Insect Molecular Biology最新文献

As an alternative splicing co-factor in most insect sex determination systems, transformer-2 (tra-2) plays an essential role in regulating sexual development. Although the functions of tra-2 have been well clarified in holometabolous insects, research in hemimetabolous insects is still very limited. In the present study, we identified the tra-2 homologue in Gryllus bimaculatus (Orthoptera: Gryllidae) and cloned two isoforms. Silencing of Gbtra-2 in nymphs led to abnormal development of forewings and a lethal phenotype. In addition, silencing Gbtra-2 impaired reproductive ability in both male and female adults, manifested as inhibiting ovarian development and leading to abnormal development of spermatozoa. Moreover, maternal RNAi of Gbtra-2 in adult females resulted in embryonic lethality. These findings suggested the crucial role of Gbtra-2 in the development of forewings, embryos, and nymphs as well as fertility in both sexes.

RNA interference (RNAi) has evolved into a powerful tool for functional genomics and species-specific pest management. This editorial introduces the Special Issue of Insect Molecular Biology titled “Recent Insights into RNAi in Insect Biology and Pest Management,” comprising three reviews and five research articles. The articles can be categorised under six thematic sections: mechanistic foundations, target identification, transcriptome-guided discovery, formulation strategies, functional genomics applications and resistance management frameworks. Collectively, these papers chart a comprehensive path from fundamental understanding to practical deployment, underscoring the transformative potential of RNAi in both basic research and sustainable agriculture.

The ectoparasitoid wasp Sclerodermus guani (Hymenoptera: Bethylidae), as a subsocial insect, is widely applied in biological control against beetle vectors of pine wood nematodes. Despite significant advances in behavioural research, functional genetics in S. guani remains underdeveloped due to the absence of efficient gene manipulation tools. In this study, we employed CRISPR-mediated mutagenesis to achieve germline gene knockout targeting the eye pigment-associated gene kynurenine 3-monooxygenase (KMO). Phylogenetic analysis revealed that S. guani KMO shares a close relationship with its homologue in Prorops nasuta (Hymenoptera: Bethylidae). Two single-guide RNAs (sgRNAs), coupled with Cas9 protein with and without nuclear localisation signal (NLS) were tested. Both sgRNAs induced specific in vitro DNA cleavage and in vivo heritable indels at the target genomic loci. Homozygous null mutant females and males exhibit a white-eye phenotype, which was identified during pupal stage. Optimal editing efficiency in vivo was achieved using the Cas9-NLS variant. Given the complication of germline gene editing in eusocial Hymenopterans, the application of CRISPR in the subsocial parasitoid wasp S. guani provides an accessible research platform for the molecular evolution of insect sociality.

Cytochrome P450 monooxygenase (CYP), an important detoxifying enzyme in insects, is involved in the metabolism and degradation of both exogenous compounds and endogenous substances. To investigate the involvement of the T. castaneum TcCYP4C1 gene in detoxification metabolism under high CO₂ and the protective role of trehalose against hypoxic stress in insects. In the present study, after successfully silencing the TcCYP4C1 gene of T. castaneum by double-stranded RNA(dsRNA), the larvae were exposed to 95% CO₂. This exposure resulted in a statistically significant increase in larval mortality and a significant elevation in the activity of the carboxylesterase enzyme (CarE). However, a decrease in mortality from 18.15% to 11.24% was observed when larvae were fed trehalose after dsRNA injection. In addition, the gene expression levels of the trehalose metabolism pathway related genes TRE1-3, TRE1-4 and TPS2 were significantly up-regulated after 95% CO₂ treatment. In summary, the TcCYP4C1 gene emerges as a pivotal factor in the adaptive response of T. castaneum to high CO₂. Trehalose effectively mitigates the detrimental effects resulting from the silencing of TcCYP4C1 and exposure to high CO₂ stress in T. castaneum. Our findings not only establish a theoretical foundation for the development of novel pesticides tailored for low-oxygen grain storage environments but also inspire innovative, environmentally sustainable pest management strategies in the grain storage sector.

