Silkworm Breeding Research Articles

The Mechanisms of Silkworm Resistance to the Baculovirus and Antiviral Breeding.

Silkworm (Bombyx mori) is not only an economic insect but also a model organism for life science research. Bombyx mori nucleopolyhedrovirus (BmNPV) disease is a major infectious disease in the world's sericulture industry. The cocoon loss caused by this disease accounts for more than 60% of the total loss caused by all silkworm diseases. To date, there has been no effective solution for preventing and treating this disease. The most effective measure is to breed disease-resistant varieties. The quickest way to breed disease-resistant varieties is to apply genetic modification. However, this requires that we obtain disease resistance genes and know the mechanism of disease resistance. Since the discovery of disease-resistant resources in 1989, scholars in the sericulture industry around the world have been inspired to search for resistance genes. In the past two decades, with the help of multi-omics technologies, screening of resistance genes, gene localization, protein modification, virus-host interactions, etc., researchers have found some candidate genes that have been proposed to function at the cellular or individual level. Several disease-resistant varieties have been obtained and used in production through hybrid breeding, RNA interference, and genetic modification. This article summarizes and reviews the discovery of and research advances related to silkworm resistance to BmNPV. It is anticipated that the review will inspire scientific researchers to continue searching for disease resistance genes, clarify the molecular mechanism of silkworm disease resistance, and promote disease-resistant silkworm breeding.

Importance of the correct organization of papillonage in sericulture

According to the history of sericulture, the domestication and utilization of the silkworm as a source of silk began in the Shang-tung province of China around 3000 BC, and silk weaving began 2700 BC. Only intimate members of the imperial family and women of high birth were allowed to work in the manufacture of cocoons and silk in ancient China, which was considered to be nearly holy. From ancient times, the Chinese have rigorously controlled the breeding of silkworms and the monopoly of silk, safeguarding the lucrative business with regulations that make it illegal to receive raw silk, disclose methods for producing cocoons, or even have the desire to export silk. This article deals with sericulture in general, its grain production, the role of papillonage in pedigree sericulture stations, where pre-breeding grain is prepared, super-elite and elite, in grain factories where hybrid or industrial grain is prepared for the production of industrial windows in farms and other farms.

Appearance of biological and productivity indicators of foreign breeds and hybrids of bombyx mori l. propagated in seed enterprises in different conditions

At the global level, special attention is paid to the care of the mulberry silkworm Bombyx mori L. in different climatic conditions, the adaptation of monovoltine breeds and hybrids to different ecological regions, and the production of high-quality raw silk that meets the requirements of the international standard 2A, 3A, 4A. being directed. Today, creating a new generation of mulberry silkworm breeds and hybrids and improving the technological properties of cocoons and silk raw materials obtained from them, determining the effects of various environmental factors and objectively evaluating the physical and mechanical properties of cocoons are considered as urgent problems on a global scale. Currently, some of the mulberry silkworm seeds, which are not enough for farms in our country, are imported from the People's Republic of China. The economic value of these imported elite and industrial hybrids, namely silkworm egg viability, worm viability, length of larval larval period, biological factors such as mulberry silkworm, cocoon and shell weight, cocoon yield, silkiness and cocoon productivity such as fertile and non-fertile cocoons. It is scientifically based on the extent to which the natural climatic conditions of the regions of Uzbekistan affect productivity indicators such as percentage, dry weight of cocoons, percentage of defective cocoons.

