Silkworm Races Research Articles

A New Silkworm Race for Sericin Production, “Sericin Hope” and its Product, “Virgin Sericin”

A New Silkworm Race for Sericin Production, “Sericin Hope” and its Product, “Virgin Sericin”

Identification and association of ISSR markers for thermal stress in polyvoltine silkworm Bombyx mori

Evaluation of genetic resources is an essential prerequisite for their effective utilization. In India, the tropical climate prevails in most of the sericultural belts, where temperature goes beyond the ambient during summer, adversely affecting the silkworm rearing. Although polyvoltine silkworms are poor in silk content, they are mostly tolerant to tropical conditions and diseases. With an aim to identify potential silkworm races/breeds specific to thermo-tolerance for their effective utilization in breeding programme, 15 selected polyvoltine silkworm races were studied for their thermo-tolerance behaviour. Their genomic DNA samples were analyzed for ISSR-PCR using 15 selected primers. The UPGMA analysis based on Nei and Li algorithm has clustered the 15 silkworm races into five groups and one isolate. ALSCAL-multidimensional scaling has not only supported the information generated by the dendrogram, but it has made the genetic distance among races more clear and substantiating their status in terms of thermal stress where pupation rate was taken as indicator. Further, discriminant function analysis (DFA) was done with three groups of silkworms classified for thermal stress viz. susceptible, moderately tolerant and tolerant. The canonical correlation value was estimated to be 0.987 (Wilk's lambda = 0.004; chi2 = 36.044, p < 0.05). DFA clearly discriminated the above three groups. Beta statistics with t value and its significance for the markers identified through stepwise multiple regression analysis (MRA) revealed a total of five bands (807(1300), 808(3000), 808(4000), 834(4000), and 834(3000)) showing correlation with pupation rate after thermal treatment. Out of them, marker 8083000 showed maximum and highly significant correlation (r = 0.757, p < 0.001, t = 4.182) with pupation rate among the silkworm races. The identified putative markers are being used to develop DNA marker to be used in evolving thermo-tolerant silkworm breeds using marker assisted selection programme.

Analysis of SSR Fingerprints in Introduced Silkworm Germplasm Resources

Thirty-five SSR markers were used to construct 96 silkworm races fingerprint. All the SSR markers were polymorphic and unambiguously separated silkworm strains from each other. A total of 467 alleles were detected with a mean value of 13.34 alleles/locus (range 3-28). The mean polymorphism index content (PIC) was 0.71 (range 0.299-0.919). UPGMA cluster analysis of Nei's genetic distance grouped silkworm strains on the basis of their origin. The results indicated that SSR markers are efficient tools for fingerprinting cultivars and conducting genetic diversity studies in the silkworm.

The lusters and color values of the cocoon thread among the silkworm races.

The lusters and color values of the cocoon thread among the silkworm races.

新品種 (世界一×中515号交雑種) の諸形質と生糸の力学特性

新品種 (世界一×中515号交雑種) の諸形質と生糸の力学特性

Effective induction of egg diapause in multivoltine silkworm races by low temperature and short-photoperiod rearing condition

Effective induction of egg diapause in multivoltine silkworm races by low temperature and short-photoperiod rearing condition

施肥量の異なる桑葉による「はくぎん」の繭糸質について

施肥量の異なる桑葉による「はくぎん」の繭糸質について

Caracterização de oito raças do bicho-da-seda (Bombyx mori L.)

O experimento foi conduzido na Estação Experimental de Zootecnia de Gália, do Instituto de Zootecnia, SAA-SP, no ano de 2000. Oito raças de bicho-da-seda, de origem Japonesa e Chinesa foram estudadas (B101, B102, B104, B109, C201, C202, C203, C208) em relação a caracteres biológicos (Ganho de peso total de uma lagarta-GP, Porcentagem de mortalidade-MO, Número de machos-NM, Número de fêmeas-NF, Número de ovos/postura-OP e Porcentagem de eclosão-EC) e caracteres de produção de casulo (Peso unitário da glândula sericígena-GS, Peso de 30 cascas séricas-CS, Peso de 30 crisálidas-PC, Teor de seda líquido-TS, Casulos desclassificados-CD, Comprimento do casulo-CC e Largura do casulo-LC). O delineamento experimental foi o inteiramente casualizado, com quatro repetições/raça. Não houve variação entre as raças para GP, MO, NF e OP. A raça B101 apresentou, no geral, um menor NM e uma menor EC. Quanto à produção de casulos, no geral, os melhores resultados foram apresentados pela raça C202, com um bom GS (38% do peso final da lagarta), um dos mais altos CS e TS e valores próximos da média para PC, CD, CC e LC. A raça C201, em relação ao casulo produzido, apresentou os piores resultados.

