Distinct defense strategies allow different grassland species to cope with root herbivore attack
Root-feeding insect herbivores are of substantial evolutionary, ecological and economical importance. Plants defend themselves against insect herbivores through a variety of tolerance and resistance strategies. To date, few studies have systematically assessed the prevalence and importance of these strategies for root–herbivore interactions across different plant species. Here, we characterize the defense strategies used by three different grassland species to cope with a generalist root herbivore, the larvae of the European cockchafer Melolontha melolontha. Our results reveal that the different plant species rely on distinct sets of defense strategies. The spotted knapweed (Centaurea stoebe) resists attack by dissuading the larvae through the release of repellent chemicals. White clover (Trifolium repens) does not repel the herbivore, but reduces feeding, most likely through structural defenses and low nutritional quality. Finally, the common dandelion (Taraxacum officinale) allows M. melolontha to feed abundantly but compensates for tissue loss through induced regrowth. Thus, three co-occurring plant species have evolved different solutions to defend themselves against attack by a generalist root herbivore. The different root defense strategies may reflect distinct defense syndromes.
KeywordsBelowground herbivores Chemical and structural defenses Generalist herbivores Host resistance and tolerance
We thank Zoe Bont, Wei Huang, Noëlle Schenk, Elias Zwimpfer, Gabriel Ulrich, Marlise Zimmermann and Julia Fricke for field collection of M. melolontha larvae, rearing of larvae and technical assistance during experiments, as well as the gardeners of the IPS for their help with plant cultivation.
Author contribution statement
MRH and ME conceived and designed the experiments. MRH performed the experiments and analyzed the data. MRH and ME interpreted the data and wrote the manuscript.
This work was supported by a CJS grant from Institut National de la Recherche Agronomique, the Swiss National Science Foundation (Grants #153517 and 157884) and the University of Bern.
Compliance with ethical standards
All applicable institutional and/or national guidelines for the care and use of animals were followed.
The data of this manuscript have been deposited on Figshare ( https://doi.org/10.6084/m9.figshare.9163724).
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