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Percent light penetration: Effect of N Addition on Vegetation With Mammalian Herbivory Initially on Disked Ground

This experiment is identical to E008 except the ground was disked thoroughly before the plots were laid out. From 1989-1994, plots with fertilizer treatment 1 were treated as complete controls (treatment 9), receiving no nutrients at all.

Gopher mounds: Effect of N Addition on Vegetation With Mammalian Herbivory Initially on Disked Ground

Grasshopper data: Effect of N Addition on Vegetation With Mammalian Herbivory Initially on Disked Ground

Grasshopper individual characteristics: Effect of N Addition on Vegetation With Mammalian Herbivory Initially on Disked Ground

openCC (other)Jan 2020View details →

Climate Change Across Seasons Experiment (CCASE) Sapling Study at the Hubbard Brook Experimental Forest: Herbivory Damage and Snow Depth

During the winter 2014-15 there was extensive over-winter herbivory damage to sapling stems in the Climate Chaneg Across Seasons (CCASE) sapling experiment in the form of partial or complete girdling from bark consumption. Measurements of the extent of bark damage, the recovery class of the saplings, and the average snow depth during winter were made for each experimental treatment. There were seven treatments for each species of maple. For each species, ten saplings experienced ambient temperatures (reference), ten experienced growing season warming with no induced freeze-thaw cycles in winter (warmed), ten in each of four groups experienced warming in the growing season coupled with two, four, six, or eight soil freeze-thaw cycles in winter (warmed + 2 FTC, warmed + 4 FTC, warmed + 6 FTC, warmed + 8 FTC), and ten experienced snow removal in winter with ambient temperatures in the growing-season (snow removal). These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.

opencc-zeroDec 2019View details →

Data from: Fungal volatiles influence plant defence against aboveground and belowground herbivory

<ol> <li>Plants have evolved resistance traits that negatively affect attackers, and tolerance traits that sustain plant growth despite herbivore damage. These mechanisms often co-occur in a mixed-defence strategy, balancing resistance and tolerance. These plant defences can be enhanced upon interaction with soil microorganisms.</li> <li>Here, we investigated the effects of volatiles emitted by soil-borne fungi on plant defence to insect herbivory, and on plant phenology.</li> <li>We exposed roots of Brassica rapa plants to volatiles emitted by four soil-borne fungi. As a proxy of plant resistance, we assessed the performance of Pieris brassicae, a caterpillar feeding on leaves and inflorescences, and of Delia radicum, an insect root herbivore. As a proxy of plant tolerance, we compared growth of volatile-exposed plants challenged with or without insects. Additionally, we assessed the effects on plant phenology by recording bolting time and by counting the number of buds and flowers.</li> <li>Plant exposure to fungal volatiles differentially affected plant resistance to above- and belowground herbivory. Performance of P. brassicae caterpillars differed between the fungal volatile-exposed plants but were variable between experimental batches. In contrast, the effects of fungal volatiles on D. radicum performance was predominantly negative, indicating an increased plant resistance. Despite root consumption by D. radicum, root dry weight remained unchanged in infested plants compared with uninfested ones, irrespectively of the volatile exposure, suggesting compensation for the tissue loss, sometimes at the cost of undamaged aboveground tissues. When B. rapa plants were attacked by P. brassicae caterpillars, only exposure to volatiles of some fungi led to compensation for the loss of aboveground tissues consumed by the caterpillars, which differed between leaves and inflorescences. Furthermore, bolting was accelerated in response to volatiles of some fungi, resulting in more buds and flowers, which suggests a potential enhancement of plant fitness.</li> <li>Our data show that fungal volatiles can modulate the mixed-defence strategies of B. rapa plants, balancing plant resistance and tolerance to above- and belowground herbivory. These effects may be variable and were fungus-specific. Ultimately, plant fitness may be enhanced upon root exposure to fungal volatiles. </li> </ol>

opencc-zeroAug 2020View details →

Data from: Genetic identity and herbivory drive the invasion of a common aquatic microbial invader - phytoplankton and zooplankton abundance

