Identification of Behaviorally Active Odorants for Adult Chilo sacchariphagus Based on the Binding Properties of Odorant-Binding Proteins toward Host Volatiles

Chilo sacchariphagus is the key pest of sugar cane. Due to the difficulty associated with pesticide application in middle and late growth stages of sugar cane, the use of odorant attractants is a beneficial alternative to pesticides. Odorant-binding proteins (OBPs) in the insect olfactory system represent excellent targets for screening odorant attractants. Here, we identified 12 OBPs from the head transcriptome of C. sacchariphagus adults, with four OBPs (CsacOBP1/2/5/12) highly enriched in adult antennae. Ligand-binding assays for the four CsacOBPs showed that they can bind with 10 of the 30 host volatiles tested. Behavioral assays revealed that (+)-cedrol and 1-hexadecanol from the 10 compounds can attract the moths of both sexes. Protein-ligand interaction analyses identified five key amino acid residues involved in CsacOBPs' binding to (+)-cedrol and 1-hexadecanol. These findings have enhanced our molecular understanding of the host plant selection in C. sacchariphagus and have facilitated the development of attractants for C. sacchariphagus.