Background & Summary

The Scolytinae (Coleoptera: Curculionidae) is a highly diverse subfamily of weevils with a worldwide distribution1. It includes about 6,500 species distributed in all continents except Antarctica, with a high diversity especially at the lower latitudes2. Scolytine beetles, commonly known as “bark and ambrosia beetles”, inhabit typically forest habitats where they usually attack stressed, dying, or dead trees3,4 by excavating breeding galleries under the bark, into the wood, twigs, or other plant parts and tissues, including seeds and fruits5. However, healthy trees can also be targeted by a few species during population outbreaks6. The successful mass colonization usually leads to large tree mortality at a landscape scale, altering forest structure7, ecological functions and ecosystem services8, and timber production9.

The impact of bark and ambrosia beetle outbreaks increased over the last years and is likely to grow even more due to climate change and international trade6. Climate change accelerates the development of insects2,10, facilitates the expansion of species outside their historical range11 and the spread of alien species12,13. Moreover, it was demonstrated that climate changes, affecting rainfall and temperature patterns, make trees weaker; as a consequence, trees become more susceptible to scolytines attacks14. International trade also contributes to the spread of alien and potentially invasive species outside their native range through the exportation of plants, plant parts, wood, and wooden packaging material15,16. However, the efforts to predict the invasiveness of alien scolytines are hampered by the lack of clear information about the interactions between beetle species and their hosts. Therefore, we provide an updated and comprehensive dataset for sixteen selected scolytine tribes and their hosts.

The previous contributions in this series treated the tribe Xyleborini17 and seven additional tribes separated from the former tribe Cryphalini18. In this work we assembled an extensive dataset on the remaining 16 scolytine tribes that feed mainly (but not exclusively) on broadleaf trees: Amphiscolytini Mandelshtam & Beaver, 2003, Bothrosternini Blandford, 1896, Carphodicticini Wood, 1971, Chaetophloeini Jordal, 2021, Crypturgini LeConte, 1876, Diamerini Hagedorn, 1909, Dryocoetini Lindemann, 1876, Hexacolini Eichhoff, 1878, Hylesinini Erichson, 1836, Hyorrhynchini Hopkins, 1915, Hypoborini Nusslin, 1911, Micracidini LeConte, 1876, Phloeotribini Chapuis, 1869, Phrixosomatini Wood, 1978, Scolytini Latreille, 1807, and Scolytoplatypodini Blandford, 1893. From this dataset we excluded those tribes whose members are primarily associated with conifers (i.e., Hylastini LeConte, 1876, Hylurgini LeConte, 1876, Ipini Bedel, 1888, Phloeosinini Nusslin, 1912, and Polygraphini Chapuis, 1869), which will be treated in a separate paper.

Although the majority of scolytine species belonging to these 16 tribes do not cause significant damage to forests, a few species are known to be considerably harmful. For instance, Scolytus scolytus (Fabricius, 1775), S. multistriatus (Marsham, 1802), and S. schevyrewi Semenov, 1902, among many others, are vectors of ascomycete fungi that cause the Dutch elm disease19,20. This fungal infection is responsible of the death of millions of elm trees in Europe and North America since the beginning of the 20th century, causing devastating economic, ornamental, and ecological damage.021. Other Scolytus species, like S. ventralis LeConte, 1868 and S. quadrispinosus Say, 1924 are also economically important, causing mass tree mortality and wood damage20.

Methods

Host plant definition

In accordance with the previous works17,18, a specific definition of host plant was adopted in the compilation of this database. Only records of scolytine species observed boring inside any plant part or tissue (either at adult or larval stage) were accepted as a true insect-plant association. Records derived from trapping or other observations of occurrence in forests or plantations (including monocultures) were considered unreliable and therefore not included in the dataset. In addition, we do not distinguish between primary or secondary host plants, as well as usual or occasional hosts. These categorizations are not essential for preventing new introductions (that is the primary purpose of this dataset): in fact, even a secondary or occasional host can act as a pathway of introduction22. Moreover, several species exhibit a high level of ecological stochasticity, which may lead them to attack either the same host trees with different intensity, phylogenetically related species or completely different plants21,22,23,24,25. For this reason, it was preferred to adopt a broader and more precautionary definition of “host”.

Data collection

The initial scolytine checklist was based on the Wood & Bright catalog1 and following supplements26,27,28,29, and it was integrated with all taxonomic papers on these tribes published afterwards, such as Jordal’s works on Micracidini30,31 and Hypoborini32. The current version of the dataset includes all the species described prior to 31 December 2023 and belonging to following 16 sixteen tribes: Amphiscolytini, Bothrosternini, Carphodicticini, Chaetophloeini, Crypturgini, Diamerini, Dryocoetini, Hexacolini, Hylesinini, Hyorrhynchini, Hypoborini, Micracidini, Phloeotribini, Phrixosomatini, Scolytini, and Scolytoplatypodini.

