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1
Montti, Lía, María Marta Ayup, Roxana Aragón, Weilong Qi, Honghua Ruan, Romina Fernández, Sergio A. Casertano et Xiaoming Zou. « Herbivory and the success of Ligustrum lucidum : evidence from a comparison between native and novel ranges ». Australian Journal of Botany 64, no 3 (2016) : 181. http://dx.doi.org/10.1071/bt15232.
Texte intégralRésumé :
Invasive plant species may benefit from a reduction in herbivory in their introduced range. The reduced herbivory may cause a reallocation of resources from defence to fitness. Here, we evaluated leaf herbivory of an invasive tree species (Ligustrum lucidum Aiton) in its native and novel ranges, and determined the potential changes in leaf traits that may be associated with the patterns of herbivory. We measured forest structure, damage by herbivores and leaf traits in novel and native ranges, and on the basis of the literature, we identified the common natural herbivores of L. lucidum. We also performed an experiment offering leaves from both ranges to a generalist herbivore (Spodoptera frugiperda). L. lucidum was more abundant and experienced significantly less foliar damage in the novel than in the native range, in spite of the occurrence of several natural herbivores. The reduced lignin content and lower lignin : N ratio in novel leaves, together with the higher herbivore preference for leaves of this origin in the laboratory experiment, indicated lower herbivore resistance in novel than in native populations. The reduced damage by herbivores is not the only factor explaining invasion success, but it may be an important cause that enhances the invasiveness of L. lucidum.
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Johnson, Scott N., Olivia L. Reynolds, Geoff M. Gurr, Jessica L. Esveld, Ben D. Moore, Gavin J. Tory et Andrew N. Gherlenda. « When resistance is futile, tolerate instead : silicon promotes plant compensatory growth when attacked by above- and belowground herbivores ». Biology Letters 15, no 7 (juillet 2019) : 20190361. http://dx.doi.org/10.1098/rsbl.2019.0361.
Texte intégralRésumé :
Plants have evolved numerous herbivore defences that are resistance- or tolerance-based. Resistance involves physical and chemical traits that deter and/or harm herbivores whereas tolerance minimizes fitness costs of herbivory, often via compensatory growth. The Poaceae frequently accumulate large amounts of silicon (Si), which can be used for herbivore resistance, including biomechanical and (indirectly) biochemical defences. To date, it is unclear whether Si improves tolerance of herbivory. Here we report how Si enabled a cereal ( Triticum aestivum ) to tolerate damage inflicted by above- and belowground herbivores. Leaf herbivory increased Si concentrations in the leaves by greater than 50% relative to herbivore-free plants, indicating it was an inducible defensive response. In plants without Si supplementation, leaf herbivory reduced shoot biomass by 52% and root herbivory reduced root biomass by 68%. Si supplementation, however, facilitated compensatory growth such that shoot losses were more than compensated for (+14% greater than herbivore-free plants) and root losses were minimized to −16%. Si supplementation did not improve plant resistance since Si did not enhance biomechanical resistance (i.e. force of fracture) or reduce leaf consumption and herbivore relative growth rates. We propose that Si-based defence operates in wheat via tolerance either in addition or as an alternative to resistance-based defence.
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Beaumont, Kieren P., Duncan A. Mackay et Molly A. Whalen. « Ant defence of a dioecious shrub, Adriana quadripartita (Euphorbiaceae), with extrafloral nectaries ». Australian Journal of Botany 64, no 6 (2016) : 539. http://dx.doi.org/10.1071/bt16034.
Texte intégralRésumé :
Extrafloral nectaries (EFNs) can function to indirectly reduce herbivory by attracting ants that interfere with or predate on herbivorous insects. So as to examine the efficacy of ants as defenders of plants with extrafloral nectaries (EFNs) against herbivores, an ant-exclusion experiment was conducted on plants of the dioecious species Adriana quadripartita (Euphorbiaceae). The experiment was conducted on Torrens Island, South Australia, and adds to previous work that examined the associations among adrianas, ants and invertebrate herbivores at several locations across Australia. The aim of the present study was to investigate whether ants that tend EFNs reduce herbivore numbers and levels of herbivory, and whether this ant–plant–herbivore interaction differs between male and female A. quadripartita plants. The abundances of ants and invertebrate herbivores were overall greater on male than on female plants. The exclusion of ants from branches resulted in an increase in herbivore abundance on male and female plants; however, ant exclusion resulted in an increase of foliar damage on male plants only. Whereas previous research on A. tomentosa shows that ants can decrease herbivore abundance, the results here provide the first evidence that EFNs on adrianas can function to decrease foliar herbivory.
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Barrio, Isabel C., David S. Hik, Kristen Peck et C. Guillermo Bueno. « After the frass : foraging pikas select patches previously grazed by caterpillars ». Biology Letters 9, no 3 (23 juin 2013) : 20130090. http://dx.doi.org/10.1098/rsbl.2013.0090.
Texte intégralRésumé :
Interactions among herbivores can shape the structure of their communities and drive their dynamics. However, detecting herbivore interactions can be challenging when they are deferred in space or time. Moreover, interactions among distantly related groups of herbivores, such as vertebrates and invertebrates, are poorly understood. We investigated the effect of invertebrate herbivory on the subsequent foraging choices of a small alpine-dwelling vertebrate, the collared pika ( Ochotona collaris ). We carried out a field experiment within pika territories, by presenting them with a choice of foraging sites following manipulation of invertebrate (caterpillar) herbivory. Pikas actively selected areas with increased, recent invertebrate herbivory. While the underlying mechanisms behind this interaction remain unknown, our results demonstrate a positive effect of invertebrate herbivores on subsequent vertebrate foraging preferences for the first time. Even among distantly related taxa, such interactions where one herbivore is cueing on the foraging of another, could drive the creation of herbivory hotspots, with cascading consequences for ecosystem processes.
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Liu, Xiaoyu, Carri J. LeRoy, Guobing Wang, Yuan Guo, Shuwang Song, Zhipei Wang, Jingfang Wu et al. « Leaf defenses of subtropical deciduous and evergreen trees to varying intensities of herbivory ». PeerJ 11 (7 novembre 2023) : e16350. http://dx.doi.org/10.7717/peerj.16350.
Texte intégralRésumé :
Generally, deciduous and evergreen trees coexist in subtropical forests, and both types of leaves are attacked by numerous insect herbivores. However, trees respond and defend themselves from herbivores in different ways, and these responses may vary between evergreen and deciduous species. We examined both the percentage of leaf area removed by herbivores as well as the percentage of leaves attacked by herbivores to evaluate leaf herbivore damage across 14 subtropical deciduous and evergreen tree species, and quantified plant defenses to varying intensities of herbivory. We found that there was no significant difference in mean percentage of leaf area removed between deciduous and evergreen species, yet a higher mean percentage of deciduous leaves were damaged compared to evergreen leaves (73.7% versus 60.2%). Although percent leaf area removed was mainly influenced by hemicellulose concentrations, there was some evidence that the ratio of non-structural carbohydrates:lignin and the concentration of tannins contribute to herbivory. We also highlight that leaf defenses to varying intensities of herbivory varied greatly among subtropical plant species and there was a stronger response for deciduous trees to leaf herbivore (e.g., increased nitrogen or lignin) attack than that of evergreen trees. This work elucidates how leaves respond to varying intensities of herbivory, and explores some of the underlying relationships between leaf traits and herbivore attack in subtropical forests.
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Barnes, A. D., C. Scherber, U. Brose, E. T. Borer, A. Ebeling, B. Gauzens, D. P. Giling et al. « Biodiversity enhances the multitrophic control of arthropod herbivory ». Science Advances 6, no 45 (novembre 2020) : eabb6603. http://dx.doi.org/10.1126/sciadv.abb6603.
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Arthropod herbivores cause substantial economic costs that drive an increasing need to develop environmentally sustainable approaches to herbivore control. Increasing plant diversity is expected to limit herbivory by altering plant-herbivore and predator-herbivore interactions, but the simultaneous influence of these interactions on herbivore impacts remains unexplored. We compiled 487 arthropod food webs in two long-running grassland biodiversity experiments in Europe and North America to investigate whether and how increasing plant diversity can reduce the impacts of herbivores on plants. We show that plants lose just under half as much energy to arthropod herbivores when in high-diversity mixtures versus monocultures and reveal that plant diversity decreases effects of herbivores on plants by simultaneously benefiting predators and reducing average herbivore food quality. These findings demonstrate that conserving plant diversity is crucial for maintaining interactions in food webs that provide natural control of herbivore pests.
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Brocklehurst, Neil, Christian F. Kammerer et Roger J. Benson. « The origin of tetrapod herbivory : effects on local plant diversity ». Proceedings of the Royal Society B : Biological Sciences 287, no 1928 (10 juin 2020) : 20200124. http://dx.doi.org/10.1098/rspb.2020.0124.
