Search Results (127)

The appressorium is a specialized infection structure formed by Metarhizium anisopliae during host invasion. To investigate the correlation between appressorium formation and fungal pathogenicity, as well as its impact on insect cuticular metabolism, different concentrations of sulforaphane were used to inhibit the appressorium formation rate of M. anisopliae. The relationship between appressorium formation rate and pathogenicity against Opisina arenosella larvae was evaluated, and LC-MS-based metabolomics was employed to characterize changes in cuticular compounds during the appressorium formation stage, thereby elucidating the chemical responses of the insect cuticle to appressorium formation. The appressorium formation rate of M. anisopliae was significantly and positively correlated with its pathogenicity (p ≤ 0.05). As the appressorium formation rate increased, pathogenicity against O. arenosella larvae increased and the killing speed accelerated. LC-MS metabolomics revealed that after appressorium formation, 102 differential cuticular compounds unique to O. arenosella larvae were identified, mainly including benzenes and substituted derivatives, amino acids and derivatives, and heterocyclic compounds. In addition, metabolic pathways associated with immune defense (tyrosine metabolism), antifungal defense (histidine metabolism), and toxin degradation (flavonoid degradation) in the larval cuticle were activated. These results demonstrate that the appressorium plays an important role in host infection by M. anisopliae, markedly alters cuticular metabolism, and activates defense- and detoxification-related metabolic pathways in the host. This study provides a theoretical basis for further investigations into fungus–insect cuticle interactions. Full article

In the complex interplay among parasitic wasps, their insect hosts, and pathogenic microbes, the system involving Sclerodermus guani (Hymenoptera: Bethylidae) (a parasitoid wasp), Monochamus alternatus (Coleoptera: Cerambycidae) (the pine sawyer beetle, its host), and Beauveria bassiana (Hypocreales: Cordycipitaceae) (a fungus) presents a unique scenario where wasp offspring develop within a nearly sealed host gallery. This nursery is vulnerable to fungal invasion, often introduced by the foraging female wasps or M. alternatus itself, creating a three-way interaction where the fungus can infect both M. alternatus and S. guani. To assess how the route and timing of fungal exposure impact the S. guani population, we simulated this system by introducing different concentrations of B. bassiana either directly to the female wasps or to M. alternatus prior to parasitism. We further examined the effect of exposure timing by applying the fungus at different developmental stages of the S. guani offspring. Key population parameters, including the reproductive capacity of female wasps, the survival and developmental fitness of S. guani offspring and the germination period of hyphae, were measured. The results indicated that the most severe damage to populations of S. guani occurs when its host, M. alternatus, is infected by B. bassiana. Among the various developmental stages, S. guani offspring exhibited the greatest vulnerability during mid-to-late larval stages, whereas the egg and pupa within cocoon stages demonstrated a higher tolerance. We conclude that both the pathway and the timing of fungal exposure are critical factors influencing its impact. These findings provide valuable insights for optimizing the integrated use of biological agents in pest management, informing strategies that mitigate adverse effects on beneficial parasitoid wasps. Full article

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, is a destructive forest disease leading to rapid mortality. Although Chongqing is a major epidemic region in China, the population genetic structure of B. xylophilus and the ecological interactions among nematode occurrence, blue stain formation, and microbial community dynamics remain insufficiently clear. This study systematically surveyed nematode incidence and performed morphological and molecular identification, revealing strong correlations between nematode presence, blue stain, and insect infestation (p < 0.0001). Within Monochamus alternatus, nematodes were mainly distributed in the abdomen and thorax (p < 0.0001). High-throughput sequencing showed significantly higher fungal (e.g., Leptographium) and bacterial (e.g., Burkholderia-Caballeronia-Paraburkholderia) diversity in diseased than healthy pinewood, indicating pronounced microbial shifts during disease progression. mtCOI-based genetic analyses of 162 nematodes from 11 populations revealed five haplotypes, with Hap1 shared across all populations. AMOVA indicated that over 80% of genetic variation occurred within populations, and neutrality and mismatch analyses suggested recent expansion in some populations (Beibei, Jiangbei, Rongchang). These findings clarify nematode epidemiology, microbial shifts, and genetic characteristics in Chongqing, providing a scientific basis for precise sampling, rapid detection, and integrated management of PWD, and suggest that microbial community changes may contribute to rapid pine decline. Full article

