Bombyx Mori Research Articles

MIG1, TUP1 and NRG1 mediated yeast to hyphal morphogenesis inhibition in Candida albicans by ganciclovir.

Candida albicans is a polymorphic human fungal pathogen and the prime etiological agent responsible for candidiasis. The main two aspects of C. albicans virulence that have been suggested are yeast-to-hyphal (Y-H) morphological transitions and biofilm development. Anti-fungal agents targeting these virulence attributes enhances the antifungal drug development process. Repositioning with other non-fungal drugs offered a one of the new strategies and a potential alternative option to counter the urgent need for antifungal drug development. In the current study, an antiviral drug ganciclovir was screened as an antifungal agent against ATCC 90028, 10231 and clinical isolate (C1). Ganciclovir at 0.5mg/ml concentration reduced 50% hyphal development on a silicon-based urinary catheter and was visualized using scanning electron microscopy. Ganciclovir reduced ergosterol biosynthesis in both strains and C1 isolate of C. albicans in a concentration-dependent manner. Additionally, a gene expression profile study showed that ganciclovir treatment resulted in upregulation of hyphal-specific repressors MIG1, TUP1, and NRG1 in C. albicans. Additionally, an in vivo study on the Bombyx mori silkworm model further evidenced the virulence inhibitory ability of ganciclovir (0.5mg/ml) against C. albicans. This is the first report that explore the novel anti-morphogenic activities of ganciclovir against the pathogenic C. albicans strains, along with clinical isolates. Further, ganciclovir may be considered for therapeutic purpose after combinations with standard antifungal agents.

Effect of auxins on biochemical composition of apical cuttings of Mulberry (Morus indica l.) Using mini clonal technology

A research study was carried out to examine the effects of auxin and rooting hormone on the biochemical composition of the mini clonal mulberry leaves raised using mini-clonal technique of (Morus indica L.) variety 'V1'.Two hormones, such as indole-3-butyric acid (IBA) and napthalene acetic acid (NAA), were used in the experiment. The hormones were replicated four times in each of the following concentration ranges: 1000, 2000, 3000, 4000, and 5000 ppm. Different hormone concentrations were applied to apical shoot cuttings before they were planted in the appropriate rooting medium in a greenhouse condition. The biochemical parameters analysed during the research study include leaf moisturecontent, nitrogen, phosphorous, potassium, chlorophyll-a, chlorophyll-b, carotenoid, total chlorophyll, crude protein, total carbohydrates, crude fat, total protein content present in mulberry leaves. The nutritive value of mulberry varieties depends on its biochemical constituents present in it. The results indicated that V1 mulberry mini clones have recorded better biochemical constituents and suitable for rearing of mulberry silkworms to get successful cocoon crop.

Biochemical analysis of defensive enzymes in the hemolymph of bivoltine silkworm breeds of Bombyx mori (Lepidoptera: Bombycidae)

Biochemical analysis of defensive enzymes in the hemolymph of bivoltine silkworm breeds of Bombyx mori (Lepidoptera: Bombycidae)

Contrasting gut bacteriomes unveiled between wild Antheraea assamensis Helfer (Lepidoptera: Saturniidae) and domesticated Bombyx mori L. (Lepidoptera: Bombycidae) silkworms.

