Cocoon Shell Percentage Research Articles

معرفی هیبرید‌های برتر کرم‌ ابریشم در مناطق مختلف جغرافیایی استان گیلان

Considering the importance of studying the performance of commercial silkworm hybrids at the level of silkworm rearing units in different rural areas, in the spring of 2019, the 14 hatched silkworm egg boxes per hybrids (12 imported and two Iranian boxes) were delivered to skilled sericulturists in 35 eastern and 32 western villages of Guilan province and then monitored till the end of the rearing period. The random samples including 200 cocoons were purchased from each farmer to record data. The performance of each silkworm box, the percentage of good cocoons, pupal mortality percentage, number and weight of cocoons in a liter, cocoon weight, cocoon shell weight, and cocoon shell percentage were measured. The interaction between areas and hybrids was not significant for all traits (P>0.05). The highest and the lowest performance per silkworm box were for 872× 871 and 103×104 hybrids, respectively (P<0.05). The heaviest and the biggest cocoons were for 153×154 and 872×871 hybrids, respectively; and the lowest was for Baiyu×Qiufeng (P<0.01). The highest and the lowest good cocoon percentages were obtained from 103×104 and HaoyuB×JingsongA, respectively (P<0.05). The highest and the lowest cocoon shell percentages were for 103×104 and BaiyuB×QiufengA, respectively (P<0.05). Among the four studied areas, the lowest average for all studied traits belonged to the plain areas of eastern Guilan. Among the six pairs of examined reciprocal crosses (imported hybrids), the performance of 872×871 and 871×872 and Suju×Minghu and Minghu×Suju can serve the interests of both cocoon producers and silk thread producers.

Investigation on effects of delay and acceleration in round up and accumulation of matured silkworm larvae and transferring them to cocoon making frames

The aim of this experiment was investigation on effects of delay and acceleration in round up and accumulation of matured silkworm larvae in order to transferring them to cocoon making frames. Three different ways of silkworm making cocoon-starting time was studied. The larvae hatching and rearing was conducted based on standard and similar methods. Ttreatments were (1) treatment 1: the completion time of larvae feeding and larvae transfer from rearing tray to cocoon frame was standard and performed individually based on larvae mature time; treatment 2: the completion time of larvae feeding and larvae transfer time from rearing tray to cocoon frame was 12 hours before larvae mature time; treatment 3: the completion time of larvae feeding and larvae transfer time from rearing tray to cocoon frame was 12 hours after larvae mature. Production traits recorded and analyzed using generalized linear models procedure based completely randomized design model. From obtained results, it is showed that among studied methods, the highest level of best cocoon number belonged to 2nd treatment (80.50), and 1st treatment (74.75) remained at lower level than other methods (P&gt;0.05). Among studied methods, the highest level of best cocoon alive pupae number belonged to 3rd treatment (79.75), and 1st treatment (71.25) remained at lower level than other methods (P&gt;0.05). Among studied methods, the highest level of best cocoon weight belonged to 3rd treatment (147.88 gr), and 2nd treatment (124.32 gr) remained at lower level than other methods (P&gt;0.05). Among studied methods, the highest level of male Cocoon shell percentage belonged to 3rd treatment (24.11%), and 2nd treatment (23.44%) remained at lower level than other methods. Other methods were between these two groups (P&gt;0.05). Among studied methods, the highest level of male cocoon weight belonged to 3rd treatment (1.66 gr), and 1st treatment (1.64 gr) remained at lower level than other methods (P&gt;0.05). Among studied methods, the highest level of male cocoon shell weight belonged to some treatments (0.443 gr), and 2nd treatment (0.38 gr) remained at lower level than other methods. Other methods were between these two groups. Meanwhile statistical differences between studied methods for this trait were not significant (P&gt;0.05).

