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.