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The origin of herbivory in the Carboniferous was a landmark event in the evolution of terrestrial ecosystems, increasing ecological diversity in animals but also giving them greater influence on the evolution of land plants. We evaluate the effect of early vertebrate herbivory on plant evolution by comparing local species richness of plant palaeofloras with that of vertebrate herbivores and herbivore body size. Vertebrate herbivores became diverse and achieved a much greater range of body sizes across the Carboniferous–Permian transition interval. This coincides with an abrupt reduction in local plant richness that persists throughout the Permian. Time-series regression analysis supports a negative relationship of plant richness with herbivore richness but a positive relationship of plant richness with minimum herbivore body size. This is consistent with studies of present-day ecosystems in which increased diversity of smaller, more selective herbivores places greater predation pressures on plants, while a prevalence of larger bodied, less selective herbivores reduces the dominance of a few highly tolerant plant species, thereby promoting greater local richness. The diversification of herbivores across the Carboniferous–Permian boundary, along with the appearance of smaller, more selective herbivores like bolosaurid parareptiles, constrained plant diversity throughout the Permian. These findings demonstrate that the establishment of widespread vertebrate herbivory has structured plant communities since the late Palaeozoic, as expected from examination of modern ecosystems, and illustrates the potential for fossil datasets in testing palaeoecological hypotheses.
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Potter, Arjun B., Muhammad Ali Imron, Satyawan Pudyatmoko et Matthew C. Hutchinson. « Short-term plant-community responses to large mammalian herbivore exclusion in a rewilded Javan savanna ». PLOS ONE 16, no 7 (22 juillet 2021) : e0255056. http://dx.doi.org/10.1371/journal.pone.0255056.
Texte intégralRésumé :
Grassy biomes such as savannas are maintained by an interacting suite of ecosystem processes from herbivory to rainfall to fire. Many studies have examined the impacts of large mammalian herbivores on herbaceous plant communities, but few of these studies have been conducted in humid, fertile savannas. We present the findings of a short-term experiment that investigated the effects of herbivory in a fertile, humid, and semi-managed savanna. We erected large-herbivore exclosures in Alas Purwo National Park, Java, Indonesia where rainfall is high and fire is suppressed to test how herbivores impact plant community development across the growing season. Where large mammalian herbivores were excluded, herbaceous plant communities contained more non-grasses and were less similar; diverging in their composition as the growing season progressed. Effects of herbivore exclusion on plant species richness, evenness, and biomass per quadrat were generally weak. Notably, however, two weedy plant species (one native, Imperata cylindrica and one introduced, Senna cf. tora) appeared to benefit most from herbivore release. Our results suggest that heavy grazing pressure by native large mammalian herbivores controlled the composition of the herbaceous plant community. Moreover, exclusion of large mammalian herbivores led to divergence in the plant species composition of exclosures; compositional dissimilarity between herbivore-exclusion plots was higher than between plots exposed to large mammalian herbivores. Our findings suggest that, at this high-rainfall site, large mammalian herbivores constrained the developmental trajectory of plant communities across the growing season.
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Rusman, Quint, Peter N. Karssemeijer, Dani Lucas-Barbosa et Erik H. Poelman. « Settling on leaves or flowers : herbivore feeding site determines the outcome of indirect interactions between herbivores and pollinators ». Oecologia 191, no 4 (4 novembre 2019) : 887–96. http://dx.doi.org/10.1007/s00442-019-04539-1.
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Abstract Herbivore attack can alter plant interactions with pollinators, ranging from reduced to enhanced pollinator visitation. The direction and strength of effects of herbivory on pollinator visitation could be contingent on the type of plant tissue or organ attacked by herbivores, but this has seldom been tested experimentally. We investigated the effect of variation in feeding site of herbivorous insects on the visitation by insect pollinators on flowering Brassica nigra plants. We placed herbivores on either leaves or flowers, and recorded the responses of two pollinator species when visiting flowers. Our results show that variation in herbivore feeding site has profound impact on the outcome of herbivore–pollinator interactions. Herbivores feeding on flowers had consistent positive effects on pollinator visitation, whereas herbivores feeding on leaves did not. Herbivores themselves preferred to feed on flowers, and mostly performed best on flowers. We conclude that herbivore feeding site choice can profoundly affect herbivore–pollinator interactions and feeding site thereby makes for an important herbivore trait that can determine the linkage between antagonistic and mutualistic networks.
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Johnson, Scott N., Rhiannon C. Rowe et Casey R. Hall. « Silicon is an inducible and effective herbivore defence against Helicoverpa punctigera (Lepidoptera : Noctuidae) in soybean ». Bulletin of Entomological Research 110, no 3 (9 décembre 2019) : 417–22. http://dx.doi.org/10.1017/s0007485319000798.
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AbstractThe role of silicon (Si) in alleviating the effects of biotic and abiotic stresses, including defence against insect herbivores, in plants is widely reported. Si defence against insect herbivores is overwhelmingly studied in grasses (especially the cereals), many of which are hyper-accumulators of Si. Despite being neglected, legumes such as soybean (Glycine max) have the capacity to control Si accumulation and benefit from increased Si supply. We tested how Si supplementation via potassium, sodium or calcium silicate affected a soybean pest, the native budworm Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae). Herbivory reduced leaf biomass similarly in Si-supplemented (+Si) and non-supplemented (–Si) plants (c. 29 and 23%, respectively) relative to herbivore-free plants. Both Si supplementation and herbivory increased leaf Si concentrations. In relative terms, herbivores induced Si uptake by c. 19% in both +Si and –Si plants. All Si treatments reduced H. punctigera relative growth rates (RGR) to a similar extent for potassium (−41%), sodium (−49%) and calcium (−48%) silicate. Moreover, there was a strong negative correlation between Si accumulation in leaves and herbivore RGR. To our knowledge, this is only the second report of Si-based herbivore defence in soybean; the rapid increase in leaf Si following herbivory being indicative of an induced defence. Taken together with the other benefits of Si supplementation of legumes, Si could prove an effective herbivore defence in legumes as well as grasses.
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Haas, Stephanie M., et Christopher J. Lortie. « A systematic review of the direct and indirect effects of herbivory on plant reproduction mediated by pollination ». PeerJ 8 (8 juin 2020) : e9049. http://dx.doi.org/10.7717/peerj.9049.
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Background Plant reproduction is influenced by the net outcome of plant–herbivore and plant–pollinator interactions. While both herbivore impacts and pollinator impacts on plant reproduction have been widely studied, few studies examine them in concert. Methodology Here, we review the contemporary literature that examines the net outcomes of herbivory and pollination on plant reproduction and the impacts of herbivores on pollination through damage to shared host plants using systematic review tools. The direct or indirect effects of herbivores on floral tissue and reported mechanisms were compiled including the taxonomic breadth of herbivores, plants and pollinators. Results A total of 4,304 studies were examined producing 59 relevant studies for synthesis that reported both pollinator and herbivore measures. A total of 49% of studies examined the impact of direct damage to floral tissue through partial florivory while 36% of studies also examined the impact of vegetative damage on pollination through folivory, root herbivory, and stem damage. Only three studies examined the effects of both direct and indirect damage to pollination outcomes within the same study. Conclusions It is not unreasonable to assume that plants often sustain simultaneous forms of damage to different tissues and that the net effects can be assessed through differences in reproductive output. Further research that controls for other relative drivers of reproductive output but examines more than one pathway of damage simultaneously will inform our understanding of the mechanistic relevance of herbivore impacts on pollination and also highlight interactions between herbivores and pollinators through plants. It is clear that herbivory can impact plant fitness through pollination; however, the relative importance of direct and indirect damage to floral tissue on plant reproduction is still largely unknown.
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Neylan, Isabelle P., Rodolfo Dirzo et Mar Sobral. « Cumulative effects of transgenerational induction on plant palatability to generalist and specialist herbivores ». Web Ecology 18, no 1 (16 mars 2018) : 41–46. http://dx.doi.org/10.5194/we-18-41-2018.
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Abstract. Herbivore damage can induce anti-herbivore traits in plants. However, there is little data regarding how these induced traits affect a plant's palatability (an important factor in determining the likelihood and magnitude of herbivore damage) across multiple generations post-induction, or whether the effect of transgenerational induction differs between generalist and specialist herbivores. Here we used palatability as a measure of the effects of transgenerational defensive induction in wild radish plants. We conducted a greenhouse experiment to determine whether generalist (slugs) and specialist (caterpillars of the white cabbage butterfly) herbivores' preference for wild radish differed depending on the number of previous generations that experienced herbivory. We found lowered palatability in plants with two or three inductions in their past in the case of generalist slugs, while palatability to a specialist herbivore was not affected by transgenerational induction. We conclude that the history of herbivory experienced by a plant's ancestors over multiple generations may play an important role in its ability to defend itself against generalist herbivores, but not against the specialists with whom they have co-evolved. Our findings suggest that the effects that multiple past inductions may have on palatability down the family line can be expected to have ecological and evolutionary implications.
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Bakker, Elisabeth S., Jacquelyn L. Gill, Christopher N. Johnson, Frans W. M. Vera, Christopher J. Sandom, Gregory P. Asner et Jens-Christian Svenning. « Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation ». Proceedings of the National Academy of Sciences 113, no 4 (26 octobre 2015) : 847–55. http://dx.doi.org/10.1073/pnas.1502545112.
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Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World’s terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions.
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Turkington, Roy. « Top-down and bottom-up forces in mammalian herbivore – vegetation systems : an essay review ». Botany 87, no 8 (août 2009) : 723–39. http://dx.doi.org/10.1139/b09-035.