Evaluation of Thermotolerant Bivoltine Silkworm Breeds through Cocoon Yield and Filament Characteristics against Beauveria bassiana (Bals-Criv.) Vuill. Inoculation

Silkworm, Bombyx mori L. being a poikilothermic insect is susceptible to both biotic and abiotic factors. The present study was carried to assess the performance of few thermotolerant bivoltine silkworm breeds under high temperature treatment (36 ± 1⁰ C for 6 hours) and Beauveria bassiana (Bals-Criv.) Vuill. inoculation (6.86 ̕X 104 spores / ml @ 0.5 ml / silkworm). Seven thermotolerant bivoltine silkworm breeds viz., B1, B2, B4, B6, B8, APS12, and APS45 and two popular bivoltine breeds, CSR2 and CSR4 breeds and one popular multivoltine breed Pure Mysore were utilized for the study. Among the thermotolerant breeds studied, the breed B4 was found to perform better with respect to cocoon yield by number, cocoon yield by weight, average filament length, filament weight under both high temperature treatment and B. bassiana inoculation. CSR4 breed was found to be least performer for all the parameters. Therefore, the breed B4 can be a better parent for hybridization and improvement under both the stress conditions.

The general situation, problems and solution proposals of silkworm breeding in the Defne, Antakya, Samandag and Yayladag Districts of Hatay city

Amaç: Bu çalışmada Hatay ili, Defne, Antakya, Samandağ ve Yayladağı ilçelerinde İpek böceği ile uğraşan yetiştiricilere anket soruları yöneltilmiş ve ipek böceği yetiştiriciliğinin genel durumu tespiti edilmiştir. Yöntem ve Bulgular: Hatay ilinde ipek böceği yetiştiriciliğinin genel durumu incelendiğinde, dut yaprağı temini, yetiştirme sorunları, hastalık ve elde edilen kozaların satılmasında sıkıntılar yaşandığı tespit edilmiştir. Çalışmada arazisi olmayanlar, ankete katılanların % 53.8'ini oluşturmuştur. Yetiştiricilerin arazisi olmaması dut yaprağı elde edilmesini zorlaştırmaktadır. İpek böceği bakımının zor oluşu ve ipek böceği yetiştiriciliğinin karlı bir iş olmaması diğer sıkıntıları oluşturmaktadır. Genel Yorum: Anket çalışmasına katılan ipek böceği yetiştiricileri daha çok arazisinin olmaması nedeniyle dut yaprağı elde edilmesinin zorlaşması, bakım ve besleme, hastalık ve zararlı ile mücadele konusunda sorun yaşamaktadırlar. Ayrıca elde edilen kozaların satılması konusunda da sıkıntılar yaşanmakta olup, bu sıkıntıların giderilmesi için alternatif çözümler üretilmelidir. Ülkemizdeki bu alanda tek birlik olan Kozabirlik, gerek Hatay ve gerekse diğer illerdeki ipek böceği yetiştiricilerine daha fazla destek sağlamalıdır. Çalışmanın Önemi ve Etkisi: Türkiye’de İpek böceği yetiştiriciliği ile ilgili az sayıda çalışma bulunmaktadır. Bu çalışma kapsamında, Hatay ili, Defne, Antakya, Samandağ ve Yayladağı ilçelerinde İpek böceği yetiştiriciliğinin genel durumu belirlenip, sorunları tespit edilerek çözüm önerileri sunulmuştur.

Genetically Modified Silkworm Breeds (Bombyx mori L.) with Sexual Dimorphism at the Initial Stage of Ontogenesis

The purpose of the work was to evaluate the breeds of the world silkworm collection of the Scientific Research Institute of Sericulture (SRIS) labelled by sex at the stage of eggs of silkworm by biological characteristics for their use in hybridization. The eggs of silkworm of these genetically modified breeds can be easily separated by color (by sex) before reaching the imago stage.
 The work was carried out in the laboratory of genetics and breeding of the silkworm of the SRIS on the materials of the living collection of the silkworm in 2020-2022.
 The search and selection of breeds for hybridization was carried out by the ranking method. The ranking method consists in the ability to establish a relationship between the features, which are expressed by the order of the place occupied by each member in the aggregate, i.e. the place of rank in the variation series.
 Hybrids from breeds labeled by sex at the stage of silkworm eggs with 100% purity of preparation, with the maximum manifestation of heterosis in reproductive and biological indicators, differ in: a high number of normal eggs in a clutch of C-12×C-10 - 614pcs, C–5×C-13 - 598pcs, C-12×C-14 – 598 pieces; caterpillar viability – C-12×C-10 – 96,5%, C-5×C-13 – 96,0%, C-12×C-14 – 96,2%; content of raw silk, – C-12×C-10 – 22,2%, C-5×C-13 – 22,0%, C-12×C-14 – 20,3%.
 By the methods of traditional breeding selection at all stages of development, improved lines of silkworm breeds C-5, C-10, C-12, C-13, C-14 were bred in terms of reproductive indicators, hatching of silkworm eggs, the viability of caterpillars, weight and content of raw silk of cocoons.

