Nematicidal Potential of Purpureocillium takamizusanense PMEPF27 Against Motile Bursaphelenchus rainulfi In Vitro

<i>Bursaphelenchus rainulfi</i> is a pine-associated, non-pathogenic nematode that serves as a motile comparative species for evaluating nematophagous fungi. We investigated the in vitro biocontrol activity of <i>Purpureocillium takamizusanense</i> strain PMEPF27, originally isolated from insect cadavers in Taiwan, against mixed motile stages of <i>B. rainulfi</i>. Identity of the fungus was confirmed by morphology and <i>ITS</i>/<i>EF-1α</i> sequencing. Nematodes were exposed in liquid suspension to PMEPF27 conidia, with sterile water as the negative control and fluopyram as the positive control. Mortality was monitored over 7 days, and scanning electron microscopy was used to observe fungus-nematode interactions. PMEPF27 caused significantly higher mortality than the water control, reaching ~80% by day 7, and showed surface disruption of nematode cuticles, although no direct spore penetration was observed. These findings expand the nematophagous profile of <i>P. takamizusanense</i> beyond egg and sedentary stages, validate <i>B. rainulfi</i> as a motile comparative species in pine-nematode bioassays, and highlight PMEPF27 as a promising candidate for biocontrol development.