Odorant-Binding Protein Interactions with Herbivore-Induced Volatiles Drive Behavioral Attraction of Harmonia axyridis (Coleoptera: Coccinellidae) to Tuta Absoluta-Infested Tomato Plant

Tuta absoluta severely constrains global tomato production. We investigated the behavioral attraction of Harmonia axyridis to infested plants and the molecular basis of herbivore-induced plant volatile (HIPV) recognition. Y-tube bioassays showed statistically significant attraction of H. axyridis to the infested plant (χ 2 = 13.72, P < 0.05). Molecular docking showed strong HaxyOBP-HIPV interactions, with predicted binding energies reaching −7.6 kl mol –1 and ligand efficiencies of more than 0.30 kl mol –1 per heavy atom. HaxyOBP13, HaxyOBP19, and HaxyOBP23 were found to have the most stable complexes with 1,3-cyclohexadiene-1-carboxaldehyde, 2,6,6-trimethyl, 1-methyl-3-(1-methylethyl), and beta-phellandrene during 100 ns molecular dynamics simulations, maintaining RMSD values within 0.15–0.30 nm. The competitive binding assays confirmed micromolar affinities, with dissociation constants ( K d ) ranging between 6.45 and 14.58 μM. These behavioral, computational, and biochemical findings define important OBPs that mediate the perception of HIPV in H. axyridis, which forms the basis of volatile-mediated improvement of biological control measures against T. absoluta .