Comparison of different selection strategies for mulberry silkworm, Bombyx mori

This study was conducted to determine optimum selection strategies for economically important traits in mulberry silkworm Bombyx mori. A total of 450 cocoons (225 males, 225 females) in each of two strains, 107 (Japanese) and 110 (Chinese), were used to establish base populations. Studied traits were cocoon weight (CW), cocoon shell weight (CSW) and cocoon shell percentage (CSP), which were recorded individually. Six selection strategies including random selection (control), subjective selection based on cocoon appearance, selection based on CW, selection based on CSW, selection based on a selection index using phenotypic values and selection based on a selection index using estimated breeding values (EBVs) for CW, CSW and CSP, were used for three consecutive generations. Breeding values were estimated using an animal model based on derivative-free algorithm of restricted maximum likelihood. In each strategy, a total of 12 males and 12 females were selected and randomly mated to constitute 12 full-sib families in next generation. In each family a total of 50 individuals (25 males and 25 females) were randomly recorded for CW, CSW and CSP. Results showed higher CW and CSW in strain 110 and higher CSP in 107. Selection index based on EBVs resulted in higher values of CSW and CSP, compared to the control group. Selection strategies had different effects on different generations. However, EBVs for all traits significantly increased in total population. It seems that selection based on selection indices, especially using breeding values, is more efficient to improve all economically important traits.

THE EFFECT OF MULBERRY TYPES ON THE PRODUCTIVITY OF COCOON OF TWO Bombyx mori L SILKWORM HYBRIDS

Mulberry ( Morus sp. ) is the only food for silkworm of Bombyx mori L and larvae that is fed with highly nutritious mulberry leaves will have more resistant to disease and able to produce the better cocoon. The study was aimed to determine the effect of mulberry SULI 01, ASI, and Morus cathayana as feeding materials for cocoon production from PS 01 and C 301 silkworm hybrids. The study was arranged in Block Randomized Design, with a factorial design of three type of mulberry’s leaf and two hybrids of silkworm. Feed setup and maintenance of a silkworm cocoon until harvest time was carried out at Cipeuteuy village, Kabandungan, Sukabumi district. The determined parameters were rendement of rearing, the weight of cocoon, the weight of cocoon shell, and cocoon shell percentage. The result showed that rendement of rearing to all treatment was not significantly affected, in which all treatment showed average percentage above 90%. The treatments combination of ASI mulberry and PS 01 silkworm hybrid gave the best result for parameters of rendement rearing around 96.6%, the weight of cocoon 1.78 g, and the weight of cocoon shell 0.37 g, while cocoon cell percentage is around 21.18%. The result of a combination between SULI 01 and PS 01 is rendement rearing around 95.20%, the weight of cocoon 1.6 g, the weight of cocoon shell 0.34 g, and cocoon shell around 21.47%.

Estimates of genetic traits in silkworm (Bombyx moriL.) Under temperate conditions of Kashmir

The genetic parameters, trait association and path coefficient analysis between silkgland weight and its attributes of 10 silkworm genotypes were studied during spring and summer seasons of 2010–11 at TSRI, SKUAST-Kashmir (Mirgund). The genotypes exhibited wide range variability for all the traits studied. High heritability accompanied by moderate to high genotypic coefficient of variation and genetic gain were observed for filament length, shell ratio, single shell weight and filament size. Correlation studies indicated that during spring season, silkgland weight showed positive and significant correlation with shell ratio, while it showed significantly negative association with silkgland somatic index, while during summer season it showed significant positive association with all the traits except silk conversion index. The silkgland attributes exhibited varied magnitude of direct effects on silkgland weight during both spring and summer season. During summer season single shell weight showed the highest direct positive effect on silkgland weight which was followed by the filament length, while during spring season, highest positive direct effect on silkgland weight was exhibited by cocoon shell percentage(3.574) and single shell weight (3.346).

Comparison of phenotypic value changes in pure lines of Bombyx mori (Lepidoptera: Bombycidae) during consecutive generations following initial selection on cocoon weight.