Worm-cocoon qualities and mechanical properties of raw silk of the new silkworm races , hybrid Koishimaru

Worm-cocoon qualities and mechanical properties of raw silk of the new silkworm races , hybrid <i>Koishimaru</i>

Studies on the analysis of characteristics on the preserved silkworm races (2) In the cace of japanese improved race

Studies on the analysis of characteristics on the preserved silkworm races (2) In the cace of japanese improved race

Effect of Fenvalerate-20EC on Sericigenous Insects: I. Food Utilization in the Late-Age Larva of the Silkworm, Bombyx mori L.

The effect of the common pyrethroid insecticide fenvalerate-20EC (Sumicidine-20EC) on food utilization parameters in the pure multivoltine (Pure Mysore) and pure bivoltine (NB 4D 2) races of silkworm, Bombyx mori, fed ad libitum with Morus alba, was studied in the final two instars. Insecticide treatment was found to reduce the rates of feeding, assimilation, and conversion along with the efficiencies of conversion of ingested and digested food into body substance. This was due to the toxic effects, which interfered with the silkworms' feeding behavior, and physiology of digestion, and the magnitude of changes increased with the increase in the concentration of fenvalerate used. To overcome the deleterious effects of such pyrethroid insecticides, it has been suggested that the safe periods for use of mulberry leaves contaminated with fenvalerate for summer and winter.

DNA fingerprinting with homologous multilocus probes and search for DNA markers associated with yield attributes in silkworm, Bombyx mori

RFLP clones harbouring multi-copy DNA sequences were isolated from the Pst I sub-genomic library of the indigenous silkworm race, Nistari, and were used for DNA fingerprinting studies in 13 stocks of silkworm, Bombyx mori L. Six multilocus probes produced 180 RFLP markers that showed a high level (98%) of polymorphism and are highly useful in molecular mapping, genotype characterization and marker assisted selection (MAS). The dendrogram derived from UPGMA analysis clearly divides the 13 silkworm stocks into two major clusters: high- and low-yield stocks. Furthermore, adopting multiple regression analyses, the RFLP marker(s) associated with characters of economic importance were identified, a first of its kind for any species of insect of commercial importance. The results obtained create an opportunity of using germplasm stocks directly for isolating specific RFLP band(s) and use it for MAS in breeding programs.

The effect of mulberry varieties on the performance of chul thai 5 silkworm race

An assessment of eight mulberry varieties namely, S54, S41, S36, S34, S30, S14, K2 and NG1 in Ibadan under the lowland rainforest ecological zone of Nigeria showed that within a period of fifteen months the lowest survival of 25.1% occurred in the S36 variety of mulberry while the highest survival of 86.9% was recorded for the S54 variety. The leaf yield/ha/annum/variety showed that varieties S14 and S30 are the most productive respectively. While S14 produced the highest wet leaf weight of 17,204.5 Kg., K2 produced the lowest of 11,131.7 Kg. The relationship in leaf yield for the eight mulberry varieties is as follows: S14>S30>NG1>S34>S54>S41>S36>K2. After feeding the mulberry varieties to the Chul Thai 5 silkworm race, the highest cocoon yield of 74 Kg per 100 Disease free layings (Dfl's) was recorded for S30. The level of Sodium (Na) in the leaves appear to be a critical factor in the observed cocoon yield of the silkworm because S30 with 0.02% Na produced highest cocoon yield compared with other varieties with 0.03% Na. Further research into sodium metabolism as it affects cocoon production by silkworms is essential. Since palm-fronds are easily accessible to peasant farmers, their use as an alternative for the construction of mountages for the worms will reduce the overhead costs for cocoon production to peasant farmers. However, cocoons produced shall be for domestic consumption qualitywise. Keywords: mulberry, silkworm, cocoon Resume Une evaluation de huit varietes de murier dont S54, S41, S36, S34, S30, S14, K2 et NG1 faite a Ibadan dans la zone ecologique de foret humide de basse altitude du Nigeria a prouve, qu'au cours d'une periode de quinze mois, la variete S36 a accuse la plus faible survie (25,1%) tandis que la variete S54 affichait la survie la plus elevee (86,9%). Le rendement annuel par ha en feuilles fraiches a montre que les varietes S14 et S30 etaient les plus productives respectivement. Au moment ou la variete S14 avait le rendement annuel en feuilles fraiches le plus eleve (17.204,5 kg/ha), K2 affichait le rendement le plus bas (11.131,7 kg/ha). Le classement des rendements en feuilles fraiches pour les huit varietes de murier se presentait comme suit: S14>S30>NG1 > S34>S54>S41 > S36>K2. Apres alimentation du ver a soie, race Chul Thai 5, sur les varietes de murier, le rendement en cocons le plus eleve (74kg par 100 femelles bien portantes) a ete enregistre pour S30. La teneur en sodium (Na) dans des feuilles du murier semble etre un facteur critique pour le rendement en cocons observe chez le ver a soie puisque la variete S30 avec une teneur de 0,02% Na a donne le rendement en cocons le plus eleve, comparee a d'autres varietes avec 0,03% Na. Des recherches plus poussees sur le metabolisme du sodium et ses effets sur la production de cocons par les vers a soie restent essentielles. Puisque les frondes de palmier sont facilement a la portee des paysans, leur utilisation comme une alternative dans les structures d'elevage du vers a soie vont reduire les frais generaux pour la production de cocons au niveau rural. Cependant etant donnee leur qualite, les cocons produits seront pour l'utilisation locale. Mots-cles: murier, ver a soie, cocon (Discovery and innovation: 14(1-2): 77-83)

