Identification and Expression Analysis of G-Protein-Coupled Receptors Provide Insights into Functional and Mechanistic Responses to Herbivore-Induced Plant Volatiles of Paracarophenax alternatus

Herbivore-induced plant volatiles (HIPVs) play a pivotal role in mediating tritrophic interactions between plants, herbivores, and their natural enemies. <i>Paracarophenax alternatus</i>, a parasitic mite targeting the egg stage of <i>Monochamus alternatus</i>, has emerged as a promising biocontrol agent. However, its ability to detect <i>Pinus massoniana</i>-derived HIPVs for host insect localization remains unclear. G-protein-coupled receptors (GPCRs) may play a role in mediating the perception of HIPVs and associated chemosensory signaling pathways in mites. In this study, a total of 85 GPCRs were identified from <i>P. alternatus.</i> All GPCRs exhibited conserved transmembrane domains and stage-specific expression patterns, with 21 receptors significantly upregulated in viviparous mites. Combined with two previously identified odorant receptors (ORs), six candidate chemosensory receptors were selected for molecular dynamics simulations to validate their binding stability with key volatile compounds. The results demonstrate that specific GPCRs likely facilitate HIPV detection in mites, enabling precise host localization within dynamic ecological niches. Our findings provide critical insights into the molecular basis of mite-host interactions and establish a framework for optimizing <i>P. alternatus</i>-based biocontrol strategies against pine wilt disease vectors.