Urbanisation alters the environment of organisms, creating new challenges and opportunities. In ants, urbanisation has been shown to increase resistance to temperature and to pollutants. Here we assessed how urbanisation affects gene expression in workers and queens of the ant Temnothorax nylanderi, a species that inhabits both city and forest habitats. We further examined whether there was a differential expression between two distinct conditions, in the field or after laboratory rearing for 8 months. As expected, the number of differentially expressed genes (DEGs) between workers and queens was large (2830 genes). However, we found that habitat (city or forest) had no clear influence on gene expression in queens and workers of T. nylanderi even when individuals were directly collected from the field. Interestingly, we also found 661 DEGs between field colonies and laboratory-reared ones. The effect of rearing conditions on gene activity was greater in workers than in queens, suggesting that queens are more resilient to environmental changes. The lack of transcriptional differences between habitats is intriguing because of the previously observed differences in life-history traits between city and forest populations.

The genome of Triatoma rubrofasciata, a representative of the North American Triatomini lineage, was analysed to characterise its repetitive DNA content and satellite DNA (satDNA) organisation. Using RepeatExplorer2, we determined that repetitive elements comprise approximately 25% of the genome in a male sample from Vietnam and 16% in a female sample from China, with satDNA being the most abundant component. The satellitome analysis revealed 126 satDNA families in the male and 114 in the female, with marked quantitative differences driven by the amplification of two satDNA families: TrubSat001-166 and TrubSat002-9. Fluorescence in situ hybridization (FISH) confirmed that TrubSat002-9 is enriched in the Y chromosome, explaining its lesser abundance in the female genome. Chromosomal mapping revealed three distribution patterns of satDNA: (i) localisation in autosomal heterochromatin, (ii) restriction to the Y chromosome, and (iii) presence in euchromatin. SatDNA landscapes showed sharp peaks at low divergence values, consistent with recent amplifications in heterochromatic regions, and broader peaks at higher divergence levels, suggesting older satDNAs located in euchromatic regions. Additionally, several satDNA families are conserved among T. rubrofasciata, T. infestans, T. delpontei and Rhodnius prolixus, supporting the “library hypothesis” of satDNA evolution. Our findings highlight the differential amplification of satDNA families linked to heterochromatin expansion, particularly in autosomes, and the conservation of Y-linked repeats. This study provides new insights into the dynamic role of satDNAs in the karyotypic evolution of Triatominae bugs.

Copper (Cu), a trace element with crucial roles in physiological processes, can exert detrimental effects when imbalanced. Despite growing research on Cu's impacts on biota, its effects on terrestrial organisms, particularly insects, at environmental concentrations remain poorly understood. This study aims to elucidate the mechanisms underlying Cu-induced damage in silkworms (Bombyx mori L., 1758 (Lepidoptera: Bombycidae)) and identify potential targets to mitigate such damage. Using an integrated approach of physiological, histopathological, biochemical and multi-omics analyses, we investigated the effects of Cu exposure throughout most of the silkworms' larval stage. Our findings reveal that Cu exposure significantly hampers the growth and development of silkworms, evidenced by reduced intestinal trehalose levels, compromised peritrophic membrane (PM) structure in the midgut (MG) and altered composition and diversity of the intestinal microbiota. Furthermore, Cu exposure leads to an increase in pathogenic bacteria and a decrease in probiotics and induces inflammation and apoptosis in the midgut and fatbody (FB) tissues. Biochemical and transcriptomic analyses indicate that Cu disrupts nutrient metabolism and energy homeostasis, resulting in decreased adenosine triphosphatase (ATP) levels. Chronic Cu exposure activates the PI3K/AKT/mTOR signalling pathway, triggering abnormal apoptosis and autophagy, altering detoxification processes, immune enzyme activities and gene expression. This study provides novel insights into the mechanisms of Cu toxicity in silkworms and establishes a foundation for identifying targets to reduce Cu's biotoxicity, offering valuable data for managing Cu pollution in insects.