The experiments reported here were conducted to investigate the effect of selection on three quantitative traits, namely cocoon weight, cocoon shell weight, and cocoon shell percentage, during four generations by rearing six pure breeds of domesticated silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) of Chinese and Japanese origin compared with random unselected groups as controls. All stages of rearing and data recording were performed over four rearing periods, with generations 1–3 during successive spring seasons and generation 4 during the autumn season in year 3. Each pure line contained two groups of selected and random (control) groups. Comparisons included the effect of selection methods, pure line, and generation on the phenotypic values. We found strong main effects of pure line, generation, sex, and group and support for nearly all interactions between these main effects for all three response traits. The results indicated that cocoon weight and cocoon shell weight in the selected group were higher than in the control or nonselected group. Both selected and nonselected groups had the lowest cocoon weight, cocoon shell weight, and cocoon shell percentage in the fourth generation when environmental conditions during the autumn season were less favorable than spring. The cocoon weight and cocoon shell weight averages were higher for nonselected groups in the second and third generations, and for the selected group in the first generation due to the direct effect of selection.

Cocoon Characteristics of Antheraea pernyi Silkworm Reared in Korean Oak Field

Antheraea pernyi silkworm is a well known wild silkworm to produce a valuable silk fiber. A. pernyi silkworm was reared in Korean oak field and examined the cocoon characteristics, such as cocoon weight, cocoon shell weight, and percentage of cocoon shell weight. Degumming loss was also measured after alkali degumming process. A. pernyi silkworm spins tawny color cocoon in oval shape. Cocoon shell weight of A. pernyi silkworm, 0.78 g, was heavier than that of B. mori silkworm, 0.51 to 0.63 g. Cocoon shell percentage of A. pernyi silkworm, 32.8%, was higher than that of B. mori silkworm, 23.4 to 25.2%. Degumming loss percentage of A. pernyi silkworm, 17.1%, was lower than that of B. mori silkworm, 25.0%. SEM showed that the surface of the cocoon filament was coarse and oriented with longitudinal direction.

Study of thirty-one economically important traits in twenty silkworm Bombyx mori varieties

The aim of this experiment was to study thirty-one economically important traits in twenty silkworm Bombyx mori breeds varieties. These varieties included 31, 1005, 113 (2029), 153 (Xihang-1), 5118 × 10133-3-3, F6 × 101, 1433-15, 1126 (111), 113-K, 1003-4, M2-6-18 (109), M2-6-22 (107), 151 (103 × M-1-1), Xihang 2/3, M-1-1 × 103, 7409, 107-K, 103, T5-M and 101433-1-4. Rearing of young silkworm instars was performed by feeding with chopped leaves and by using paraffin paper as a coverage while to the last instars, entire leaves and branches were administered. Rice straw was used as cocoon frames for spinning in each replication separately. Seven days after the starting of cocoon spinning, obtained cocoons were gathered and sorted on the basis of form, thickness, clarity, etc., into four classes including good, middle, double and low cocoons. The ratio of each cocoon class was calculated for each replication separately. The data obtained for different parameters were subjected to analysis of variance (ANOVA) to determine if the differences found among treatments were significant. Following ANOVA, Tukey’s studentized range test in a complete randomized design was used at p < 0.05. Obtained results showed that among studied varieties, the highest level of percentage of hatchability was observed in 107-K (97.77%), while 1003-4 variety (63.07%) remained at lower level than other varieties. Meanwhile, among studied varieties, the highest level of good cocoon number belonged to Xihang-1 (328.33), and 109 variety (159.67) remained at the lowest level with respect to other varieties (p < 0.05). Also, the highest level of good cocoon weight belonged to 1003-4 (341.83 g) and 7409 variety (194.09 g) remained at the lowest level in comparison to other varieties (p < 0.05). Finally, it is shown that the highest level of cocoon shell percentage belonged to 111 (1126) (23.11%) and 113-k variety (18.10%) remained at the lowest level as compared to other varieties (p < 0.05). Keywords: Silkworm, performance, germplasm, cocoon, fecundity, disease

