From Molecular Recognition to Behavioral Control: Dual-Target Aphid Repellent Discovery of Novel Ionone Derivatives

Odorant-binding proteins (OBPs) are promising targets for insect behavior regulators. We established an original target-to-behavior strategy for developing dual-target aphid repellents. Structure-based virtual screening initially identified β-ionone as a lead compound, from which 24 novel ionone derivatives were designed and synthesized targeting Acyrthosiphon pisum OBP3 and OBP7. Most ionone derivatives exhibited enhanced binding affinities to both ApisOBP3 (5.14-20.70 μM) and ApisOBP7 (3.64-28.68 μM). Molecular dynamics simulations and alanine site-directed mutagenesis revealed that mutation of ASN109 in ApisOBP3 induced pocket remodeling and binding affinity compensation, while mutation of MET73 in ApisOBP7 disrupted the residue-ligand interactions, leading to decreased binding affinity. Consistently, these ionone derivatives exhibited improved aphid repellency (28.85-62.22%). RNA interference studies further confirmed that ApisOBP3 and ApisOBP7 cooperatively mediate olfactory perception and repellent responses. Collectively, this target-to-behavior strategy provides a systematic paradigm to link OBPs with insect behavioral regulation, facilitating the rational design of insect behavior regulators targeting multiple OBPs.