Coordinated mediation of the response to ethyl linoleate by two odorant-binding proteins in Plodia interpunctella larvae

The Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae), is a ubiquitous pest in stored products, with the larvae inflicting the most damage. The molecular mechanisms underlying larval olfaction and associated behaviors remain poorly understood. Reverse transcription quantitative polymerase chain reaction (RT–qPCR) analysis revealed two odorant binding proteins of P. interpunctella (PintOBPs) with antenna-biased expression in larvae. Competitive binding assays revealed that both PintOBP18 and PintOBP19 bind to a variety of volatile compounds emitted from stored food products, with ethyl linoleate identified as the best ligand for both proteins. According to RNA interference tests, the attractiveness of ethyl linoleate to P. interpunctella larvae was not significantly affected by the silencing of PintOBP18 or PintOBP19 separately. Nevertheless, the attractiveness of this odorant to larvae was severely impaired when both OBPs were knocked down. Furthermore, molecular docking and site-directed mutagenesis studies demonstrated that Ser66 in PintOBP18 and Val62 in PintOBP19 play crucial roles in binding ethyl linoleate. These findings advance our understanding of olfactory recognition in P. interpunctella larvae and provide potential targets for developing olfactory disruption strategies to control storage pests.