Estimation of genetic parameters in three commercial silk-worm lines of Iran

In order to estimate genetic parameters of the cocoon weight (CW), cocoon shell weight (CSW) and cocoon shell percentage (CSP) of three industrial lines of silk-worm (number 31, 103 and 107), data were collected from three successive generations. (Co)variance components were as follows: additive genetic variation (δ 2 g) and environmental variation (δ 2 e ) of traits and additive genetic covariance (cov g1, 2 ) and environmental covariance (cov e1, 2 ). Heritability of traits was estimated with maximum likelihood procedure (REML) by using algorithms (DFREML) based on a three trait animal model. Data were from half-sibs and the heritability and genetic, phenotypic and environmental correlation were estimated between traits. The highest heritability for CW was estimated in lines 31 and 107 (0.58 and 0.58, respectively) and the lowest heritability for CW was in line number 103 (0.28). The highest and lowest heritability for CSW was in lines 107 and 103 (0.70 and 0.01, respectively). Also, the highest heritability for CWP was in line 31 (0.48) and the lowest value was in line 103 (0.077). The highest δ 2 g for CSP was estimated in line 103 (0.004) and lowest δ 2 g was estimated in line 107 (0.001). The highest and lowest δ 2 g for CW were estimated in lines 103 and 31 (0.0004 and 0.00003, respectively). The δ 2 g for CW was high inline 31 (0.604) but low in line 103 (0.257). The highest and lowest δ 2 e for CW were in lines 103 and 107 (0.02 and 0.01, respectively). Furthermore, the highest δ 2 e for CSW was estimated in line 103 (0.0013) butminimum δ 2 e was in line 107 (0.0007). Maximum cov g1, 2 for CW-CSW was estimated in line 103 (0.00087) and minimum value was estimated in line 31 (0.00012). A high cov e1,2 for CW- CSP was estimated in line 103 (0.093) but it was low in line 31 (0.00026). The highest cov g1, 2 for CSW-CSP was in line 103 (0.002) but it was low in line 31 (0.00079). Key words : Cocoon, correlation, heritability, genetic (Co) variance.

Evaluation of the genetic potential of six native strains of silkworm, Bombyx mori L.

The aim of this study was to evaluate six native strains of silkworm, Bombyx mori L., available in Iran based on different quantitative traits. In this experiment, the studied six native strains are Lemon Khorasan; Lemon Haratee, White Haratee, Yellow Haratee, Pink Khorasan and Baghdadi. From the obtained results, it is shown that the amount of percentage of hatchability in the six studied local varieties was between 84.93 and 98.87%. Among the studied local varieties, the highest level of percentage of hatchability belonged to Pink Khorasan (98.87%), and White Haratei variety (84.93%) remained at a lower level than other varieties (P<0.05). The amount of average of cocoon weight in the six studied local varieties was between 14.70 and 20.35%. Among the studied local varieties, the highest level of average of cocoon weight belonged to White Haratee and Yellow Haratee (14.70), and Lemon Haratee variety (20.35) remained at a lower level than other varieties (P<0.05). Also, the highest level of cocoon shell percentage belonged to Pink Khorasan (13.36%), and Lemon Haratee variety (19.11%) remained at a lower level than other varieties (P<0.05). Key words: Bombyx mori, local race, cocoon, fertility, larvae duration.