Insect gut microbiomes play a fundamental role in various aspects of insect physiology, including digestion, nutrient metabolism, detoxification, immunity, growth and development. The wild Muga silkworm,Antheraea assamensisHelfer holds significant economic importance, as it produces golden silk. In the current investigation, we deciphered its intricate gut bacteriome through high-throughput 16S rRNA amplicon sequencing. Further, to understand bacterial community dynamics among silkworms raised under outdoor environmental conditions, we compared its gut bacteriomes with those of the domesticated mulberry silkworm,Bombyx moriL. Most abundant bacterial phyla identified in the gut ofA. assamensiswere Proteobacteria (78.1%), Bacteroidetes (8.0%) and Firmicutes (6.6%), whereas the most-abundant phyla inB. moriwere Firmicutes (49-86%) and Actinobacteria (10-36%). Further, Gammaproteobacteria (57.1%), Alphaproteobacteria (10.47%) and Betaproteobacteria (8.28%) were the dominant bacterial classes found in the gut ofA. assamensis. The predominant bacterial families inA. assamensisgut wereEnterobacteriaceae(27.7%),Comamonadaceae(9.13%),Pseudomonadaceae(9.08%)Flavobacteriaceae(7.59%)Moraxellaceae(7.38%)Alteromonadaceae(6.8%) andEnterococcaceae(4.46%). InB. mori, the most-abundant bacterial families were Peptostreptococcaceae, Enterococcaceae, Lactobacillaceae and Bifidobacteriaceae, though all showed great variability among the samples. The core gut bacteriome ofA. assamensisconsisted ofPseudomonas, Acinetobacter, Variovorax, Myroides, Alteromonas, Enterobacter, Enterococcus, Sphingomonas, Brevundimonas, Oleispira, Comamonas, Oleibacter Vagococcus, Aminobacter, Marinobacter, Cupriavidus, Aeromonas, andBacillus.Comparative gut bacteriome analysis revealed a more complex gut bacterial diversity in wildA. assamensissilkworms than in domesticatedB. morisilkworms, which contained a relatively simple gut bacteriome as estimated by OTU richness. Predictive functional profiling of the gut bacteriome suggested that gut bacteria inA. assamensiswere associated with a wide range of physiological, nutritional, and metabolic functions, including biodegradation of xenobiotics, lipid, amino acid, carbohydrate metabolism, and biosynthesis of secondary metabolites and amino acids. These results showed great differences in the composition and diversity of gut bacteria between the two silkworm species. Both insect species harbored core bacterial taxa commonly found in insects, but the relative abundance and composition of these taxa varied markedly.

The circadian clock affects starvation resistance through the pentose phosphate pathway in silkworm, Bombyx mori.

Disruption of the circadian clock can affect starvation resistance, but the molecular mechanism is still unclear. Here, we found that starvation resistance was significantly reduced in the core gene BmPer deficient mutant silkworms (Per-/-), but the mutant's starvation resistance increased with larval age. Under natural physiological conditions, the weight of mutant 5th instar larvae was significantly increased compared to wild type, and the accumulation ability of triglycerides and glycogen in the fat bodies was upregulated. However, under starvation conditions, the weight consumption of mutant larvae was increased and cholesterol utilization was intensified. Transcriptome analysis showed that beta-oxidation was significantly upregulated under starvation conditions, fatty acid synthesis was inhibited, and the expression levels of genes related to mitochondrial function were significantly changed. Further investigations revealed that the redox balance, which is closely related to mitochondrial metabolism, was altered in the fat bodies, the antioxidant level was increased, and the pentose phosphate pathway, the source of reducing power in cells, was activated. Our findings suggest that one of the reasons for the increased energy burden observed in mutants is the need to maintain a more robust redox balance in metabolic tissues. This necessitates the diversion of more glucose into the pentose phosphate pathway to ensure an adequate supply of reducing power.

TALEN-mediated homologous-recombination-based fibroin light chain in-fusion expression system in Bombyx mori.