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For almost 50 years ecologists have debated why herbivores generally don’t increase in numbers to such levels as to deplete or devastate vegetation. One hypothesis is that herbivore populations are regulated at low densities by predators, and a second hypotheses is that plants are fundamentally poor food for herbivores. This has lead to two main hypotheses about the role of herbivores in structuring vegetation: the “bottom-up” and “top-down” hypotheses. Here I survey the literature, with a focus on field experiments designed to investigate the soil resource – vegetation – mammalian herbivore system, specifically asking five questions about how each trophic level responds to (i) resource addition, (ii) vegetation removal, (iii) herbivore removal or reduction, (iv) herbivore addition, and (v) the interaction of resource levels and herbivory? I use these to develop 12 testable predictions. I document the major areas of research as they relate to these 12 predictions, and use these to evaluate weaknesses and limitations in field methods. There are surprisingly few terrestrial studies that conduct factorial manipulations of multiple nutrients or herbivores, even though it is clear that these are essential. Specifically, I argue that a manipulative experimental approach is the most valuable way to advance our theory and understanding, and I advocate the continued use of long-term factorial field experiments that simultaneously manipulate soil resources levels and herbivory (preferably at multiple levels), repeated in a range of environments in which individual species or functional groups are monitored.
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Aguirrebengoa, Martin, Caroline Müller, Peter A. Hambäck et Adela González-Megías. « Density-Dependent Effects of Simultaneous Root and Floral Herbivory on Plant Fitness and Defense ». Plants 12, no 2 (7 janvier 2023) : 283. http://dx.doi.org/10.3390/plants12020283.
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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 root-chewing 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 below- and aboveground herbivore densities to minimize negative impacts on fitness.
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Wise, Michael J., et Erika L. Mudrak. « An experimental investigation of costs of tolerance against leaf and floral herbivory in the herbaceous weed horsenettle (Solanum carolinense, Solanaceae) ». Plant Ecology and Evolution 154, no 2 (24 juin 2021) : 161–72. http://dx.doi.org/10.5091/plecevo.2021.1805.
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Background and aims – A plant’s tolerance of herbivory depends on its ability to endure and compensate for damage so as to lessen the impact that herbivores have on the plant’s performance (e.g. its growth, reproduction, or fitness). While tolerance of herbivory is beneficial to plants, it is rarely complete, and individuals in plant populations tend to vary in their levels of tolerance. The goal of this study was to investigate potential costs associated with tolerance of leaf and floral herbivory in horsenettle (Solanum carolinense), a perennial herbaceous weed that is often subjected to high levels of damage from a diversity of herbivores. Material and methods – We exposed 96 potted individuals across eight genets of horsenettle to factorial treatments of leaf herbivory by lace bugs and simulated floral herbivory by weevils. We quantified tolerance for each plant genet for both types of herbivory in terms of the impact of damage on the number of flowers opened, number of seeds produced, and root biomass (i.e. paternal, maternal, and vegetative tolerance, respectively).Key results – Plant genets ranged widely in their ability to compensate for leaf and flower damage. While there was little evidence for tradeoffs in tolerance through the different routes, there was strong evidence of tradeoffs in genets’ abilities to tolerate herbivore damage to leaves and damage to flowers.Conclusion – Tolerance is a useful defence strategy to cope with damage caused by herbivores, but its evolution may be constrained by concomitant costs and tradeoffs. The evolutionary role of the tradeoffs identified in this study are likely to be greater the more species of herbivores a plant hosts, and the more that herbivore levels vary both spatially and temporally.
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Kozlov, Mikhail V., et Elena L. Zvereva. « Variations in the effects of local foliar damage on life span of individual leaves of downy birch (Betula pubescens) ». Botany 92, no 7 (juillet 2014) : 477–84. http://dx.doi.org/10.1139/cjb-2013-0324.
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Although the premature abscission of leaves damaged by herbivores has been discovered decades ago, the reduction in leaf life span caused by herbivory remains poorly documented, and the sources of variation in the magnitude of this effect have only rarely been studied. We aimed at exploring the effects of several herbivore species (at their background densities) and simulated herbivory on the leaf life span of downy birch, Betula pubescens Ehrh. Leaves damaged by herbivores abscised on average 12.6 days earlier and punched leaves 3.5 days earlier than the intact leaves of the control shoots. Different herbivores reduced the life span of the birch leaves from 0% to 27% depending on the intensity and timing of the damage but not on the insect feeding guild. The reduction in leaf life span was greater when the damage was imposed on expanding and growing leaves compared with mature leaves. However, the effect of herbivore species remained significant after accounting for intensity and timing of damage. This fact, together with greater reduction in leaf life span due to natural herbivory compared with mechanical damage, indicates that premature abscission in response to injury is considerably enhanced by insect-specific elicitors.
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Taylor, Benton N., et Laura R. Ostrowsky. « Nitrogen-fixing and non-fixing trees differ in leaf chemistry and defence but not herbivory in a lowland Costa Rican rain forest ». Journal of Tropical Ecology 35, no 6 (27 août 2019) : 270–79. http://dx.doi.org/10.1017/s0266467419000233.
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AbstractNitrogen-fixing plants provide critical nitrogen inputs that support the high productivity of tropical forests, but our understanding of the ecology of nitrogen fixers – and especially their interactions with herbivores – remains incomplete. Herbivores may interact differently with nitrogen fixers vs. non-fixers due to differences in leaf nitrogen content and herbivore defence strategies. To examine these potential differences, our study compared leaf carbon, nitrogen, toughness, chemical defence and herbivory for four nitrogen-fixing tree species (Inga oerstediana, Inga sapindoides, Inga thibaudiana and Pentaclethra macroloba) and three non-fixing species (Anaxagorea crassipetala, Casearia arborea and Dipteryx panamensis) in a lowland tropical rain forest. Leaf chemical defence, not nutritional content, was the primary driver of herbivore damage among our species. Even though nitrogen fixers exhibited 21.1% higher leaf nitrogen content, 20.1% lower C:N ratios and 15.4% lower leaf toughness than non-fixers, we found no differences in herbivory or chemical defence between these two plant groups. Our results do not support the common hypotheses that nitrogen fixers experience preferential herbivory or that they produce more nitrogen-rich defensive compounds than non-fixers. Rather, these findings suggest strong species-specific differences in plant–herbivore relationships among both nitrogen-fixing and non-fixing tropical trees.
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de Bobadilla, Maite Fernández, Roel Van Wiechen, Gerrit Gort et Erik H. Poelman. « Plasticity in induced resistance to sequential attack by multiple herbivores in Brassica nigra ». Oecologia 198, no 1 (13 octobre 2021) : 11–20. http://dx.doi.org/10.1007/s00442-021-05043-1.
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AbstractIn nature, plants interact with multiple insect herbivores that may arrive simultaneously or sequentially. There is extensive knowledge on how plants defend themselves against single or dual attack. However, we lack information on how plants defend against the attack of multiple herbivores that arrive sequentially. In this study, we investigated whether Brassica nigra L. plants are able to defend themselves against caterpillars of the late-arriving herbivore Plutella xylostella L., when plants had been previously exposed to sequential attack by four other herbivores (P. xylostella, Athalia rosae, Myzus persicae and Brevicoryne brassicae). We manipulated the order of arrival and the history of attack by four herbivores to investigate which patterns in sequential herbivory determine resistance against the fifth attacker. We recorded that history of sequential herbivore attack differentially affected the capability of B. nigra plants to defend themselves against caterpillars of P. xylostella. Caterpillars gained less weight on plants attacked by a sequence of four episodes of attack by P. xylostella compared to performance on plants that were not previously damaged by herbivores. The number of times the plant was attacked by herbivores of the same feeding guild, the identity of the first attacker, the identity and the guild of the last attacker as well as the order of attackers within the sequence of multiple herbivores influenced the growth of the subsequent herbivory. In conclusion, this study shows that history of sequential attack is an important factor determining plant resistance to herbivores.
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Fellaouine, R., et Alain Louveaux. « Herbivorie/omnivorie chez Praephippigera pachygaster Lucas, 1849 (Orthoptera, Tettigoniidae), dans l'est algérien ». Ecologia mediterranea 19, no 3 (1993) : 9–18. http://dx.doi.org/10.3406/ecmed.1993.1717.
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Wise, Michael J. « Why fitness impacts of different herbivores may combine nonadditively, and why it matters to the ecology and evolution of plant-herbivore communities ». Plant Ecology and Evolution 156, no 1 (8 février 2023) : 13–28. http://dx.doi.org/10.5091/plecevo.95982.
