Associations Between Bark Beetles and Pseudomonas

Bacteria-host interactions play essential roles in the biology of animals. One of such interactions implies bacteria and bark beetles. Bark beetles are considered to be serious pests that devastate entire forests worldwide. Different studies have investigated the microbiome of bark beetles. Some of them have even demonstrated the role of microbes in the protection or nutrition of their beetle host. Particularly, bacteria belonging to the genus Pseudomonas seem to be relevant players of these holobionts. Here, we review the current knowledge of Pseudomonas-bark beetle interactions, suggesting for this bacterial genus to have key roles within the core microbiome of Dendroctonus, Ips, and several other bark beetle genera. Many studies report the ability of different Pseudomonas strains to antagonize entomopathogenic fungi, to aid in the beetle nutrition by the degradation of complex nutrients which the beetle cannot digest and the capability to break down chemical defenses produced by the tree in response to bark beetles. A better understanding of the basis of this insect-bacteria interaction will enable researchers to deep in the biology of the beetle and to better design strategies to overcome this forest pest.