Haemolymph amylase activities in different silkworm (Bombyx mori L.) breeds during the last four days of 5th instar and correlation studies with economic traits

Haemolymph amylase activities in different silkworm (Bombyx mori L.) breeds during the last four days of 5th instar and correlation studies with economic traits

Studies on the digestive juice protein in various bivoltine silkworm breeds and correlations with economic variables

Studies on the digestive juice protein in various bivoltine silkworm breeds and correlations with economic variables

Evaluation of nutritional indices and conversion efficiency in multivoltine, cross-breeds and popular bivoltine double hybrid of mulberry silkworm Bombyx mori

In sericulture, the nutritional ability of mulberry varieties and conversional traits of silkworm breeds have an important role in the improvement of silk yield. The present study aims to evaluate silk conversion efficiency in a few breeds and hybrids. The silkworm Bombyx mori breeds and hybrids viz., MVI, PMxCSR2, MV1xS8 and FC1xFC2 were assessed during the fifth instar, with PM as control during the years 2019 and 2020. The study focused on the nutritional indices and conversion traits of silkworms by feeding V1 mulberry leaves, reared under the same environmental conditions. Significant variations were observed among silkworm breeds and hybrids. The test breed and hybrids were found superior to the control PM, which recorded an ingestion of 2.33g and a conversion ability of 8.65%. The bivoltine double hybrid FC1xFC2 showed high food ingestion (3.25g) and conversion (18.18%), followed by the cross breed MV1xS8 with moderate ingestion (3.17g) and conversion (16.63%). The values for ingesta and conversion in PMxCSR2 were 3.43 g and 8.92%, respectively. Further, in respect of Efficiency Conversion of Ingesta (ECI) of shell, the highest conversion of shell is shown by FC1xFC2 (13.56%) followed by MV1xS8 (10.14%), MV1 (9.73%) and PMxCSR2 (9.36%), having a percentage difference of 63.27%, 36.08%, 32.11% and 28.30% respectively over PM. The silk conversion efficiency of bivoltine double hybrid FC1xFC2 was found to be profoundly high, followed by multivoltine cross-breeds and pure line (PM) tested.

The importance and role of sericulture development and silkworm breeding in the economy of Azerbaijan

The importance and role of sericulture development and silkworm breeding in the economy of Azerbaijan

The use of methods for controlling the reproduction of the silkworm (<i>Bombyx mori L.</i>) in practical sericulture

Relevance.The importance of breeding in increasing the productivity of agricultural animals can be perfectly demonstrated on the mulberry silkworm. For 5 thousand years, continuous selection was carried out, the main feature for which was silkiness. However, the more productive the object becomes, the more difficult and complicated traditional breeding turns out to be.Methods.New methods of breeding can be developed as a result of the use of artificial methods of reproduction. The implementation of all methods of artificial reproduction known to science (ameiotic and meiotic parthenogenesis, gynogenesis, androgenesis, polyploidy) with various cytogenetic mechanisms and methods of sex regulation to the silkworm has opened up new experimental possibilities. This makes it possible to control the inheritance of traits in a population within a wide range, which is especially effective when using artificial breeding methods in combination, for example, when breedinghybridizing parthenogenetic clones and sex-determined silkworm. Mеthods of breeding, preservation and use of genetically modified silkworm breeds have been worked out and repeatedly tested.Results.The industrial hybrids created in our research by breeding parthenogenetic clones and sex-labeled breeds at the egg stage are characterized by high heterosis in caterpillar viability (95.0–96.0%), ease of preparation of hybrid grene, economic benefits due to the abolition of breeding work, cocoon sorting, as well as expensive, lengthy and very inaccurate cocoon division by gender.