Texte intégralRésumé :
Background and aims – The manner by which the effects of multiple antagonists combine is a fundamental issue in ecology. This issue has been especially important in plant-herbivore evolutionary ecology—particularly predicting whether the combined fitness impacts of multiple herbivores on a shared host plant can be inferred by simply adding the individual impacts that each herbivore has when feeding alone. Despite accumulating empirical data, relatively little theoretical progress has been made in explaining why impacts of herbivore damage often combine nonadditively, as well as predicting the conditions that lead to a greater-than-additive (synergistic) or to a less-than-additive (subadditive) pattern. Material and methods – Based on considerations of limiting resources and source-sink relationships, I proposed and tested two hypotheses: 1) The fitness impacts of two species of herbivores that affect the same resource (i.e. feed on the same tissue in a similar fashion) will combine in a synergistic pattern (if that resource is not limiting reproduction when plants do not experience herbivory), and 2) The fitness impacts of two herbivores that affect different resources (i.e. feed on different tissues) will combine in a subadditive pattern. I performed a field experiment in which horsenettle (Solanum carolinense) was exposed to a factorial combination of four levels of leaf herbivory and five levels of simulated floral herbivory. Key results – The results were consistent with both hypotheses: 1) The combined fitness impact of flower damage that was simulated as being caused by two florivorous species feeding on the same plants was greater than the sum of the same total amount of damage when the two species were simulated as feeding individually; and 2) The combined fitness impact of the leaf and floral damage was less than the sum of the same total amount of damage when the two species fed individually. Conclusions – The main ecoevolutionary implication of these results is that subadditive impacts of leaf- and flower-feeding herbivores could weaken selection for resistance in horsenettle (or any plant species that hosts multiple herbivores), and thus subadditive impacts may contribute to the maintenance of diverse herbivore communities sharing a species of host plant.
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Silva, Maiara Matilde, João Carlos Ferreira Melo Júnior et Maria Regina Torres Boeger. « Plasticidade fenotípica foliar em Varronia curassavica Jacq. (Boraginaceae) em resposta à herbivoria simulada ». Revista Brasileira de Geografia Física 16, no 4 (25 juillet 2023) : 1989–2002. http://dx.doi.org/10.26848/rbgf.v16.4.p1989-2002.
Texte intégralRésumé :
O processo pelo qual as plantas ajustam seu fenótipo frente às condições abióticas as quais estão submetidas é denominado de plasticidade fenotípica. Na interação planta-herbívoro, pode ocorrer modificações no fenótipo defensivo em resposta ao dano por herbívoros. Embora tal resposta seja amplamente documentada, o efeito de repetidos eventos de herbivoria em diferentes graus ainda é um conhecimento incipiente. Neste estudo, avaliamos se as respostas fenotípicas das defesas são proporcionais à intensidade de dano e se a ausência da herbivoria leva ao relaxamento das defesas. Na espécie arbustiva Varronia curassavica, em ambiente natural, aplicamos um experimento de desfolhação, utilizando os seguintes tratamentos: T1: 40% de dano, T2: 80% de dano, TE: plantas isoladas dos herbívoros e controle (C). Os tratamentos de desfolhação foram aplicados três vezes com intervalo de três meses entre eles. Atributos químicos e físicos de defesa e a qualidade nutricional foram mensurados e a porcentagem de folhas danificadas por mastigadores após o experimento quantificada. Os fenótipos dos indivíduos sob herbivoria simulada diferiram do controle. O índice de plasticidade fenotípica mostrou que área foliar, concentração de taninos, conteúdo de água e concentração de nitrogênio foram os atributos mais plásticos. A análise de componentes principais indicou que os tratamentos T1 e T2 foram similares entre si em relação à área foliar e conteúdo de água e dissimilares do C e do TE. Varronia curassavica apresentou distintas estratégias de resposta à herbivoria, as quais são multidimensionais e influenciadas pela intensidade do dano.Palavras-chave: defesa induzida, defesas anti-hebivoria, potencial plástico, restinga, síndromes de defesas Leaf phenotypic plasticity in Varronia curassavica Jacq. (Boraginaceae) in response to simulated herbivory A B S T R A C TThe process by which plants adjust their phenotype to the abiotic conditions to which they are subjected is called phenotypic plasticity. In the plant-herbivore interaction, modifications in defensive phenotype can occur in response to herbivore damage. Although such response is widely documented, the effect of repeated herbivory events in different degrees is still an incipient knowledge. In this study, we evaluated whether phenotypic responses of defenses are proportional to damage intensity and whether the absence of herbivory leads to relaxation of defenses. On the shrub species Varronia curassavica in the natural environment, we applied a defoliation experiment using the following treatments: T1: 40% damage, T2: 80% damage, TE: plants isolated from herbivores and control (C). The defoliation treatments were applied three times with a three-month interval between them. Chemical and physical defense attributes and nutritional quality were measured and the percentage of leaves damaged by chewers after the experiment quantified. The phenotypes of individuals under simulated herbivory differed from the control. The phenotypic plasticity index showed that leaf area, tannin concentration, water content, and nitrogen concentration were the most plastic attributes. Principal component analysis indicated that treatments T1 and T2 were similar to each other with respect to leaf area and water content and dissimilar from C and TE. Varronia curassavica showed distinct herbivory response strategies, which are multidimensional and influenced by damage intensity.Keywords: induced defense, anti-hebivory defenses, plastic potential, sandbank, defense syndromes
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SCHMIDT, GEROLD, et GERHARD ZOTZ. « Herbivory in the epiphyte, Vriesea sanguinolenta Cogn. & ; Marchal (Bromeliaceae) ». Journal of Tropical Ecology 16, no 6 (novembre 2000) : 829–39. http://dx.doi.org/10.1017/s0266467400001747.
Texte intégralRésumé :
Although herbivory in ground-rooted flora is well documented, current knowledge of the herbivore pressure on vascular epiphytes remains mostly anecdotal. Here, we present the results of a 3-year study on the herbivory in a population of the epiphytic bromeliad Vriesea sanguinolenta. In different years, 26–61% of all epiphytes showed traces of herbivore attack, while up to 4.4% of the entire leaf area of the epiphyte population was consumed annually. The recorded levels of damage to photosynthetic tissue, mostly caused by the larvae of Napaea eucharilla (Riodinidae, Lepidoptera), indicate that vascular epiphytes may be regularly and sometimes even lethally attacked by insect herbivores. The level of damage is comparable to ground-rooted tropical flora, which certainly does not support the prevalent notion of low and negligible levels of herbivory in vascular epiphytes.
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Thompson, K. A., D. M. Sora, K. S. Cross, J. M. St. Germain et K. Cottenie. « Mucilage reduces leaf herbivory in Schreber’s watershield, Brasenia schreberi J.F. Gmel. (Cabombaceae) ». Botany 92, no 5 (mai 2014) : 412–16. http://dx.doi.org/10.1139/cjb-2013-0296.
Texte intégralRésumé :
Insect herbivores negatively affect plants by consuming biomass that could otherwise be used for growth or reproduction. To reduce their impact, plants have evolved a wide range of antiherbivore defenses. Schreber’s watershield (Brasenia schreberi J.F. Gmel.; Cabombaceae) is a freshwater, aquatic plant that produces a thick mucilage on the underside of leaves and all underwater organs. The mucilage has been proposed as a mechanism of defense against herbivory, but this hypothesis is untested. We conducted a comparative study to determine whether the quantity of mucilage on the underside of leaves is associated with herbivore damage on the leaves. We found that leaves with the thickest mucilage layer were the least damaged. To determine whether mucilage is directly responsible for defense against herbivores, we conducted a manipulative study where we removed the mucilage from the abaxial surface of leaves. We found that demucilated leaves experienced higher amounts of herbivore damage than leaves with their mucilage left intact. We conclude that the mucilage produced by B. schreberi functions to reduce herbivory on leaves, although its association with underwater herbivores and its specific antiherbivore properties remain unknown.
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Bont, Zoe, Marc Pfander, Christelle A. M. Robert, Meret Huber, Erik H. Poelman, Ciska E. Raaijmakers et Matthias Erb. « Adapted dandelions trade dispersal for germination upon root herbivore attack ». Proceedings of the Royal Society B : Biological Sciences 287, no 1921 (26 février 2020) : 20192930. http://dx.doi.org/10.1098/rspb.2019.2930.
Texte intégralRésumé :
A plant's offspring may escape unfavourable local conditions through seed dispersal. Whether plants use this strategy to escape insect herbivores is not well understood. Here, we explore how different dandelion ( Taraxacum officinale agg.) populations, including diploid outcrossers and triploid apomicts, modify seed dispersal in response to root herbivore attack by their main root-feeding natural enemy, the larvae of the common cockchafer Melolontha melolontha. In a manipulative field experiment, root herbivore attack increased seed dispersal potential through a reduction in seed weight in populations that evolved under high root herbivore pressure, but not in populations that evolved under low pressure. This increase in dispersal potential was independent of plant cytotype, but associated with a reduction in germination rate, suggesting that adapted dandelions trade dispersal for establishment upon attack by root herbivores. Analysis of vegetative growth parameters suggested that the increased dispersal capacity was not the result of stress flowering. In summary, these results suggest that root herbivory selects for an induced increase in dispersal ability in response to herbivore attack. Induced seed dispersal may be a strategy that allows adapted plants to escape from herbivores.
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Cherif, Mehdi, et Michel Loreau. « Plant–herbivore–decomposer stoichiometric mismatches and nutrient cycling in ecosystems ». Proceedings of the Royal Society B : Biological Sciences 280, no 1754 (7 mars 2013) : 20122453. http://dx.doi.org/10.1098/rspb.2012.2453.
