The Odorant-Binding Proteins AspiOBP1 and AspiOBP2 in Aleurocanthus spiniferus Are Involved in the Perception of Host Volatiles

<i>Aleurocanthus spiniferus</i>, an invasive pest native to Southeast Asia, exhibits rapid dispersal capacity and high eradication resistance. In recent years, there have been continuous records of its invasion into new host plants. Odorant-binding proteins (OBPs) are essential at the peripheral level of olfaction, and their olfactory function has been partially confirmed by research. This study explores the functions of key OBPs mediating host selection by measuring the in vivo and in vitro binding capabilities of OBPs from <i>A. spiniferus</i> to host volatiles. Under exposure to more than five host volatiles, the two <i>OBPs</i>, <i>AspiOBP1</i> and <i>AspiOBP2</i>, exhibited significant differential transcriptional regulation. AspiOBP1 exhibited good binding affinity to (<i>Z</i>)-3-hexenol and 3-carene, and with binding energies greater than -3 kcal/mol, ARG-79 might be the critical amino acid site for AspiOBP1 binding to host volatiles. AspiOBP2 exhibited no binding to any of the six tested volatiles in fluorescent competitive binding assays. Adults fed with <i>dsAspiOBP1</i> showed significantly reduced behavioral and EAG responses to the attractant 3-carene and two repellents [(<i>Z</i>)-3-hexenol and nonanal]. Adults fed with <i>dsAspiOBP2</i> lost both behavioral and EAG responses to the attractant 3-carene and the repellent (<i>Z</i>)-3-hexenol. The findings of this study not only elucidate the binding mechanisms between OBPs of <i>A. spiniferus</i> and host volatiles but also provide new targets for the future development of novel plant-derived insecticides and RNA-based pesticides to control this pest.