Abstract In global sericulture, the most economically important and primary causative pathogen is Bombyx mori nucleopolyhedrovirus (BmNPV), but the host immune metabolism that restricts the viral replication is not completely defined. A recently identified insect multifunctional apolipoprotein (apolipophorin‐III [ApoLp‐III]) was shown to suppress BmNPV proliferation by enhancing ceramide accumulation. However, it is unknown how this antiviral action is mediated through coordinated transcriptional and metabolic changes. In this study, we dissect the ApoLp‐III‐mediated antiviral mechanism by constructing an ApoLp‐III‐overexpressing BmN cell line and integrating RNA‐seq data with a previously published metabolomic profile. A total of 1067 differentially expressed genes (DEGs) with significantly opposing expression trends were identified. These DEGs were prominent in DNA replication, oxidative phosphorylation (OXPHOS) and amino sugar nucleotide sugar metabolism. Genes associated with amino acid metabolism were down‐regulated, while genes linked with DNA replication and OXPHOS were up‐regulated. Bidirectional regulation of sphingolipids was also confirmed by quantitative real‐time PCR (qRT‐PCR) and transcriptomic data. Ceramide accumulation resulted from the down‐regulation of alkaline ceramidase ( ACER ) and up‐regulation of regulatory subunit of the rate‐limiting ceramide synthesis enzyme, SPTssA . Integrated multi‐omics correlation analysis further showed that ceramide species positively correlated with OXPHOS and negatively correlated with amino sugar metabolism. Meanwhile, down‐regulated triglycerides showed negative correlation with DNA replication and OXPHOS genes. In addition, we identified ApoLp‐III interacting proteins, that is, the integrin‐associated cytoskeletal regulator, Talin‐1 and lepidopteran‐specific immune receptor Haemolin, using Flag‐based co‐immunoprecipitation coupled with mass spectrometry. Our results show that ApoLp‐III suppresses BmNPV replication by the coordinated reprogramming of host cellular energy (OXPHOS) and lipid (sphingolipid) metabolism. Thus, ApoLp‐III acts as an important immunometabolic hub in the antiviral defence of lepidopterans, and our research also offers a theoretical foundation for controlling silkworm diseases by targeting sphingolipid‐energy pathway.
Abstract Proprotein convertases of the subtilase family process protein precursors and regulate essential biological processes, including development, metabolism and reproduction. The role of furin 1 (Fur1) in insects remains poorly understood, especially in Tribolium castaneum , a major pest of stored grains. This study describes the TcFur1 ortholog and investigates its effects on development, reproduction and energy metabolism. Phylogenetic analyses establish that TcFur1 is a 1:1 ortholog of type 1 furins from other insects. Quantitative PCR (qPCR) expression profiling indicates that TcFur1 is most highly expressed during the pupal stage, denoting a role in metamorphosis. RNA interference (RNAi)‐mediated gene knockdown does not affect viability or development but markedly decreases oviposition in adult females. Triacylglycerol levels and total lipase activity remain unchanged, indicating that TcFur1 is not essential for lipid homeostasis under these conditions. In contrast, TcFur1 knockdown increases circulating trehalose and reduces transcript levels of insulin‐like peptides ( TcILP1 and TcILP2 ) and the adipokinetic hormone receptor ( TcAKHR ), as determined by qPCR. While the corresponding protein levels were not measured due to the lack of specific antibodies, these transcriptional changes are consistent with a role for TcFur1 in the endocrine regulation of carbohydrate metabolism. These results show that TcFur1 is involved in carbohydrate homeostasis and reproduction in T. castaneum , likely through insulin and AKH signalling, without directly affecting lipid metabolism. This data expands the current understanding of proprotein convertase functions in insects and suggests that TcFur1 may serve as a target for RNAi‐based population control.
Abstract The brown planthopper ( Nilaparvata lugens , BPH) is one of the most destructive pests of rice. The prolonged cultivation of insect‐resistant rice varieties dominated by limited resistance genes has driven rapid BPH adaptation, while the underlying molecular mechanisms remain poorly understood. In this study, the resistant rice variety IR36 was used as the primary research material. Through trait segregation and transcriptome sequencing analysis of two contrasting BPH populations (susceptible P‐TN1 and virulent P‐IR36), 17 differentially expressed genes potentially associated with virulence variation were identified. Functional validation assays revealed that knockdown of cystathionine‐γ‐lyase ( CysL ) significantly reduced the virulence of BPH on IR36 rice, indicating that CysL markedly regulated BPH virulence against resistant rice carrying the brown planthopper resistance gene bph2 . These findings provide a novel genetic target for understanding and disrupting pest adaptation to resistant varieties.
Abstract Parasitoids closely rely on their hosts for successful reproduction and development. This dependence, combined with exposure to different environmental conditions, can lead to ecological specialisation and divergent selection. The parasitoid Microctonus aethiopoides serves as a valuable model for investigating such processes, as its use as a biocontrol agent against weevils of the genera Hypera and Sitona has revealed clear intraspecific divergence largely driven by different host pressures. This study examined M. aethiopoides strains from three different host species ( Hypera postica , Sitona discoideus , Sitona obsoletus ) and 10 geographic regions. We generated eight high‐quality genome assemblies and compared them with each other and to two publicly available genomes. Comparative analyses revealed a strong host‐associated phylogenetic structure separating the H. postica‐ associated strain from those associated with Sitona species. This separation was accompanied by distinct heterozygosity patterns, with the H. postica strain showing the highest heterozygosity, followed by S. discoideus and S. obsoletus ‐associated strains, and the lowest heterozygosity observed in the S. obsoletus ‐associated Irish strain, most likely due to its asexual reproductive mode. Further comparisons indicated that most gene families were conserved across strains, with rapid evolution of transposable element‐related genes suggesting ongoing genomic diversification among strains. Chemosensory gene family classification showed broad conservation of these genes across strains, with modest variation in odourant receptor copy numbers. Overall, our study suggests that host associations may be key drivers of genomic divergence within M. aethiopoides strains, with this primarily driven by genome‐level variation and limited evidence for major changes at the gene family level.
Self-grooming behaviour is a crucial adaptation in honey bees for maintaining individual hygiene and combating parasite infestations. The miRNA-mediated influence on self-grooming behaviour has been recently demonstrated in Apis mellifera but remains largely unexplored in Apis cerana. This study combined behavioural analysis, miRNA sequencing and molecular biology techniques to investigate these mechanisms. We first identified two distinct behavioural phenotypes in A. cerana: strong groomers (CS) and weak groomers (CW). miRNA sequencing of bee brains revealed 12 differentially expressed miRNAs between CS and CW groups. Notably, miR-281-x, previously associated with grooming in A. mellifera, was significantly upregulated in CW bees, suggesting a conserved role. Subsequent qPCR and functional experiments confirmed that miR-281-x overexpression suppressed grooming behaviour and reduced brain octopamine (OA) levels in A. cerana. Furthermore, through a dual-luciferase assay, qPCR and fluorescence in situ hybridization (FISH), we identified tyrosine decarboxylase (tdc-1), a key enzyme in OA synthesis, as a direct target of miR-281-x. Finally, RNAi-mediated knockdown of tdc-1 significantly reduced both brain OA levels and grooming behaviour, mirroring the effects of miR-281-x overexpression. Our findings identify a conserved miR-281-x/tdc-1/OA axis that is associated with grooming behaviour in A. cerana, providing new insights into the molecular basis of this essential innate behaviour.