Texte intégralRésumé :
Plant stoichiometry is thought to have a major influence on how herbivores affect nutrient availability in ecosystems. Most conceptual models predict that plants with high nutrient contents increase nutrient excretion by herbivores, in turn raising nutrient availability. To test this hypothesis, we built a stoichiometrically explicit model that includes a simple but thorough description of the processes of herbivory and decomposition. Our results challenge traditional views of herbivore impacts on nutrient availability in many ways. They show that the relationship between plant nutrient content and the impact of herbivores predicted by conceptual models holds only at high plant nutrient contents. At low plant nutrient contents, the impact of herbivores is mediated by the mineralization/immobilization of nutrients by decomposers and by the type of resource limiting the growth of decomposers. Both parameters are functions of the mismatch between plant and decomposer stoichiometries. Our work provides new predictions about the impacts of herbivores on ecosystem fertility that depend on critical interactions between plant, herbivore and decomposer stoichiometries in ecosystems.
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Frederickson, Megan E., et Deborah M. Gordon. « The devil to pay : a cost of mutualism with Myrmelachista schumanni ants in ‘devil's gardens’ is increased herbivory on Duroia hirsuta trees ». Proceedings of the Royal Society B : Biological Sciences 274, no 1613 (13 février 2007) : 1117–23. http://dx.doi.org/10.1098/rspb.2006.0415.
Texte intégralRésumé :
‘Devil's gardens’ are nearly pure stands of the myrmecophyte, Duroia hirsuta , that occur in Amazonian rainforests. Devil's gardens are created by Myrmelachista schumanni ants, which nest in D. hirsuta trees and kill other plants using formic acid as an herbicide. Here, we show that this ant–plant mutualism has an associated cost; by making devil's gardens, M. schumanni increases herbivory on D. hirsuta. We measured standing leaf herbivory on D. hirsuta trees and found that they sustain higher herbivory inside than outside devil's gardens. We also measured the rate of herbivory on nursery-grown D. hirsuta saplings planted inside and outside devil's gardens in ant-exclusion and control treatments. We found that when we excluded ants, herbivory on D. hirsuta was higher inside than outside devil's gardens. These results suggest that devil's gardens are a concentrated resource for herbivores. Myrmelachista schumanni workers defend D. hirsuta against herbivores, but do not fully counterbalance the high herbivore pressure in devil's gardens. We suggest that high herbivory may limit the spread of devil's gardens, possibly explaining why devil's gardens do not overrun Amazonian rainforests.
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Bebber, Dan, Nick Brown et Martin Speight. « Drought and root herbivory in understorey Parashorea Kurz (Dipterocarpaceae) seedlings in Borneo ». Journal of Tropical Ecology 18, no 5 (21 août 2002) : 795–804. http://dx.doi.org/10.1017/s0266467402002511.
Texte intégralRésumé :
The influence of herbivory on dipterocarp seedling growth and survival in Bornean primary lowland forest understorey during and after the 1997–8 El Niño-Southern Oscillation was investigated. During the drought, a coleopteran (Scolytidae) root borer attacked dipterocarp seedlings, primarily of the genus Parashorea. Infestation was spatially heterogeneous on a large (c. 100 m) scale. Attack rate decreased with plant vigour within infested areas. Experiments showed that root damage was fatal under drought conditions, but not after rain. Defoliation and apical meristem removal did not increase mortality. The spatio-temporal heterogeneity of herbivore outbreaks and difficulties involved in experimenting with root herbivores limit the power of such short-term investigations. However, the study shows that herbivores can cause differential mortality between species, and can therefore influence dipterocarp regeneration dynamics. The effect of herbivory depends on the plant organ attacked and interactions with other stresses such as drought. El Niño-related droughts are increasing in frequency in South-East Asian rain forests, which may lead to increased numbers of herbivore outbreaks and greater seedling mortality due to these factors.
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Robinson, M. L., P. G. Hahn, B. D. Inouye, N. Underwood, S. R. Whitehead, K. C. Abbott, E. M. Bruna et al. « Plant size, latitude, and phylogeny explain within-population variability in herbivory ». Science 382, no 6671 (10 novembre 2023) : 679–83. http://dx.doi.org/10.1126/science.adh8830.
Texte intégralRésumé :
Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sparse data. We collected standardized surveys of herbivory for 503 plant species at 790 sites across 116° of latitude. With these data, we show that within-population variability in herbivory increases with latitude, decreases with plant size, and is phylogenetically structured. Differences in the magnitude of variability are thus central to how plant-herbivore biology varies across macroscale gradients. We argue that increased focus on interaction variability will advance understanding of patterns of life on Earth.
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Kliebenstein, Daniel, Deana Pedersen, Bridget Barker et Thomas Mitchell-Olds. « Comparative Analysis of Quantitative Trait Loci Controlling Glucosinolates, Myrosinase and Insect Resistance in Arabidopsis thaliana ». Genetics 161, no 1 (1 mai 2002) : 325–32. http://dx.doi.org/10.1093/genetics/161.1.325.
Texte intégralRésumé :
Abstract Evolutionary interactions among insect herbivores and plant chemical defenses have generated systems where plant compounds have opposing fitness consequences for host plants, depending on attack by various insect herbivores. This interplay complicates understanding of fitness costs and benefits of plant chemical defenses. We are studying the role of the glucosinolate-myrosinase chemical defense system in protecting Arabidopsis thaliana from specialist and generalist insect herbivory. We used two Arabidopsis recombinant inbred populations in which we had previously mapped QTL controlling variation in the glucosinolate-myrosinase system. In this study we mapped QTL controlling resistance to specialist (Plutella xylostella) and generalist (Trichoplusia ni) herbivores. We identified a number of QTL that are specific to one herbivore or the other, as well as a single QTL that controls resistance to both insects. Comparison of QTL for herbivory, glucosinolates, and myrosinase showed that T. ni herbivory is strongly deterred by higher glucosinolate levels, faster breakdown rates, and specific chemical structures. In contrast, P. xylostella herbivory is uncorrelated with variation in the glucosinolate-myrosinase system. This agrees with evolutionary theory stating that specialist insects may overcome host plant chemical defenses, whereas generalists will be sensitive to these same defenses.
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Kanda, Yasukazu, Tomonori Shinya, Satoru Maeda, Kadis Mujiono, Yuko Hojo, Keisuke Tomita, Kazunori Okada, Takashi Kamakura, Ivan Galis et Masaki Mori. « BSR1, a Rice Receptor-like Cytoplasmic Kinase, Positively Regulates Defense Responses to Herbivory ». International Journal of Molecular Sciences 24, no 12 (20 juin 2023) : 10395. http://dx.doi.org/10.3390/ijms241210395.
Texte intégralRésumé :
Crops experience herbivory by arthropods and microbial infections. In the interaction between plants and chewing herbivores, lepidopteran larval oral secretions (OS) and plant-derived damage-associated molecular patterns (DAMPs) trigger plant defense responses. However, the mechanisms underlying anti-herbivore defense, especially in monocots, have not been elucidated. The receptor-like cytoplasmic kinase Broad-Spectrum Resistance 1 (BSR1) of Oryza sativa L. (rice) mediates cytoplasmic defense signaling in response to microbial pathogens and enhances disease resistance when overexpressed. Here, we investigated whether BSR1 contributes to anti-herbivore defense responses. BSR1 knockout suppressed rice responses triggered by OS from the chewing herbivore Mythimna loreyi Duponchel (Lepidoptera: Noctuidae) and peptidic DAMPs OsPeps, including the activation of genes required for biosynthesis of diterpenoid phytoalexins (DPs). BSR1-overexpressing rice plants exhibited hyperactivation of DP accumulation and ethylene signaling after treatment with simulated herbivory and acquired enhanced resistance to larval feeding. As the biological significance of herbivory-induced accumulation of rice DPs remains unexplained, their physiological activities in M. loreyi were analyzed. The addition of momilactone B, a rice DP, to the artificial diet suppressed the growth of M. loreyi larvae. Altogether, this study revealed that BSR1 and herbivory-induced rice DPs are involved in the defense against chewing insects, in addition to pathogens.
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Reader, R. J., et S. P. Bonser. « Predicting the combined effect of herbivory and competition on a plant's shoot mass ». Canadian Journal of Botany 76, no 2 (1 février 1998) : 316–20. http://dx.doi.org/10.1139/b97-182.
Texte intégralRésumé :
This study tested whether the shoot mass of a plant growing with both herbivores and neighbours present could be predicted using results of a herbivore-exclusion and neighbour-removal experiment. Since herbivory and competition from neighbours reduce shoot mass in different ways (i.e., tissue loss versus reduction in resource availability), we predicted that the shoot mass of a plant growing with both herbivores and neighbours present should equal the product of three terms; namely, the shoot mass of a plant growing without herbivores or neighbours present, the fraction to which herbivores alone reduced this shoot mass in the herbivore-exclusion treatment, and the fraction to which neighbours alone reduced this shoot mass in the neighbour-removal treatment. We tested this prediction for six herbaceous species, each growing in a different habitat. Values of shoot mass predicted for plants growing with herbivores and neighbours present did not differ significantly (P = 0.05) from actual values of shoot mass measured for the six species. Based on this result, we conclude that combined effect of herbivores and neighbours on shoot mass can be predicted accurately by simply multiplying the individual effects of these two factors, since herbivores and neighbours often have independent, complementary effects on shoot mass.Key words: plant growth, interactive effects, predators, neighbour effects.
