Sensory Genomics of the Emerald Ash Borer: Characterization of the Odorant Binding Proteins and Receptors

The emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Buprisidae) is an invasive pest of ash trees in North America. EAB management is a challenging task because of its cryptic feeding behavior, delayed symptoms of the host trees and lack of sensitive trapping system for the EAB. We initiated study on the sensory genomics of EAB in order to decipher the olfactory signals involved in host and mate finding. The insect olfactory system comprises odorant binding proteins (OBPs) and odorant receptors (ORs). OBPs are small water soluble proteins that act like molecular chaperones towards semiochemicals, transporting them to odorant receptors present on the sensory neurons.  During this study, we have generated 16,000 Expressed Sequence Tag (ESTs) from the antennae and legs of male and female EAB. Five putative OBPs and one chemosensory protein (CP) were identified. Amino acid comparison analysis revealed that OBPs have a six-cysteine classical pattern. Phylogenetic analyses showed that majority of OBPs belong to a classical antennal-binding protein x (ABPx) family. Structural homology modeling (SWISS-MODEL) reveals that OBPa, OPBb and OBPd has homology to OBP1 of Anopheles gambiae (AGAMOBP1; 3n7h), whereas OBPc has homology to Drosophila melanogaster OBP LUSH protein (1oohA).  To our knowledge this is the first study on the sensory genomics of EAB. It is hoped that this study will lay foundation for future work, so that OBPs and ORs can be targeted for early pest detection and/or control.