Heat shock response in mulberry silkworm races with different thermotolerances

The thermal sensitivity and heat shock response of the different races of the mulberry silkworm Bombyx mori have been analysed. The multivoltine race, strains C. Nichi and Pure Mysore showed better survival rates than the bivoltine race, strain NB4D2 exposed to 41 degrees C and above. In general, the fifth instar larvae and the pupae exhibited maximum tolerance compared to the early larval instars, adult moths or the eggs. Exposure up to 39 degrees C for 1 or 2 h was tolerated equally whereas temperatures above 43 degrees C proved to be lethal for all. Treatment of larvae at 41 degrees C for Ih resulted in a variety of physiological alterations including increased heart beat rates, differential haemocyte counts, enlargement of granulocytes and the presence of additional protein species in the tissues and haemolymph. The appearance of a 93 kDa protein in the haemolymph, fat bodies and cuticle, following the heat shocking of larvae in vivo was a characteristic feature in all the three strains examined although the kinetics of their appearance itself was different. In haemolymph, the protein appeared immediately in response to heat shock in C. Nichi reaching the maximal levels in 2-4 h whereas its presence was noticeable only after 2-4 h recovery time in Pure Mysore and bivoltine races. The fat body from both C. Nichi and NB4D2 showed the presence of 93 kDa, 89 kDa and 70 kDa proteins on heat shock. The haemocytes, on the other hand, expressed only a 70 kDa protein consequent to heat shock. The 93 kDa protein in the haemolymph, therefore could have arisen from some other tissue, possibly the fat body. The 93 kDa protein was detected after heat shock in pupae and adult moths as well, although the presence of an additional (56 kDa) protein was also apparent in the adults. The presence of 46 kDa and 28 kDa bands in addition to the 93 kDa band in the cuticular proteins immediately following heat shock was clearly discernible. The 70 kDa band did not show much changes in the cuticular proteins on heat shock. In contrast to the changes in protein profiles seen in tissues and haemolymph following heat shock in vivo, the heat treatment of isolated fat body or haemolymph in vitro resulted in protein degradation.

Spore replication rate of Nosema bombycis (Microsporidia: Nosematidae) in the silkworm Bombyx mori L. in relation to pupal development and age of moths

The spore replication rate of the parasitic microsporidian, Nosema bombycis, was investigated in the pupal and adult stages of two popular tropical silkworm races of India, Pure Mysore (multivoltine race) and NB18 (bivoltine race). The rate was assessed in terms of spore yield per unit weight of tissue. In pupae, spore replication in the bivoltine race was higher than that in the multivoltine race. Spore replication in both races followed a logistic pattern. Spore production increased substantially with age of moths in both races. The cephalothoracic region of each race had the highest spore concentration, especially around the wing and wing muscles.

Crystal Size and Minimum Enthalpy of Various Races of Silk Fibers

Wide angle x-ray diffraction studies of silk fibers from various races of silkworms were made to evaluate the crystal size and lattice disortion parameters, since these determine the properties of silk fibers. Also, minimum enthalpy for the formation of these fibers was estimated and compared for the various races. Crystal size in the univoltine race along the [ 210 ] direction is smaller, even though the univoltine fibers are thick compared to those from multivoltine races.

