Two chemosensory proteins in Aleurocanthus spiniferus are involved in the recognition of host VOCs

CSPs are known for their complex and arguably obscure function(s), particularly in chemical olfaction. It is unclear which CSPs in Aleurocanthus spiniferus are involved in the identification of host VOCs. This study on A. spiniferus utilized gene expression, ligand binding, RNAi and molecular docking to determine the CSPs involved in the binding and transport of six host VOCs. Four (AspiCSP7, 9, 12 and 16) of the 12 CSPs underwent transcriptional up- or down-regulation after induction by host VOCs. AspiCSP16 can bind to six VOCs, and AspiCSP7 can bind to five except linalool. dsAspiCSP7-treated adults showed significantly lower tendency to 3-carene, hexanol, (E)-2-hexenal, and lost avoidance of (Z)-3-hexenol; the preference for 3-carene, hexanol, and the avoidance of nonanal and (Z)-3-hexenol were reduced when AspiCSP16 was knocked down. Although it is difficult to convince the results on EAG after silencing 63% of AspiCSP7 and AspiCSP16. dsAspiCSP7 and dsAspiCSP16 treatments reduced the electrophysiological (EAG) response to attractive (3-carene and hexanol), and repellent chemicals [nonanal and (Z)-3-hexenol], which demonstrated the behavioral results. Molecular docking indicated that critical hydrophobic residues, LYS-95 and ILE-59, might be involved in the binding of AspiCSP7 and AspiCSP16 to six host VOCs, respectively. AspiCSP7 and AspiCSP16 are involved in the recognition of host VOCs, including four attractants [(E)-2-hexenal, linalool, 3-carene, hexanol] and two repellents [nonanal and (Z)-3-hexenol]. This study will deepen the understanding of the olfactory mechanisms of host VOCs recognition by A. spiniferus and will support the development of novel compounds and RNA pesticides for controlling pests.