Density-Dependent Effects of Simultaneous Root and Floral Herbivory on Plant Fitness and Defense Aguirrebengoa Barreña, Martin Müller, Caroline Hambäck, Peter A. González Megías, Adela Brassicaceae Resistance Tolerance Compensation Density-dependence Plant defenses Belowground–aboveground Insect herbivory Semiarid Transgenerational effects Supplementary Materials: The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/plants12020283/s1. Supplementary material 1, Table S1: Model structure and fit of GLMMs and GAMMs. Supplementary material 2, Figure S1: Plots with absolute values for analyzed variables. Supplementary material 3, Table S2: SEM 1 stepwise selection procedure. Supplementary material 3, Table S3: SEM 1 standardized direct, indirect and total size effects. Supplementary material 3, Figure S2: Initially hypothesized SEM 1. Supplementary material 4, Table S4: SEM 2 stepwise selection procedure. Supplementary material 4, Table S5: SEM 2 standardized direct, indirect and total size effects. Supplementary material 4, Figure S3: Initially hypothesized SEM 2. Supplementary material 5, Figure S4: Relationship between FH caterpillar development time, glucosinolate concentrations and flower number. Supplementary material 6, Table S6: GLMM/GAMM results for the effect of RH and FH on insect herbivore abundance, pollinator visitation and FH caterpillar parasitism rate. Plants are attacked by multiple herbivores, and depend on a precise regulation of responses to cope with a wide range of antagonists. Simultaneous herbivory can occur in different plant compartments, which may pose a serious threat to plant growth and reproduction. In particular, plants often face co-occurring root and floral herbivory, but few studies have focused on such interactions. Here, we investigated in the field the combined density-dependent effects of rootchewing cebrionid beetle larvae and flower-chewing pierid caterpillars on the fitness and defense of a semiarid Brassicaceae herb. We found that the fitness impact of both herbivore groups was independent and density-dependent. Increasing root herbivore density non-significantly reduced plant fitness, while the relationship between increasing floral herbivore density and the reduction they caused in both seed number and seedling emergence was non-linear. The plant defensive response was non-additive with regard to the different densities of root and floral herbivores; high floral herbivore density provoked compensatory investment in reproduction, and this tolerance response was combined with aboveground chemical defense induction when also root herbivore density was high. Plants may thus prioritize specific trait combinations in response to varying combined belowand aboveground herbivore densities to minimize negative impacts on fitness. 2023-02-22T12:10:28Z 2023-02-22T12:10:28Z 2023-01-07 journal article Aguirrebengoa, M.; Müller, C.; Hambäck, P.A.; González-Megías, A. Density-Dependent Effects of Simultaneous Root and Floral Herbivory on Plant Fitness and Defense. Plants 2023, 12, 283. [https://doi.org/10.3390/plants12020283] https://hdl.handle.net/10481/80152 10.3390/plants12020283 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional MDPI