High-resolution silkworm pan-genome provides genetic insights into artificial selection and ecological adaptation

The silkworm Bombyx mori is an important economic insect for producing silk, the “queen of fabrics”. The currently available genomes limit the understanding of its genetic diversity and the discovery of valuable alleles for breeding. Here, we deeply re-sequence 1,078 silkworms and assemble long-read genomes for 545 representatives. We construct a high-resolution pan-genome dataset representing almost the entire genomic content in the silkworm. We find that the silkworm population harbors a high density of genomic variants and identify 7308 new genes, 4260 (22%) core genes, and 3,432,266 non-redundant structure variations (SVs). We reveal hundreds of genes and SVs that may contribute to the artificial selection (domestication and breeding) of silkworm. Further, we focus on four genes responsible, respectively, for two economic (silk yield and silk fineness) and two ecologically adaptive traits (egg diapause and aposematic coloration). Taken together, our population-scale genomic resources will promote functional genomics studies and breeding improvement for silkworm.

О ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ НЕКОТОРЫХ СОРТОВ ШЕЛКОВИЦЫ ПРИ ВЫКОРМКЕ РАЙОНИРОВАННЫХ ПОРОД ТУТОВОГО ШЕЛКОПРЯДА

Sericulture has been and remains one of the most important branches of agriculture in Uzbekistan, with centuries-old traditions and proven technologies for keeping silkworms. However, global climate changes across the planet and the shift in the development of the national economy trigger the need for search of new methods of the silkworm reproduction and other sources of feed. Repeated attempts to transfer the silkworm to artificial food or other plant species have not proven succesfully. In our research, we have explored a possibility of using non-fodder caterpillars, namely decorative mulberry varieties, for feeding. The findings gained indicate the validity of the weeping mulberry varieties use in the breeding of silkworms in the case of an early start of feeding. Early vegetation of mulberry trees in urban conditions, a large leaf blade and a large green mass of weeping mulberry, make it good for feeding young silkworm caterpillars.

Emergy-Based Sustainability Evaluation of the Mulberry-Dyke and Fish-Pond System on the South Bank of Taihu Lake, China

The Taihu Lake drainage basin is the birthplace of the Mulberry-dyke and Fish-pond System (MFS), a traditional eco-agricultural system. In 2017, the largest and best-preserved “Zhejiang Huzhou Mulberry-dyke and Fish-pond System” located by the South Bank of Taihu Lake, China was recognized as Globally Important Agricultural Heritage Systems (GIAHS) by the Food and Agriculture Organization of the United Nations (FAO), and its value has been appreciated. As a dynamic heritage, the sustainable development of MFS is a fundamental requirement of the conservation of GIAHS. In this regard, it is necessary to figure out an approach to evaluating the status of its sustainable development. This paper analyzes and contrasts the emergy embodied in the three patterns of MFS over different periods, then constructs an index system of sustainability evaluation involving the production and consumption processes based on that. Finally, it provides the evaluation and analysis. The three patterns of MFS differ in the system structure. In the Ming and Qing Dynasties (abbreviated as Ming-Qing pattern), MFS was an integrated system compromised of mulberry cultivation, silkworm breeding, fish breeding, and sheep breeding, while other patterns exclude sheep breeding, but increase the input of fertilizer, and add the production of mulberry-leaf tea and other local specialties. The results show that the MFS in the Ming-Qing pattern has the highest integrated evaluation index of sustainable development, followed by the traditional MFS pattern and the new MFS pattern employed nowadays. This indicates that the current capability of sustainable development has decreased compared to that in the Ming and Qing Dynasties. The integrated evaluation index regarding the consumption process of the new MFS pattern is higher than the traditional one, suggesting that it needs to promote sustainability in the production process, especially via the utilization rates of renewable resources and wastes.