Over time, populations of Apis cerana across diverse geographical regions have undergone distinct phenotypic adaptations in response to varied climates, arising from prolonged natural evolutionary processes. Understanding the molecular genetic underpinnings and the implications of climate change on the adaptive evolution of A. cerana is crucial for its conservation amidst environmental shifts. Here, we conducted a comprehensive analysis of 110 bee individuals sourced from 11 regions at comparable temperatures, environments, and altitudes. A total of 525.56 Gb of filter-trimmed sequencing data were utilised for population genetic analysis of honeybees. The findings indicate genetic differentiation among bee populations from various geographical regions, with higher levels of population divergence observed in different altitudinal environments. Particularly noteworthy is the significant genetic divergence of the bee population from Haikou (HK) compared to populations in other areas, characterised by higher inbreeding coefficients and runs of homozygosity (ROHs), as well as lower nucleotide diversity. However, populations from Guangzhou (GZ), Jinzhai (JZ), Qimen (QM), Shennongjia (SNJ), and Suzhou (SZ) exhibit a close genetic relationship. Using comparisons across multiple bee populations from different groups, we identified selective signatures across different environmental temperatures and altitudes. Furthermore, by integrating genomic selection signals with comparative transcriptomic analysis, we identified genes potentially involved in bee adaptation to high altitude, such as g9950.t1 (alcohol dehydrogenase), g5267.t1 (diacylglycerol kinase theta-like isoform 2), gene g4025.t1 (Tyrosine 3-monooxygenase), and g3609.t1 (heme oxygenase). Our results indicate that both temperature and altitude contribute to the genetic differentiation and geographical adaptability of A. cerana populations.

Antimicrobial peptides (AMPs) are increasingly being recognised as promising alternatives to conventional antibiotics due to their distinctive antimicrobial mechanisms and reduced likelihood of inducing drug resistance. Insects represent a significant source of AMPs. In this study, a potential AMP gene, MdAMP5, was identified based on its strong immunoinducibility and the presence of a signal peptide, and an amphipathic α-helix in the encoded protein. MdAMP5 encoded a 50-amino acid precursor protein with an N-terminal 22-amino acid signal peptide. The calculated molecular mass of the mature protein was 2.92 kDa, with an estimated isoelectric point of 6.23. Structural analyses revealed that the N-terminus of mature MdAMP5 contained an irregularly coiled segment, while the C-terminus featured an amphipathic α-helix with a glycine-lysine residue at the end. Furthermore, the MdAMP5 gene was successfully expressed in the yeast Pichia pastoris, and the recombinant MdAMP5 (rMdAMP5) protein exhibited effective and broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria in vitro and in vivo. Treatment with rMdAMP5 resulted in significant changes in bacterial morphology, including cell lysis and deformation of bacteriophages. In conclusion, this study identified and successfully expressed a novel AMP that showed low cytotoxicity to mammalian cells and high selectivity towards bacterial cells. This research offers a new candidate for therapeutic drug development, and enhances the understanding of the mechanism and application of AMPs.

Bombyx mori is an economically crucial lepidopteran insect, and its health is closely related to the gut microbiota and metabolic status. Our previous research confirmed that metal–organic frameworks nanocomposite ZIF8@ZIF67 supplementation can significantly enhance silkworm survival rates upon bacterial challenges without adversely affecting its growth or cocoon weight. To elucidate the mechanism, this study integrated non-targeted metabolomics and 16S rRNA sequencing to dissect ZIF8@ZIF67-driven midgut modulations. The results showed that ZIF8@ZIF67 supplementation led to significant metabolic shifts in the midgut of B. mori, with 96 metabolites up-regulated and 54 down-regulated in the negative ion model, and 117 up-regulated and 43 down-regulated in the positive ion model. Key pathways included glutathione metabolism, purine/pyrimidine metabolism, and histidine metabolism, which are involved in antioxidant defence, nucleotide and protein synthesis for growth and immunity regulation. Furthermore, the gut microbiota composition of B. mori was significantly altered after ZIF8@ZIF67 supplementation, with a marked increase in the relative abundance of Mammaliicoccus and Enterococcus. Lastly, the correlation between metabolites and microbiomes was analysed, including Enterococcus and 1-methylhistidine (r = 0.8895, p = 0.0001), Akkermansia and N-acetyl-d-galactosamine (r = 0.8674, p = 0.0003). These findings demonstrated that ZIF8@ZIF67 could optimise silkworm health by orchestrating metabolite-microbe interactions to enhance nutrient assimilation and oxidative stress resilience, while simultaneously activating pathways essential for growth regulation and immune function.