Search Results (669)

Steroidal glycoalkaloids (GAs) are key plant defense compounds, yet their effects on insect gut physiology are not fully understood. We investigated how purified α-chaconine and Solanum tuberosum leaf extract influence the gut function and growth of the mealworm Tenebrio molitor. Larvae were exposed to sublethal doses of GAs, and gut contractility, midgut digestive enzyme activity and body weight were analysed over time. Both α-chaconine and potato extract caused a rapid decrease in digestive enzyme activity 2 h after exposure, followed by a clear increase above control levels after 24 h, indicating a time-dependent compensatory response of the digestive system. Gut contractility was significantly enhanced in treated larvae, and larvae exposed to both treatments exhibited a body weight loss over 72 h. These results show that potato glycoalkaloids strongly modulate the gut physiology of T. molitor while allowing continued growth, highlighting both the plasticity of insect digestive responses and the need to consider sublethal, gut-centered effects when evaluating glycoalkaloids as candidates for bioinsecticidal agents. Full article

Background/Objectives: Ticks evade host hemostasis and immunity in part by injecting serine protease inhibitors (serpins) into the host during feeding, yet the genomic organization of tick serpins has remained unresolved. To understand how ticks deploy these proteins, there is a need to elucidate their gene structure, arrangement and copy number in the genome. Methods: We annotated the recent Ixodes scapularis chromosome-level assembly and identified all the serpin genes to build a genome-wide atlas of serpin loci identifying the gene structure and duplication patterns. The gene expression of serpins during blood meal was also analyzed. Results: We identified 74 serpin genes across eight chromosomes and one unplaced scaffold, with a strongly non-random distribution dominated by chromosome 10, which harbored 67.6% of serpin genes in dense tandem clusters. Most genes were intronless and encoded secreted, N-glycosylated proteins, whereas a minority were conserved two-exon loci sharing a common splice junction. Pairwise amino acid comparisons revealed exact duplicates as well as very recent and divergent paralogs, indicating continued local duplication and diversification. Expression analysis across tissues and feeding time showed that serpin expression is structured primarily by organ and feeding stage, including a late feeding increase in midgut serpins that are predicted to inhibit trypsin-like proteases. Conclusions: This atlas provides a comprehensive description of I. scapularis serpins, provides a framework for understanding tick gene structure and function, prioritizes serpins as target candidates for tick control, and functions as a library for other serpin uses in medicine and industry. Full article

The silkworm (Bombyx mori) is an economically important insect that plays a crucial role in agricultural development. Antimony tin oxide, a high-tech multifunctional nanomaterial, is extensively utilized in contemporary industries due to its properties of transparency, conductivity, and stability. Nevertheless, the toxicity and potential adverse effects of antimony tin oxide on living organisms remain poorly understood. In this study, we evaluated the effects of antimony tin oxide at varying concentrations (0–3.2 μg/μL) on the growth, oxidative stress response, gene expression, and midgut integrity of fifth-instar silkworm larvae. Exposure to high concentrations of antimony tin oxide resulted in a significant reduction in larval weight and severely disrupted the antioxidant defense system. RNA sequencing (RNA-Seq) analysis identified 239 differentially expressed genes (DEGs), which were confirmed by qPCR, revealing up-regulated lipid synthesis gene AGPAT5, down-regulated chitin degradation gene Chi, and suppressed glycerolipid hydrolysis gene H9J6N7_BOMMO. Histopathological and ultrastructural examinations revealed severe damage to the structure of midgut epithelial cells. Structural and functional analysis of conserved domains in key DEG-encoded proteins revealed that gene dysregulation disrupted energy metabolism and compromised the physical barrier, ultimately linking molecular abnormalities to observed tissue damage. These findings elucidate the mechanisms by which antimony tin oxide induces midgut toxicity through interference with critical metabolic pathways and functional perturbations at the molecular level. Full article

