The effects of short-term dietary exposure to SiO2 nanoparticle on the domesticated lepidopteran insect model silkworm (Bombyx mori): Evidence from the perspective of multi-omics

Microbial community formation during dietary exposure to Fe3O4-urease nanoconjugates in silkworm (Bombyx mori): Principal fungi groups facilitate functional flux

The gut microbiota of the silkworm (Bombyx mori) is essential for metabolic processes, including digestion and immunity. Nonetheless, the role of specific gut fungi in optimizing nutrient recycling influenced by infiltrated biomaterials remains inadequately elucidated. This study investigates the potential mechanisms through which gut fungi affect the dynamics of nutrient absorption in silkworms. For this purpose, 5th instar silkworms were exposed to Fe3O4-urease nanoconjugates for 168 h following the utilization of high-throughput microbiome sequencing to identify shifts in principal fungal groups. The conditional fungi groups Mucoromycota and Basidiomycota significantly increased from 10.28 % to 47.16 % and 0.53 % to 2.63 % respectively (p < 0.05), while Ascomycota decreased from 86.57 % to 52.29 %, having no negative impact on the growth and sustainability of the host insect. Functional analysis using FunGuild showed enriched trophic nodes including pathotrophs, saprotrophs and symbiotrophs while functions of DEGs demonstrated an increased metabolic capacity associated with iron and heme binding, and lipase activity. This reveals significant restructuring of the gut fungi microbiota with specific fungal taxa exhibiting enhanced abundance and diversity correlated with the presence of Fe3O4-urease nanoconjugates, serving as a potential for engineered nanomaterials to promote the sustainability and development of sericulture.

Integrated mRNA and miRNA Omics Analyses Reveal Transcriptional Regulation of the Tolerance Traits by Aquatica leii in Response to High Temperature

Within the context of global warming, understanding the molecular mechanisms behind physiological plasticity and local adaptation is essential for insect populations. This study performed an integrated miRNA and mRNA analysis on Aquatica leii larvae exposed to temperatures of 20 °C, 24 °C, 28 °C, and 32 °C. Under varying thermal conditions, 1983 genes exhibited differential expression (i.e., DEGs). These genes showed significant enrichment in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to carbohydrate metabolism, glycan biosynthesis and metabolism. Notably, we detected that the "neuroactive ligand-receptor interaction" signaling pathway, which is involved in environmental information processing, was significantly upregulated in the 28 °C and 32 °C treatment groups. This indicates that starting at 28 °C, A. leii needs to maintain normal cellular physiological functions by regulating ligand-receptor binding and signal transduction. Furthermore, 220 differentially expressed miRNAs (DEMs) were detected under the different temperature treatment conditions. An interaction network was constructed between key DEMs and DEGs, revealing 12 significant DEM-DEG regulatory pairs in A. leii under different temperature treatments. We found three miRNA-mRNA candidate modules that could be involved in A. leii's response to high temperature, including ggo-miR-1260b and ptr-miR-1260b/RN001_010114, CM069438.1_43851/RN001_014852, and CM069438.1_43851/RN001_014877. Our data provide deeper insights into the molecular responses of A. leii to the high temperature at the miRNA and mRNA levels.

Nanopesticides for managing primary and secondary stored product pests: Current status and future directions

The preservation of agricultural commodities during storage is critical for ensuring food security and minimizing post-harvest losses. Both primary storage pests such as Callosobruchus maculatus, Callosobruchus chinensis, Sitophilus weevils, Rhyzopertha dominica, and Trogoderma granarium, and secondary storage pests like Tribolium castaneum cause significant damage to stored products, resulting in substantial economic losses. Traditional pest control methods, including chemical insecticides, face limitations due to environmental concerns and pest resistance. Consequently, nanoparticle-based insecticides are being extensively suggested as a promising alternative. This review analyzes the available literature on the efficacy of nanoparticles (NPs) against primary and some secondary storage pests. Green synthesis methods using plant extracts and other biological sources are highlighted for the production of environmentally friendly NPs. Studies demonstrate that NPs of alumina, carbon, silica, silver, copper, zinc oxide, nickel oxide, titanium dioxide, nano zeolite, as well as chitosan and polymers exhibit significant insecticidal activity against a variety of pests, in some cases surpassing mortality rates caused by traditional insecticides at recommended dosages. Structural, biochemical and molecular studies reveal that NPs induce oxidative stress, disrupt cellular homeostasis, and cause structural damage in pests. Histopathological evaluations indicate specific organ-related toxicity, emphasizing the need for comprehensive biosafety assessments. Additionally, the integration of NPs with conventional insecticides shows enhanced pest control efficiency, although challenges remain in standardizing synthesis methods and evaluating long-term environmental impacts. This review highlights the potential of NPs in sustainable pest management and underlines the importance of ongoing research to optimize specific formulations for specific groups of pests and ensure safety.

