Cocoon Filament Length Research Articles

Effect of Liquid Organic Manures on Larval and Cocoon Traits of Silkworm (Bombyx mori L.)

The Study was carried out at Department of Sericulture, UAS, GKVK, Bengaluru under irrigated condition during the 2020-21 to study the effect of soil application liquid organic manures in mulberry and its effect on larval and cocoon traits of silkworm, V-1 mulberry variety planted at 90+150 × 60 cm spacing. Three different liquid organic manures were tested against recommended dose of fertilizer (control), leaf quality was assessed via feeding to silkworm. Significantly increased fifth instar larval weight (27.66 and 41.15 g/10 larvae, respectively) was recorded in both cross breed (PM x CSR2) and double hybrid (FC1 x FC2) silkworms fed with mulberry leaves produced from soil application of bio digested liquid organic manure equivalent to 150 % N ha-1 (T9). Double hybrid (FC1 x FC2) silkworm fed with treatment (T9) showed significantly higher cocoon weight (24.76 g/10 cocoons), shell weight (5.89 g/10 shells), cocoon shell ratio (23.78 %), single cocoon filament length (1138.80 m) and filament denier (3.65).

Effect of biofertilizers on mulberry silkworm

Nutrition of mulberry has a vital role in sericulture as it improves the growth, development, health, feed consumption and conversion, thereby improving the commercial traits of mulberry silkworm Bombyx mori L., as it influences its growth and cocoon production. Hence, the effect of three biofertilizers viz., vermicompost, Phosphobacteria, Azotobacter and their mixture was studied on weight of larvae, disease incidence, coccon weight, single shell weight, coccon shell ratio, effective rate of rearing, cocoon yield, cocoon filament length and weight, and denier of silkworm. The results revealed that significantly high weight of ten matured larvae (35.26 g), single cocoon weight (1.72 g), single shell weight (0.34 g), cocoon shell ratio (19.76%), cocoon yield/10, 000 larvae brushed (17.00 kg), cocoon filament length (928 m), cocoon filament weight (0.275 g), denier (2.66), lower disease incidence (1.33%) and highest effective rate of rearing (98.66%) were obtained in larvae fed with leaves of variety V-1 applied with vermicompost, Azotobacter and Phosphobacteria in equal proportions.

Effects of feeding silkworm with nanoparticulate anatase TiO2 (TiO2 NPs) on its feed efficiency.

This study aimed to investigate the effects of titanium dioxide nanoparticles (TiO2 NPs) on feed efficiency of silkworm (Bombyx mori) (B. mori). The results showed that the amount of ingested food was increased by 3.31%, the percentage of ingested food was increased by 16.36%, the instar was prolonged by 6.77 h, the body mass of mature silkworm was increased by 11.41%, the cocoon mass was increased by 5.47%, the cocoon shell mass was increased by 9.80%, and the ratio of cocoon shell was increased by 3.54%. Average cocoon filament length, reelability, and neatness were increased by 3.15, 17.57, and 1.72%, respectively, whereas the cocoon filament size was decreased by 0.19%. The gene expression profiles were also examined with digital gene expression (DGE). The results showed that among 4,011 genes detected, 127 genes were differentially expressed including 57 genes whose expression was upregulated and 70 genes whose expression was downregulated. The expression levels of five genes related to metabolism were verified with quantitative real-time PCR, and the results were consistent with the DGE data. The activities of three major digestive enzymes in the midgut were also assayed; the results showed that the activities of trehalase, protease, and lipase in TiO2 NP-fed group were increased by 42.55, 78.13, and 33.33%, respectively. These results indicate that feeding B. mori with TiO2 NPs can stimulate the transcriptional level of genes related to digestion and absorption of nutrients in the midgut and increase the activities of trehalase, protease, and lipase and, thus, increase the feed efficiency of B. mori.

Evaluation of Some Mulberry Varieties for Rearing Performance and Economic Traits of Silkworm (Bombyx Mori L)

The studies on Disease free eggs of silkworm hybrids MY 1 x CSR 2 were utilized. The treatments were V-1, Kanva-2, BER-1, BER-779, Mizosava, A-1, S-30, S-34, S-36, and S-54. Observations on the different economic traits of silkworm Bombyx mori L. were taken. Larval weight varied in the range of 33.77 g to 40.67 g. Variety V-1 (40.67 g), Larval duration was observed in the range of 21.04 days to 22.28 days. Variety BER-1 (21.04 days), Single cocoon weight 1.664 g to 1.863 g. The highest single cocoon weight was V-1 (1.863 g), Single shell weight 0.297 g to 0.364 g. Maximum shell weight V-1 (0.364 g), Shell percentage 17.60 per cent to 19.82 per cent. Maximum yield variety V-1 (18.63 kg), was observed significantly superior, Cocoon filament length in the range of 680.00 m to 836.66 m. Longest filament length variety V-1 (836.66 m). These findings will help the sericulturists in finding suitable variety for getting more economic returns from silkworm rearing. It is observed that V-1 is becoming popular in Marathwada region.

