Caffeic acid: A game changer in pine wood nematode overwintering survival.

Following the invasion by the pine wood nematode (PWN) into north-east China, a notable disparity in susceptibility was observed among Pinaceae species. Larix olgensis exhibited marked resilience and suffered minimal fatalities, while Pinus koraiensis experienced significant mortality due to PWN infection. Our research demonstrated that the PWNs in L. olgensis showed a 13.43% reduction in lipid content compared to P. koraiensis (p < 0.05), which was attributable to the accumulation of caffeic acid in L. olgensis. This reduction in lipid content was correlated with a decreased overwintering survival of PWNs. The diminished lipid reserves were associated with substantial stunting in PWNs, including reduced body length and maximum body width. The result suggests that lower lipid content is a major factor contributing to the lower overwintering survival rate of PWNs in L. olgensis induced by caffeic acid. Through verification tests, we concluded that the minimal fatalities observed in L. olgensis could be attributed to the reduced overwintering survival of PWNs, a consequence of caffeic acid-induced stunting. This study provides valuable insights into PWN-host interactions and suggests that targeting caffeic acid biosynthesis pathways could be a potential strategy for managing PWN in forest ecosystems.