Microbial function matters: Microbiome-aware nano-ecotoxicology needs functional endpoints besides compositional data

The microbiome provides an active barrier to the external environment and aids in the metabolism of the host. Nanomaterials are known to interact with this microbiome host plane. Given the recent advances in techniques to study the microbiome, there has been a vast increase in studies trying to find causality in host response via the microbiome in nano-ecotoxicology. Our review integrates the latest advancements in understanding the microbiome's role in elucidating host health related to nanomaterial exposure, thereby explicitly emphasizing the gap between compositional and functional studies. Both the techniques used to interfere and the current understanding of microbiome-host relationships in nano-ecotoxicology are discussed. To further highlight the functional side of the microbiome, we performed an explorative meta-analysis to bridge the gap between top-down and bottom-up studies. This review gives a perspective on generalising microbiome-aware nano-ecotoxicology and discusses methodologies to enhance the interpretation of nanomaterial or chemical exposure to host-microbiome interactions. The current study discloses that correlations built on compositional data are not a good proxy for host outcome and more in-depth analysis coupled with functional analysis should be explored more in microbiome-aware nano-ecotoxicology.

In Vivo Efficacy of a Nanoconjugated Glycopeptide Antibiotic in Silkworm Larvae Infected by Staphylococcus aureus

To contrast the rapid spread of antibiotic resistance in bacteria, new alternative therapeutic options are urgently needed. The use of nanoparticles as carriers for clinically relevant antibiotics represents a promising solution to potentiate their efficacy. In this study, we used Bombyx mori larvae for the first time as an animal model for testing a nanoconjugated glycopeptide antibiotic (teicoplanin) against Staphylococcus aureus infection. B. mori larvae might thus replace the use of mammalian models for preclinical tests, in agreement with the European Parliament Directive 2010/63/EU. The curative effect of teicoplanin (a last resort antibiotic against Gram-positive bacterial pathogens) conjugated to iron oxide nanoparticles was assessed by monitoring the survival rate of the larvae and some immunological markers (i.e., hemocyte viability, phenoloxidase system activation, and lysozyme activity). Human physiological conditions of infection were reproduced by performing the experiments at 37 °C. In this condition, nanoconjugated teicoplanin cured the bacterial infection at the same antibiotic concentration of the free counterpart, blocking the insect immune response without causing mortality of silkworm larvae. These results demonstrate the value and robustness of the silkworm as an infection model for testing the in vivo efficacy of nanoconjugated antimicrobial molecules.

Environmental concentrations of microplastic-induced gut microbiota and metabolite disruption in silkworm, Bombyx mori

Microplastics (MPs) existing extensively in various ecosystems can be ingested by marine organisms and enter the food chain, resulting the health risks from the presence of MPs in aquatic and terrestrial ecosystems. In the present study, an ideal model for Lepidoptera, the silkworm, Bombyx mori, was exposed to environmental concentrations (0.125 μg, 0.25 μg or 0.5 μg/diet) of MPs for 5 days, and the global changes in gut microbes and metabolites were subsequently examined via 16S rDNA sequencing and GC‒MS-based metabolomics. The results showed that MPs exposure did not seriously threaten survival but may regulate signaling pathways involved in development and cocoon production. MPs exposure induced gut microbiota perturbation according to the indices of α-diversity and β-diversity, and the functional prediction of the altered microbiome and associated metabolites demonstrated the potential roles of the altered microbiome following MPs exposure in the metabolic and physiological states of silkworm. The metabolites markedly altered following MPs exposure may play vital biological roles in energy metabolism, lipid metabolism, xenobiotic detoxification and the immune system by directly or indirectly affecting the physiological state of silkworms. These findings contribute to assessing the health risks of MPs exposure in model insects and provide novel insight into the toxicity mechanism of MPs.

Nanoparticles-mediated entomotoxicology: lessons from biologica

Nanotechnology has grown in importance in medicine, manufacturing, and consumer products. Nanoparticles (NPs) are also widely used in the field of insect pest management, where they show a variety of toxicological effects on insects. As a result, the primary goal of this review is to compile and evaluate available information on effects of NPs on insects, by use of a timely, bibliometric analysis. We also discussed the manufacturing capacity of NPs from insect tissues and the toxic effects of NPs on insects. To do so, we searched the Web of Science database for literature from 1995 to 2023 and ran bibliometric analyses with CiteSpace© and Bibliometrix©. The analyses covered 614 journals and identified 1763 relevant documents. We found that accumulation of NPs was one of the top trending topics. China, India, and USA had the most published papers. The most overall reported models of insects were those of Aedes aegypti (yellow fever mosquito), Culex quinquefasciatus (southern house mosquito), Bombyx mori (silk moth), and Anopheles stephensi (Asian malaria mosquito). The application and methods of fabrication of NPs using insect tissues, as well as the mechanism of toxicity of NPs on insects, were also reported. A uniform legal framework is required to allow nanotechnology to fully realize its potential while minimizing harm to living organisms and reducing the release of toxic metalloid nanoparticles into the environment.

