The fungus Cordyceps javanica is known for entomopathogenicity and effective in the control of various arthropods. Here, we aimed to reveal the chitinase GH18 gene family expansion through the high throughput sequencing of the genome of C. javanica strain Bd01 isolated from Xylotrechus quadripes larvae. The genome was 34 Mb in size with 9590 protein-coding genes. By comparative genome analysis, it was found that the family GH18 of chitinase genes was expanded in C. javanica Bd01. The phylogenetic analysis of 27 GH18 genes, compared with those from four other species, revealed that the genes could be categorized into three distinct groups based on their conserved domains. Genes within the same cluster exhibited shared protein motifs and orthologous relationships. The molecular mass of these GH18 genes ranged from 14.03 kDa to 81.41 kDa, while their theoretical isoelectric point (pI) values spanned from 4.40 to 7.92. Most chitinases were characterized as extracellular, hydrophilic, and thermostable proteins with a negative charge. Additionally, they demonstrated favorable in vivo half-life stability. A three-dimensional structural model of the GH18 protein was further generated using the SWISS-MODEL server. These findings establish a robust genomic framework elucidating the functional diversity, evolutionary conservation patterns, and mechanistic contributions of virulence-associated genetic determinants.

The fungus Cordyceps javanica is known for entomopathogenicity and effective in control of various arthropods. Here, we aimed to reveal chitinase GH18 gene family expansion through high put sequencing of genome of C. javanica strain Bd01 isolated from Xylotrechus quadripes larvae. The genome was 34 Mb in size with 9,590 protein-coding genes. By comparative genome analysis, it was found that family GH18 of chitinase genes was expanded in C. javanica Bd01. Phylogenetic analysis of twenty-seven GH18 genes with those of 4 other species showed that genes were clustered into three groups based on their conserved domains. The GH18 genes clustered in same group had the same protein motifs and orthologs. The molecular mass of GH18 genes varied from 14.03 kDa - 81.41 kDa, and theoretical pI from 4.40 - 7.92. Most of the chitinases were extracellular, hydrophilic, thermostable and negatively charged with good in vivo half-life. Furthermore, a three-dimensional model of GH18 was constructed using SWISS-MODEL server. These findings provide comprehensive insights into pathogenicity-related genes, their role and conservatism.

The extensive application of synthetic insecticides like emamectin benzoate (EB) and indoxacarb (IN), threatens ecologically beneficial parasitoids such as Telenomus remus. This study evaluated the transgenerational impacts of continuous exposure (over seven generations) to EB and IN on T. remus by integrating toxicity assays, life-history analysis, microbiome profiling, and transcriptomics. Acute risk assessment indicated EB posed a moderate risk (Risk Quotient, RQ > 50), while IN showed low acute risk (RQ < 50). After multigenerational selection, T. remus developed only minor tolerance (ratios of 1.47 for EB and 1.46 for IN) but incurred significant fitness costs; prolonged development (EB: 10.33 days vs. control: 9.00 days), reduced parasitism (EB: 82.07%; IN: 85.00% vs. control: 90.29%), and shortened female longevity. Host-associated microbiome analysis revealed disrupted community homeostasis, with a notable decline in dominant Wolbachia abundance (from 33.20% in controls). Transcriptomics identified limited differentially expressed genes (53 for EB, 52 for IN), suggesting physiological adaptation, with key changes enriched in detoxification (e.g., cytochrome P450s, UGTs) and immune pathways. Integrated correlation analyses (Mantel tests) linked microbial dysbiosis to altered host gene expression and reduced fitness. These findings highlight that even insecticides with low acute toxicity (like IN) or those inducing only minor tolerance shifts can cause severe transgenerational impairments. Correlations between microbiome alterations and transcriptomic changes suggest potential interactive mechanisms that warrant further validation. Field application rates and ecological risk assessments should be re-evaluated to account for these chronic sublethal effects to conserve T. remus in sustainable agro-ecosystems.