Hierarchical clustering of 54 races and strains of the mulberry silkworm, Bombyx mori L: Significance of biochemical parameters

A detailed analysis was undertaken to test the efficacy of hierarchical agglomerative clustering (UPGMA method) in grouping the races and strains of the mulberry silkworm, Bombyx moti L., and to ascertain the importance of biochemical parameters in the clustering process. The analysis was based on data from two rearing seasons with 54 selected races/strains of different geographic origin and varying yield potentials. The results indicate that seven clusters can be realised with yield parameters alone, whereas the inclusion of biochemical parameters in clustering resulted into two broad groups: one having all the breeds with high cocoon weight and shell weight, the other having all the low-yielding silkworm strains both from India and from other countries. Further sub-grouping under these two groups highlights genetical differences associated with the differentiation of various groups of races in temperate and tropical areas as well as their significance for silkworm breeding. Estimates of all ten variables were further subjected to 'quick clustering' and the results showed that cluster 5, constituted by 38 lowyielding strains of India, China and Europe, had the highest values of the final cluster centre for amylase and the effective rate of rearing (ERR), while clusters 1 and 4 had the highest values for invertase and alkaline phosphatase. The evolutionary aspect of the genetic channelisation of silkworm races from various countries is discussed against the background of differences in the biochemical parameters and yield variables.

EFFECT OF PARAFORMALDEHYDE, BENZOIC ACID WITH LIME AS BED DISINFECTANT FOR PREVENTION OF DISEASES IN SILKWORM, Bombyx mori L.

The effect of paraformaldehyde and benzoic acid with lime at different concentrations as bed disinfectant for disease control in silkworm race KGL was studied by dusting the chemical uniformly on the bed daily once in the morning before first feeding. The disin- fectants were dusted in different patterns from first stage upto Cocoon formation It was observed that dusting of paraformaldehyde 2 percent and benzoic acid 2 percent with lime from Ill stage upto cocoon formation was effective in controlling grasserie disease and also in improving the economic characters of silkworm.

Photoperiodic induction of diapause in the silkworm, Bombyx mori: location of the photoreceptor using a chemiluminescent paint

ABSTRACT. To locate the photoreceptor involved in the photoperiodic induction of diapause in Bombyx mori L., covering of larval head with black paint or local illumination using chemiluminescent paint was carried out. A silkworm race showing a response of long‐day type during the larval stage was employed. The results demonstrated that the photoreceptor is located in the head but is extraocular. The optical properties of the larval body suggest that during the first and second stadia light is admitted through the translucent clypeus of the head, but during later stadia enters over the entire larval body including the head, and that it reaches the cerebral lobe where a photoreceptor is possibly located.

In vivo and in vitro photoperiodic induction of diapause using isolated brain-suboesophageal ganglion complexes of the silkworm, Bombyx mori

By use of a bivoltine silkworm race which shows a long-day photoperiodic response after induction during the last (5th) instar, we tried to programme photoperiodic induction in the isolated brain-suboesophageal ganglion complex in vivo and in vitro. A pair of the complexes from a newly ecdysed 5th-instar female was transplanted into the abdomen of a late 5th-instar larva and exposed to long-day (20 h light: 4 h dark) or short-day (8 h light: 16 h dark) conditions for 3 cycles. The short-day-exposed complexes elicited the production of diapause eggs in the recipient silkworms destined to become non-diapause egg producers, whereas the long-day-exposed brain complexes produced non-diapause eggs. Transplant experiments of the brain-suboesophageal ganglion complex using isolated abdomens showed a similar result. The brain complexes from newly ecdysed females of the 5th-instar were cultured in Grace's insect medium under 20 h light: 4 h dark or 8 h light: 16 h dark for 4 cycles, respectively. After in vitro culture, a pair of complexes was implanted into the abdomen of a late 5th-instar larva destined to become a non-diapause egg producer, and the diapause incidence in the resultant moths was examined. The brain complexes which received the short-day cycles induced a large portion of diapause eggs, whereas those which received the long-day conditions induced non-diapause eggs. The connection of corpora cardiaca and corpora allata with the brain complex had no influence on the result. Suboesophageal ganglia which had been cultured in vitro and implanted elicited a remarkable production of diapause eggs, but cultured brains were ineffective in producing diapause eggs, regardless of the photoperiod experienced. These results demonstrate that photoperiodic induction of the silkworm can be programmed in in vivo and in vitro culture systems, and that components of the photoperiodic clock (photoreceptor, clock, and counter system) are located in the brain-suboesophageal ganglion complex, possibly in the brain itself.