Nematicidal Effects of Juniperus chinensis  Leaf Extracts on the Pine Wood Nematode ( Bursaphelenchus xylophilus )

Pine wood nematode (PWN), Bursaphelenchus xylophilus , as a plant parasitic nematode, can induce pine wilt disease (PWD) which is a highly destructive forest disease causing huge losses to the global ecological environment and economy. Therefore, it has been a increasingly hot topic to develop eco-friendly and efficient nematicides against PWNs. In this study, three nematicidal compounds were isolated from the n -hexane extract of Juniperus chinensis leaves through bioactivity-guided fractionation, and identified as abietic acid, 8 α ,11-elemadiol and parabenzlactone by mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. By the assays on PWN vitality, all the three compounds were confirmed to have inhibitory effect on the motility, oviposition, fecundity, feeding, and development of PWNs, especially, parabenzlactone demonstrated the most pronounced efficacy. The bioassays on PWN pathogenicity showed that all the three compounds alleviated wilting symptoms of Japanese black pine seedlings caused by PWNs. These findings indicated that the three compounds from J. chinensis leaves have potential utility in controlling PWNs, providing valuable insights for the development of novel nematicidal agents.