biology Review A New Perspective of Pseudomonas—Host Interactions: Distribution and Potential Ecological Functions of the Genus Pseudomonas within the Bark Beetle Holobiont Zaki Saati-Santamaría 1,2,* , Raúl Rivas 1,2,3 , Miroslav Kolaˇrik 4,5 and Paula García-Fraile 1,2,3,* 1 Microbiology and Genetics Department, University of Salamanca, 37007 Salamanca, Spain;
[email protected] 2 Spanish-Portuguese Institute for Agricultural Research (CIALE), Villamayor, 37185 Salamanca, Spain 3 Associated Research Unit of Plant-Microorganism Interaction, USAL-CSIC (IRNASA), 37008 Salamanca, Spain 4 Department of Botany, Faculty of Science, Charles University, 128 01 Prague, Czech Republic;
[email protected] 5 Institute of Microbiology of the Czech Academy of Sciences, Vídeˇnská 1083, 142 20 Prague, Czech Republic * Correspondence:
[email protected] (Z.S.-S.);
[email protected] (P.G.-F.) Simple Summary: Microbes play essential roles in the health of animals and plants. Hence, the study of microbe–host interactions is of utmost importance to understand nature. In the present work, we aimed to understand the ecological distribution and functions of the bacterial genus Pseudomonas in bark beetles. These beetles are small insects that live under the bark of trees. Some bark beetle species cause mass attacks in woodlands, decimating tree populations worldwide. Thus, a better understanding of its associated microbes may aid in finding solutions for these forest pests. Our Citation: Saati-Santamaría, Z.; Rivas, revision summarizes how members of the genus Pseudomonas are ubiquitous in all life stages of R.; Kolaˇrik,M.; García-Fraile, P. A different bark beetle species. Moreover, we found that these bacteria may benefit these insects New Perspective of by providing them with nutrients, protecting them from tree chemical defenses and antagonizing Pseudomonas—Host Interactions: entomopathogenic fungi.