Silkworm was the first domesticated insect and has important economic value. It has also become an ideal model organism with applications in genetic and expression studies. In recent years, the use of transgenic strategies has made the silkworm silk gland an attractive bioreactor for the production of recombinant proteins, in particular, piggyBac-mediated transgenes. However, owing to differences in regulatory elements such as promoters, the expression levels of exogenous proteins have not reached expectations. Here, we used targeted gene editing to achieve site-specific integration of exogenous genes on genomic DNA and established the fibroin light chain (FibL) in-fusion expression system by TALEN-mediated homology-directed recombination. First, the histidine-rich cuticular protein (CP) was successfully site-directed inserted into the native FibL, and the FibL-CP fusion gene was correctly transcribed and expressed in the posterior silk gland under the control of the endogenous FibL promoter, with a protein expression level comparable with that of the native FibL protein. Moreover, we showed based on molecular docking that the fusion of FibL with cuticular protein may have a negative effect on disulfide bond formation between the C-terminal domain of fibroin heavy chain (FibH) and FibL-CP, resulting in abnormal spinning and cocoon in homozygotes, indicating a significant role of FibL in silk protein formation and secretion. Our results demonstrate the feasibility of using the FibL fusion system to express exogenous proteins in silkworm. We expect that this bioreactor system will be used to produce more proteins of interest, expanding the application value of the silk gland bioreactor.

The mechanoreceptor Piezo is required for spermatogenesis in Bombyx mori

BackgroundThe animal sperm shows high diversity in morphology, components, and motility. In the lepidopteran model insect, the silkworm Bombyx mori, two types of sperm, including nucleate fertile eupyrene sperm and anucleate unfertile apyrene sperm, are generated. Apyrene sperm assists fertilization by facilitating the migration of eupyrene spermatozoa from the bursa copulatrix to the spermatheca. During spermatogenesis, eupyrene sperm bundles extrude the cytoplasm by peristaltic squeezing, while the nuclei of the apyrene sperm bundles are discarded with the same process, forming matured sperm.ResultsIn this study, we describe that a mechanoreceptor BmPiezo, the sole Piezo ortholog in B. mori, plays key roles in larval feeding behavior and, more importantly, is essential for eupyrene spermatogenesis and male fertility. CRISPR/Cas9-mediated loss of BmPiezo function decreases larval appetite and subsequent body size and weight. Immunofluorescence analyses reveal that BmPiezo is intensely localized in the inflatable point of eupyrene sperm bundle induced by peristaltic squeezing. BmPiezo is also enriched in the middle region of apyrene sperm bundle before peristaltic squeezing. Cytological analyses of dimorphic sperm reveal developmental arrest of eupyrene sperm bundles in BmPiezo mutants, while the apyrene spermatogenesis is not affected. RNA-seq analysis and q-RT-PCR analyses demonstrate that eupyrene spermatogenic arrest is associated with the dysregulation of the actin cytoskeleton. Moreover, we show that the deformed eupyrene sperm bundles fail to migrate from the testes, resulting in male infertility due to the absence of eupyrene sperm in the bursa copulatrix and spermatheca.ConclusionsIn conclusion, our studies thus uncover a new role for Piezo in regulating spermatogenesis and male fertility in insects.

Haplotype determination of the Bombyx mori nucleopolyhedrovirus by Nanopore sequencing and linkage of single nucleotide variants.

Naturally occurring isolates of baculoviruses, such as the Bombyx mori nucleopolyhedrovirus (BmNPV), usually consist of numerous genetically different haplotypes. Deciphering the different haplotypes of such isolates is hampered by the large size of the dsDNA genome, as well as the short read length of next generation sequencing (NGS) techniques that are widely applied for baculovirus isolate characterization. In this study, we addressed this challenge by combining the accuracy of NGS to determine single nucleotide variants (SNVs) as genetic markers with the long read length of Nanopore sequencing technique. This hybrid approach allowed the comprehensive analysis of genetically homogeneous and heterogeneous isolates of BmNPV. Specifically, this allowed the identification of two putative major haplotypes in the heterogeneous isolate BmNPV-Ja by SNV position linkage. SNV positions, which were determined based on NGS data, were linked by the long Nanopore reads in a Position Weight Matrix. Using a modified Expectation-Maximization algorithm, the Nanopore reads were assigned according to the occurrence of variable SNV positions by machine learning. The cohorts of reads were de novo assembled, which led to the identification of BmNPV haplotypes. The method demonstrated the strength of the combined approach of short- and long-read sequencing techniques to decipher the genetic diversity of baculovirus isolates.

