摘要: The black soldier fly, Hermetia illucens, comes with big promises for industrial purposes since its larvae feed polyphagously on a broad spectrum of organic substrates. However, research focusing on adult flies is scarce, which is inconsistent with their reproductive relevance within the rearing cycle. In particular, directed oviposition is a challenge in artificial systems. Currently, decomposing organic matter is commonly used as oviposition substrate, which has extensive potential for improvement in view of the lack of standardization and the risk of microbial contamination. Here, we identified three fatty acids and one fatty acid methyl ester derived from the surface of old oviposition sites and targeted to elucidate their effect on preference behavior and oviposition site selection using Y-olfactometry and prepared oviposition sites, respectively. Exposure to tetradecanoic acid attracted gravid females and stimulated oviposition most strongly, while decanoic acid demonstrated a repulsive effect. Females kept in mixed-sex populations were attracted by tetradecanoic acid, resulting in a higher egg mass found in the compound box (3.0-11.4 fold), a >= 2.3 fold reduction of nonspecifically deposited eggs, and the highest total egg mass. Conversely, decanoic and dodecanoic acid caused females to lay a greater proportion of eggs nonspecifically outside both boxes. Our data suggest that fatty acids, especially tetradecanoic acid, are important cues for oviposition site selection in black soldier flies. In order to achieve a directed oviposition behavior, the role of further short- and long-chain fatty acids as attractants should be examined.

摘要: The fat body of the holometabolous insect is remodeled by the degradation of the larval fat body and the development of the adult fat body during metamorphosis. However, the mechanism of adult fat body development is quite unclear. Using the agricultural pest Helicoverpa armigera, the cotton bollworm, as a model, we revealed that the development of adult fat body was regulated by glycolysis, triglyceride (triacylglycerol [TAG]) synthesis, cell proliferation, and cell adhesion. RNA sequencing detected a set of genes that were upregulated in the 8-d late pupal fat body at a late metamorphic stage compared with the 2-d pupal fat body at an earlier metamorphic stage. The pathways for glycolysis, TAG synthesis, cell proliferation, and cell adhesion were enriched by the differentially expressed genes, and the key genes linked with these pathways showed increased expression in the 8-d pupal fat body. Knockdown of phosphofructokinase (Pfk), acetyl-CoA carboxylase (Acc1), phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit (P110) and collagen alpha-1(IV) chain (Col4a1) by RNA interference resulted in abnormal eclosion and death at pupal stages, and repressed lipid droplets accumulation and adult fat body development. The expression of Acc1, P110, and Col4a1 was repressed by the insect steroid hormone 20-hydroxyecdysone (20E). The critical genes in the 20E pathway appeared to decrease at the late pupal stage. These data suggested that the development of the insect adult fat body is regulated by glycolysis, lipids synthesis, cell proliferation, and cell adhesion at the late pupal stage when the 20E signal decreases. PFK, ACC1, COL4A1, and PI3K (P110) were upregulated to promote the formation of adult fat body when 20E signal decreased. image

摘要: The escalating use of nanodiamonds (NDs) has raised concerns about their ecotoxicological impact, prompting exploration of therapeutic interventions. This paper pioneers the examination of Vitamin B12-conjugated sericin (VB12-SER) as a potential therapeutic approach against ND-induced toxicity in darkling beetles (Blaps polychresta). The study analyzes mortality rates and organ-specific effects, covering the testis, ovary, and midgut, before and after treatments. Following exposure to 10 mg NDs/g body weight, within a subgroup of individuals termed ND2 with a mortality rate below 50%, two therapeutic treatments were administered, including pure sericin (SER) at 10 mg/mL and VB12-SER at 10.12 mg/mL. Consequently, five experimental groups (control, SER, ND2, ND2+SER, ND2+SER+VB12) were considered. Kaplan-Meier survival analysis was performed to assess the lifespan distribution of the insects in these groups over a 30-d period. Analyses revealed increased mortality and significant abnormalities induced by NDs within the examined organs, including cell death, DNA damage, enzyme dysregulation, antioxidant imbalances, protein depletion, lipid peroxidation, and morphological deformities. In contrast, the proposed treatments, especially (ND2+SER+VB12), demonstrated remarkable recovery, highlighting VB12-conjugated SER's potential in mitigating ND-triggered adverse effects. Molecular docking simulations affirmed binding stability and favorable interactions of the VB12-SER complex with target proteins. This research enhances understanding of NDs' effects on B. polychresta, proposing it as an effective bioindicator, and introduces VB12-conjugated SER as a promising therapeutic strategy in nanotoxicological studies.

