Pests that feed on the roots of crops impose a significant cost to growers. Such costs range from limited establishment and development of planted stands, to those associated with implementation of diverse management tactics; many highly variable in their success. Attraction of pests to roots through the soil matrix is often chemically-mediated. Increasingly, it is being recognized that a number of chemical signals important for mediating interactions between host plants and their belowground pests may be of microbial origin. As microbes within the rhizosphere are increasingly targeted for management to improve the sustainability of crop production, characterizing microbial semiochemicals and their role in mediating pest attraction and performance is imperative. Here, we investigate the role of microbial semiochemicals in mediating interactions between a nitrogen-fixing bacterium (Ensifer meliloti), legume host (Medicago sativa), and weevil pest (Sitona hispidulus) across life-history stages. Sitona has emerged as a pest of significant concern to alfalfa producers in the West, as larvae and adults target rhizobia nodules for feeding and oviposition. Rhizobia-produced cues that affect this attraction however are unknown. Through increased understanding of linkages between microbial semiochemicals and pest attraction and performance, we can develop sustainable strategies for improved management of this pest.