Biosynthesis of Pteridines in Insects: A Review

Pteridines are important cofactors for many biological functions of all living organisms, and they were first discovered as pigments of insects, mainly in butterfly wings and the eye and body colors of insects. Most of the information on their structures and biosynthesis has been obtained from studies with the model insects Drosophila melanogaster and the silkworm Bombyx mori. This review discusses, and integrates into one metabolic pathway, the different branches which lead to the synthesis of the red pigments “drosopterins”, the yellow pigments sepiapterin and sepialumazine, the orange pigment erythropterin and its related yellow metabolites (xanthopterin and 7-methyl-xanthopterin), the colorless compounds with violet fluorescence (isoxanthopterin and isoxantholumazine), and the branch leading to tetrahydrobiopterin, the essential cofactor for the synthesis of aromatic amino acids and biogenic amines.

Effect of Methyl Violet to Mulberry Silkworm Some Breeds Eggs

To liquidate the larvae, the methyl violet (C24H28N3Cl), used against fungal diseases in fish farming, was used. The goal is to establish physiological responses in different phases of development after treating local and introduced mulberry silkworm breeds of with aqueous solutions of methyl violet. Exogenous exposure to eggs led to the formation of a negative reaction. It has been established that treatment of silkworm eggs with water and a 0.001% solution of methyl violet (from October 20 to November 15, 2018) reduces the weight of the silk layer of cocoons with statistical accuracy by 33.0% (−78.5 mg) and 22.5% (−49 .0 mg) respectively (p<0.001). A negative effect also occurs in other physiological indicators: there is a difference in the weight of caterpillars, cocoons and pupae, and a slight deviation occurs in the weight of caterpillars before cocooning in the aquatic version. The results of this research can be used in developing issues such as identifying more stable and promising mulberry silkworm breeds in the conditions of Azerbaijan, as a prerequisite for predicting the successful introduction of mulberry silkworm.

Cocoon Care : Transformative Monitoring For Sericulture

Sericulture is the process of cultivating silkworms and extracting silk from them. The caterpillars of the domestic silk moth (also called „Bombyx Mori‟) are the most commonly used silkworm species in sericulture. Other types of silkworms (such as Eri, Muga, and Tasar) are also cultivated for the production of „wild silks‟. Silk is known as the queen of textiles due to its softness, durability, and luster. Furthermore, the silk fibers provide characteristics that are superior toany other type of fiber (e.g., water absorbency, heat resistance, dyeing efficiency, and luster). This textile is obtained from cocoons spun by larvae known as silkworm (Bombyx mori), which were discovered in China between 2600 and 2700 BC. The process of silk production is known as sericulture, beginning with the rearing of the silkworm1

Improvement of Silkworm (Bombyx mori L.) Growth and Cocoon Quality Using Nickel Sulfate Supplementation

The silkworm belongs to the order Lepidoptera and the family Bombycidae (Bombyx mori L.). The silkworm industry plays a crucial role in providing employment opportunities in India. This study investigated the effects of nickel sulfate supplementation on the growth and cocoon quality of silkworm (Bombyx mori L.). The experiment was conducted at a silkworm-rearing center in Palayamkottai, India, from December 2022 to January 2023. Silkworms were fed Victory-1 (V1) mulberry leaves soaked in different nickel sulfate solutions (100 ppm, 300 ppm, and 500 ppm). Larval weight, duration, cocoon weight, shell weight, shell ratio, and pupal weight were measured for 10 healthy silkworms with good quality cocoons selected from each treatment group. Compared to the control group, supplementation with 500-ppm nickel sulfate solution significantly improved silkworm growth performance (weight) and economic traits (cocoon weight and quality). GRAPHICAL ABSTRACT

Impact of Surface Functionality on Biodistribution of Gold Nanoparticles in Silkworms

