Two new species and four new host records of Fusarium species (Nectriaceae, Hypocreales) associated with Semanotus bifasciatus causing Taxodium hybrid ‘ Zhongshanshan’ dieback

Semanotus bifasciatus (Motschulsky) (Cerambycidae, Coleoptera) is a quarantine wood-boring pest that severely damages cypress trees in China and poses a significant threat to forest ecological security. However, the knowledge of Fusarium species associated with this beetle is inadequate in China. In this study, 16 strains of Fusarium were isolated from beetle galleries in infected Taxodium hybrid ‘ Zhongshanshan’ samples.

Morphological and molecular multi-locus analyses, based on internal transcribed spacer region of the translation elongation factor 1 - alpha (TEF- 1 α), RNA polymerase largest subunit (RPB 1) and RNA polymerase second largest subunit (RPB 2) genes, identified four new host records species (F. annulatum, F. fujikuroi, F. ipomoeae and F. oblongum) and two new species (F. semanoti sp. nov. and F. taxodii sp. nov.) are introduced in the present study, with pathogenicity tests confirming all six species could cause T. hybrid ‘ Zhongshanshan’ dieback.

This study provides the first documentation of Fusarium diversity associated with S. bifasciatus in China, offering new perspectives for understanding the beetle-fungus symbiotic system and their synergistic pathogenicity to T. hybrid ‘ Zhongshanshan’.