Molecular Characterization and Binding Properties of Odorant Binding Protein 7 in Western Flower Thrips, Frankliniella occidentalis (Thysanoptera: Thripidae)

Odorant-binding proteins (OBPs) play a critical role in the olfactory communication systems of insects. Western flower thrips (WFT), Frankliniella occidentalis (Pergande), are devastatingly invasive pests that cause significant damage to a wide range of crops globally. However, there is limited research investigating the functional roles of OBPs in WFT. In this study, we successfully cloned and expressed the recombinant protein FoccOBP7. Fluorescence competition binding assays demonstrated that FoccOBP7 exhibited a high affinity for dibutyl phthalate (DBP) and β-ionone. Three amino acid residues (Q101A, Y112A, and M115A) and two residues (Q101A and Y112A) were essential in influencing the binding affinity of FoccOBP7 to DBP and β-ionone, respectively. DBP could elicit the most significant electroantennogram (EAG) responses among the 11 volatile compounds. Following RNA interference (RNAi), both the EAG response and Y-tube behavioral tropism to DBP were significantly decreased. This study highlighted the importance of FoccOBP7 in mediating olfactory responses and DBP as potential disorienting odorants for pest management strategies in the future.