Fungal Isolates Associated With Pinus koraiensis Infected With Pine Wood Nematode, Bursaphelenchus xylophilus

ABSTRACT

Pine wilt disease (PWD), caused by the pine wood nematode Bursaphelenchus xylophilus (PWN), is one of the most destructive forest diseases worldwide. In Korea, PWD has intensified since its first detection in 1988, posing a serious threat to economically important pine species such as Pinus koraiensis (Korean white pine). However, effective and comprehensive control strategies remain limited. Because PWN relies on fungi as a food source during its life cycle (mycetophagy), the first part of the study aimed to characterise the culturable fungal isolates associated with P. koraiensis in Gapyeong‐gun, South Korea. Fungi were isolated from three sample types: (i) asymptomatic P. koraiensis trees, (ii) PWN‐infected trees, and (iii) pupal chambers of the long horn beetle Monochamus saltuarius , a vector of PWN, within infected trees. In total, 28 isolates were identified based on ITS and LSU rDNA sequence analyses. For the second part of the study these isolates were evaluated in vitro for their effect on PWN proliferation. Six fungal isolates supported moderate to high levels of PWN proliferation under in vitro conditions. Notably, blue‐stain fungi (Ophiostomatales), frequently reported as primary PWN associates in other regions, were not recovered under the culture conditions used in this study. Taken together, these findings suggest that non‐Ophiostomatales fungi may represent additional culturable fungal taxa capable of supporting PWN proliferation. Further studies are required to determine their ecological significance under natural conditions.