A New Perspective of Pseudomonas—Host Interactions: Distribution and Potential Ecological Functions of the Genus Pseudomonas within the Bark Beetle Holobiont

Symbiosis between microbes and insects has been raised as a promising area for understanding biological implications of microbe–host interactions. Among them, the association between fungi and bark beetles has been generally recognized as essential for the bark beetle ecology. However, many works investigating bark beetle bacterial communities and their functions usually meet in a common finding: Pseudomonas is a broadly represented genus within this holobiont and it may provide beneficial roles to its host. Thus, we aimed to review available research on this microbe–host interaction and point out the probable relevance of Pseudomonas strains for these insects, in order to guide future research toward a deeper analysis of the importance of these bacteria for the beetle’s life cycle.