Background: High-energy diets enriched in simple sugars and saturated fatty acids alter metabolic homeostasis, yet how distinct nutrients are integrated at the transcriptional level remains incompletely understood. Methods: Here, we profiled the larval midgut transcriptome of Drosophila melanogaster following 24 h exposure to diets enriched with 5% fructose (FD), 1% palmitic acid (PD), or their combination (MD). RNA sequencing (Illumina NovaSeq) was performed on pooled third-instar larval midguts, and differential expression analyses were conducted to identify diet-associated transcriptional changes. Results: The results revealed extensive transcriptional remodeling, with most responses being diet-specific, alongside a conserved core of genes regulated across all treatments. Shared transcriptional signatures were associated with proteostasis and amino acid transport pathways. Comparative and pattern-based analyses further uncovered discordant gene sets and pathway enrichments that were unique to individual diets or to the combined exposure. Notably, the mixed diet induced distinct expression patterns with specific functional signatures that were not predictable from either nutrient alone. Conclusions: Together, these findings indicate that the larval midgut integrates carbohydrate and lipid inputs through coordinated and context-dependent transcriptional responses, highlighting the importance of nutrient combinations in shaping epithelial metabolic programs. Full article

Hybridization is pivotal for germplasm innovation, yet how reciprocal crossing regulates digestive characteristics in sub-cold-water fish remains unclear. This study systematically compared differences in intestinal morphology, physiological function, and microbial community assembly among herbivorous Schizothorax prenanti, carnivorous S. davidi, and their reciprocal hybrids using histological analysis, digestive enzyme assays, and 16S rRNA sequencing. Results indicated that parental intestinal characteristics were highly consistent with their feeding habits. Orthogonal hybrids exhibited a mosaic phenotype, combining the maternal muscular gut structure with high paternal-like lipase activity, and were characterized by an enrichment of the potential probiotic Lactococcus. In contrast, reciprocal hybrids presented a mismatch between morphology and function: despite developed hindgut folds, key digestive enzyme activities were low, and the gut microbiota was dominated by environmental bacteria such as Methylobacterium. Our findings indicate a spatially dependent assembly dynamic: the host genetic background strongly drives microbiome divergence in the anterior segments (foregut and midgut), whereas the long-term administration of a standardized diet ultimately promotes structural convergence in the hindgut. The orthogonal cross yielded a phenotype characterized by an apparent co-occurrence of specific host enzymes and distinct microbiota, suggesting an inferred physiological potential for lipid digestion that requires further multi-omics validation. These findings provide preliminary insights into the associations between genetic background and intestinal traits, providing a theoretical basis for the targeted breeding of Schizothorax species. Full article

Pyriproxyfen, a juvenile hormone analog insecticide, poses severe risks to non-target silkworms (Bombyx mori), as evidenced by disrupted metamorphosis—a process strictly dependent on chitin synthesis and its precursor trehalose. However, the specific molecular interference of pyriproxyfen in these metabolic pathways remains unclear. This study investigated the transcriptional response of silkworm midguts to pyriproxyfen using RNA-Seq and validated spatiotemporal gene expression via qRT-PCR. By integrating transcriptomic data with long-term spatiotemporal profiling, we revealed novel tissue-specific expression dynamics. RNA-Seq identified 2059 differentially expressed genes, primarily enriched in metabolic pathways. Spatiotemporal analysis revealed that most chitin- and trehalose-related genes generally exhibited a biphasic “suppression–compensation” trend (initial downregulation followed by upregulation). Notably, tissue-specific responses were evident, with ChsA being continuously suppressed in the middle silk gland, which may be associated with impaired sericin secretion, while showing abnormal upregulation in the posterior silk gland. Additionally, trehalose metabolism genes (Treh and Tret) paralleled the fluctuation of chitin genes, indicating systemic metabolic reprogramming. These results suggest that the toxicity of pyriproxyfen is associated with a decoupling of trehalose metabolism from chitin synthesis and the induction of tissue-specific metabolic disorders. The tissue-specific, long-term spatiotemporal profiling of chitin and trehalose genes presented in this study fills a critical knowledge gap. This study characterizes the transcriptional profile associated with pyriproxyfen toxicity and provides a robust molecular reference for assessing its environmental risks to beneficial insects. Full article

