Niemann-Pick type C2 protein PpseNPC2-1 binding volatile nerolidol mediates prey localization of the pond wolf spider Pardosa pseudoannulata.

As a key natural enemy of common agricultural pests, the pond wolf spider Pardosa pseudoannulata preys on planthoppers, leafhoppers and other pests. Chemoreception is essential for P. pseudoannulata in locating prey and searching for mates. Although our previous work identified Niemann-Pick type C2 (NPC2) proteins as olfactory-related in P. pseudoannulata, the molecular mechanisms underlying prey detection remain unclear. Here, we demonstrated that the P. pseudoannulata spiders showed a significant preference for rice plants infested with Nilaparvata lugens (brown planthoppers). Nerolidol, a major component of herbivore-induced plant volatiles (HIPVs), elicited robust electrophysiological and behavioral responses in the spiders. Real-time quantitative PCR (qPCR) and in situ hybridization revealed that PpseNPC2-1 was highly expressed in the pedipalps-the primary chemosensory appendages. Fluorescence binding assays showed that recombinant PpseNPC2-1 protein bound strongly to nerolidol with a dissociation constant (Ki) below 10 μM. Molecular docking further validated the strong binding interaction between PpseNPC2-1 and nerolidol. RNA interference (RNAi)-mediated knockdown of PpseNPC2-1, which achieved a 90.2 ± 2.4 % reduction in transcript levels, abolished the spiders' behavioral preference for nerolidol. These findings establish that PpseNPC2-1 plays a crucial role in perceiving HIPVs in P. pseudoannulata, which aids spiders in detecting their prey and promotes the plant's indirect defense.