Chemical Communication in Two Closely Related Carposina Fruit Borers: Shared and Species-Specific Pheromone Components and Their Recognition by Pheromone-Binding Proteins

Abstract

Chemical communication between closely related insect species often involves shared and species-specific signals, yet their molecular recognition mechanisms remain poorly understood. We show that two related fruit borers, Carposina coreana and Carposina sasakii, share (Z)-7-eicosen-11-one, while (Z)-7-tricosene and (Z)-7-nonadecen-11-one are species-specific. GC-EAD revealed differential detection by male antennae of both species. From the antennal transcriptome of C. coreana, we identified six pheromone-binding proteins (PBPs)─twice the number in C. sasakii─with CcorPBP4 and CcorPBP6 showing male-biased expression. Fluorescence binding assays showed that key PBPs from both species bind the shared component with high affinity (Ki = 3.19–7.62 μM), while CcorPBP6 and CsasPBP3 show reciprocal preferences for species-specific components. Molecular dynamics and MM/PBSA identified key residues (Tyr23/Trp183 in CcorPBP6; Phe17/Ile57 in CsasPBP3) governing binding specificity. These findings reveal conserved recognition of the shared signal coupled with divergent recognition of species-specific signals, providing a molecular basis for PBP-targeted behavioral control strategies.