摘要: Wing dimorphism in Nilaparvata lugens is controlled by the insulin-like growth factor 1 (IGF-1) signaling - Forkhead transcription factors (IIS-FoxO) pathway. However, the role of this signal in the wing development program remains largely unclear. Here, we identified 2 R-SMAD proteins, NlMAD1 and NlMAD2, in the brown planthopper (BPH) transcriptome, derived from the intrinsic transforming growth factor-beta pathway of insect wing development. Both proteins share high sequence similarity and conserved domains. Phylogenetic analysis placed them in the R-SMAD group and revealed related insect orthologs. The expression of Nlmad1 was elevated in the late instar stages of the macropterous BPH strain. Nlmad1 knockdown in nymphs results in malformed wings and reduced wing size in adults, which affects the forewing membrane. By contrast, Nlmad2 expression was relatively consistent across BPH strains and different developmental stages. Nlmad2 knockdown had a milder effect on wing morphology and mainly affected forewing veins and cuticle thickness in the brachypterous strain. NlMAD1 functions downstream of the IIS-FoxO pathway by mediating the FoxO-regulated vestigial transcription and wing morph switching. Inhibiting Nlmad1 partially reversed the long-winged phenotype caused by NlFoxO knockdown. These findings indicate that NlMAD1 and NlMAD2 play distinct roles in regulating wing development and morph differentiation in BPH. Generally, NlMAD1 is a key mediator of the IIS-FoxO pathway in wing morph switching.

摘要: Entomopathogenic fungi may interact with insects' symbiotic bacteria during infection. We hypothesized that topical infection with Beauveria bassiana may alter the microbiota of the Colorado potato beetle (CPB) and that these modifications may alter the course of mycoses. We used a model with two concentrations of conidia: (1) high concentration that causes rapid (acute) pathogenesis with fast mortality followed by bacterial decomposition of insects; (2) lower concentration that leads to prolonged pathogenesis ending in conidiation on cadavers. The fungal infections increased loads of enterobacteria and bacilli on the cuticle surface and in hemolymph and midgut, and the greatest increase was detected during the acute mycosis. By contrast, stronger activation of IMD and JAK-STAT signaling pathways in integuments and fat body was observed during the prolonged mycosis. Relatively stable (nonpathogenic) conditions remained in the midgut during both scenarios of mycosis with slight changes in bacterial communities, the absence of mesh and stat expression, a decrease in reactive oxygen species production, and slight induction of Toll and IMD pathways. Oral administration of antibiotic and predominant CPB bacteria (Enterobacteriaceae, Lactococcus, Pseudomonas) led to minor and mainly antagonistic effects in survival of larvae infected with B. bassiana. We believe that prolonged mycosis is necessary for successful development of the fungus because such pathogenesis allows the host to activate antibacterial reactions. Conversely, after infection with high concentrations of the fungus, the host's resources are insufficient to fully activate antibacterial defenses, and this situation makes successful development of the fungus impossible.

摘要: The silk gland of the silkworm Bombyx mori serves as a valuable model for investigating the morphological structure and physiological functions of organs. Previous studies have demonstrated the notable regulatory role of let-7 microRNA in the silk gland, but its specific molecular mechanism remains to be elucidated across different segments of this organ. In this study, we further investigated the functional mechanism of let-7 in the middle silk gland (MSG). The MSG of a let-7 knockout strain was analyzed using a combined proteomic and metabolomic technique, revealing the enrichment of differential proteins and metabolites in the DNA synthesis and energy metabolism pathways. BmCentrin was identified as a novel target gene of let-7 in the MSG, and its downregulation inhibited the proliferation of BmN4-SID1 cells, which is exactly opposite to the role of let-7 in these cells. CRISPR/Cas9 genome editing and transgenic technologies were employed to manipulate BmCentrin in the MSG. Knockout of BmCentrin led to severe MSG atrophy, whereas the overexpression of BmCentrin resulted in beaded MSG. Further measurements of these knockout or overexpression strains revealed significant changes in the expression levels of sericin protein genes, the weight of the cocoon and the mechanical properties of the silk. Investigating the biological role of BmCentrin in the silk gland offers valuable insights for elucidating the molecular mechanisms by which let-7 controls silk gland development and silk protein synthesis in the silkworm.