Pomacea canaliculata, a pervasive invasive gastropod, inflicts significant ecological and economic damage in Chinese rice ecosystems. With the limitations of chemical molluscicides, sustainable biological control solutions are urgently required. This study presents a comprehensive investigation into the biocontrol potential of larvae of the endemic aquatic firefly, Aquatica leii, against Pomacea canaliculata. Through controlled laboratory experiments, we evaluated the feeding preference of larvae when offered a choice between Pomacea canaliculata and a native snail (Cipangopaludina chinensis), and systematically quantified the predatory efficiency (lethal time and consumption amount) across the 3rd to 6th larval instars. Furthermore, the lethal activity of crude extracts from distinct anatomical regions of the larval digestive tract (mouthpart, foregut, midgut, and hindgut) was assayed via injection into Pomacea canaliculata. The larvae accepted Pomacea canaliculata as a viable prey source. Predatory performance varied markedly among instars; 4th-instar larvae exhibited optimal efficacy, characterized by the shortest mean lethal time (7.37 min) and the highest mean consumption (1.23 g). Midgut extract was identified as the principal causative agent of mortality, inducing a 96.7% mortality rate in Pomacea canaliculata, which was significantly superior to the minimal effects observed from other extract types. This points to the midgut secretion as a likely source of potent bioactive compounds responsible for rapid snail lethality, warranting further investigation. responsible for rapid snail lethality. Our results conclusively demonstrate, from both behavioral and physiological vantage points, the feasibility of Aquatica leii larvae as a highly effective native biocontrol agent. This work establishes a critical foundation for future research aimed at the isolation and characterization of the midgut-specific active substances, paving the way for the development of novel, target-selective biogenic molluscicides. Full article

The exceptional adaptability of insects to diverse food sources is central to their survival and evolutionary success. However, the molecular mechanisms underlying this rapid adaptation remain largely uncharacterized. In this study, adaptive phenotypic, transcriptomic, and metabolomic differences in silkworms fed mulberry leaves versus artificial diets were investigated. The results showed that dietary changes induced enrichment of multiple detoxification pathways in the fat body, midgut, and Malpighian tubules, accompanied by significant accumulation of secondary metabolites and xenobiotics such as flavonoids, terpenoids and saponins in these tissues. Stimulation experiments with nine upregulated metabolites in silkworm BmE cells revealed that most metabolites inhibited cell viability and induced detoxification genes such as GST, UGT and CYP upregulated, with flavonoids like genistein and daidzin exhibiting obvious inductive effects. Among the upregulated genes, GSTd2 frequently responded and was significantly upregulated in artificial diet-fed silkworms. Notably, overexpressing GSTd2 in BmE cells enhanced cell tolerance to genistein and daidzin. Furthermore, silkworms overexpressing GSTd2 showed higher flavonoid tolerance and better adaptability to artificial diets. In conclusion, this study provides valuable genetic targets for improving silkworm rearing efficiency on artificial diets, providing reference to optimize feed formulations and theoretical basis for understanding metabolic adaptation mechanisms to artificial diets in silkworms. Full article