To date, animal models are still indispensable for studying biodistribution and elimination of nanomaterials. However, the use of mammals for in vivo experiments faces various challenges including increasing regulatory hurdles and costs. This study aims to validate larvae of the domestic silkworm Bombyx mori as an alternative invertebrate model for preliminary in vivo research. Organ distribution and elimination of gold nanoparticles (AuNPs) are compared with four different surface functionalities in silkworms after systemic administration: AuNPs coated with poly(ethylene glycol) (PEG), with polyglycidols (PGs) that are slightly hydrophobic (PG(alkyl)), positively charged (PG(+)), or negatively charged (PG(−)). Subsequent inductive coupled plasma mass spectrometry 6 or 24 h after AuNPs administration reveals the biodistribution in silkworm hemolymph, midgut, epidermis, and excrements. Even after 24 h incubation, hemolymph contains the highest AuNPs concentrations, independent of surface functionalization indicating a prolonged circulation time and slow distribution into different silkworm organs and tissues. Positively charged PG(+)AuNPs show three times higher concentrations in the midgut and are excreted at the fastest rate when compared to other AuNPs. In the findings, a surface‐dependent biodistribution and elimination of AuNPs are indicated in silkworms, and the feasibility of using this inexpensive animal model for time‐ and cost‐effective, preliminary in vivo studies of NPs is confirmed.

Pediococcus pentosaceus ZZ61 enhances growth performance and pathogenic resistance of silkworm Bombyx mori by regulating gut microbiota and metabolites

Probiotics have attracted considerable attention in animal husbandry due to their positive effect on animal growth and health. This study aimed to screen candidate probiotic strain promoting the growth and health of silkworm and reveal the potential mechanisms. A novel probiotic Pediococcus pentosaceus strain (ZZ61) substantially promoted body weight gain, feed efficiency, and silk yield. These effects were likely mediated by changes in the intestinal digestive enzyme activity and nutrient provisioning (e.g., B vitamins) of the host, improving nutrient digestion and assimilation. Additionally, P. pentosaceus produced antimicrobial compounds and increased the antioxidant capacity to protect the host against pathogenic infection. Furthermore, P. pentosaceus affected the gut microbiome and altered the levels of gut metabolites (e.g., glycine and glycerophospholipids), which in turn promotes host nutrition and health. This study contributes to an improved understanding of the interactions between probiotic and host and promotes probiotic utilization in sericulture.

Evaluation of Reproductive and Growth Performance in New Breeds and Hybrids of Bivoltine Silkworm (Bombyx mori L.)

This study aimed to evaluate the reproductive and growth performance of recently developed bivoltine silkworm parental breeds and their hybrids to improve silk production and ensure the long-term sustainability of sericulture. Utilizing five thermotolerant pure breeds (B1, B2, B4, B6 and B8) and four popular CSR breeds (CSR2, CSR27, CSR6 and CSR26), six foundation crosses and eight double hybrids were developed and evaluated for ten traits. Results showed that B1 exhibited superior performance in fecundity (524.00), hatching percentage (98.67%), dead eggs (1.33%), pupal weight (1.31 g), pupation rate (96.84%) and cumulative survival index (CSI) (93.84%). The foundation cross B1 × B2 excelled in fecundity (553.67), larval mortality (2.67%), pupal weight (1.53 g), ERR (97.33%) and CSI (93.27%) while FC2 performed better in hatching percentage (97.60%), dead eggs percentage (2.40%), fifth instar larval duration (157.21 h), fifth instar larval weight (35.64 g/10 larvae) and pupation rate (96.33%). Among the double hybrids, (B1 × B2) × (FC1) demonstrated superior performance in fecundity (614.33), larval mortality (1.41%), pupal weight (2.06 g), ERR (98.59%) and CSI (97.24%). FC2 × FC1 excelled in larval duration (141.11 h), fifth instar larval weight (51.96 g/10 larvae) and pupation rate (98.94%). Double hybrids showed significant improvements compared to parental breeds and foundation crosses, indicating potential for field testing and further development. These results indicate the potential of using the newly identified breeds and foundation crosses in silkworm breeding, particularly in developing new double hybrids as an alternative to established CSR breeds and hybrids.