Each scolytine species in the dataset was treated individually through a deep search. To search for host plants, we first consulted the Wood & Bright catalog and following supplements, then the research was followed by consultation of Google Scholar, Google and other sources referring to reliable scientific papers, books or databases (e.g., the Atkinson online database33 for American species). The species name was used first (e.g., “Scolytus amygdali”) and was then integrated with the use of other keywords such as “host”, “pest” in combination with Boolean operators. Synonyms of scolytine species and host taxa were also used in the search. In addition, we extensively reviewed reports, government documents and online sources in multiple languages (e.g., Chinese, English, French, German, Italian, Japanese, Portuguese, Russian, Spanish) using, when necessary, multilingual neural machine translators (DeepL or Google Translate). When the host species in the original sources were reported only with vernacular or local names, or when uncertain and unreliable records were found, we discarded the information.

Plant taxonomy follows the “Plant of The World Online” database34. The plant economic uses are reported from the “U.S. National Plant Germoplasm System” database35, which includes all the commercial uses of the whole plant, part of it, or from the materials and chemicals obtained by processing it. The three use categories adopted consist of 1) “Food and pharmaceutical” (production of human and animal food, including bee plants; production of cosmetics, drugs, traditional medicine remedies, narcotics, vertebrate and invertebrate poison); 2) “Material” (production of fuel or raw materials used in other industries, such as wood, gum, and resins); 3) “Environmental” (plants with ornamental value and plants used for reforestations or for environmental remediation, such as soil protection from erosion, shade, and shelter).

The references included in the database were both the most relevant, the most updated and those specifically referring to a determined species and its hosts. In the case of multiple references dealing with the same species or reporting the same information, only one, and generally the first recovered or the most exhaustive, was selected and included in the database.

Data Records

The database for the host plants species of these tribes is available on Zenodo with the original database in XLSX format (i.e., “Complete_dataset_sixteen_tribes.xlsx”)36; the reference list is included in the same file as a different spreadsheet (“References”). The database is organized in four sheets. The first (i.e., Versions) summarizes all the updates introduced with respect to the previous version of the dataset. The second (i.e., Dataset) is organized in nine columns as follows: “Tribe” and “Species” include the taxonomic information on the scolytine beetles; “Host Family”, “Host Genus”, and “Host Species” include information on the plants; “Reference” is where the beetle-plant association is reported (entries left blank refer to those scolytine species whose hosts remain unknown, both for lacking of data and publications specifically indicating the missing information). The last three columns (i.e., “Food and pharmaceutical”, “Material”, and “Environmental”) refers to the economic categories (“1” if the plant belongs to that category, “0” otherwise). Information was reported for plant species). In the dataset, scolytine species are sorted alphabetically by tribe and species. Plant family and genus records (without plant species) do not imply that a specific scolytine species feeds on all the plants belonging to that category, but instead that family or genus is the most specific/detailed information available in the reviewed literature, thereby suggesting that a determined species feeds on at least one plant species belonging to that specific family/genus. The third sheet (i.e., Economic Uses) provides the alphabetically ordered plant list with associated economic usages. The fourth (i.e., References) lists all the references (in alphabetical order) used in the creation of the second sheet “Dataset”.

The database will be periodically updated with new versions (namely Version 1.0 onwards); the latest and most updated database will be the first to access via the DOI provided here, however previous versions of the same file will also remain available in the repository. The first version (1.1) provides information for 2,193 species of Scolytinae, of which 918 have no host records available. Of the 1,275 species in which at least one host is known, 917 species have their host known at species level, while for 358 our knowledge of the host is limited to the family or genus. The dataset includes records for 1,504 plant species, distributed among 133 families and 699 genera; 796 plant species belong to at least one of the three economic categories considered

Technical Validation

All host records included in the database are based on articles published in scientific journals, books, reports and databases managed by leading experts on scolytine beetles (e.g., Atkinson database: Bark and Ambrosia Beetles of the Americas)33; therefore, their accuracy is verified by the peer-review process. In addition, we included host records recovered from databases managed by international phytosanitary agencies (e.g., CABI37 and EPPO38), aware that in a few cases data provided may be considered uncertain as not counter-validated by scientific publications.

As already specified in materials and methods, to standardize and harmonize the information, we critically reviewed all the data collected, keeping only that related to the species whose relationship with the host plant could be recognized unequivocally; for this reason, we have excluded all possible cases that do not fall within the standards defined in the materials and methods section. Each record in the dataset is associated with a bibliographic reference, allowing users to assess the validity of the record, and reuse the data. We listed the references cited in the database, making it possible for users to access the original sources.

The complete list of genera and species belonging to the target tribes was compiled using Bright’s catalog29 and integrated/updated with the latest publications. Plant taxonomy follows the International Code of Nomenclature for algae, fungi and plants39. Taxon names and authors, including subspecies, varieties and hybrids are consistent with those provided in the internationally recognized POWO database and the International Plant Names Index (IPNI)40.

Since listing host plants is a dynamic activity, especially for non-native and invasive species, and scolytins taxonomy is in continuous evolution, our aim is to keep updating the species list and host plant data starting from our direct research upon literature, as well as direct contribution from scolytine beetle researchers and stakeholders. Data will be corrected and updated if any errors or updates are reported to the first author (matteo.marchioro@unipd.it).

Usage Notes

The data descriptor was peer reviewed in 2024 based on the data available on the platform at the time. Since this is a dynamic dataset, it may undergo changes or updates in the future.