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Botzat, Alexandra, Lena Fischer et Nina Farwig. « Forest-fragment quality rather than matrix habitat shapes herbivory on tree recruits in South Africa ». Journal of Tropical Ecology 29, no 2 (mars 2013) : 111–22. http://dx.doi.org/10.1017/s0266467413000102.
Texte intégralRésumé :
Abstract:Forest fragmentation can alter herbivory on tree recruits with possible consequences for regeneration. We assessed effects of forest-fragment quality (tree diversity, vegetation complexity, relative abundance of pioneer trees) and matrix habitat on arthropods and herbivory in KwaZulu-Natal, South Africa. We compared arthropod abundances and herbivory on woody seedlings and saplings among four forest-fragment types differing in size and matrix (large fragments and small fragments surrounded by natural grassland, eucalypt and sugarcane plantations; nplots = 24) using analyses of covariance. We recorded 3385 arthropods and inspected 897 seedlings (71 species) and 876 saplings (91 species). Relative abundance of predators increased with fragment quality; that of herbivores decreased. Herbivory responses to fragment quality varied: seedling herbivory decreased with relative abundance of pioneers and sapling herbivory increased with vegetation complexity. Matrix effects were low with little variation in relative abundance of predators (0.39–0.53) and herbivores (0.22–0.32), proportion of seedling (8.3–11.0%) and sapling herbivory (12.4–14.3%) among the forest-fragment types. These findings indicate that herbivory on tree recruits is mediated by forest-fragment quality rather than matrix habitat. Future studies should evaluate whether contrasting effects of fragment quality on arthropods and herbivory are caused by weak trophic interactions and variable herbivore compositions.
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Tsunoda, Tomonori, Naoki Kachi et Jun-Ichirou Suzuki. « Effects of the vertical distribution of a root-feeding insect (Anomala cuprea) on the yield, mortality, and size structure of Lolium perenne populations at different plant densities ». Botany 95, no 1 (janvier 2017) : 37–44. http://dx.doi.org/10.1139/cjb-2016-0105.
Texte intégralRésumé :
The vertical distribution of belowground herbivores plays an important role in determining the performance of an individual plant, but we still do not know the effects of this distribution on plant populations. A grass (Lolium perenne L.) was, therefore, grown at two densities with three vertical distributions of the belowground herbivore Anomala cuprea Hope (Coleoptera: Scarabaeidae). The population yield decreased significantly in the treatments with a herbivore, and decreased most when the herbivore was in the top feeding zone (i.e., the shallowest soil). Plants only died when the herbivore was in the top zone or was free to move within the pot. At low plant density, the biomass of the three largest shoots decreased significantly in the presence of a herbivore, but that of shoots in the fourth and smaller ranks did not. At high plant density, shoot biomass was not significantly affected by herbivory, irrespective of plant size. The standard deviation of shoot size was larger at low densities than at high densities. At low, but not high plant densities, the standard deviation decreased when herbivory occurred in the shallowest soil layer. To our knowledge, this study is the first to demonstrate that the vertical distribution of a belowground herbivore can markedly affect the size dynamics of a plant population.
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Chinarelli, Henrique D., Anselmo Nogueira et Laura C. Leal. « Extrafloral nectar production induced by simulated herbivory does not improve ant bodyguard attendance and ultimately plant defence ». Biological Journal of the Linnean Society 135, no 3 (29 décembre 2021) : 429–46. http://dx.doi.org/10.1093/biolinnean/blab159.
Texte intégralRésumé :
Abstract Highly competitive and aggressive ant species are efficient bodyguards that monopolize the more attractive plants bearing extrafloral nectaries. Given that herbivory often increases the quality of extrafloral nectar, we hypothesized that plants damaged by herbivory would be more prone to interact with high-quality ant bodyguards and be better defended against herbivores. We performed an experiment with Chamaecrista nictitans plants. We induced anti-herbivore responses by applying jasmonic acid to a group of plants while keeping another group unmanaged. We measured extrafloral nectar production, censused ants visiting extrafloral nectaries and, subsequently, added herbivore mimics to measure the efficiency of ant anti-herbivore defence in both conditions. Induction increased the volume of extrafloral nectar and the mass of sugar per nectary without affecting the sugar concentration or the patterns of plant attendance and defence by ants. Thus, we found no evidence that defence-induced C. nictitans plants are more prone to interact with high-quality bodyguards or to receive better anti-herbivore defence. These findings highlight that increases in extrafloral nectar production are not always rewarded with increases in the biotic defences; instead, these rewards might be dependent on the traits of the nectar induced by herbivory events and/or on the ecological context in which the interaction is embedded. Consequently, herbivory might increase the costs of this induced biotic defence to plants bearing extrafloral nectaries when the induced defence does not increase the attractiveness of the plants to ants.
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Carlson, Jane E., et Kyle E. Harms. « The benefits of bathing buds : water calyces protect flowers from a microlepidopteran herbivore ». Biology Letters 3, no 4 (17 avril 2007) : 405–7. http://dx.doi.org/10.1098/rsbl.2007.0095.
Texte intégralRésumé :
Protective floral structures may evolve in response to the negative effects of floral herbivores. For example, water calyces—liquid-filled, cup-like structures resulting from the fusion of sepals—may reduce floral herbivory by submerging buds during their development. Our observations of a water-calyx plant, Chrysothemis friedrichsthaliana (Gesneriaceae), revealed that buds were frequently attacked by ovipositing moths (Alucitidae), whose larvae consumed anthers and stigmas before corollas opened. Almost 25% of per-plant flower production was destroyed by alucitid larvae over two seasons, far exceeding the losses to all other floral herbivores combined. Experimental manipulation of water levels in calyces showed that a liquid barrier over buds halved per-flower alucitid egg deposition and subsequent herbivory, relative to buds in calyces without water. Thus, C. friedrichsthaliana 's water calyx helps protect buds from a highly detrimental floral herbivore. Our findings support claims that sepal morphology is largely influenced by selection to reduce floral herbivory, and that these pressures can result in novel morphological adaptations.
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Fáveri, Sarita B., Heraldo L. Vasconcelos et Rodolfo Dirzo. « Effects of Amazonian forest fragmentation on the interaction between plants, insect herbivores, and their natural enemies ». Journal of Tropical Ecology 24, no 1 (janvier 2008) : 57–64. http://dx.doi.org/10.1017/s0266467407004592.
Texte intégralRésumé :
Abstract:We evaluated the effects of forest fragmentation on herbivory on central Amazonian trees. Levels of herbivory were measured on leaves from a total of 1200 saplings from 337 species. There was a positive and significant effect of forest fragment area on herbivore damage, with plants from continuous forest having twice as much damage as plants in the smallest fragments studied (1 ha). Measurements of herbivory rates on two species, however, indicate that the effect can be species-specific. Forest area had a positive and linear effect on rates of herbivory in Henriettella caudata (Melastomataceae), whereas in Protium hebetatum (Burseraceae), rates of herbivory were greater in the 10-ha fragments than in the 1-ha fragments and in continuous forest. There is no evidence that the nutritional and defensive characteristics of the leaves of the species we studied changed as a result of forest fragmentation, at least not in a manner consistent with the observed herbivory patterns. Herbivore predation levels, measured with artificial caterpillars, also showed no significant relationship with forest area. Therefore, neither of these top-down and bottom-up forces could explain the observed patterns of herbivory. It is suggested, instead, that forest fragmentation may affect the dispersal of insect herbivores, and reduce their abundances on small forest isolates. Altered patterns of herbivory on tree saplings may have important consequences for forest structure and dynamics.
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Ngugi, Mary W., Duncan M. Kimuyu, Ryan L. Sensenig, Wilfred O. Odadi, Samuel K. Kiboi, Joyce K. Omari et Truman P. Young. « Fire and Herbivory Interactively Suppress the Survival and Growth of Trees in an African Semiarid Savanna ». Fire 5, no 5 (18 octobre 2022) : 169. http://dx.doi.org/10.3390/fire5050169.
Texte intégralRésumé :
There has been a long-standing interest in understanding how interactions between fire and herbivory influence woody vegetation dynamics in savanna ecosystems. However, controlled, replicated experiments examining how different fire regimes interact with different herbivore groups are rare. We tested the effects of single and repeated burns, crossed with six replicated herbivore treatments, on the mortality and growth of woody vegetation in the Kenya Long-term Exclosure Experiment plots located in a semi-arid savanna system in central Kenya. Burned plots experienced higher tree mortality overall, but differences between burns and non-burns were only significant in plots excluding all wild herbivores and in plots accessible to megaherbivores. Cattle ameliorated the negative effects of repeat burns on tree mortality, perhaps by suppressing fuel load accumulation. Across all herbivore treatments, trees experienced a significant reduction in height within the first two years after fire (top-kill), which was followed by a gradual recovery. Saplings and coppices subjected to repeated burns regrew faster than those that were burned once, except in the presence of megaherbivores. This study highlights strong context-dependent interactions between fire and different herbivore groups, and extends previous approaches to understanding fire–herbivory interactions, which have tended to lump the effects of different herbivore groups, or study them separately.