The pressing need for sustainable, plant-based alternatives is highlighted by the growing resistance of agricultural pests to synthetic pesticides. This study examined the pesticidal potential of phytocompounds from C. tora discovered by GC–MS analysis against important tomato insect (T. absoluta) and fungal pathogen (A. solani). The binding stability and interaction dynamics of specific metabolites with fungal virulence (polygalacturonase, MAP kinase HOG1, and effector AsCEP50) and insect neuromuscular (ryanodine receptor and sodium channel protein) targets were assessed using molecular docking and 100 ns molecular dynamics simulations. Among the screened compounds, squalene and 4,7,10,13,16,19-docosahexaenoic acid, methyl ester (DHAME) exhibited the strongest binding affinities and conformational stability, with MM-GBSA binding free energies of −38.09 kcal·mol⁻¹ and −52.81 kcal·mol⁻¹ for squalene complexes in T. absoluta and A. solani, respectively. Persistent hydrophobic and mixed hydrophobic–polar contacts that stabilised active-site residues and limited protein flexibility were found by ProLIF analysis. These lively and dynamic profiles imply that DHAME and squalene may interfere with calcium signalling and stress-response pathways, which are essential for the survival and pathogenicity of pests. Hydrophobic interactions were further confirmed as the primary stabilising force by the preponderance of van der Waals and nonpolar solvation energies. The findings show that C. tora metabolites, especially squalene and DHAME, are promising environmentally friendly biopesticide candidates that have both insecticidal and antifungal properties. Their development as sustainable substitutes in integrated pest management systems are supported by their stability, binding efficacy and predicted biosafety. Full article

Plant viral diseases cause significant agricultural losses worldwide and are shaped by complex virus-host and virus-virus interactions. Unlike fungal or bacterial pathogens, viruses cannot be directly controlled with chemicals, and their management relies on insect vector control and the development of virus-resistant plant varieties. Plants deploy endogenous epigenetic (DNA/chromatin-based) and epitranscriptomic (RNA-based) mechanisms to limit viral infections. RNA silencing pathways, particularly post-transcriptional gene silencing (PTGS) mediated by small RNAs, restrict viral replication and shape viral populations. Additional layers, including RNA-directed DNA methylation (RdDM), N6-methyladenosine (m⁶A) RNA modifications, histone modifications and chromatin remodeling, further modulate host–virus interactions. DNA methylation can be inherited and may confer resistance to future generations, although its stability is partial and context-dependent. Virus-derived 24-nt small interfering RNAs (siRNAs) act as mobile signals, inducing systemic gene silencing and potentially influencing viral population dynamics. Understanding these epigenetic and epitranscriptomic mechanisms can improve virus diagnosis, pathogenesis studies and disease management, while also providing insights into viral diversity and co-infection dynamics. This review synthesizes current knowledge of these mechanisms and discusses their implications for developing sustainable antiviral strategies. Full article

Over the last few decades, the frequency of outbreaks of Ips acuminatus has rapidly increased in Latvia. These beetles are commonly associated with blue-stain fungi, which increase tree mortality and decrease the timber quality of affected trees. The aims of this study were: (i) to identify fungi associated with I. acuminatus in Latvia and (ii) to determine the influence of different factors (such as locality, month of beetle capture, beetle sex) on the diversity of associated fungi. From a total of 590 analysed I. acuminatus beetles, 564 resulted in fungal growth and yielded 1247 fungal isolates, representing 36 fungal taxa. Among the fungi isolated, the most common were Akanthomyces muscarius, followed by Penicillium spp., Mucor spp., Cladosporium cladosporioides, Leptographium cucullatum, Ophiostoma minus, and Graphilbum acuminatum. No significant differences in fungal diversity between different locations and between male and female I. acuminatus were observed. However, significant seasonal differences were observed between months in which I. acuminatus beetles were captured and fungal communities isolated from them. More research is needed on the potential of the entomopathogenic fungi isolated in this study for the biological control of I. acuminatus. Also, the pathogenicity of isolated Ophiostomatoid fungi and their ability to cause blue-stain in Pinus sylvestris timber could be further evaluated. Full article

