Conserved gut microbiota in a herbivorous beetle mediates the degradation of host plant defenses

The gut microbiome of insects is known to play essential roles in host's fitness through a variety of functions including nutritional supplementation of diets, influencing development, and mediating parasite and pathogen resistance. In this thesis, we have explored the role that gut microbes may play in the degradation of plant secondary metabolites that are toxic to insects, focusing primarily on the pine weevil (Hylobius abietis) and terpenoids. Characterization of the gut bacterial community of the pine weevil revealed a relatively stable microbiota at higher taxonomical levels (e.g. family and genus) across different locations in Europe, especially within the Enterobacteriaceae family. Despite showing some variation between locations, the pine weevil harbors a "core microbiota" composed of close relatives of Rahnella sp, Erwinia sp and Serratia sp

Fusarium phytopathogens as insect mutualists

AU As vectors: Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly of numerous plant pathogens, herbivorous insects : play a key role in the epidemiology of plant disease. But how phytopathogens impact the metabolism, physiology, and fitness of their insect vectors is often unexplored within these tripartite interactions. Here, we examine the diverse symbioses forged between insects and members of the ascomycete fungal genus Fusarium. While Fusarium features numerous plant pathogens that are causal to diseases such as wilts and rots, many of these microbes also engage in stable mutualisms across several insect clades. Matching a diversity in symbiont localization and transmission routes, we highlight the various roles fusaria fulfill towards their insect hosts, from upgrading their nutritional physiology to providing defense against natural enemies. But as the insect partner is consistently herbivorous, we emphasize the convergent benefit Fusarium derives in exchange: propagation to a novel host plant. Collectively, we point to the synergy arising between a phytopathogen and its insect vector, and the consequences inflicted on their shared plant.</p

Microbial degradation of plant toxins

Plants produce a variety of secondary metabolites in response to biotic and abiotic stresses. Although they have many functions, a subclass of toxic secondary metabolites mainly serve plants as deterring agents against herbivores, insects, or pathogens. Microorganisms present in divergent ecological niches, such as soil, water, or insect and rumen gut systems have been found capable of detoxifying these metabolites. As a result of detoxification, microbes gain growth nutrients and benefit their herbivory host via detoxify- ing symbiosis. Here, we review current knowledge on microbial degradation of toxic alkaloids, glucosinolates, terpenes, and polyphenols with an emphasis on the genes and enzymes involved in breakdown pathways. We highlight that the insect-associated microbes might find application in biotechnology and become targets for an alternative microbial pest control strategy

Bacterial and fungal symbionts of parasitic Dendroctonus bark beetles

Bark beetles (Curculionidae: Scolytinae) are one of the most species-rich herbivorous insect groups with many shifts in ecology and host-plant use, which may be mediated by their bacterial and fungal symbionts. While symbionts are well studied in economically important, tree-killing species, little is known about parasitic species whose broods develop in living trees. Here, using culture-dependent and independent methods, we provide a comprehensive overview of the associated bacteria, yeasts and filamentous fungi of the parasitic Dendroctonus micans, D. punctatus and D. valens, and compare them to those of other tree-inhabiting insects. Despite inhabiting different geographical regions and/or host trees, the three species showed similar microbial communities. Enterobacteria were the most prevalent bacteria, in particular Rahnella, Pantoea and Ewingella, in addition to Streptomyces. Likewise, the yeasts Candida/Cyberlindnera were the most prominent fungi. All these microorganisms are widespread among tree-inhabiting insects with various ecologies, but their high prevalence overall might indicate a beneficial role such as detoxification of tree defenses, diet supplementation or protection against pathogens. As such, our results enable comparisons of symbiont communities of parasitic bark beetles with those of other beetles, and will contribute to our understanding of how microbial symbioses facilitate dietary shifts in insects.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Data from: The gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer-feeding beetles

The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta-analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on non-conifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis-associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or supplementation of essential nutrients

Data from: The gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer-feeding beetles

The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta-analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on non-conifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis-associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or supplementation of essential nutrients