Despite the increasing number of species invasions, the factors driving invasiveness are still under debate. This is particularly the case for 'invisible' invasions by aquatic microbial species. Since in many cases only a few individuals or propagules enter a new habitat, their genetic variation is low and might limit their invasion success, known as the genetic bottleneck. Thus, a key question is, how genetic identity and diversity of invading species influences their invasion success and, subsequently, affect the resident community. We conducted invader-addition experiments using genetically different strains of the globally invasive, aquatic cyanobacterium Raphidiopsis raciborskii (formerly: Cylindrospermopsis raciborskii) to determine the role of invader identity and genetic diversity (strain richness) at four levels of herbivory. We tested the invasion success of solitary single strain invasions against the invader genetic diversity, which was experimentally increased up to ten strains (multi-strain populations). By using amplicon sequencing we determined the strain-specific invasion success in the multi-strain treatments and compared those with the success of these strains in the single-strain treatments. Furthermore, we tested for the invasion success under different herbivore pressures. We showed that high grazing pressure by a generalist herbivore prevented invasion, whereas a specialist herbivore enabled coexistence of consumer and invader. We found a weak effect of diversity on invasion success only under highly competitive conditions. When invasions were successful, the magnitude of this success was strain-specific and consistent among invasions performed with single-strain or multi-strain populations. A strain-specific effect was also observed on the resident phytoplankton community composition, highlighting the strong role of invader genetic identity. Our results point to a strong effect of the genetic identity on the invasion success under low predation pressure. The genetic diversity of the invader population, however, had little effect on invasion success in our study, in contrast to most previous findings. Instead, it is the interaction between the consumer abundance and type together with the strain identity of the invader that defined invasion success. This study underlines the importance of strain choice in invasion research and in ecological studies in general.

opencc-zeroAug 2020View details →

Data and analyses from: Herbivory and time since flowering shape floral rewards and pollinator-pathogen interactions

Herbivory can induce chemical changes throughout plant tissues including flowers, which could affect pollinator-pathogen interactions. Pollen is highly defended compared to nectar, but no study has examined whether herbivory affects pollen chemistry. We assessed the effects of leaf herbivory on nectar and pollen alkaloids in Nicotiana tabacum, and how herbivory-induced changes in nectar and pollen affect pollinator-pathogen interactions. We damaged leaves of Nicotiana tabacum using the specialist herbivore Manduca sexta and compared nicotine and anabasine concentrations in nectar and pollen. We then pooled nectar and pollen by collection periods (within and after one month of flowering), fed them in separate experiments to bumble bees (Bombus impatiens) infected with the gut pathogen Crithidia bombi, and assessed infections after seven days. We did not detect alkaloids in nectar, and leaf damage did not alter the effect of nectar on Crithidia counts. In pollen, herbivory induced higher concentrations of anabasine but not nicotine, and alkaloid concentrations rose and then fell as a function of days since flowering. Bees fed pollen from damaged plants had Crithidia counts 15 times higher than bees fed pollen from undamaged plants, but only when pollen was collected after one month of flowering, indicating that both damage and time since flowering affected interaction outcomes. Within undamaged treatments, bees fed late-collected pollen had Crithidia counts 10 times lower than bees fed early-collected pollen, also indicating the importance of floral phenology. Our results emphasize the role of herbivores in shaping pollen chemistry, with consequences for interactions between pollinators and their pathogens.

opencc-zeroSep 2020View details →

Invasive earthworms reduce chemical defense and increase herbivory and pathogen infection in native trees

<ol> <li>Recent research shows that earthworms can alter defense traits of plants against herbivores and pathogens by affecting soil biochemistry. Yet, the effects of invasive earthworms on defense traits of native plants from previously earthworm-free ecosystems as well as the consequences for multitrophic interactions are virtually unknown.</li> <li>Here we use a combination of an observational study and a complementary experimental study to investigate the effects of invasive earthworms on leaf defense traits, herbivore damage, and pathogen infection in two poplar tree species (Populus balsamifera and Populus tremuloides) native to North American boreal forests.</li> <li>Our observational study showed that earthworm invasion was associated with enhanced leaf herbivory in saplings of both tree species. However, we only detected significant shifts in the concentration of chemical defense compounds in response to earthworm invasion for P. balsamifera. Specifically, leaf phenolic concentrations, including salicinoids and catechin, were lower in P. balsamifera from earthworm-invaded sites.</li> <li>Our experimental study confirmed an earthworm-induced reduction in leaf defense levels in P. balsamifera for one of the defense compounds, tremulacin. The experimental study additionally showed that invasive earthworms reduced leaf dry matter content, potentially increasing leaf palatability, and enhanced susceptibility of trees to infection by a fungal pathogen, but not to aphids, in the same tree species.</li> <li> Synthesis. Our results show that invasive earthworms can decrease the concentrations of some chemical defense compounds in P. balsamifera, which could make them susceptible to leaf-chewing insects. Such potential impacts of invasive earthworms are likely to have implications for tree survival and competition, native tree biodiversity, and ecosystem functioning.</li> </ol>

opencc-zeroOct 2020View details →

The impact of herbivory and pollination on the evolution of herbivore-induced plasticity

