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The Gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer-feeding beetles
Dep. of Biochemistry, Max Planck institute for Chemical Ecology.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. (Ekologisk kemi)ORCID iD: 0000-0003-4970-8352
Dep. of Ecology, SLU.
Max Planck Institute for Chemical Ecology. (Dep of Biochemistry)
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2016 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

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.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016.
Keyword [en]
Hylobius abietis, conifer, terpenes, insect symbiosis, bark beetle, microbiota
National Category
Microbiology Ecology
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-187816DOI: 10.1111/mec.13702OAI: oai:DiVA.org:kth-187816DiVA: diva2:931673
Note

QC 20160530

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2016-05-30Bibliographically approved
In thesis
1. Chemical signals in interactions between Hylobius abietis and associated bacteria
Open this publication in new window or tab >>Chemical signals in interactions between Hylobius abietis and associated bacteria
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The pine weevil (Hylobius abietis L.) is one of the two topmost economically important insect pests in Swedish conifer forests. The damage increase in areas were the silvicultural practice is to use clear cuttings were the insects gather and breed. During egglaying the female protects her offspring by creating a cave in roots and stumps were she puts her egg and covers it with frass, a mixture of weevil feces and chewed bark. Adult pine weevils have been observed to feed on the other side of the egg laying site and antifeedant substance has been discovered in the feces of the pine weevil. We think it is possible that microorganisms present in the frass contribute with antifeedant/repellent substances. Little is known about the pine weevils associated bacteria community and their symbiotic functions. In this thesis the bacterial community is characterized in gut and frass both from pine weevils in different populations across Europe as well as after a 28 day long diet regime on Scots pine, silver birch or bilberry. Volatile substances produced by isolated bacteria as well as from a consortium of microorganisms were collected with solid phase micro extraction (SPME) and analyzed with GC-MS. The main volatiles were tested against pine weevils using a two-choice test. Wolbachia, Rahnella aquatilis, Serratia and Pseudomonas syringae was commonly associated with the pine weevil. 2-Methoxyphenol, 2-phenylethanol, 3-methyl-1-butanol were found in the headspace from Rahnella aquatilis when grown in substrate containing pine bark. 2-Methoxyphenol and 3-methyl-1-butanol, phenol and methyl salicylate were found in pine feces. Birch and bilberry feces emitted mainly linalool oxides and bilberry emitted also small amounts of 2-phenylethanol.

A second part of the thesis discusses the role of fungi in forest insect interactions and the production of oxygenated monoterpenes as possible antifeedants. Spruce bark beetles (Ips typhographus L.) aggregate with the help of pheromones and with collected forces they kill weakened adult trees as a result of associated fungi growth and larval development. A fungi associated with the bark beetle, Grosmannia europhoides, was shown to produce de novo 2-methyl-3-buten-2-ol, the major component of the spruce bark beetle aggregation pheromone. Chemical defense responses against Endoconidiophora polonica and Heterobasidion parviporum were investigated using four clones of Norway spruce with different susceptibility to Heterobasidion sp. Clone specific differences were found in induced mono-, sesqui and diterpenes. A number of oxygenated monoterpenes which are known antifeedants for the pine weevil were produced in the infested areas.

Place, publisher, year, edition, pages
Stockholm: Kungliga tekniska högskolan, 2016. 51 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 21
Keyword
Pine weevil, Hylobius, Rahnella, Pseudomonas, bacteria, fungi, metabolites, 2-methoxyphenol, 2-phenylethanol
National Category
Analytical Chemistry Ecology Microbiology Biochemistry and Molecular Biology Organic Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-187817 (URN)978-91-7595-972-6 (ISBN)
Public defence
2016-06-15, F3, Lindstedtvägen 26, Stockholm, 12:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council FormasSwedish Foundation for Strategic Research
Note

QC 20160601

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2016-06-01Bibliographically approved

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