Interactions Involving Rhizobacteria and Foliar-Feeding Insects

Rhizobacteria are key belowground drivers of plant–insect higher trophic interactions aboveground. Conventionally, rhizobacteria have been studied in the context of their effects on plant growth and yield in agricultural situations. However, the focus of rhizobacterial studies shifted recently to explore their effects on plant biochemistry, defense signaling, the plant microbiome, and insect herbivores. Here, we review the interactions between rhizobacteria and foliar-feeding insects and consider some of the mechanisms by which these interactions occur. To develop a robust understanding of whether and how rhizobacteria govern plant–insect interactions, a multidisciplinary approach involving ecological and -omics approaches is imperative. Such an approach will not only elucidate the key mechanisms underpinning these intricate interactions, including a wide range of variables at spatiotemporal scales, but also open new avenues for their applicability in agricultural and allied fields. This review attempts to (1) synthesize existing knowledge of rhizobacteria–plant–herbivore interactions, (2) identify and address the key issues in the current study systems, and (3) discuss the potential importance of rhizobacteria in insect community ecology.