Leaf defense syndromes in tropical ferns

Farias, Rafael de Paiva; Costa, Lucas Erickson Nascimento da; Oliveira, Antônio Fernando Morais de; Barros, Iva Carneiro Leão; Mehltreter, Klaus

doi:10.1007/s11258-019-00983-4

Cited by 13 publications

(8 citation statements)

References 72 publications

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“…The understanding of interactions between ferns and insect herbivores has been marked by theoretical gaps, and very few studies have yet evaluated mechanisms of host plant selection, overlooking, therefore, the ecological and functional importance of ferns to trophic interactions and ecosystem processes (see Balick et al 1978;Mehltreter 2010;Farias et al 2019;Santos et al 2019). Our study demonstrated that the tree fern C. phalerata suffers simultaneous damage from gallers and leaf chewers, and may represent a key resource for several herbivores, regulating the dynamics of leaf exploration.…”

Section: Discussionmentioning

confidence: 84%

“…Ferns served as a good model group to understand insect community organization globally (see Lawton 1982;Lawton & MacGarvin 1985;Lawton & Gaston 1989), but the current knowledge on insect-plant interactions for this plant group is still very limited (Balick et al 1978;Mehltreter 2010). Because ferns are abundant in tropical forests (Sharpe et al 2010), host a wide variety of potential herbivores, such as ants, gall formers, caterpillars, leaf miners and spore feeders (Farias et al 2018a;Santos et al 2019), and contain a variety of structural, physical and chemical defensive traits against insects (Kessler et al 2015;Farias et al 2019), we suggest that they are a suitable, yet overlooked, plant group to model and test hypotheses on plant-herbivore interactions (Mehltreter 2010). Most ferns have few specific biochemical defence mechanisms against herbivores (Radhika et al 2012) compared with seed plants, yet ferns and seed plants exhibit similar levels of herbivore damage (Mehltreter 2010).…”

Section: Introductionmentioning

confidence: 99%

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Interactions of gall‐formers and leaf‐chewers on a tropical tree fern: evidence for non‐repulsion and co‐occurrence between insect guilds

et al. 2021

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Host plant selection by herbivores is driven by a complex array of cues, including leaf traits and previous leaf damage. Herbivore-associated cues to host selection at the plant and leaf scale aid understanding of mechanisms responsible for host preference that might translate into increased performance, as well as processes structuring herbivore populations mediated by interactions. We investigated how changes induced by a galling insect in the tropical fern Cyathea phalerata act as repellent or attractant cues for sawfly feeding and the effects of leaf size on herbivory levels.• We recorded gall abundance, damage by chewers, leaf size, plant nutritional quality, phenolic concentration and leaf anatomical traits between galled and non-galled leaf samples.• Galled samples contained less N, higher levels of phenolics and higher C/N ratio. However, leaf-chewing damage did not differ between galled and non-galled leaves. The gall structure was avoided by chewers, as it had high concentrations of phenolics, lignification and suberization. Larger leaves sustained higher gall abundance, but leaf size did not have a significant effect on chewer damage. A co-occurrence index calculated for both guilds indicated that galls and chewers exhibited a distribution that did not differ from random, reinforcing that the two guilds on C. phalerata do not show patterns of repulsion such as those maintained by interspecific competition.• Sawflies dismissing chemical cues indicate that the increase in phenolics caused by galling insects does not generate increased protection of the galled pinnules. Our results highlight ferns as key resources for herbivores and as a potential plant group to study new research avenues on plant-insect interactions.

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Section: Discussionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Interactions of gall‐formers and leaf‐chewers on a tropical tree fern: evidence for non‐repulsion and co‐occurrence between insect guilds

et al. 2021

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“…If the function of fern nectaries is to attract mutualistic ants and other beneficial arthropods to protect the plant from herbivores, this limited activity of nectar production seems counterintuitive. However, ferns are known to possess mainly constitutive, structural defense mechanisms such as fibers and lignified walls, and high phenol and tannin content, which become functional only in mature leaves (Mehltreter, 2010; Farias et al, 2020). In this case, young leaves would need some other kind of protection from herbivores, which ants could provide.…”

Section: Discussionmentioning

confidence: 99%

Nectaries in ferns: their taxonomic distribution, structure, function, and sugar composition

Mehltreter

Tenhaken

Jansen

2022

American J of Botany

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Premise Extrafloral nectaries have mainly been studied in angiosperms, but have also been reported in 39 fern species. Here we provide a global review of nectaries in ferns and examined their structure, function, and nectar sugar composition in two genera. Methods We searched in the literature and living plant collections of botanical gardens for indications of fern nectaries, observed nectar‐feeding animals, studied the morphoanatomy in the two genera Aglaomorpha and Campyloneurum, and analyzed the total sugar concentrations and ratios of 16 species. Diurnal nectar release was observed with time‐lapse photography. Results We found evidence for nectaries in 101 species of ferns from 11 genera and 6 families. Most of the nectary‐bearing species were tree ferns (Cyatheaceae) and epiphytic ferns of the family Polypodiaceae. Nectaries consisted of cytoplasm‐rich parenchyma with large nuclei and an epidermis with or without stomata, were attached to amphiphloic vascular bundles, and released nectar on the lower leaf surface mainly on expanding leaves during the night. Sugar concentrations varied between species (3.8–15.3%) but not between genera, and were sucrose‐dominant (3 spp.), sucrose‐rich (7), or hexose‐rich (3). In the greenhouse, introduced ants, scale insects, and snails fed on the nectar. Conclusions The wide taxonomic distribution, variable morphology, locations, and sugar compositions point to multiple evolutionary origins of fern nectaries. Nectar release in young leaves might attract mutualistic ants to protect leaves against herbivores only during this most vulnerable developmental stage. Even ex‐situ, fern nectar is a valuable food source because it attracted several opportunistic animal species.

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“…The previous examples have shown that fern-insect coevolution has occurred in insect clades with different feeding habits. This seems counterintuitive at the rst sight because ferns defend themselves with an array of ecological, biochemical, and morphological traits (Farias et al 2020) to which insects have to adapt when selecting their host plants (Thorsteinson 1960). For instance, Orthoptera feed mainly on grasses (Joern 1979) and one would expect that fern species to which they have switched might have similar defense syndromes as their original host plants.…”

Section: Discussionmentioning

confidence: 99%

“…Historically, most ferns have been assumed to be of Paleozoic origins, to possess a low nutritional value, and to be well protected by high ber and tannin content (Mehltreter 2010). However, most of the extant fern species evolved after the angiosperms (Schneider 2016), can have similar nutrient contents in their tissues as do angiosperms (Wright et al 2004; Richardson and Walker 2010), and do not possess the most developed defense strategies (Farias et al 2020). After a revision of the scienti c literature, several authors found about 400 fern-feeding insect species worldwide and concluded that this record of fern-insect interactions suffers from both sampling bias and insu cient data (Balick et al 1978;Cooper-Driver 1978;Hendrix 1980).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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Leaf defense syndromes in tropical ferns

Cited by 13 publications

References 72 publications

Interactions of gall‐formers and leaf‐chewers on a tropical tree fern: evidence for non‐repulsion and co‐occurrence between insect guilds

Interactions of gall‐formers and leaf‐chewers on a tropical tree fern: evidence for non‐repulsion and co‐occurrence between insect guilds

Nectaries in ferns: their taxonomic distribution, structure, function, and sugar composition

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

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