Amplified Fragment Length Polymorphism Mapping of Quantitative Trait Loci for Economically Important Traits in the Silkworm,Bombyx mori

Cocoon related characteristics are economically important traits in the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae). In this study a genetic linkage map was developed that identified QTL controlling the cocoon weight, cocoon shell weight, and cocoon shell percentage using 161 amplified fragment length polymorphism (AFLP) markers. Twenty PstI/TaqI primer combinations were employed to genotype 78 F2 progenies derived from a cross between P107 Japanese inbred line and Khorasan Lemon Iranian native strain. Among polymorphic markers, 159 AFLP markers were assigned to 24 linkage groups at the LOD threshold of 2.5 that varied in length from 4 to 299 cM. The total length of the linkage map was 2747 cM, giving an average marker resolution of 19.31 cM. A total of 21 AFLP markers were identified that were distributed over the ten linkage groups linked to the three studied traits using the composite interval mapping method. The explained variation rate by QTL controlling cocoon weight, cocoon shell weight, and cocoon shell percentage ranged from 0.02% to 64.85%, 0.2% to 49.11%, and 0.04% to 84.20%, respectively. These QTL controlled by different actions as well as under dominance, additive, partial dominance, dominance, and over dominance.

THE EFFECT OF FEEDING MULBERRY HYBRID ON THE PRODUCTIVITY AND THE QUALITY OF COCOON SILKWORM

Hybridization Morus sp, has given a significant impact increasing leaf productivity. There ore some good performaning Morus hybrids such as M. nigra x M. indica (M.N1). M. australis x M. indica (M.AsI). and M. alba var kanva which might be good forfeeding materials of silkworm. However, it is necessariy to test the leafsuitability asfeeding material to the quality of cocoon that will be produced. For that purpose one set offeeding experimentation using Bombyx mori L, (bivoltine silkworm egg F1 China and Japan double crossed with the code C 301) and three kinds of mulberry was established. The researeh located in Grogolan village, with 500 m asl. altitude, 2.500 mm - 3.000 mm rain per year, 75% relative humidity and 25° .3,0°C temperature. The study was arranged Randomized Completely Design with three replications. The result showed that the effects of mulberry leaves were non signifcant for the survival percentage of silkvorm instar I-III, the survival percentage of silkworm instar IV-V, weight of cocoon, weight of cocoon shell, cocoon shell percentage, length of filament, weight of filament, filament percentage and reelability of cocoon, There were significant differences in rendement ofrearing. In general, leaves those three hybrids are suitable for silkwonn feeding.

Study on genetic parameters of some economic traits in Iranian indigenous silkworm races

Silkworms are well-known industrial insects, which produce natural fiber silk. Because of economic importance for silk yarn, an effort to breed new silkworm variety has been made for thousand years. High cocoon yielding due to high resistance, high silk reeling ability and productivity, better silk quality in neatness and lousiness is essential for new silkworm variety to increase silk productivity. Today, several hundred varieties have been bred accordingly various interests and purposes (Kang et al., 2001, 2002). Pupation rate, single cocoon weight, cocoon shell weight and cocoon shell percentage are the main factors affecting the high yielding of cocoon (Kang et al., 2001, 2002). Native silkworm varieties have the low performance and could not be commercially employed. Indigenous strains are valuable genetic resources. They have been affected by natural selection in the successive generations and adapted to indigenous diseases and environmental conditions. Genetic and phenotypic characterization of locally available native silkworm populations provides essential information to make rational decisions for the improvement and development of effective breeding programmes. Hence, the present study was undertaken to identify genetic potential of indigenous silkworm for designing suitable breeding programmes.

Relationships of Actual Performance of Double Cross Hybrids and Predicted Value based on the Mean Value of the Single Crosses concerned in the Silkworm, Bombyx Mori L.

The correlation between actual performances of double cross hybnds and mean values of corresponding measurements obtained for single crosses produced among parenta, 1 four strains were examined in the silkworm, in order to evaluate the possibility of prediction of double cross performance frorn the single cross data. It was found that the correlations were high for some traits such as cocoon shell percentage, raw silk percentage, Iength of cocoon filarnent and size of cocoon filament, but they were low for others such as pupation rate, cocoon yield and reelability.

Effects of reduced feeding and of premature mounting of larvae upon the cocoon weight, cocoon shell weight cocoon shell percentage and egg number

Effects of reduced feeding and of premature mounting of larvae upon the cocoon weight, cocoon shell weight cocoon shell percentage and egg number