Genomic resources of aquatic Lepidoptera, Elophila obliteralis and Hyposmocoma kahamanoa, reveal similarities with Trichoptera in amino acid composition of major silk genes.

While most species of butterflies and moths (Lepidoptera) have entirely terrestrial life histories, ∼0.5% of the described species are known to have an aquatic larval stage. Larvae of aquatic Lepidoptera are similar to caddisflies (Trichoptera) in that they use silk to anchor themselves to underwater substrates or to build protective cases. However, the physical properties and genetic elements of silks in aquatic Lepidoptera remain unstudied, as most research on lepidopteran silk has focused on the commercially important silkworm, Bombyx mori. Here, we provide high-quality PacBio HiFi genome assemblies of 2 distantly-related aquatic Lepidoptera species [Elophila obliteralis (Pyraloidea: Crambidae) and Hyposmocoma kahamanoa (Gelechioidea: Cosmopterigidae)]. As a step toward understanding the evolution of underwater silk in aquatic Lepidoptera, we used the genome assemblies and compared them to published genetic data of aquatic and terrestrial Lepidoptera. Sequences of the primary silk protein, h-fibroin, in aquatic moths have conserved termini and share a basic motif structure with terrestrial Lepidoptera. However, these sequences were similar to aquatic Trichoptera in that the percentage of positively and negatively charged amino acids was much higher than in terrestrial Lepidoptera, indicating a possible adaptation of silks to aquatic environments.

Impact of Silk-Ionomer Encapsulation on Immune Cell Mechanical Properties and Viability.

Encapsulation of single cells is a powerful technique used in various fields, such as regenerative medicine, drug delivery, tissue regeneration, cell-based therapies, and biotechnology. It offers a method to protect cells by providing cytocompatible coatings to strengthen cells against mechanical and environmental perturbations. Silk fibroin, derived from the silkworm Bombyx mori, is a promising protein biomaterial for cell encapsulation due to the cytocompatibility and capacity to maintain cell functionality. Here, THP-1 cells, a human leukemia monocytic cell line, were encapsulated with chemically modified silk polyelectrolytes through electrostatic layer-by-layer deposition. The effectiveness of the silk nanocoating was assessed using scanning electron microscopy (SEM) and confocal microscopy and on cell viability and proliferation by Alamar Blue assay and live/dead staining. An analysis of the mechanical properties of the encapsulated cells was conducted using atomic force microscopy nanoindentation to measure elasticity maps and cellular stiffness. After the cells were encapsulated in silk, an increase in their stiffness was observed. Based on this observation, we developed a mechanical predictive model to estimate the variations in stiffness in relation to the thickness of the coating. By tuning the cellular assembly and biomechanics, these encapsulations promote systems that protect cells during biomaterial deposition or processing in general.

Estrogen-related receptor, a molecular target against lepidoptera pests

Until recently, chemical pesticides were one of the most effective means of controlling agricultural pests; therefore, the search for insecticide targets for agricultural pests has been an ongoing problem. Estrogen-related receptors (ERRs) are transcription factors that regulate cellular metabolism and energy homeostasis in animals. Silkworms are highly sensitive to chemical pesticides, making them ideal models for pesticide screening and evaluation. In this study, we detected ERR expression in key organs involved in pesticide metabolism in silkworms (Bombyx mori), including the fat body and midgut. Using ChIP-seq technology, many estrogen- related response elements were identified in the 2000-bp promoter region upstream of metabolism-related genes, almost all of which were potential ERR target genes. The ERR inhibitor, XCT-790, and the endocrine disruptor, bisphenol A, significantly inhibited expression of the ERR target genes, BmTreh-1, BmTret-1, BmPK, BmPFK, and BmHK, in the fat bodies of silkworms, resulting in pupation difficulties in silkworm larvae that ultimately lead to death. In addition, based on the clarification that the ERR can bind to XCT-790, as observed through biofilm interferometry, its three-dimensional spatial structure was predicted, and using molecular docking techniques, small-molecule compounds with a stronger affinity for the ERR were identified. In summary, utilizing the powerful metabolic regulatory function of ERR in Lepidoptera pests, the developed small molecule inhibitors of ERR can be used for future control of Lepidoptera pests.

