Genome-wide identification of chemosensory receptor genes in the small brown planthopper, Laodelphax striatellus.

The small brown planthopper (SBPH), Laodelphax striatellus is one of the major insect pests of rice, but little is known about the molecular-level means by which it locates its hosts. SBPH host-seeking behavior heavily relies on chemosensory receptors (CRs). In this study, we utilized genome analysis of the SBPH to identify 169 CRs, including: 133 odorant receptors (ORs), 13 gustatory receptors (GRs) and 23 ionotropic receptors (IRs). The phylogenetic relationships of OR genes from three rice planthoppers and other insect species revealed that the odorant co-receptor (Orco) clade is the most conserved group. Among the candidate GRs, two sugar receptors and five fructose receptors have been identified but no carbon dioxide receptors investigated. Furthermore, we identified homologs of the three highly conserved IR co-receptors. The obtained results will provide us with precious information needed to better understand the interaction between insect pests and crop plants required for effective crop protection.