Tachykinins (TKs), a conserved family of neuropeptides, play critical roles in regulating multiple physiological processes such as feeding and energy metabolism in insects. This study identified the TK gene (ApTK) from the Chinese oak silkworm, Antheraea pernyi, an economically important insect species. Bioinformatic analysis showed that ApTK possesses four FX₁GX₂R motifs (X₁ and X₂ represent variable amino acid residues), comprising FMGVR, FYGVR, FIGVR, and FFGMR, in the C-terminus and shares a close phylogenetic relationship with TKs from Bombyx mori and Manduca sexta. Tissue-specific expression profiling demonstrated that ApTK was mainly expressed in the brain and midgut. Starvation–refeeding experiments showed that the expression of ApTK was significantly upregulated during food deprivation and returned to baseline after refeeding, evincing its involvement in hunger signaling. RNA interference (RNAi)-mediated knockdown of ApTK led to a significant increase in larval body weight and increased levels of triglyceride, glycogen, and trehalose, indicating enhanced energy storage. Collectively, these results demonstrate that ApTK acts as a key regulator in restraining feeding and modulating energy homeostasis in A. pernyi. Our findings provide insights into the neuroendocrine mechanisms underlying feeding behavior and energy metabolism in A. pernyi. Full article

Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae) is notorious for its wide host range, serious damage caused, and the difficulties involved in controlling it. Populus deltoides ‘Shalinyang’ (PdS) has demonstrated a strong inhibitory effect on the larval growth and the adult lifespan of A. glabripennis and can be used as an “attract-and-kill” tree in mixed shelterbelt construction. However, how A. glabripennis react to this resistant poplar remains unclear. This research employed transcriptomics techniques to study transcriptional responses in the midgut of A. glabripennis after consuming PdS, Elaeagnus angustifolia L. (EA), and Salix matsudana Koidz (SM), respectively. One of the key findings revealed that the PIK3-Akt signaling pathway was suppressed in A. glabripennis feeding on PdS compared with those feeding on EA or SM. Further RNA interference results demonstrated that silencing the AglaAkt gene significantly decreased the levels of AKT, phospho-AKT, vitellogenin, vitellogenin receptor, and vitellin in A. glabripennis. Therefore, we speculate that the AglaAkt gene may be an underlying target gene that causes the low reproductive capacity of A. glabripennis when feeding on PdS. This finding provides important insights into the role of the AglaAkt gene in mediating the reproductive development in A. glabripennis and its molecular response to the resistant poplar. Full article

In mosquitoes, digestion involves the foregut (including the crop), midgut, and hindgut, with the midgut and crop playing important roles in processing sugar and blood meals. The well-studied midgut is a known major pathogen entry point; however, the less-explored crop may affect vector fitness and immunity. This review provides an overview of the anatomy and function of the crop, before drawing together the current state of knowledge of (I) the crop’s role in digestion, (II) its immune function, and (III) the importance of the crop microbiome and its potential role in mosquito fitness. After decades of chemical control, vector management must move beyond immediate disease prevention toward a global approach that considers mosquito biology and the crop’s diverse roles. This may make it a suitable target for new innovations by providing insights into detoxification mechanisms, microbiome-mediated functions, and their potential combined effects on vectorial capacity. Future research is needed to better understand crop function. Full article

Monochamus alternatus larvae, as concealed trunk-boring pests, evade conventional insecticide contact due to their cryptic feeding niche. To overcome this limitation, previous studies have engineered strains of the naturally entomopathogenic bacterium Yersinia entomophaga. The lethality of these strains against M. alternatus was enhanced by incorporating extracellular secretion systems and enriching insecticidal proteins within the larval midgut. However, plasmid loss occurs during serial subculturing. Here, we established an engineered strain that expresses the red fluorescent protein gene mCherry to explore the applicability of bacterial conjugation transfer to Yersinia. We then constructed a chromosomally integrated strain (CSLH88-pCHSW) that incorporates extracellular secretion systems. The results of stability assays demonstrated 100% retention of the mCherry and Cry3Aa-T-HasA genes over 78 generations. SDS-PAGE and Western blot analyses confirmed the extracellular secretion of the Cry3Aa-T protein in the CSLH88-pCHSW strain. Bioassays revealed that the CSLH88-pCHSW strain was significantly more virulent against M. alternatus larvae than both the wild-type strain (CSLH88) and the plasmid-transformed strain (CSLH88-pCHKW), and exhibited markedly faster insecticidal kinetics. Our study reveals the application of bacterial conjugation transfer technology for constructing biocontrol strains. This genomically stabilized Yersinia strain eliminates the risks of failure associated with plasmid loss in the field, enabling the sustainable control of M. alternatus. Full article