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Nihranz, Chad T., Anjel M. Helms, John F. Tooker, Mark C. Mescher, Consuelo M. De Moraes et Andrew G. Stephenson. « Adverse effects of inbreeding on the transgenerational expression of herbivore-induced defense traits in Solanum carolinense ». PLOS ONE 17, no 10 (25 octobre 2022) : e0274920. http://dx.doi.org/10.1371/journal.pone.0274920.
Texte intégralRésumé :
In addition to directly inducing physical and chemical defenses, herbivory experienced by plants in one generation can influence the expression of defensive traits in offspring. Plant defense phenotypes can be compromised by inbreeding, and there is some evidence that such adverse effects can extend to the transgenerational expression of induced resistance. We explored how the inbreeding status of maternal Solanum carolinense plants influenced the transgenerational effects of herbivory on the defensive traits and herbivore resistance of offspring. Manduca sexta caterpillars were used to damage inbred and outbred S. carolinense maternal plants and cross pollinations were performed to produced seeds from herbivore-damaged and undamaged, inbred and outbred maternal plants. Seeds were grown in the greenhouse to assess offspring defense-related traits (i.e., leaf trichomes, internode spines, volatile organic compounds) and resistance to herbivores. We found that feeding by M. sexta caterpillars on maternal plants had a positive influence on trichome and spine production in offspring and that caterpillar development on offspring of herbivore-damaged maternal plants was delayed relative to that on offspring of undamaged plants. Offspring of inbred maternal plants had reduced spine production, compared to those of outbred maternal plants, and caterpillars performed better on the offspring of inbred plants. Both herbivory and inbreeding in the maternal generation altered volatile emissions of offspring. In general, maternal plant inbreeding dampened transgenerational effects of herbivory on offspring defensive traits and herbivore resistance. Taken together, this study demonstrates that inducible defenses in S. carolinense can persist across generations and that inbreeding compromises transgenerational resistance in S. carolinense.
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Graham, Mark D., et Rolf D. Vinebrooke. « Trade-offs between herbivore resistance and competitiveness in periphyton of acidified lakes ». Canadian Journal of Fisheries and Aquatic Sciences 55, no 4 (1 avril 1998) : 806–14. http://dx.doi.org/10.1139/f97-309.
Texte intégralRésumé :
It was hypothesized that herbivores regulate periphyton succession in acidified lakes by suppressing loosely attached filamentous algae that otherwise persist and outcompete other growth forms for resources, such as dissolved inorganic carbon (DIC). This hypothesis was tested by conducting grazer-exclosure experiments over an ice-free season in acidified and circumneutral lakes that differed in DIC concentrations. In each lake, the two-factor experimental design had two herbivore (presence-absence) and five succession (early-late) treatments. Total periphyton biomass was greater and significantly suppressed by herbivores in the circumneutral lake. Here, acid-sensitive green frog (Rana clamitans) tadpoles suppressed loosely attached (i.e., zygnematacean taxa) while stimulating firmly attached (i.e., Coleochaete scutata) algae, causing succession towards a herbivore-resistant physiognomy. Conversely, a loosely attached and tall physiognomy persisted in the absence of significant grazing and greater resource limitation in the acid lake. Our findings suggest that trade-offs between competitiveness and herbivore resistance help predict changes in periphyton in recovering acidified lakes. During recovery, concomitant increases in herbivory and resources should favour a firmly attached and short periphyton physiognomy that is resistant to removal by herbivores, but that lacks the competitiveness of loosely attached and tall forms in DIC-limited acid lakes.
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Zhu, Ya-Ru, Min Yang, Jana C. Vamosi, W. Scott Armbruster, Tao Wan et Yan-Bing Gong. « Feeding the enemy : loss of nectar and nectaries to herbivores reduces tepal damage and increases pollinator attraction in Iris bulleyana ». Biology Letters 13, no 8 (août 2017) : 20170271. http://dx.doi.org/10.1098/rsbl.2017.0271.
Texte intégralRésumé :
Floral nectar usually functions as a pollinator reward, yet it may also attract herbivores. However, the effects of herbivore consumption of nectar or nectaries on pollination have rarely been tested. We investigated Iris bulleyana , an alpine plant that has showy tepals and abundant nectar, in the Hengduan Mountains of SW China. In this region, flowers are visited mainly by pollen-collecting pollinators and nectarivorous herbivores. We tested the hypothesis that, in I. bulleyana , sacrificing nectar and nectaries to herbivores protects tepals and thus enhances pollinator attraction. We compared rates of pollination and herbivory on different floral tissues in plants with flowers protected from nectar and nectary consumption with rates in unprotected control plants. We found that nectar and nectaries suffered more herbivore damage than did tepals in natural conditions. However, the amount of tepal damage was significantly greater in the flowers with protected nectaries than in the controls; this resulted in significant differences in pollinator visitation rates. These results provide the first evidence that floral nectar and nectaries may be ‘sacrificed’ to herbivores, leading to reduced damage to other floral tissues that are more important for reproduction.
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Gandhi, Akanksha, Rupesh Kariyat, Amaravadhi Harikishore, Marzieh Ayati, Anirban Bhunia et Nirakar Sahoo. « Deciphering the Role of Ion Channels in Early Defense Signaling against Herbivorous Insects ». Cells 10, no 9 (27 août 2021) : 2219. http://dx.doi.org/10.3390/cells10092219.
Texte intégralRésumé :
Plants and insect herbivores are in a relentless battle to outwit each other. Plants have evolved various strategies to detect herbivores and mount an effective defense system against them. These defenses include physical and structural barriers such as spines, trichomes, cuticle, or chemical compounds, including secondary metabolites such as phenolics and terpenes. Plants perceive herbivory by both mechanical and chemical means. Mechanical sensing can occur through the perception of insect biting, piercing, or chewing, while chemical signaling occurs through the perception of various herbivore-derived compounds such as oral secretions (OS) or regurgitant, insect excreta (frass), or oviposition fluids. Interestingly, ion channels or transporters are the first responders for the perception of these mechanical and chemical cues. These transmembrane pore proteins can play an important role in plant defense through the induction of early signaling components such as plasma transmembrane potential (Vm) fluctuation, intracellular calcium (Ca2+), and reactive oxygen species (ROS) generation, followed by defense gene expression, and, ultimately, plant defense responses. In recent years, studies on early plant defense signaling in response to herbivory have been gaining momentum with the application of genetically encoded GFP-based sensors for real-time monitoring of early signaling events and genetic tools to manipulate ion channels involved in plant-herbivore interactions. In this review, we provide an update on recent developments and advances on early signaling events in plant-herbivore interactions, with an emphasis on the role of ion channels in early plant defense signaling.
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Canavan, K., I. D. Paterson, M. P. Hill et T. L. Dudley. « Testing the Enemy Release Hypothesis on tall-statured grasses in South Africa, using Arundo donax, Phragmites australis, and Phragmites mauritianus as models ». Bulletin of Entomological Research 109, no 3 (17 août 2018) : 287–99. http://dx.doi.org/10.1017/s0007485318000627.
Texte intégralRésumé :
AbstractThe Enemy Release Hypothesis (ERH) predicts that introduced plant species can escape herbivory and therefore have a competitive advantage over native plants, which are exposed to both generalist and specialist natural enemies. In this study, the ERH was explored using the invasive alien species, Arundo donax and two native tall-statured grasses, the cosmopolitan Phragmites australis and African endemic Phragmites mauritianus in South Africa. It was predicted that A. donax would have reduced species richness of herbivores compared with the native Phragmites spp., that it would be devoid of specialist herbivores and would thus be experiencing enemy escape in the adventive range. The herbivore assemblages were determined from both field surveys and a literature review. The assumptions of the ERH were for the most part not met; 13 herbivores were found on A. donax compared with 17 on P. australis and 20 on P. mauritianus. Arundo donax had two specialist herbivores from its native range, and shared native herbivores with Phragmites spp. Although A. donax had reduced species richness and diversity compared with that found in the native distribution, it has partially re-acquired a herbivore assemblage which is similar to that found on analogous native species. This suggests that enemy release may not fully explain the invasive success of A. donax in South Africa.
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Malé, Pierre-Jean G., Kyle M. Turner, Manjima Doha, Ina Anreiter, Aaron M. Allen, Marla B. Sokolowski et Megan E. Frederickson. « An ant–plant mutualism through the lens of cGMP-dependent kinase genes ». Proceedings of the Royal Society B : Biological Sciences 284, no 1862 (13 septembre 2017) : 20170896. http://dx.doi.org/10.1098/rspb.2017.0896.
Texte intégralRésumé :
In plant–animal mutualisms, how an animal forages often determines how much benefit its plant partner receives. In many animals, foraging behaviour changes in response to foraging gene expression or activation of the cGMP-dependent protein kinase (PKG) that foraging encodes. Here, we show that this highly conserved molecular mechanism affects the outcome of a plant–animal mutualism. We studied the two PKG genes of Allomerus octoarticulatus, an Amazonian ant that defends the ant–plant Cordia nodosa against herbivores. Some ant colonies are better ‘bodyguards’ than others. Working in the field in Peru, we found that colonies fed with a PKG activator recruited more workers to attack herbivores than control colonies. This resulted in less herbivore damage. PKG gene expression in ant workers correlated with whether an ant colony discovered an herbivore and how much damage herbivores inflicted on leaves in a complex way; natural variation in expression levels of the two genes had significant interaction effects on ant behaviour and herbivory. Our results suggest a molecular basis for ant protection of plants in this mutualism.
