybrids ${SR_1} {\times} {SR_5}and {CSR_2} {\times} {SR_5}$ are adjudged as most promising ones and can be exploited commercially in tropical climates to increase the cocoon productivity.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.29-36
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• 2003

Phytoecdysteroids with moulting hormone (MH) activity induce different responses in silkworms when used on different day of final instar, which can be manipulated for maximum benefit like early and uniform spinning behaviour, reducing crop loss and to increase cocoon yield. The results showed that application of this hormone on seed crop viz., CSR2, CSR4 and BL44 and BL67 in early stage of 5$^{th}$ instar i.e., at 72 hrs and 96 hrs though induced early and uniform spinning behaviour, there was an adverse effect by 9-36% on the economic characters like cocoon yield, cocoon weight, cocoon shell weight and also on fecundity etc. Application of this hormone in late stage of $5^th$ instar i.e., at the onset of spinning showed non-significant variations in some of the characters like cocoon weight, cocoon shell weight, cocoon shell ratio and fecundity. The physiological implications of phytoecdysteroid in hastening the maturation events and synchronization of spinning activities in different breeds are discussed.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.75-79
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• 2003

Oral supplementation of zinc chloride to silkworm larvae in different concentrations (30, 60 and 90 ${\mu}g$/ml) to the fourth and fifth instar resulted in a significant increase in commercial traits, like larval weight, silk gland weight, cocooning percentage in lower concentrartion (30 ${\mu}g$) treated group. The female cocoon weight, shell weight and its ratio were significantly increased in 30 and 60 ${\mu}g$ treated groups, male cocoon weight, and shell weight in 30 ${\mu}g$ treated group and its ratio in 60 and 90 ${\mu}g$ treated groups, filament length, weight and moth emergence percentage in all the treated groups and egg productivity in 90 ${\mu}g$ treated group were increased significantly. The remaining groups did not show any significant changes compared with that of carrier control.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.1
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• pp.69-74
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• 2001

The effect of topical application with androstenedione on economic parameters was analyzed following treatment of last larval stadium. The treated larvae showed significantly increased larval weight along with other enhanced larval, cocoon and adult parameters. The larval period was significantly shortened in all the treated groups with increased cocooning percentages cocoon weight and its shell weight in female and filament length, weight and denier in all the treated groups. Hatching percentage increased significantly in dose dependent manner in all the treated groups when compared with the corresponding parameters of the carrier control group. This suggests that androstenedione can be used effectively for commercial silkworm rearing.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.1
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• pp.79-81
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• 2001

A study was conducted to establish the degree of genetic divergence between different hybrid forms and rearing conditions through estimation of the minimum number of genes (allelic pairs) differentiating parents in terms of specific quantitative traits. It was established that the minimum gene numbers differentiating parental lines in the inheritance of cocoon was 1, of cocoon shell weight- between 1 and 2, and of silk filament length- between 2 and 3. The variability in the specific genetic parameter could be explained by the reliability of the statistical-and-genetic method used and the expression of genes affecting the formation of each of the characters tested. Gene expression, in its turns is conditioned both by the gene interaction within the genotypes and the different genotype response to environmental change. To go deep in the problem, experiments should be conducted under strictly controlled conditions, reducing the mathematical-and-genetic analysis to a physiological levels and hence to analyse the genetic nature of the specific quantitative character formation and its genetic control.

• Journal of Sericultural and Entomological Science
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• v.18 no.1
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• pp.11-15
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• 1976

These surveys were designed to know decreasing rate of cocoon production all over the country and purchased amount of cocoons at public market which had been caused by various diseases in autumn of 1975. The results can be summarized as follows; 1. Percentage of sericuitural houses which sustain disease damage was 18.5 percent, and cocoon yield per box in bad crop houses was 8.8kg smaller than that in normal houses. 2. About 838M/T of decreased cocoons and 5.6 percent of damaging rate can be estimated in this autumn throughout the country. 3. In our country, it was 40.9 per cent of Grasseril and 34.5 per cent of Flacherie of silkworm diseases.

• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.1
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• pp.47-52
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• 2000

The effect of supplementation with potassium nitrate on economic parameters was analysed following treatment of last larval stadium. The treated larvae showed a significant increase in larval weight at 500$\mu\textrm{g}$/ml and silk gland weight in all the treated groups along with other enhanced larval, cocoon and adult parameters. The larval period was significantly decreased in all the treated groups with increased female and male cocoon weights its shell weights filament lengths at 500$\mu\textrm{g}$/ml. The denier was significantly decreased in all the groups. The filament weight moth emergence percentaged length of the ovariole were unaffected. However, eggs per ovariole, fecundity and hatching percentage significantly decreased compared with the corresponding parameters of the carrier control.