Theory predicts that herbivory should primarily determine the evolution of herbivore-induced plasticity in plant defenses, but little is known about the influence of other interactions like pollination. Pollinators may exert negative selection on the herbivore-induced plasticity of chemical defenses when floral signals and rewards are indirectly affected, provoking deterrent effects on these mutualists. We investigated the influence of constant herbivory and pollination on the evolved patterns and degree of herbivore-induced plasticity in chemical plant defenses and floral morphometry and volatiles in fast-cycling Brassica rapa plants. To do this, we used plants from an evolution experiment that had evolved under bee/hand pollination and herbivory manipulated in a 2*2 factorial design during six generations, producing four selection treatments. We grew sibling plant pairs from each of the four selection treatments of the last generation and infested one group with herbivores and left the other uninfested. Herbivore-induced plasticity was analyzed within and between selection treatments. We found support for the hypothesis that constant herbivory favors the evolution of higher constitutive yet lower herbivore-induced plasticity in defenses. However, this only occurred in plants that evolved under hand pollination and constant herbivory. Bee pollination had a strong influence on the evolution of herbivore-induced plasticity of all traits studied. Plants that evolved under bee pollination, with and without constant herbivory, showed remarkably similar patterns of herbivore-induced plasticity in their defense- and floral traits and had a higher number of plastic responses compared to plants of hand pollination. Such patterns support the hypothesis that bee pollination influenced the evolution of herbivore-induced plasticity, most likely via indirect effects, such as links between defense- and floral traits. We conclude that interactions other than herbivory, such as pollination, may impact herbivore-induced plasticity, through indirect effects and metabolic tradeoffs, when it contributes to trait evolution in plants.

opencc-zeroOct 2020View details →

Global meta-analysis of how marine upwelling affects herbivory

Aim: Nutrient subsidies support high primary productivity, increasing herbivore abundance and influencing their top-down control of producers. Wind-driven upwelling events deliver cold nutrient-rich water to coastlines, supporting highly productive marine environments. Results from studies comparing ecological processes across upwelling regimes are mixed: some reveal weaker herbivory in upwelling regions, while others report a positive relationship between upwelling and herbivory. In this synthesis we examine the influence of upwelling on top-down control of producers across the globe. Location: Global; marine ecosystems. Time period: 1978-2017. Major taxa studied: Marine herbivores and algae. Methods: We used data from herbivory studies focusing specifically on the influence of upwelling activity (upwelling studies), and a broader collection of herbivore exclusion studies dating back four decades. For the upwelling studies we compared herbivore effects between experiments replicated across sites for which upwelling conditions were described by the authors. Meanwhile, for the broader collection of experiments we used externally sourced oceanographic data to characterize upwelling activity, and examined how herbivory changed along a gradient of upwelling activity. Results: Our results consistently reveal that upwelling weakens herbivore effects on producers. Herbivory was, on average, four times weaker in upwelling sites relative to sites under weak upwelling or downwelling regimes in studies that specifically examined upwelling. The analysis of the broader herbivory literature revealed a similar weakening influence of upwelling on herbivory; however, the effect size was smaller and varied across producer functional groups. Main conclusions: Nutrient subsidies from upwelling events reduce top-down control by herbivores in coastal ecosystems, however, the negative relationship between upwelling intensity and herbivory is likely the result of a combination of co-occurring processes. First, increased primary production overwhelms consumption by herbivores. Second, cold water reduces herbivore metabolism and activity. Finally, surface currents associated with upwelling activity transport herbivore larvae offshore, decoupling secondary production from herbivory.

opencc-zeroNov 2020View details →

Targeting diamondback moth in greenhouses by attracting specific native parasitoids with herbivory-induced plant volatiles