Coleoptera, specifically leaf beetles (Chrysomelidae) and weevils (Curculionidae), are the dominant pests in tea plantations, significantly impacting tea yield and quality. Insect endosymbiont microbial communities play a crucial role in the physiological metabolism and pathogenicity of their hosts. However, there is still a lack of understanding regarding the composition and function of these communities in coleopteran pests in tea plantations. This study utilized high-throughput sequencing technology to analyze the composition and function of the endosymbiont microbial communities in four species of coleopteran insects from tea plantations. The results indicated that at the phylum level, the dominant bacteria in both leaf beetles and weevils were Proteobacteria and Firmicutes, while the dominant fungi were Ascomycota and Basidiomycota. At the genus level, the primary dominant bacteria in leaf beetles were Enterobacter and Lactococcus, whereas in weevils, they were Klebsiella, Pantoea, and Cedecea. The dominant fungi in leaf beetles consisted of Mortierella, Fusarium, Cladosporium, Aspergillus, and Penicillium, while those in weevils were Aspergillus, Thelebolus, Cladosporium, and Fusarium. Each species harbored its own distinct set of dominant genera. Furthermore, the abundance profiles of shared and unique bacterial and fungal genera revealed distinct characteristics in leaf beetles versus weevils. Although overall microbial diversity did not differ significantly among the four species, their bacterial community structures varied markedly. Functional prediction indicated ‘Plant Pathogen’ as the predominant type in leaf beetles, contrasting with ‘Membrane Transport’ in weevils. These findings provide a foundation for understanding endosymbionts in tea plantation beetles and their potential interactions with host insects. Full article

Management of invasive species is especially difficult when the organisms involved are endophagous and their interactions complex. Such is the case with laurel wilt disease (LWD), a lethal vascular condition caused by Harringtonia lauricola, the fungal symbiont of the non-native redbay ambrosia beetle (RAB), Xyleborus glabratus Eichoff (Coleoptera: Curculionidae). LWD has caused extensive mortality of coastal redbay, Persea borbonia, and is expanding to utilize additional lauraceous hosts, including sassafras, Sassafras albidum. Current management has not been successful in preventing its spread, warranting investigation into additional techniques. RNA interference (RNAi) is a highly specific gene-silencing mechanism used for integrated pest management of crop pests and currently being investigated for use in forests. When targeting essential genes, RNAi can cause rapid insect mortality. Here we focus on RAB, identifying for the first time species-specific reference genes for quantitative real-time PCR (qPCR) and assessing mortality and gene expression after oral ingestion of double-stranded RNAs (dsRNAs) targeting essential genes (hsp, shi, and iap). Our study validates reference genes for expression analyses and shows significant mortality and changes in gene expression for all three target genes. Our research aims to contribute to the development of innovative management strategies for this invasive pest complex. Full article

Defensins are a class of small cysteine-rich cationic antimicrobial peptides (AMPs) that play vital roles in immune-regulating insect–microbe interaction, offering great potential for developing pest control approaches using RNA interference (RNAi) and insect pathogens. However, the biocontrol potential of defensins from the destructive rice pest Nilaparvata lugens (brown planthopper, BPH) remains largely unexplored. Here, we identified and functionally characterized a defensin-encoding gene NldefB in BPH. The open reading frame (ORF) of NldefB is 315 bp in length, encoding 104 amino acids with a conserved Knot1 domain. The qRT-PCR results showed that the transcription level of NldefB went upward with the increasing developmental stages, with the highest expressions in the female adults and their fat body. The expression of NldefB was continuously induced by bacterial pathogens but exhibited a pattern of initial increase followed by a decrease when challenged by a fungal pathogen Metarhizium anisopliae. RNAi-mediated silencing of NldefB significantly decreased the host survival rate, egg production and hatchability, as well as the capability to resist fungal infection. Additionally, NldefB suppression resulted in a significant increase in microbial loads. Our findings underscored that NldefB plays essential roles in regulating host development, pathogen defense, and microbial maintenance, providing a potential target for RNAi- and microbe-mediated BPH biocontrol. Full article

