Niemann–Pick type C2 Proteins Mediate the Perception of Herbivore-Induced Plant Volatiles in the Predatory Mite <i>Neoseiulus californicus</i>

The citrus crop is severely damaged by the citrus red mite, <i>Panonychus citri</i>. The predatory mite <i>Neoseiulus californicus</i> is an effective natural enemy used for its biocontrol. To enhance predator efficiency, this study investigated the role of odorant-binding proteins in recognizing herbivore-induced plant volatiles (HIPVs). We identified two Niemann-Pick type C2 genes, <i>NcNPC2</i>-a and <i>NcNPC2</i>-b, which were highly expressed in adult females, particularly in the legs. RNAi-mediated silencing of <i>NcNPC 2s</i> impaired the mite's ability to locate HIPVs. Fluorescence binding assays and molecular docking confirmed that NcNPC2 proteins strongly bind undecylcyclohexane. Field trials using slow-release dispensers showed that HIPVs attracted predatory mites effectively within 2 m. These findings reveal that NcNPC2 proteins mediate the perception of HIPVs in <i>N. californicus</i>, providing insights for developing attractants to enhance biocontrol efficacy.