Into the ant nest: Molecular evolution of chemoreception and host specialization in predatory paussine beetles

In insects, olfaction plays a major role in many behaviors, including host preference. Localization and identification of a host by an insect begins with processing of volatiles by small antennary proteins such as odorant-binding proteins, which transport odorant ligands in the air-fluid interface to odorant receptors located in the antennal sensilla. As specificity for certain ligands can be high, OBPs are thought to play a significant role in the selectivity of the insect olfactory system. Our current work focuses on the molecular evolution of chemoreception and host specialization in an ecologically and evolutionarily interesting group of flanged bombardier beetles with myrmecophilous relationships, Paussinae. We reconstruct the evolutionary history of odorant binding protein and odorant receptor chemoreception genes while also examining functional divergence to explore the influence of molecular evolution on life history in predatory paussine beetles. In addition, we investigate the functional importance of the OBP binding pocket that is essential for interaction between these proteins and their respective ligands by studying evolutionary selection acting on specific sites.