The pea aphid, Acyrthosiphon pisum, possesses horizontally acquired fungal carotenoid biosynthesis genes, enabling de novo production of carotenoids. Although carotenoids are known to contribute to photo-protection and coloration, their potential role in energy metabolism and population fitness under thermal stress is still unclear. This study investigated the interactive effects of temperature and light intensity on energy homeostasis and life-history traits in A. pisum. Using controlled environmental regimes, we demonstrate that light intensity significantly influenced the ATP content, development, and reproductive output of A. pisum at 12 °C, but not at 22 °C. Under cold stress (12 °C), high light intensity (5000 lux) increased ATP content by 240%, shortened the pre-reproductive period by 46%, extended reproductive duration by 62%, and enhanced the net reproductive rate (R₀) and intrinsic rate of increase (rₘ) compared to low light intensity (200 lux). These effects were abolished at the optimal temperature (22 °C), indicating a temperature-gated, light-dependent mechanism. Demographic analyses revealed that carotenoid-associated solar energy harvesting significantly improves fitness under cold conditions, likely compensating for metabolic depression. Our findings reveal a novel ecological adaptation in aphids, where horizontally transferred genes may enable light-driven energy supplementation during thermal stress. This study provides new insights into the physiological mechanisms underlying insect resilience to climate variability and highlights the importance of light as a key environmental factor in shaping life-history strategies in temperate agroecosystems. Full article

Fig (Ficus carica) orchards in the Salento peninsula (southeastern Apulia region, Italy) are increasingly affected by decline syndromes whose etiology remains poorly resolved. In this paper, we provide a first characterization of a complex disease outbreak, integrating field surveys, fungal isolation, molecular phylogenetics, and pathogenicity assays. Symptomatic trees displayed chlorosis, defoliation, cankers, vascular discoloration, and wilting, frequently associated with bark beetle galleries. Mycological analyses revealed a diverse assemblage of fungi, dominated by Botryosphaeriaceae (including Neofusicoccum algeriense, and Lasiodiplodia theobromae), the Fusarium solani species complex (notably Neocosmospora perseae), and Ceratocystis ficicola. While C. ficicola was isolated with lower frequency, its recovery from adult beetles—including Cryphalus dilutus—supports a role in insect-mediated dissemination in addition to soilborne infection. Pathogenicity tests demonstrated that N. algeriense and N. perseae, together with C. ficicola, caused severe vascular lesions and wilting, confirming their contribution to fig decline. By contrast, other Fusarioid strains showed no pathogenicity, consistent with their role as latent or stress-associated pathogens. This study provides the first evidence that N. algeriense and N. perseae act as pathogenic agents on fig, highlights their interaction with C. ficicola within a multifactorial decline syndrome, and identifies dual epidemiological pathways involving both soil/root infection and insect-facilitated dissemination via beetles such as C. dilutus. These findings redefine fig decline in the Salento peninsula (southern Italy) as a multifactorial disease rather than a single-pathogen outbreak, with significant implications for diagnosis, epidemiology, and integrated management strategies. Full article

Paralipsa gularis (Zeller) has become an increasingly destructive pest in both storage and field ecosystems, particularly affecting maize crops across China. As chemical control methods face limitations due to resistance development and environmental concerns, biological control presents a promising alternative. In this study, we isolated and identified a novel strain of Metarhizium sp. from naturally infected P. gularis larvae collected in Yunnan Province, China. Morphological characterization, along with ITS-rDNA and EF-1α-rDNA sequencing, confirmed the fungus as Metarhizium rileyi. The optimal growth medium for this strain was SMAY, and the optimal conditions were 25 °C under continuous light (L:D = 24:0). Laboratory bioassays showed that the strain exhibited high virulence against P. gularis larvae, with cumulative mortality reaching 82% following infestation with 5 × 10⁸ conidia/mL. Biochemical analyses revealed that fungal infection significantly inhibited the activity of the key antioxidant enzyme SOD in the host, while activities of POD, CAT, and detoxification enzymes (P450, CarE, AChE, and GSTs) were significantly increased. These results indicate that immune responses were triggered, and systemic colonization of the host was achieved. Overall, this native M. rileyi strain demonstrates strong potential as an effective biological control agent. Its ability to overcome insect defenses and induce high mortality supports its integration into pest management programs targeting P. gularis. This work advances the understanding of fungal–insect interactions and contributes to sustainable, environmentally safe strategies for managing a pest of economic importance in agricultural ecosystems. Full article

