Objective Fungi associated with pine bark beetles are an important and distinctive fungal resource. In order to supplement the research data of this kind of fungi in related areas, the associated fungal resources of bark beetles in Pinus massoniana forests damaged by pine wilt disease in Qingyuan and Zhaoqing of Guangdong Province were investigated.

Method Using tissue isolation and molecular sequencing techniques, this study compared the diversity and differences of fungal species among different regions. Molecular phylogenetic analyses based on the internal transcribed spacer (ITS), large subunit ribosomal RNA (LSU), β-tubulin (TUB2), and translation elongation factor (TEF-1α) gene fragments, together with morphological characterization, were used to describe newly discovered species. Plate co-culture and the Baermann funnel method were employed to measure the effects of representative fungal strains on the reproduction of the pine wood nematode.

Result A total of 42 samples were collected. After isolation and purification, 382 fungal isolates were obtained. There were 224 strains of 7 genera of Ophiostomatales: Ceratocystiopsis, Graphilbum, Ophiostoma, Leptographium, Masuyamyces, Raffaelea, and Sporothrix. Ophiostoma ips was the dominant species, accounting for 32.59% of the total number of the ophiostomatoid isolates. The next most common were Ceratocystiopsis sp. and Sporothrix zhejiangensis, representing 23.70% and 22.30% of the isolates, respectively. The one undescribed taxon discovered was proposed as a new species, named Masuyamyces qingyuanensis sp. nov.. Nine kinds of ophiostomatoid fungi were selected to co-culture with pine wood nematode. The results showed that the strain Raffaelea subfusca had the best effect, and the instantaneous growth rate (IGR) of pine wood nematode was 0.48 after 3 days of co-culture, while the strain M. cf. lotiformis had the highest growth inhibitory activity against pine wood nematode, and the IGR of pine wood nematodes was only 0.27 after 3 days of co-culture.

Conclusion The diversity of fungi associated with bark beetles is relatively high in both Qingyuan and Zhaoqing, and although the species composition of the communities differs between the two regions, the dominant species are consistent. All the tested blue-stain fungi exhibited varying degrees of inhibitory effects on the reproduction of pine wood nematode.