No release for the wicked: enemy release is dynamic and not associated with invasiveness

Schultheis, Elizabeth H.; Berardi, Andrea E.; Lau, Jennifer A.

doi:10.1890/14-2158.1

Cited by 71 publications

(64 citation statements)

References 77 publications

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“…Here exotic species did not escape herbivores (compare [31,71,72]). The concept of enemy release relies, among others, on two main criteria.…”

Section: Discussionmentioning

confidence: 99%

“…One would expect that when simultaneously manipulating the diversity of native and exotic trees, the exotic species would have lower susceptibility to herbivores ([29,30], but see [31]), independent of tree diversity, while native species will show either associational resistance or associational susceptibility. Surprisingly, to the best of our knowledge, this has never been tested with congeneric pairs of native and exotic species in a controlled experimental setting.…”

Section: Introductionmentioning

confidence: 99%

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Tree Species Richness Promotes Invertebrate Herbivory on Congeneric Native and Exotic Tree Saplings in a Young Diversity Experiment

et al. 2016

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Tree diversity in forests is an important driver of ecological processes including herbivory. Empirical evidence suggests both negative and positive effects of tree diversity on herbivory, which can be, respectively, attributed to associational resistance or associational susceptibility. Tree diversity experiments allow testing for associational effects, but evidence regarding which pattern predominates is mixed. Furthermore, it is unknown if herbivory on tree species of native vs. exotic origin is influenced by changing tree diversity in a similar way, or if exotic tree species escape natural enemies, resulting in lower damage that is unrelated to tree diversity. To address these questions, we established a young tree diversity experiment in temperate southwestern Germany that uses high planting density (49 trees per plot; plot size 13 m2). The species pool consists of six congeneric species pairs of European and North American origin (12 species in total) planted in monocultures and mixtures (1, 2, 4, 6 species). We assessed leaf damage by leaf-chewing insects on more than 5,000 saplings of six broadleaved tree species. Plot-level tree species richness increased leaf damage, which more than doubled from monocultures to six-species mixtures, strongly supporting associational susceptibility. However, leaf damage among congeneric native and exotic species pairs was similar. There were marked differences in patterns of leaf damage across tree genera, and only the genera likely having a predominately generalist herbivore community showed associational susceptibility, irrespective of the geographical origin of a tree species. In conclusion, an increase in tree species richness in young temperate forests may result in associational susceptibility to feeding by generalist herbivores.

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“…Here exotic species did not escape herbivores (compare [31,71,72]). The concept of enemy release relies, among others, on two main criteria.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tree Species Richness Promotes Invertebrate Herbivory on Congeneric Native and Exotic Tree Saplings in a Young Diversity Experiment

et al. 2016

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“…According to the new associations hypothesis, biotic resistance should be amplified by the lack of co‐evolutionary history between exotic plants and their new enemies (Hokkanen and Pimentel ). Most studies providing evidence for either of them, however, focused on the response of exotic species but ignored the comparison with native species (but see Dawson et al , Maron et al , Pearson et al , Schultheis et al ). Experiments comparing a large number of exotic and native species found in general no difference in their response to herbivores (Blaney and Kotanen , Agrawal and Kotanen , Maron et al , Preukschas et al ), which is in line with our findings.…”

Section: Discussionmentioning

confidence: 99%

Stronger effect of gastropods than rodents on seedling establishment, irrespective of exotic or native plant species origin

Korell

Stein

Hensen

et al. 2016

Oikos

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Experimental evidence about how generalist consumers aff ect exotic plant invasions is equivocal, but most tests have been limited to few plant species, single herbivore guilds, and single locations. Using a seed-addition experiment, we studied eff ects of gastropods and rodents on recruitment success of 37 exotic and 37 native plant species affi liated to three diff erent functional groups (i.e. grasses, legumes and non-legume herbs). We replicated our seed addition x herbivore exclusion experiment at multiple grassland sites, located within a few km of each other in two regions, coastal central California (USA) and southern Saxony -Anhalt (Germany). Th e two study regions diff ered in climate, land-use, invasion history and species pools which allowed us to disentangle general from context-specifi c eff ects. In both regions, herbivory by gastropods had a stronger impact on the proportion of recruited seedlings and the proportion of recruited species than rodent herbivory, but this eff ect was much more pronounced in California than in Germany. Especially, seedling recruitment of non-legume herbs and legumes suff ered from gastropod herbivory. Contrastingly, the eff ect of rodents was negative at the German sites and positive at the Californian sites, likely driven by context-specifi c diff erences in the rodent assemblages. Across both study regions, exotics had higher seedling recruitment than natives, indicating that higher recruitment success constitutes an inherent feature of exotic species. After two years, more exotic than native species established at grassland sites in California while the opposite was true for the German grassland sites. Consistently across regions, native and exotic species did, however, not diff er in their response to herbivory, suggesting that generalist consumers suppress recruitment and colonization of plant species irrespective of their origin. Our results demonstrate the importance of a multi-species, multi-site approach to separate general responses of exotic and native plants to generalist herbivory from local, regional or species-specifi c peculiarities.

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“…Some tests have confirmed it only partially [25][26][27], have proved negative (e.g., [28][29][30]), or have led to conclusions contradicting it [31][32][33]. A review of the results of ERH tests [34] indicated that for alien plant species the hypothesis was confirmed in about 57% of experimental studies.…”

Section: Introductionmentioning

confidence: 99%

Do local enemies attack alien and native Impatiens alike?

2017

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The enemy release hypothesis (ERH) attributes the invasive behavior of some alien species to decreased pressure from natural enemies, as they have been left behind in the hosts' native range. The majority of research supports this idea, but some studies confirm it only partially or even contradict it. Here, we present the results of ERH tests of three Impatiens species studied in southern Poland in 2010-2011. Two of them are alien and invasive in Europe (Impatiens glandulifera, I. parviflora) and one is native (I. noli-tangere). We compared the three species in terms of the percentage of all leaves showing symptoms of disease and/or damage, and also the number of pests recorded on the monitored plants.In 1071 individual plant controls, we assessed 17 180 leaves, 7552 of which showed symptoms of disease/damage, and we recorded 5721 invertebrates, 5220 of them were pests. Rusts and spots were the predominant symptoms and Aphidoidea were the dominant group of pests. Comparisons of the two alien and one native Impatiens did not confirm the ERH in 90% of the performed tests. Most of the differences between the species were not significant, and most of the significant ones contradicted the ERH. The only results confirming the ERH were found in comparisons between I. parviflora and I. noli-tangere. The tests between two alien species showed that I. parviflora was under higher pest pressure, while I. glandulifera had more disease and damage symptoms, thus, plant-enemy relations differed between the two balsams. In summary, the presented results add evidence that the success of some alien species may depend on factors related to biotic and/or abiotic conditions in ways that are not explained by the enemy release hypothesis.

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No release for the wicked: enemy release is dynamic and not associated with invasiveness

Cited by 71 publications

References 77 publications

Tree Species Richness Promotes Invertebrate Herbivory on Congeneric Native and Exotic Tree Saplings in a Young Diversity Experiment

Tree Species Richness Promotes Invertebrate Herbivory on Congeneric Native and Exotic Tree Saplings in a Young Diversity Experiment

Stronger effect of gastropods than rodents on seedling establishment, irrespective of exotic or native plant species origin

Do local enemies attack alien and native Impatiens alike?

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