Cephalcia chuxiongica has caused significant damage to pine forests, becoming a major biological disaster that hinders the sustainable development of forestry in China. To investigate the efficacy of biological control measures, entomopathogenic fungi were isolated and purified from the larvae of Ce. chuxiongica that had succumbed to diseases. The pathogenic capacity of strains was assessed using bioassay methods, and their infection process was observed using scanning electron microscopy. ITS, LSU, and TEF analysis disclosed Clonostachys rogersoniana as the highly virulent strain responsible for the death of Ce. chuxiongica. The optimal medium for its mycelial growth and sporulation was found to be PPDA. In addition, the bioassay revealed that the median lethal time (LT₅₀) for Ce. chuxiongica was 24.34 h and median lethal concentration (LC₅₀) was 2.35 × 10⁵ conidia/mL, indicating that C. rogersoniana possesses potent virulence and demonstrates rapid pathogenicity. Furthermore, scanning electron microscopy demonstrated that C. rogersoniana initially entered the body of Ce. chuxiongica through the spiracle and progressively made its way into the body wall, resulting in the insect’s death. The mode of infection for C. rogersoniana is exceedingly rare. As a consequence, the results of this study can serve as a reference for the management of chewing insects, such as Ce. chuxiongica.

Rhododendron hybridum Ker Gawl, a widely cultivated horticultural species in China, is highly valued for its ornamental and medicinal properties. However, with the expansion of its cultivation, leaf spot disease has become more prevalent, significantly affecting the ornamental value of R. hybridum Ker Gawl. In this study, R. hybridum Ker Gawl from the Kunming area was selected as the experimental material. The tissue isolation method was employed in this study to isolate pathogenic strains. The biological characteristics of the pathogens were determined using the mycelial growth rate method. The pathogens’ influence on the host plant’s ultrastructure was investigated using transmission electron microscopy (TEM). Colletotrichum nymphaeae was identified as the pathogen implicated in the development of leaf spot disease in R. hybridum Ker Gawl across three regions in Kunming City through the integration of morphological traits and phylogenetic analyses of multiple genes (ITS, ACT, GAPDH, HIS3, CHS1, and TUB2). Its mycelial growth is most effective at a temperature of 25 °C. pH and light have relatively minor effects on the growth of mycelium. The preferred carbon and nitrogen sources were identified as mannitol and yeast extract, respectively. Additionally, TEM observations revealed significant damage to the cell structure of R. hybridum Ker Gawl leaves infected by the pathogen. The cell walls were dissolved, the number of chloroplasts decreased markedly, starch granules within chloroplasts were largely absent, and the number of osmiophilic granules increased. This is the first report of leaf spot disease in R. hybridum Ker Gawl caused by C. nymphaeae. The results of this study provide valuable insights for future research on the prevention and control of this disease.

To investigate the effects of the endophytic fungus Setophoma terrestris (isolated from Panax notoginseng roots) on the growth and rhizosphere microbiota of understory-cultivated P. notoginseng, we prepared liquid and solid fermentates of the fungus and applied them separately via irrigation. Rhizosphere soil of P. notoginseng was subjected to non-targeted metabolomics and microbiome sequencing for detection and analysis. Relative to the control, P. notoginseng treated with liquid and solid fermentates exhibited increases in plant height (3.5% and 0.7%), chlorophyll content (23.4% and 20.4%), and total saponin content (14.6% and 17.0%), respectively. Non-targeted metabolomics identified 3855 metabolites across 23 classes, with amino acids and their derivatives (21.54%) and benzene derivatives (14.21%) as the primary components. The significantly altered metabolic pathways shared by the two treatment groups included ABC transporters, purine metabolism, and the biosynthesis of various other secondary metabolites. Exogenous addition of S. terrestris significantly affected the composition of the rhizosphere soil microbial community of P. notoginseng and increased the relative abundance of genera such as Bradyrhizobium. In conclusion, the endophytic fungus S. terrestris enhances P. notoginseng growth and modulates both rhizosphere soil metabolites and microbial abundance. This study can provide certain data support for research on endophytic fungi of P. notoginseng.

Clonostachys rosea, an entomopathogenic fungus that infects Cephalcia chuxiongica, is highly pathogenic and has significant potential for controlling the damage this pest causes to pine forests. To investigate the role of C. rosea secondary metabolites in fungal pathogenicity, we conducted toxicity assays using crude metabolite extracts. These assays evaluated the effects of different concentrations, larval developmental stages, and exposure methods on larval mortality. Gas chromatography–mass spectrometry (GC–MS) was subsequently employed to identify the chemical constituents of the crude extracts, and the toxicity of the identified compounds was assessed. The results showed that the crude extract at a concentration of 7.5 μg/mL exhibited the highest toxicity. Two hours post-treatment, the mortality rate of non-diapause larvae reached 65%, which was significantly higher than that of the diapause group. Moreover, contact toxicity was more lethal to C. chuxiongica larvae than oral exposure. A total of 23 compounds were identified from the crude extract, of which nine exhibited toxicity: 2-piperidone, hydrocinnamic acid, phenethyl alcohol, oleic acid, tryptophol, stearic acid methyl ester, myristic acid, dodecanoic acid, and benzeneacetic acid. Except for 2-piperidone, which showed low toxicity, the other eight compounds demonstrated notable contact toxicity against C. chuxiongica larvae. These findings confirm the insecticidal potential of C. rosea secondary metabolites and provide a valuable reference for the biological control of C. chuxiongica and other chewing insect pests.

To explore superior biocontrol resources for Rhododendron brown spot disease, five antagonistic fungal strains exhibiting significant inhibitory activity against the pathogen responsible for RBS were isolated from healthy Rhododendron hybridum Ker Gawl leaves. Among them, strain DJW5-2-1 demonstrated the highest inhibition rate, reaching 63.88% against the pathogenic fungus. Based on morphological characteristics and multigene phylogenetic analysis (ITS, β-tubulin, and tef1-α), DJW5-2-1 was identified as Diaporthe phoenicicola (Traverso & Spessa) Udayanga, Crous & K.D. Hyde. Dual culture assays further confirmed its broad-spectrum antifungal activity, with inhibition rates ranging from 39.15% to 72.54% against various phytopathogenic fungi. Biochemical analyses revealed that DJW5-2-1 secretes multiple extracellular enzymes and exhibits plant growth-promoting traits. In both in vitro and potted plant efficacy assays, the biocontrol efficacy of strain DJW5-2-1 against RBS was 49.67% and 50.61%, respectively, indicating that strain DJW5-2-1 exhibits a certain level of control efficacy against RBS. Through pot experiments, we found that strain DJW5-2-1 could promote the growth of rhododendron seedlings and significantly increase growth indicators. Among these indicators, the growth-promoting rates of plant height and stem diameter were 15.27% and 41.27%, respectively. Moreover, DJW5-2-1 contributed to improved host resistance by elevating the activities of key defense-related enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO). Taken together, these findings suggest that strain DJW5-2-1 represents a promising microbial agent for the integrated control of RBS and the development of fungal-based biofertilizers. Further investigation is warranted to assess its performance under field conditions and elucidate its underlying mechanisms of action.