Identification of genes associated with the silk gland size using multi-omics in silkworm (Bombyx mori)

Silk gland size in silkworms (Bombyx mori) affects silk output. However, the molecular mechanisms by which genes regulate silk gland size remain unclear. In this study, silk glands from three pure silkworm strains (A798, A306 and XH) with different silk gland weight phenotypes were compared using transcriptomics and proteomics to identify differentially expressed genes (DEGs) and proteins (DEPs). When comparing A798 to A306 and A798 to XH, 830 and 469 DEGs were up-regulated, respectively. These genes were related to the gene ontology terms, metabolic process, transport activity and biosynthesis process. In addition, 372 and 302 up-regulated differentially expressed proteins were detected in A798 to A306 and A798 to XH, respectively, related to the gene ontology terms, ribosome and protein export, ribosome and polypeptide biosynthesis processes. Moreover, combined transcriptomics, proteomics and weighted correlation network analyses showed that five genes (BGIBMGA002524, BGIBMGA002629, BGIBMGA005659, BGIBMGA005711 and BGIBMGA010889) were significantly associated with the silk gland weight. Reverse Transcription-quantitative real-time Polymerase Chain Reaction (RT-qPCR) and Enzyme linked immunosorbent assay (ELISA) were used to verify the mRNA and protein expression of five genes in the silk glands and tissues of 18 silkworm strains. The results showed that four genes have higher expression levels in heavier silk glands. These genes are associated with glycogen metabolism, fatty acid synthesis and branched chain amino acid metabolism, thus potentially promoting growth and silk protein synthesis. These findings provide valuable insights into the molecular mechanisms underlying the relationship between silk gland weight and silk yield in silkworms.

Untargeted Lipidomics Analysis Unravels the Different Metabolites in the Fat Body of Mated Bumblebee (Bombus terrestris) Queens

The fat body has important functions in energy, fertility, and immunity. In female insects, mating stimulates physiological, behavioral, and gene expression changes. However, it remains unclear whether the metabolites in the fat body are affected after the bumblebee (Bombus terrestris) queen mates. Here, the ultrastructure and lipid metabolites in fat body of mated queens were compared with those of virgins. The fat body weight of mated bumblebee queens was significantly increased, and the adipocytes were filled with lipid droplets. Using LC-MS/MS-based untargeted lipidomics, 949 and 748 differential metabolites were identified in the fat body of virgin and mated bumblebee queens, respectively, in positive and negative ion modes. Most lipid metabolites were decreased, especially some biomembrane components. In order to explore the relationship between the structures of lipid droplets and metabolite accumulation, transmission electron microscopy and fluorescence microscopy were used to observe the fat body ultrastructure. The size/area of lipid droplets was larger, and the fusion of lipid droplets was increased in the mated queen's fat body. These enlarged lipid droplets may store more energy and nutrients. The observed differences in lipid metabolites in the fat body of queens contribute to understanding the regulatory network of bumblebees post mating.

The effects of polylactic acid bioplastic exposure on midgut microbiota and metabolite profiles in silkworm (Bombyx mori): An integrated multi-omics analysis

Polylactic acid (PLA) is a highly common biodegradable plastic and a potential threat to health and the environment. However, limited data are available on the effects of PLA exposure in the silkworm (Bombyx mori), a model organism used in toxicity studies. In this study, silkworms with or without PLA exposure (P1: 1 mg/L, P5: 5 mg/L, P25: 25 mg/L, and P0: 0 mg/L) for the entire 5th instar period were used to investigate the impact of PLA exposure on midgut morphology, larvae growth, and survival. Mitochondrial damage was observed in the P5 and P25 groups. The weights of the P25 posterior silk gland (5th day in the 5th instar), mature larvae and pupae were all significantly lower than those of the controls (P < 0.05). Dead worm cocoon rates and larva-pupa to 5th instar larvae ratios showed a positive and negative dose-dependent manner with respect to PLA concentrations, respectively. Additionally, reactive oxygen species levels and superoxide dismutase activity of the P25 midgut were significantly higher and lower when compared with controls, respectively (P < 0.05). The molecular mechanisms underlying the effects of PLA and associated physiological responses were also investigated. In the midgut metabolome, 127 significantly different metabolites (variable importance projection >1 and P < 0.05) were identified between the P0 and P25 groups and were mainly enriched for amino acid metabolism and energy supply pathways. The 16 S rDNA data showed that PLA altered microbial richness and structural composition. Microbiota, classified into 34 genera and 63 species, were significantly altered after 25 mg/L PLA exposure (P < 0.05). Spearman's correlation results showed that Bifidobacterium catenulatum and Schaalia odontolytica played potentially vital roles during exposure, as they demonstrated stronger correlations with the significantly different metabolites than other bacterial species. In sum, PLA induced toxic effects on silkworms, especially on energy- and protein-relevant metabolism, but at high concentrations (25 mg/L). This prospective mechanistic investigation on the effects of PLA on larval toxicity provides novel insight regarding the ecological risks of biodegradable plastics in the environment.