Expression and sex pheromone-binding characteristics of pheromone-binding protein 3 in Tuta absoluta (Lepidoptera: Gelechiidae)

The olfactory system plays a crucial role in insect survival and reproduction. Odorant-binding proteins (OBPs) are essential for odor discrimination and hold the potential to be targets for pest management. Tuta absoluta (Lepidoptera: Gelechiidae), a devastating invasive pest of Solanaceae crops, has limited research on its OBPs. In this study, 34 OBP genes were identified in T. absoluta, including TabsGOBP1, TabsGOBP2, TabsPBP1a, TabsPBP1b, TabsPBP1c, and TabsPBP3, which belong to the Lepidoptera-specific GOBP/PBP subclass. Expression profiling revealed TabsPBP3 to be predominantly expressed in male antennae and the female pheromone gland-ovipositor complex, with peak expression at 6:00 AM associated with courtship and mating behavior. Fluorescence competitive binding assays demonstrated that TabsPBP3 strongly binds to the main pheromone component (3E, 8Z, 11Z)-tetradecatrien-1-yl acetate (TDTA) but exhibits weak or no affinity for other components. Molecular docking identified key active sites in TabsPBP3, including Phe37, Tyr61, Ile77, Leu84, Ile86, Leu87, Phe101, Ala136, Ile139, and Ala140, which facilitate interaction with TDTA. These findings establish TabsPBP3 as a key player in TDTA detection and provide foundational data for innovative pest control strategies targeting T. absoluta.