A global overview of insect-fern interactions and its ecological trends

The review and data compilation were carried out based on electronically available information on three main platforms and database repositories: Web of Science , Scopus , and Google Scholar . The data was compiled from scientific articles and cover a broad time, ranging from 1920 to 2022.We used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol for paper search (Moher et al., 2000). We used the following key terms in our search: ‘fern’ AND ‘insect’ OR ‘pteridophyte’ AND ‘insect’. Several criteria needed to be met for studies to be included in the database. These criteria were as follows: (1) ferns and/or insects needed to be identified at least to the family level to be added to the list of host plants and insect guilds;. (2) studies needed to report some form of interactions between insects and ferns. Studies where insects were only recorded as hosts without additional information about interactions (e.g., unequivocal evidence of leaf consumption) were not added to the list. Exception for species where damage is less noticeable (e.g., those with sucking mouthparts) or when interactions occur in host-specific species (e.g., gall formers). Other more specific criteria had to be adopted as articles were searched. Taxonomy and/or systematic studies were considered only when interactions were reported (e.g., herbivory). Biological control studies were added to the list when experiments involving fern-consuming insects were conducted. However, studies assessing the status of biological control were not considered, nor were paleontological studies. Studies reporting interactions of insects with dead or decomposing ferns were also excluded.

Our initial search identified 796 studies (127 on Web of Science, 356 on Scopus, and 313 on Google Scholar) that had the potential to be included in our study. Of these, 351 were excluded because they were duplicates, and 121 did not meet all our initial inclusion criteria (1, 2, and others). Consequently, 324 studies remained in our database (Figure S1). As a result of compiling this database, we extracted data covering taxonomic information on insect and fern species, fern habitat types, observed interaction types (with herbivores categorized by guilds), and study site details (including coordinates, biogeographical regions, and types of vegetation).