A global review and network analysis of phytophagous insect interactions with ferns and lycophytes

Abstract

Ferns are the second largest lineage of vascular plants, yet our understanding of their interactions with phytophagous insects is very limited. Which insects feed on ferns? Do insects prefer speci c fern taxa? Which feeding habit is the most common on ferns? Is there any evidence for coevolution between insects and ferns? Is our current knowledge on fern-insect interactions biased? To answer these questions, we analyzed 2,318 records of fern-insect interactions from 122 literature sources, based on the feeding habit of insects, fern taxa, and geographic location. We found evidence for interactions comprising 809 insect species (mainly Hemiptera, Lepidoptera, and Coleoptera) and 382 fern species (mainly Dennstaedtiaceae, Dryopteridaceae, and Pteridaceae). Leaf chewers contributed over 50% of the species, followed by sapsucking insects (29.1%) and spore feeders (6.5%). The overall interaction analyses revealed that the entire fern-insect network had medium levels of nestedness (NODF = 43.37) and relatively low levels of specialization (H2' = 0.24). The interaction networks of fern-feeding Coleoptera were the most specialized at family (H2' = 0.40) and genus level (H2' = 0.65), whereas 6 out of 10 most specialized insect families were Lepidoptera (d' ≥ 0.44). At the genus level, all networks had a fern-biased asymmetry. Although fernfeeding generalists were common, few cases of coevolutionary radiation have been documented. We discuss the possible biases of our dataset, which also highlight gaps to perform future research, and suggest that many more phytophagous insects on ferns remain to be discovered, especially sap-sucking, gall-forming, and spore-feeding insects on modern fern groups.

Sampling bias and the robustness of ecological metrics for plant–damage‐type association networks

“…These functional bipartite networks are a paleoecological counterpart, or analog, to the taxonomically based plant–insect interaction networks commonly found in the modern ecological literature (Table 1; major differences between taxonomic vs. functional bipartite networks). Examples from the modern literature include undirected network associations between woody perennial species and their pathogens, specialization in plant‐host–gall interactions, and the preference of insects for particular fern hosts (Araújo & Kollár, 2019; Fodor & Hâruṭa, 2014; Fuentes‐Jacques et al, 2021). However, for fossil data, one of these node classes, the DTs functionally serve as ecological units that have links to plant taxa and would incorporate data such as one herbivore species producing multiple DTs and multiple herbivore species producing one DT, the multidamagers and monodamagers of Carvalho et al (2014).…”

Rediscovering a species not seen for a hundred years, Stathmopoda tacita (Meyrick, 1913) (Lepidoptera, Stathmopodidae), with its unusual fern-spore-feeding life history

“…Here, we present the rediscovery of S. tacita and found that they utilise spores and the mesophyll of Polypodiosida, an unusual host for Lepidoptera , as larval diet. Fern feeding is uncommon in Lepidoptera , only occurring in a few groups of moths ( Fuentes-Jacques et al 2022a ). Consumption of fern spores is even rarer, with this feeding habit only found in three families: Stathmopodidae , Micropterigidae and Tineidae ( Lees and Zilli 2019 , Fuentes-Jacques et al 2022a ).…”

“…Fern feeding is uncommon in Lepidoptera , only occurring in a few groups of moths ( Fuentes-Jacques et al 2022a ). Consumption of fern spores is even rarer, with this feeding habit only found in three families: Stathmopodidae , Micropterigidae and Tineidae ( Lees and Zilli 2019 , Fuentes-Jacques et al 2022a ). Amongst these three fern-spore-feeding families, Stathmopodidae has the highest fern-feeding species diversity.…”

Effects of experimental host‐plant switching on the life cycle of a fern spore‐feeding micromoth of the genus Stathmopoda

“…Although percentages of host specialists vary between orders, most herbivorous insects are specialists on their host plants, being restricted to one or a few related species (Strong et al, 1984; Jaenike, 1990; Forister et al, 2012). Historically, ferns have been considered herbivore‐resistant plants, and consequently they have not received much attention from researchers as host plants for insects, but a current review revealed over 800 fern‐feeding insect species worldwide and assumed that thousands of species remain to be discovered (Fuentes‐Jacques et al, 2021).…”

“…Insects attack all organs and tissues of ferns, and some species have even specialized to feed on the tiny fern spores. Yet, spore‐feeding is one of the least‐observed feeding guilds, accounting for only about 6.5% of all registered fern‐feeding insect species (Fuentes‐Jacques et al, 2021). Most specialized spore‐feeding insects on ferns belong to the Hemiptera (e.g., the tribes Briocorini and Miridae) (Konstantinov & Knyshov, 2015) and Lepidoptera, which is the second most diverse order of spore‐feeders (Hendrix, 1980).…”