We investigated whether recruitment of specific parasitoids using a specific blend of synthetic herbivory-induced plant volatiles (HIPVs) could be a novel method of pest control in greenhouses. In the Miyama rural area in Kyoto, Japan,diamondback moth (DBM) (Plutella xylostella) larvae are an important pest of cruciferous crops in greenhouses, and Cotesia vestalis, a larval parasitoid of DBM, are found in the surrounding areas. Dispensers of HIPVs that attracted C. vestalis and honey feeders were set inside greenhouses (treated greenhouses). The monthly incidence of DBM in the treated greenhouses was significantly lower than that in the untreated greenhouses across a two-year period. The monthly incidences of C. vestalis and DBM were not significantly different in the untreated greenhouses, whereas the monthly incidence of C. vestalis was significantly higher than that of DBM in the treated greenhouses. Poisson regression analyses showed that, in both years, a significantly higher number of C. vestalis was recorded in the treated greenhouses than in the untreated greenhouses when the number of DBM adults increased. We concluded that DBM was suppressed more effectively by C. vestalis in the treated greenhouses than in the untreated greenhouses.

opencc-zeroApr 2020View details →

Dynamic effects of insect herbivory and climate on tundra shrub growth: roles of browsing and ramet age

1. To predict shrub responses under climate change in tundra, we need to understand how thermal conditions and herbivory contribute to growth. We hypothesise that shrub growth increases with thermal conditions and precipitation, but that this increase is counteracted by insect herbivory, and that these climate-insect herbivory relationships are modified by both browsing and plant age. 2. We use empirical dynamic modelling (EDM) to analyse a 20-year time series on willow (Salix phylicifolia) shoot growth, growing degree days, summer precipitation and herbivory from an experiment at forest-tundra ecotone. The experiment includes manipulations of avian and mammal browsing (fences) and ramet age (pruning to rejuvenate willows). 3. Negative effects of insect herbivory on willow shoot growth were intensified during warmer years, whereas increasing precipitation led to reduced effects. Moreover, the effect of insect herbivores on shoot growth varied with ramet age and vertebrate browsing: Younger ramets generally experienced less negative insect herbivore effects, whereas Ptarmigan browsing was associated with more positive temperature effect on shoot growth, and reindeer browsing with more negative effects of insect herbivory and precipitation. 4. Synthesis. Our findings show that the negative effects of insect herbivory on shoot growth likely intensify under warmer thermal conditions, but that increasing precipitation can counteract these effects. Moreover, changing thermal conditions, precipitation and vertebrate browsers all have predictable, albeit complex and nonlinear, effects on shrub growth, highlighting the importance of long-term experimental data and flexible analytical methods such as EDM for characterizing climate and community interactions in artic systems.

opencc-zeroDec 2020View details →

Herbivory of a biocontrol agent on a native plant causes an indirect trait-mediated non-target effect on a native insect

Identifying food web linkages between biocontrol agents of invasive plants and native species is crucial for predicting indirect non-target effects. Biocontrol insects can integrate into food webs within recipient habitats and influence native insects through apparent competition (altering shared natural enemies) or density-mediated exploitation competition (changing density of native plants). However, whether and how trait-mediated exploitation competition (modifying native plant chemical defenses and volatiles profiles) can produce indirect non-target effects remains largely overlooked, despite plant phenotypic responses to insect herbivory being common and widely documented. The beetle Agasicles hygrophila was introduced into China for management of weedy Alternanthera philoxeroides, but it also attacks the native congener A. sessilis, which may have indirect non-target effects on the native beetle Cassida piperata that also feeds on A. sessilis. Here, we examined the relationships among the abundance of A. hygrophila and C. piperata, and A. sessilis coverage in the field. Then, we investigated the impact of A. hygrophila herbivory on C. piperata development and oviposition, as well as A. sessilis primary metabolites and leaf volatiles. Cassida piperata abundance was not related to A. sessilis coverage, but C. piperata was less abundant on plants with more A. hygrophila in the field survey and on plants with more prior A. hygrophila damage in the field cage experiment. Cassida piperata development was inhibited by prior A. hygrophila herbivory in bioassays in enemy-free conditions and they preferred to oviposit on A. sessilis plants that had experienced little or no A. hygrophila damage. Agasicles hygrophila herbivory decreased A. sessilis foliar glucose and protein, and substantially changed its leaf volatile blend. Synthesis. Our results show that A. hygrophila has its major indirect non-target effects on C. piperata through trait-mediated exploitation competition, rather than apparent competition or density-mediated exploitation competition. Our results demonstrate a new mechanism for indirect non-target effects of biocontrol agents. Furthermore, our results indicate that minor and temporary negative impacts on non-target plants might propagate to higher trophic levels and such negative impacts can strengthen with increasing intensity of the direct non-target effect.