Effect of different lethal temperature assay methods on thermal tolerance plasticity of three different breeds of mulberry silkworm (Bombyx mori L.)

BackgroundMulberry silkworm (Bombyx mori L.) is one of the best-studied insect models, regularly used as a type specimen for thermal tolerance experiments on insects. Still, the upper lethal limit of this lepidopteran has never been explored extensively using any sort of conventional lethal assay method. The present study deals with the employment of different lethal assay protocols for the study of survivorship of three different breeds of mulberry silkworm (B. mori) exposed to different temperatures (30–50 °C) and durations of stress (1–3 h) on different days (day 2, 4, and 6) of the fifth instar stage for formulating an extensive upper lethal temperature (ULT50 and ULT25) index.ResultsAmong treatment temperatures 30 °C, 35 °C, and 40 °C had a significant (p = < 0.0001) impact on the high-temperature survival rate of the silkworm. Among duration—1 h and 2 h influenced the survival rate significantly (p = < 0.0001). Plunging, one-way ramping, and two-way ramping assay methods seemed to exert a non-significant (Wald χ2 = 3.253, p = 0.197) influence on silkworm survival. F1 hybrid was found to exhibit the highest survivorship across different temperatures, followed by the multivoltine Nistari plain and then by the bivoltine breeds. In F1 hybrid silkworms, the upper lethal temperatures ULT50, varied within the range of 37 °C to 44 °C and ULT25 varied within the range of 40–47 °C. The mean upper lethal limit—ULT0 for all three breeds of mulberry silkworm, across all experimental groups, was computed to be ~ 49 °C.ConclusionsUltimately the overall thermal tolerance of mulberry silkworm exhibited a significant inter-breed variation based on the heterogeneous thermal plasticity of the three different breeds. The outcome of the present study in the form of upper lethal temperature ranges of the breeds under consideration can form the basis of future thermal stress experiments in mulberry silkworms.

A real-time qPCR method for early detection of Bombyx mori Bidensovirus (BmBDV) infection in silkworm

Bombyx mori bidensovirus (BmBDV) replicates in the midgut cells of the silkworm to cause fatal flacherie disease. Flacherie disease causes a major impact in silk production and severe economic loss in the silk industries of India. BmBDV possesses two single stranded DNA that encodes for putative protein-primed DNA polymerase and adopts its own mechanism for replication. Development of rapid, sensitive and simple-to-use novel technology such as real-time polymerase chain reaction (RT-qPCR) will be useful in detection of BmBDV in silkworms. This RT-PCR assay will help to understand the significant pathology of BmBDV. The primers in specific to VD2 ORF1 region of BmBDV were designed to study their sensitivity and specificity. The detection limit of qPCR was found to be 3.01 × 101 copy number in the plasmid DNA with 96.3% efficiency in RT-PCR. In accordance, results shown in our study are 1000 times more sensitive than the conventional PCR with a detection limit of 3 × 104 in PCR assay. Apart from displaying an increased sensitivity, these primers show high specificity towards BmBDV pathogenicity. On detection of flacherie infection studies with the specific primers shows gradual increase in detection of infectivity of BmBDV from 12 h to post infection for 48 h. In this case, the copy number reported at 48 h was found to be >107 copies/reaction through qPCR analysis. The validation of this method was conducted using 90 diseased samples collected from 10 different sericulture farms. Here, detected virus copy numbers range from 1.24 × 103 to 1.08 × 1010 where the optimization of RT-PCR could be used as a valuable tool in detection of BmBDV virus. Further aid in formulating appropriate disease control strategies, screening silkworm breeds for resistance during early infection stages are initiating reasons for this study. This particular analysis will provide a platform for developing silkworm hybrids to prevent further crop loss at the field level.