Genetic analysis of quantitative trait loci for cocoon and silk production quantity in Bombyx mori (Lepidoptera: Bombycidae)

Silk production quantity is the most economically important characteristic of the domesticated silkworm moth, Bombyx mori. It is controlled by multiple loci. The cocoon and silk production quantity of silkworm strains Jingsong and Lan10 have significantly diverged. A backcross population (BC1) was bred using Jingsong and Lan10 as parents to identify quantitative trait loci (QTLs) for silk quality. In this research, a genetic linkage map of the silkworm was constructed using the BC1 mapping population. The map contained 85 sequence-tagged site markers, 80 simple sequence repeat markers, and 16 single nucleotide polymorphisms. A linkage map was constructed from the data, which consisted of 181 markers distributed over 28 expected linkage groups and spans 2147.1 cM in total length. Fourteen QTLs were detected for cocoon filament length, whole cocoon weight, pupae weight, filament weight, and cocoon shell weight. The 14 QTLs were distributed in 5 linkage groups (linkage groups 1, 14, 18, 23 and 25) based on the constructed linkage map. In addition, five QTLs, which had the highest logarithm (base 10) of odds (LOD) values, were located on the first chromosome, three of which located at the same region in linkage group 1. These results represent an important foundation for the map-based cloning of QTLs and marker-assisted selection for improving the silk quality of economically important silkworm strains.

On distribution of non-broken filament length of cocoon

In accordance with the hypotheses that the length of cocoon filament is normally distributed random variable and the ratio of dropping end has optionally distributed form on cocoon filament, we derived the distribution of non-broken filament length of cocoon. Basis on the condition that the ratio of dropping end is distributed on cocoon filament with a parabola-form, we discussed on the form of the distribution of non-broken filament length of cocoon and the relation between the form and the parameters of distribution of the ratio of dropping end. We gave a method to estimate these parameters from data of reeling process. The theoretical results have been tested and verified by computer simulation.

Evaluation of various mulberry Morus spp. (Moraceae) cultivars for the rearing of the bivoltine hybrid race Shaanshi BV-333 of the silkworm Bombyx mori (Lepidoptera: Bombycidae)

The performance of the Bombyx mori Linnaeus bivoltine hybrid, Shaanshi BV-333, was evaluated on six mulberry cultivars of Morus spp. based on economic characters in rearing and mulberry leaf quality. The growth rate and morphological characteristics for all the cultivars were studied using several parameters. Specific characters such as disease resistance, survival percentage, cocoon weight, cocoon shell weight and single cocoon filament length were recorded during the rearing of silkworm larvae. Tested cultivars significantly differed in all parameters. Cultivars Kanva-2/M5, Thailand, Thika and S-36 exhibited superiority in rearing performance over other tested cultivars. Silkworms fed with cv. Thailand had the highest survival percentage of larvae in the short (S1) and long (S2) rainy seasons as compared with other cultivars. However, cv. Embu produced the lowest mortality during the dry season (S3), while S-41 produced the lowest survival rate in all seasons. Embu had significantly higher filament length and cocoon yield compared with the other cultivars during S3. However, S-41 performed poorly in survival percentage, cocoon yield, silk reeling and cocoon shell weight.

On the division of distribution of non-broken filament length of cocoon

In this paper, we discussed on the problem of the distribution of non-boken filament length of cocoon separate into a mixed form of several distributions, basis on the distribution of filament length of cocoon and the distribution of position of dropped end cocoons, we gave the mixed form of distribution of non-broken filament length of cocoon which indicated by an exponential distribution and two normal distributions. The theoretical results are tested and verified by computer simulation, and discussed on estimation of distribution parameters.

On the characteristic function of distribution of non-broken filament length of cocoon and its applications

On the characteristic function of distribution of non-broken filament length of cocoon and its applications

A theorem of generating random number of non-broken filament length of cocoon and its application

A theorem of generating random number of non-broken filament length of cocoon and its application

On the continuous distribution of non-broken filament length of cocoon

In this paper, based on discrete distribution of non-broken filament length of cocoon, we derived its continuous distribution, that is a distribution of lifetime, and the mean value and variance, with the hypotheses that the ratio of dropping end has continuorsly distributed form on cocoon filament. Basis on the condition that ratio of dropping end is distributed on cocoon filament with a parabola-form, we discussed on the relation between the distributed form and the parameters of ratio of dropping end. The theoretical results have been tested and verified by computer simuration.

Effects of selection on cocoon filament length in divergently selected lines of the silkworm, Bombyx mori

To examine the effects of selection and the degree of manifestation of heterosis, we compared the polyvoltine populations of Bombyx mori selected for long or short cocoon filament lengths for 11 generations, and performed their inter se matings and crosses of selected lines with unrelated bivoltine tester populations. We measured the selected trait, viz. the filament length, as well as other unselected traits such as survival rate, single cocoon weight, cocoon shell weight, cocoon shell ratio and filament size. The genetic improvement brought about for filament length by virtue of selection was found to be reflected in the hybrids. On an average, genes for short filament length were found to be dominant over those of long filament length. Significant difference in reciprocal crosses was observed for the selected trait in the interline matings. Matings of the lines with long or short filament lengths with the unrelated tester population reflected the filament length of the selected population. Among the unselected traits, heterosis was more extensive for the survival rate followed by the single cocoon weight and cocoon filament size in both interline matings and the crosses of the selected lines with unrelated tester population.