opencc-zeroDec 2017View details →

Data from: Jasmonic acid regulation of the anti-herbivory mechanism conferred by fungal endophytes in grasses

1. The most studied mechanism of protection against herbivores in grasses associated with Epichloë fungal endophytes has been the fungal production of alkaloids. However, the contribution of the plant immune responses on the level of resistance to herbivores in symbiotic grasses has been poorly explored. We studied the relationship between the plant hormone, jasmonic acid (JA), and Epichloë fungal endophytes on herbivore defenses in symbiotic grasses. We hypothesized that an exogenous application of methyl jasmonate (MeJA), an activator of the plant JA defense response, would increase the level of resistance of endophyte-symbiotic and non-symbiotic plants to a chewing insect. As Epichloë endophytes produce alkaloids, an enhancement of the JA defense would complement to the resistance given by these alkaloids. 2. Lolium multiflorum plants symbiotic and non-symbiotic with the endophyte Epichloë occultans were subjected to an exogenous application of MeJA followed by a challenge with the generalist chewing insect Spodoptera frugiperda. We measured the level of plant resistance to chewing insects, and the defenses conferred by host plants and fungal endophytes. 3. Symbiotic plants were more resistant to S. frugiperda than their non-symbiotic counterparts. However, despite the fact that the JA concentration significantly increased in all plants with the MeJA exposure, neither endophyte-symbiotic nor non-symbiotic plants showed an enhanced resistance to insects. Unexpectedly, the exposure of endophyte-symbiotic plants to MeJA led to a reduction in the concentration of loline alkaloids (i.e. N-formyllolines and N-acetylnorlolines), consequently decreasing the level of plant resistance to the herbivore. 4. Synthesis. Our results suggest that, rather than complementing the alkaloid-based defense, the JA hormone weakens the anti-herbivore mechanism conferred by endophytes. The present study highlights that the interaction between the JA hormone and the presence of leaf fungal endophytes can be of importance for the effectiveness of the anti-herbivore defenses of symbiotic plants.

opencc-zeroDec 2014View details →

Data from: Moose browsing alters tree diversity effects on birch growth and insect herbivory

Producer diversity is known to affect a wide range of ecosystem processes including plant growth and insect pest resistance. Consumers such as mammalian herbivores too have been shown to modify plant growth and insect herbivory by triggering changes in host plants. However, few studies have investigated whether consumer effects interact with plant species diversity effects on a focal plant. To unravel consumer-diversity interactions, we recorded both the presence and intensity of winter browsing by moose (Alces alces) on silver birch (Betula pendula) in a long-term forest diversity experiment in Finland and measured birch tree growth as well as insect chewing damage during the following growing season. Although browsing on birch by moose was not affected by tree species richness, the intensity of moose damage altered tree diversity effects on birch tree growth. At minor browsing intensity, tree height, trunk diameter and canopy projections showed positively-humped relationships with tree diversity, peaking at 3-species mixtures. Growth of moderately browsed trees increased with tree species richness, but growth of severely browsed birch trees was unaffected. Moose browsing also altered the direction of tree diversity effects on insect herbivory on birch. Unbrowsed trees experienced lower insect chewing damage in mixed stands (associational resistance) whilst browsed trees suffered more insect chewing damage in diverse stands (associational susceptibility). Increasing browsing intensity also reversed the relationship between tree species richness and insect chewing damage from negative to positive. The observed interactions between moose browsing and tree species richness effects could be explained by lower canopy cover of more diverse stands compared to birch monocultures, leading to increased re-growth capacity and more high-quality foliage of browsed birch trees in more open diverse stands. Our findings demonstrate that both the presence and intensity of mammalian browsing may modify the magnitude and even the direction of tree diversity effects on tree growth and susceptibility to insect herbivory. Differences in consumer impact among studies may thus potentially explain much of the observed variability in plant diversity effects on ecosystem functioning and must therefore be taken into account in future studies.

opencc-zeroDec 2017View details →

Data from: When is an herbivore not an herbivore? Detritivory facilitates herbivory in a freshwater system