Mulberry silkworm (Bombyx mori L.) hybrids in Uzbek selection and, viability, cocoon productivity, and reproductive indicators in summer and fall seasons

The demand for silk products with high metric number (thin) in the world market is growing every year. The main demand of cocoon processing enterprises in China, India, South Korea, Italy, France and Japan, the leading countries producing silk products, is focused on silk yarns of type 3A, 4A, and 5A. Due to the lack of special mulberries for re-worm feeding, summer-fall worm feeding usually begins after the mulberry trees and mulberries, whose seedlings have been cut down for spring worm feeding, have harvested enough leaf produce. Nutritional degradation of the leaves to worms and hot weather together make it difficult for the worms to eat and digest nutrients during repeated feeding, and the worms slow down the synthesis of silk substance in the silk gland. Therefore, in summer and fall, small, silky-thin cocoons are obtained. At the same time, it is important to try and select breeds and hybrids that are resistant to hot weather conditions and create new breeds and hybrids suitable for the summer and fall seasons. This article describes the results of research conducted on the testing of silkworm breeds and hybrids in the conditions of repeated worm feeding and the selection of the required level in terms of productivity characteristics. In separate experiments conducted during the summer and fall seasons of 2016-2018, the worm viability, cocoon productivity, and germination traits of each breed, system, and breeding hybrid were studied comparatively.

Selection of partenogenetic clones for mixing with fine silkworm breeds in the conditions of Uzbekistan

The creation and introduction into production of new breeds and hybrids that meet the needs of the world market and industrial enterprises through the development of selection methods for breeding stations and seed enterprises is of great scientific and practical importance. In this regard, the work of a number of local and international scientists is devoted to the selection and creation of new breeds and hybrids of mulberry silkworm on the basis of leading selection traits. The effectiveness of the artificial parthenogenesis method developed in our laboratory is that the effect applied suppresses the reduction division of egg cells. Also, the parthenogenetic genus immediately receives the same set of chromosomes and genes. However, ♀ clone × ♂ hybrid worms have a high viability, the cocoons are the same in shape and other characteristics, there is no work on the separation of the primary parent breed (parthenoclonus) for hybridization (because it consists of 100% only females), breeding at all stages work is not done (because all parthenoclon females are genetically the same and do not change by generation). It is also possible to obtain all the cocoons of parthenoclon in the extraction of cocoons, as their genetic homogeneity completely eliminates the sorting of cocoons in breeding stations and seed plants.

Issues of Development of Cocoon Growing and Processing Industry in Surkhandarya Region

Examples of development of silkworm breeding and recycling industry in Surkhandarya region were considered. in which the kholas in thedistricts are given and analyzed over the years. conclusions are given.

ESTIMATION OF GENETIC PARAMETERS AND VARIABILITY IN THE BIVOLTINE SILKWORM BOMBYX MORI L GERMPLASM

Genetic variability is a fundamental and an essential requirement of crop species for the development of superior breeds of high commercial value with strong genetic base. Evaluation and estimation of genetic potentials of silkworm breeds are of prime importance in order to identify promising silkworm genotypes for its commercial exploitation through breeding to enhance the silk productivity for sustainable use. The objective of this study was to evaluate the genetic variability of vast silkworm germplasm and to estimate the genetic parameters of important productive traits. 368 bivoltine silkworm accessions from the germplasm are considered for assessment of genetic variability with five year data on important productive traits. Wide range of variability was observed based on Coefficient of Variation (%) values in the productive parameters viz., fecundity (11.316), weight of the larva (9.285), cocoon yield (7.892), single cocoon weight (8.272 ), shell weight and (12.289) shell ratio (7.082). Based on the multiple trait analysis by Mano index values, 20 top performing accessions were selected and genetic parameters such as heritability, genetic advance and phenotypic &amp; genotypic coefficient of variances were estimated. Pooled ANOVA of 20 selected silkworm accessions indicates significant variations @1% level over the five generations in all the parameters. Higher heritability associated genetic advance was recorded in cocoon weight, shell ratio, shell weight and larval weight, besides, higher genotypic and phenotypic variances in cocoon weight. The results enumerate the importance of evaluation of silkworm germplasm and estimation of genetic parameters for selection of parental stocks for subsequent breeding programme in development of desired breeds.