摘要: Honeybees and bumblebees play a crucial role as essential pollinators. The special gut microbiome of social bees is a key factor in determining the overall fitness and health of the host. Although bees harbor relatively simple microbial communities at the genus level, recent studies have unveiled significant genetic divergence and variations in gene content within each bacterial genus. However, a comprehensive and refined genomics-based taxonomic database specific to social bee gut microbiomes remains lacking. Here, we first provided an overview of the current knowledge on the distribution and function of social bee gut bacteria, as well as the factors that influence the gut population dynamics. We then consolidated all available genomes of the gut bacteria of social bees and refined the species-level taxonomy, by constructing a maximum-likelihood core genome phylogeny and calculating genome-wide pairwise average nucleotide identity. On the basis of the refined species taxonomy, we constructed a curated genomic reference database, named the bee gut microbe genome sequence database (BGM-GDb). To evaluate the species-profiling performance of the curated BGM-GDb, we retrieved a series of bee gut metagenomic data and inferred the species-level composition using metagenomic intra-species diversity analysis system (MIDAS), and then compared the results with those obtained from a prebuilt MIDAS database. We found that compared with the default database, the BGM-GDb excelled in aligned read counts and bacterial richness. Overall, this high-resolution and precise genomic reference database will facilitate research in understanding the gut community structure of social bees. Social corbiculate bees harbor relatively simple microbial communities at the phylotypes level, however, genetic diversification is prevalent below phylotypes, i.e. at the species or strain level. Additionally, the genetic diversity and gene repertoires of bacterial isolates vary substantial between host species. This diverse gut microbiota exerts multifaceted effects on the host, such as diet digestion, nutrient provision, pathogen resistance, immune modulation, endocrine signaling, among others. In particular, the gut microbiota is primarily responsible for the digestion and fermentation of dietary carbohydrates, including sugars toxic to the bee host, as well as defense against various bee pathogens. To deeply understand the diversity and functions of bee gut microbiota, an accurate species-level taxonomy is fundamental and necessary. For each phylotype, the species-level taxonomy is refined by constructing a maximum-likelihood core genome phylogeny and by calculating genome-wide pairwise average nucleotide identity. The curated genomic taxonomy will greatly facilitate research on the gut community structure of social bees. image

摘要: Psyllids, or jumping plant lice (Hemiptera: Sternorrhyncha: Psylloidea), are a group of small phytophagous insects that include some important pests of crops worldwide. Sexual communication of psyllids occurs via vibrations transmitted through host plants, which play an important role in mate recognition and localization. The signals are species-specific and can be used to aid in psyllid taxonomy and pest control. Several hypotheses have been proposed for the mechanism that generates these vibrations, of which stridulation, that is, friction between parts of the forewing and thorax, has received the most attention. We have investigated vibrational communication in the European pear psyllid species Cacopsylla pyrisuga (Foerster, 1848) using laser vibrometry and high-speed video recording, to directly observe the movements associated with signal production. We describe for the first time the basic characteristics of the signals and signal emission of this species. Based on observations and analysis of the video recordings using a point-tracking algorithm, and their comparison with laser vibrometer recordings, we argue that males of C. pyrisuga produce the vibrations primarily by wing buzzing, that is, tremulation that does not involve friction between the wings and thorax. Comparing observed signal properties with previously published data, we predict that wing buzzing is the main mechanism of signal production in all vibrating psyllids.

摘要: Chlorfenapyr is a broad-spectrum halogenated pyrrole insecticide with a unique mode of action. Due to the misuse and overuse of this chemical, resistance has been reported in several arthropods, including Plutella xylostella, which is one of the most destructive insect pests afflicting crucifers worldwide. A better understanding of the cross-resistance and genetics of field-evolved chlorfenapyr resistance could effectively guide resistance management practices. Here, the chlorfenapyr resistance of a field-derived population of P. xylostella was introgressed into the susceptible IPP-S strain using a selection-assisted multigenerational backcrossing approach. The constructed near-isogenic strain, TH-BC5F2, shared 98.4% genetic background with the recurrent parent IPP-S strain. The TH-BC5F2 strain showed 275-fold resistance to chlorfenapyr, but no significant cross-resistance to spinosad, abamectin, chlorpyrifos, & beta;-cypermethrin, indoxacarb, chlorantraniliprole, or broflanilide (no more than 4.2-fold). Genetic analysis revealed that resistance was autosomal, incompletely dominant, and conferred by 1 major gene or a few tightly linked loci. The synergism of metabolic inhibitors (PBO, DEM, and DEF) to chlorfenapyr was very weak (<1.7-fold), and the metabolic enzyme activities in the TH-BC5F2 strain were not significantly elevated compared with the IPP-S strain. The results enhances our understanding of the genetic traits of chlorfenapyr resistance, and provides essential information for improving resistance management strategies.

摘要: Lipids are an important energy source and are utilized as substrates for various physiological processes in insects. Comparative gene identification 58 (CGI-58), also known as alpha/beta hydrolase domain-containing 5 (ABHD5), is a highly conserved and multifunctional gene involved in regulating lipid metabolism and cellular energy balance in many organisms. However, the biological functions of ABHD5 in insects are poorly understood. In the current study, we describe the identification and characterization of the ABHD5 gene in the lepidopteran model insect, Bombyx mori. The tissue expression profile investigated using quantitative reverse transcription polymerase chain reaction (RT-qPCR) reveals that BmABHD5 is widely expressed in all tissues, with particularly high levels found in the midgut and testis. A binary transgenic CRISPR/Cas9 system was employed to conduct a functional analysis of BmABHD5, with the mutation of BmABHD5 leading to the dysregulation of lipid metabolism and excessive lipid accumulation in the larval midgut. Histological and physiological analysis further reveals a significant accumulation of lipid droplets in the midgut of mutant larvae. RNA-seq and RT-qPCR analysis showed that genes related to metabolic pathways were significantly affected by the absence of BmABHD5. Altogether, our data prove that BmABHD5 plays an important role in regulating tissue-specific lipid metabolism in the silkworm midgut.