1. Herbivory is thought to be an inefficient diet, but it independently evolved from carnivorous ancestors in many metazoan groups, suggesting that plant-eating is adaptive in some circumstances. In this study, we tested two hypotheses to explain the adaptive evolution of herbivory: 1) the Heterotroph Facilitation hypothesis (herbivory is adaptive because herbivores supplement their diets with heterotrophic microbes); and 2) the Lipid Allocation hypothesis (herbivory is adaptive because algae, which have high lipid concentrations, are nutritionally similar to carnivory). 2. We tested these hypotheses using enclosure cages placed in the Everglades and stocked with Sailfin Mollies (Poecilia latipinna), a native herbivore. Using shading and phosphorus addition (P), we manipulated the heterotrophic microbe and lipid composition of colonizing epiphyton and examined the effects of varying food quality on Sailfin Molly life history. 3. Epiphyton grown in 'shade only' conditions had a 55% increase in bacterial fatty acids and 34% lower ratios of saturated + monounsaturated to polyunsaturated fatty acids relative to the other treatments. Biovolume of heterotrophic microbes varied throughout the experiment, with a 697% increase at 3 weeks and 98% decrease at 6 weeks compared to the other treatments. Gut contents revealed that fish fed selectively on epiphyton to compensate for apparent deficiencies in the available food. 4. Fish raised in 'shade only' cages experienced the highest survival, which was best explained by autotrophic abundance and algal- and bacterial-derived fatty acids at 3 weeks (2-6x more likely than alternative models with ∆AICc > 2.00), and by percentage of bacterial fatty acids in the diet at 6 weeks (3-8x more likely than alternative models with ∆AICc > 2.00). There were no differences in fish growth among treatments. 5. Autotrophic lipids play a role in early fish life history, but we did not find these to be the best...

opencc-zeroDec 2013View details →

Data from: Variable effects of temperature on insect herbivory

Rising temperatures can influence the top-down control of plant biomass by increasing herbivore metabolic demands. Unfortunately, we know relatively little about the effects of temperature on herbivory rates for most insect herbivores in a given community. Evolutionary history, adaptation to local environments, and dietary factors may lead to variable thermal response curves across different species. Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. Over one third of the herbivore-plant pairs showed declining consumption rates at high temperatures, while an approximately equal number showed increasing consumption rates. Such variation existed even within herbivore species, as some species exhibited idiosyncratic thermal response curves on different host plants. Thus, rising temperatures, particularly with respect to climate change, may have highly variable effects on plant-herbivore interactions and, ultimately, top-down control of plant biomass.

opencc-zeroMar 2020View details →

Ectothermic omnivores increase herbivory in response to rising temperature

Higher temperatures as a consequence of global climate change may considerably alter trophic interactions. Ectothermic herbivores and carnivores generally ingest more food with rising temperature as their metabolic rates increase with rising temperature. However, omnivorous ectotherms may respond in two ways: quantitatively by consuming more food and qualitatively by altering their degree of herbivory or carnivory through a diet shift. We hypothesize that rising temperature will increase herbivory of ectothermic omnivores as herbivory increases towards the equator. We tested the hypothesis in a freshwater model system in which ectothermic omnivores are prevalent, by applying two approaches, a temperature manipulation experiment and a literature study. We performed feeding trials with a juvenile aquatic ectothermic omnivore (pond snail Lymnaea stagnalis) at different temperatures ranging from 12 to 27°C, supplying them with both animal food and plant material, and directly quantified their consumption rates over time. The results showed that snails cultured at high temperatures (> 21°C) increased the proportion of plant material in their diets after 17 days, which supports our hypothesis. In the literature survey, we found that rising temperature increased herbivory in multiple aquatic animal taxa, including zooplankton, amphibians, crayfish, fish and snails. This suggests that aquatic ectothermic omnivores might commonly increase herbivory with rising temperature. The mechanisms underlying this temperature‐induced diet shift are not sufficiently explained by current theories related to the physiology, metabolism and stoichiometry of omnivores. We propose to incorporate the animals' ontogenetic development in the temperature metabolic stoichiometry hypothesis as a complementary explanation for the diet shift, namely that the diet shift could be due to faster development of the ectotherms and an earlier ontogenetic diet shift at higher temperatures. We conclude that future global warming will most likely alter food webs by increasing the top–down control of aquatic herbivores and omnivores on primary producers.