Identification and characterization of CAPA GPCRs in box tree moth (Cydalima perspectalis)

Box tree moth (BTM) (Cydalima perspectalis), a recently introduced invasive species in the United States, is a destructive pest threatening the nursery industry. BTM larvae voraciously feed on the foliage of boxwood (Buxus microphylla), impacting its ornamental value. The growing issues of pesticide resistance observed in pest species have driven a paradigm shift toward developing and using insecticidal peptides as alternative pest management strategies. Despite their potential, few studies have explored how neuropeptide–receptor interactions and neuropeptide chemistry influence insect biological activity. We studied the molecular interactions and activities between CAPA (capability) peptides and G-protein coupled receptors (GPCRs) of the BTM. GPCRs showing binding affinity towards CAPA peptides are characterized as CAPA receptor (CAPA-R). BTM CAPA-R was heterologously expressed in Sf9 insect cells to enable its functional characterization. Calcium assays demonstrated that BTM CAPA peptides, along with CAPAs from various insect species, activated BTM CAPA-R, resulting in an influx of extracellular Ca²⁺, a secondary messenger in signaling processes. Real-time quantitative PCR (RT-qPCR) showed the highest expression of CAPA-R in male adults, followed by female adults and larvae. Molecular docking was performed using AutoDock CrankPrep (ADCP) to identify key amino acid residues involved in the interaction between BTM CAPAs and CAPA-R. Mutants of CAPA-R will be constructed with site-directed mutagenesis at the N-terminal domain, and Ca²⁺ activity will be investigated. These findings provide valuable insight into peptide-receptor signaling in BTM and highlight the potential of peptide-based biopesticides for managing this pest.