Conidiobolus coronatus (Entomophthorales), a fungal pathogen with a broad insect host range, is a promising candidate for biocontrol applications. We sequenced a C. coronatus strain isolated from a Rhopalomyia sp. cadaver using PacBio long-read sequencing to elucidate the molecular basis of its wide host adaptability. The newly assembled 44.21 Mb genome exhibits high completeness (BUSCO score: 93.45%) and encodes 11,128 protein-coding genes, with 23.1% predicted to mediate pathogen–host interactions. Comparative genomics with the aphid-obligate pathogen C. obscurus revealed significant expansions in gene families associated with host adaptation mechanisms, including host recognition, transcriptional regulation, degradation of host components, detoxification, and immune evasion. Functional annotation highlighted enrichment in cellular component organization and energy metabolism. Pfam annotation identified one hundred twenty-five seven-transmembrane receptors (putative GPCRs), sixty-seven fungus-specific transcription factors, three hundred sixty-one peptidases (one hundred ninety-eight serine proteases and one hundred three metalloproteases), one hundred twenty-seven cytochrome P450 monooxygenases (P450s), thirty-five cysteine-rich secretory proteins, and fifty-five tyrosinases. Additionally, four hundred thirty carbohydrate-active enzymes (CAZymes) across six major modules were characterized. Untargeted metabolomics detected 22 highly expressed terpenoids, consistent with terpenoid biosynthesis gene clusters in the genome. Collectively, these expansions underpin the broad host range of C. coronatus by enabling cross-host signal decoding and gene expression reprogramming, breaching diverse host physicochemical barriers, and expanding its chemical ecological niche. This study provides genomic insights into broad host adaptability in entomopathogenic fungi, facilitating further understanding of pathogen–host interactions. Full article

The worldwide increase in antifungal resistance, particularly in Candida sp., requires the exploration of novel therapeutic agents. Natural compounds have been a rich source of antimicrobial molecules, where peptides constitute the class of the most bioactive components. Therefore, this study looks into the target-specific binding efficacy of insect-derived antifungal peptides (n = 37) as possible alternatives to traditional antifungal treatments. Using computational methods, namely the HPEPDOCK and HDOCK platforms, molecular docking was performed to evaluate the interactions between selected key fungal targets, lanosterol 14-demethylase, or LDM (PDB ID: 5V5Z), secreted aspartic proteinase-5, or Sap-5 (PDB ID: 2QZX), N-myristoyl transferase, or NMT (PDB ID: 1NMT), and dihydrofolate reductase, or DHFR, of C. albicans. The three-dimensional peptide structure was modelled through the PEP-FOLD 3.5 tool. Further, we predicted the physicochemical properties of these peptides through the ProtParam and PEPTIDE 2.0 tools to assess their drug-likeness and potential for therapeutic applications. In silico results show that Blap-6 from Blaps rhynchopeter and Gomesin from Acanthoscurria gomesiana have the most antifungal potential against all four targeted proteins in Candida sp. Additionally, a molecular dynamics simulation study of LDM-Blap-6 was carried out at 100 nanoseconds. The overall predictions showed that both have strong binding abilities and are good candidates for drug development. In in vitro studies, Gomesin achieved complete biofilm eradication in three out of four Candida species, while Blap-6 showed moderate but consistent reduction across all species. C. tropicalis demonstrated relative resistance to complete eradication by both peptides. The present study provides evidence to support the antifungal activity of certain insect peptides, with potential to be used as alternative drugs or as a template for a new synthetic or modified peptide in pursuit of effective therapies against Candida spp. Full article

The yellow peach moth (YPM), Conogethes punctiferalis, is an important agricultural insect pest causing severe damage to corn in eastern China. Beauveria bassiana is an effective, eco-friendly, and promising alternative agent for controlling this insect pest. However, insect immunity can limit the ability of fungal infections. In order to understand the immune response mechanism of YPM, a comparative proteomic analysis of non-infected and B. bassiana-infected larvae was conducted using the isobaric tags for relative and absolute quantification (iTRAQ) technique. On the basis of proteomic analysis, 4195 quantifiable proteins were identified from a total of 29,155 peptides. The functions of the identified proteins were annotated in four databases (GO, COG, KEGG, and IPR). A total of 132 immune-related proteins were screened, including 46 pathogen recognition proteins, 27 extracellular signal modulation proteins, and 59 immune effectors. Furthermore, 70 differentially expressed proteins (DEPs) were identified, including 57 up-regulated proteins and 13 down-regulated proteins. Among these, four DEPs were related to immunity, namely one defense protein and three peptidoglycan recognition proteins. Six randomly selected immune-related proteins associated with target genes were validated for qRT-PCR, and the results indicated that the accuracy and reliability of the proteome sequencing data were high. Taken together, the results enrich the fundamental knowledge of YPM immune responses to B. bassiana infection and provide a new insight into insect−pathogen interactions. Full article