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McKenzie, Scott W., Adam J. Vanbergen, Rosemary S. Hails, T. Hefin Jones et Scott N. Johnson. « Reciprocal feeding facilitation between above- and below-ground herbivores ». Biology Letters 9, no 5 (23 octobre 2013) : 20130341. http://dx.doi.org/10.1098/rsbl.2013.0341.
Texte intégralRésumé :
Interspecific interactions between insect herbivores predominantly involve asymmetric competition. By contrast, facilitation, whereby herbivory by one insect benefits another via induced plant susceptibility, is uncommon. Positive reciprocal interactions between insect herbivores are even rarer. Here, we reveal a novel case of reciprocal feeding facilitation between above-ground aphids ( Amphorophora idaei ) and root-feeding vine weevil larvae ( Otiorhynchus sulcatus ), attacking red raspberry ( Rubus idaeus ). Using two raspberry cultivars with varying resistance to these herbivores, we further demonstrate that feeding facilitation occurred regardless of host plant resistance. This positive reciprocal interaction operates via an, as yet, unreported mechanism. Specifically, the aphid induces compensatory growth, possibly as a prelude to greater resistance/tolerance, whereas the root herbivore causes the plant to abandon this strategy. Both herbivores may ultimately benefit from this facilitative interaction.
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Wetzel, William C., et Mariah H. Meek. « Physical defenses and herbivory vary more within plants than among plants in the tropical understory shrub Piper polytrichum ». Botany 97, no 2 (février 2019) : 113–21. http://dx.doi.org/10.1139/cjb-2018-0160.
Texte intégralRésumé :
There is a growing appreciation that much of the trait variation within plant species is represented within individuals, for example, occurring among leaves within a plant. Subindividual variation is predicted to have key ecological consequences, but empirical understanding of how subindividual variation relates to species interactions, such as herbivory, is limited. We measured two physical defenses and herbivore damage on multiple leaves within individual plants of Piper polytrichum C.DC. (Piperaceae), a tropical understory shrub. We partitioned variance among- and within-plants and quantified patterns of trait and damage variation vis-à-vis leaf size and architectural position. We found that variance was considerably higher within plants than among plants for toughness (97%) and trichome density (57%), and that herbivore damage also varied most within plants (74%). Surprisingly, leaf position and size explained only small amounts of variance in traits (2.5%–16.5%) and herbivory (≤4%), indicating subindividual variability had low spatial predictability. The data suggest that individual P. polytrichum plants represent heterogeneous and spatially unpredictable landscapes of physical traits, and that interactions with herbivores are similarly variable. Our results are consistent with the hypothesis that subindividual variability defends plants against herbivores by increasing the difficulty of foraging for high-quality tissue.
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Johnson, Scott N., Rhiannon C. Rowe et Casey R. Hall. « Aphid Feeding Induces Phytohormonal Cross-Talk without Affecting Silicon Defense against Subsequent Chewing Herbivores ». Plants 9, no 8 (10 août 2020) : 1009. http://dx.doi.org/10.3390/plants9081009.
Texte intégralRésumé :
Prior feeding by insect herbivores frequently affects plant quality for herbivores that subsequently feed on the plant. Facilitation occurs when one herbivore improves plant quality for other herbivores, including when the former compromises plant defenses. Silicon (Si) is an important defense in grasses that increases following activation of the jasmonic acid (JA) pathway. Given that aphids often stimulate the salicylic acid (SA) pathway, we hypothesized that this could reduce Si defense because of the well documented antagonistic cross-talk between SA and JA. We tested this in the model grass Brachypodium distachyon with and without Si (+Si and −Si, respectively); half of the plants were exposed to aphids (Rhopalosiphum padi) and half remained aphid-free. Aphid-free and aphid-exposed plants were then fed to chewing herbivores (Helicoverpa armigera). Aphids triggered higher SA concentrations which suppressed JA concentrations but this did not affect foliar Si. Chewing herbivores triggered higher JA concentrations and induced Si uptake, regardless of previous feeding by aphids. Chewer growth rates were not impacted by prior aphid herbivory but were reduced by 75% when feeding on +Si plants. We concluded that aphids caused phytohormonal cross-talk but this was overridden by chewing herbivory that also induced Si uptake.
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Goitsemodimo, Nametso. « Herbivory as a Tool in Conservation of Biological Diversity in Rangelands - Review ». International Journal of Research and Review 10, no 2 (24 février 2023) : 828–35. http://dx.doi.org/10.52403/ijrr.20230298.
Texte intégralRésumé :
There is a global concern on how the biodiversity can be maintained. Competition has a high importance in maintaining diversity, but there are mechanisms like disturbances that eliminate competition that may cause variations in species richness. Animals play a crucial role in influencing species composition and distribution in an environment. Although some studies have shown positive theoretical and practical results of herbivory, consequences are still debated among ecologists. Understanding of the herbivory contribution to biological diversity conservation and responses by plants in most regions can be the basic starting point in predicting the sustainability of plant species that can serve an ecological niche globally. The use of herbivores as biological controls and weed control has offered environmentally friendly alternative to herbicides as well as cost effectiveness and sustainability in biodiversity conservation. Timing of herbivory and herd density utilization, offer a mechanism that can manipulate ecosystem for positive results. Therefore, managing mammal densities rather than monitoring their effects could be a better approach in improving biodiversity. Large herbivores require high quantity and less quality plants and the reverse for small herbivores, thus, the plant abundance and quality requirements should differ for different herbivores depending on body sizes. This behaviour helps create plant heterogeneity or high biodiversity. Thus, this review may provide may provide more information that would be useful in establishing the relationship between herbivore and plant species diversity identifying existing and potential challenges pertaining to variation in the vegetation structure and other indices as influenced by grazing. Keywords: herd size, insects, species richness, large herbivory, sustainability.
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Rojas-Nossa, Sandra V., José María Sánchez et Luis Navarro. « Phloem-Feeding Herbivores Affect Floral Development and Reproduction in the Etruscan Honeysuckle (Lonicera etrusca Santi) ». Plants 10, no 4 (20 avril 2021) : 815. http://dx.doi.org/10.3390/plants10040815.
Texte intégralRésumé :
Floral development depends on multifactor processes related to genetic, physiological, and ecological pathways. Plants respond to herbivores by activating mechanisms aimed at tolerating, compensating, or avoiding loss of biomass and nutrients, and thereby survive in a complex landscape of interactions. Thus, plants need to overcome trade-offs between development, growth, and reproduction vs. the initiation of anti-herbivore defences. This study aims to assess the frequency of phloem-feeding herbivores in wild populations of the Etruscan honeysuckle (Lonicera etrusca Santi) and study their effects on floral development and reproduction. The incidence of herbivory by the honeysuckle aphid (Hyadaphis passerinii del Guercio) was assessed in three wild populations of the Iberian Peninsula. The effect of herbivory on floral morphology, micromorphology of stigmas and pollen, floral rewards, pollination, and fruit and seed set were studied. The herbivory by aphids reduces the size of flowers and pollen. Additionally, it stops nectar synthesis and causes malformation in pollen and microstructures of stigmas, affecting pollination. As a consequence, fruit set and seed weight are reduced. This work provides evidence of the changes induced by phloem-feeding herbivores in floral development and functioning that affect the ecological processes necessary to maintain the reproductive success of plants.
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Steinbrenner, Adam D., Maria Muñoz-Amatriaín, Antonio F. Chaparro, Jessica Montserrat Aguilar-Venegas, Sassoum Lo, Satohiro Okuda, Gaetan Glauser et al. « A receptor-like protein mediates plant immune responses to herbivore-associated molecular patterns ». Proceedings of the National Academy of Sciences 117, no 49 (23 novembre 2020) : 31510–18. http://dx.doi.org/10.1073/pnas.2018415117.
Texte intégralRésumé :
Herbivory is fundamental to the regulation of both global food webs and the extent of agricultural crop losses. Induced plant responses to herbivores promote resistance and often involve the perception of specific herbivore-associated molecular patterns (HAMPs); however, precisely defined receptors and elicitors associated with herbivore recognition remain elusive. Here, we show that a receptor confers signaling and defense outputs in response to a defined HAMP common in caterpillar oral secretions (OS). Staple food crops, including cowpea (Vigna unguiculata) and common bean (Phaseolus vulgaris), specifically respond to OS via recognition of proteolytic fragments of chloroplastic ATP synthase, termed inceptins. Using forward-genetic mapping of inceptin-induced plant responses, we identified a corresponding leucine-rich repeat receptor, termed INR, specific to select legume species and sufficient to confer inceptin-induced responses and enhanced defense against armyworms (Spodoptera exigua) in tobacco. Our results support the role of plant immune receptors in the perception of chewing herbivores and defense.