Codon Optimization-based Whole-gene Scanning Identifies Hidden Nucleotides Essential for Bombyx mori Nucleopolyhedrovirus polyhedrin Hyperexpression

During the late stage of infection, alphabaculoviruses produce many occlusion bodies (OBs) in the nuclei of the insect host’s cells through the hyperexpression of polyhedrin (POLH), a major OB component encoded by polh. The strong polh promoter has been used to develop a baculovirus expression vector system for recombinant protein expression in cultured insect cells and larvae. However, the relationship between POLH accumulation and the polh coding sequence remains largely unelucidated. This study aimed to assess the importance of polh codon usage and/or nucleotide sequences in POLH accumulation by generating a baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV) expressing mutant polh (co-polh) optimized according to the codon preference of its host insect. Although the deduced amino acid sequence of CO-POLH was the same as that of wild-type POLH, POLH accumulation was significantly lower in cells infected with the co-polh mutant. This reduction was due to decreased polh mRNA levels rather than translational repression. Analysis of mutant viruses with chimeric polh revealed that a 30 base-pair (bp) 5ʹ proximal polh coding region was necessary for maintaining high polh mRNA levels. Sequence comparison of wild-type polh and co-polh identified five nucleotide differences in this region, indicating that these nucleotides were critical for polh hyperexpression. Furthermore, luciferase reporter assays showed that the 30 bp 5ʹ coding region was sufficient for maintaining the polh promoter-driven high level of polh mRNA. Thus, our whole-gene scanning by codon optimization identified important hidden nucleotides for polh hyperexpression in alphabaculoviruses.

The composition and function of bacterial communities in Bombyx mori (Lepidoptera: Bombycidae) changed dramatically with infected fungi: A new potential to culture Cordyceps cicadae.

Cordyceps cicadae (Hypocreales: Cordycipitaceae) is a renowned entomopathogenic fungus used as herbal medicine in China. However, wild C. cicadae resources have been threatened by heavy harvesting. We hypothesised that Bombyx mori L. (Lepidoptera: Bombycidae) could be a new alternative to cultivate C. cicadae due to the low cost of rearing. Bacterial communities are crucial for the formation of Cordyceps and for promoting the production of metabolites. To better understand the bacterial community structure associated with Cordyceps, three Claviciptaceae fungi were used to explore the pathogenicity of the silkworms. Here, fifth-instar silkworms were infected with C. cicadae, Cordyceps cateniannulata (Hypocreales: Cordycipitaceae) and Beauveria bassiana (Hypocreales: Cordycipitaceae). Subsequently, we applied high-throughput sequencing to explore the composition of bacterial communities in silkworms. Our results showed that all three fungi were highly pathogenic to silkworms, which suggests that silkworms have the potential to cultivate Cordyceps. After fungal infection, the diversity of bacterial communities in silkworms decreased significantly, and the abundance of Staphylococcus increased in mummified larvae, which may play a role in the death process when the host suffers infection by entomopathogenic fungi. Furthermore, there were high similarities in the bacterial community composition and function in the C. cicadae and C. cateniannulata infected samples, and the phylogenetic analysis suggested that these similarities may be related to the fungal phylogenetic relationship. Our findings reveal that infection with different entomopathogenic fungi affects the composition and function of bacterial communities in silkworms and that the bacterial species associated with Cordyceps are primarily host dependent, while fungal infection affects bacterial abundance.