The importance of protein-based materials in agricultural pest control has received increasing attention in recent years. Herein, Plutella xylostella brush-border membrane vesicles (BBMVs) were used as a target to screen for human domain antibodies with insecticidal activity. Three rounds of panning of the phage display library yielded the domain antibody C4D, which competed with the Cry1Ac toxin to bind to P. xylostella BBMVs. Against P. xylostella larvae, the recombinant soluble C4D protein showed an LC₅₀ of 1.57 μg/cm² (95% fiducial limits: 0.83–2.54). Using pull-down assays and liquid chromatography–tandem mass spectrometry, we identified the C4D binding partner in P. xylostella midgut BBMVs to be a cadherin-like protein. Bio-Layer Interferometry assay revealed that the dissociation constant between soluble C4D and P. xylostella cadherin-like protein was 2.99 × 10⁻⁶ M. Thus, the present study explored strategies to generate insecticidal antibodies, and the human domain antibody C4D identified and characterized in this study can serve as a framework for generating novel insecticidal agents. Full article

Bacillus thuringiensis (Bt) is one of the most extensively used microbial insecticides, attributed to the action of insecticidal crystal proteins (ICPs), primarily Cry toxins, which mediate damage to the insect midgut epithelium. Recent evidence suggests that Bt toxicity is also strongly influenced by its physiological state and interactions with the host gut environment. Biofilm formation represents an important adaptive strategy that enhances bacterial stress tolerance and may modulate insecticidal performance, although the underlying mechanisms remain unclear. However, it is still unclear how Bt in the biofilm state alters host responses at the structural and transcriptomic levels. Using the tea plantation pest Ectropis grisescens as a model, we systematically evaluated the insecticidal efficacy of biofilm-state Bt formulations and their synergistic effects with a biofilm inducer system composed of Tween-80, tea saponin, matrine, and tea polyphenols. Bioassays showed that the biofilm-state Bt supplemented with composite inducers achieved the highest corrected mortality and reduced the LC₅₀ against neonate larvae by 2.88-fold compared with conventional planktonic Bt. Histopathological, biochemical, and transcriptomic analyses further revealed that biofilm-state Bt caused more severe midgut damage and induced extensive remodeling of detoxification- and stress-response-related pathways. These findings highlight Bt physiological state as a critical determinant of formulation efficacy and provide a novel framework for Bt optimization through microbial physiological regulation. Full article

Field-evolved resistance of Helicoverpa zea to crops expressing Cry insecticidal proteins from Bacillus thuringiensis (Bt) is widespread across the United States. To comparatively evaluate physiological factors associated with Bt susceptibility, we analyzed two laboratory strains (Benzon and SIMRU) and one field colony obtained from a commercial corn field near Pickens, Arkansas. Biochemical assays of larval midgut extracts showed that Pickens exhibited significantly altered activities of chymotrypsin-like proteases, aminopeptidase N (APN), and alkaline phosphatase (ALP) compared with the SIMRU or Benzon colonies, with differences varying by larval instar. In contrast, trypsin-like protease activities did not differ significantly among the three colonies. Gene expression analyses of ten serine protease genes and seven candidate Cry receptor genes (including cadherin, ATP-binding cassette family C2, ALP, and four APN genes) revealed significant transcriptional differences in the Pickens relative to the lab colonies. Collectively, these results suggest that chymotrypsin-like proteases may play an important role in the activation of Cry toxins in H. zea. Altered chymotrypsin and APN activities, together with differential gene expressions in the Pickens population, likely contribute to reduced Bt susceptibility. The biochemical and molecular differences provide insight into potential physiological factors underlying reduced Bt susceptibility and may inform future Bt resistance monitoring and management strategies. Full article