Carolina Quintero | CONICET - INIBIOMA (original) (raw)

Papers by Carolina Quintero

Ecological Entomology, 2018

Sit and wait predators hunting on flowers are considered to be exploiters of plantepollinator mut... more Sit and wait predators hunting on flowers are considered to be exploiters of plantepollinator mutualisms. Several studies have shown that plantepollinator interactions can be highly susceptible to the impact of a third trophic level, via consumptive (direct) and non-consumptive (indirect) effects that alter pollinator behavior and, ultimately, plant fitness. However, most flowering plants attract a wide array of flower visitors, from which only a subset will be effective pollinators. Hence, a negative effect of an ambush predator on plant fitness should be expected only when: (i) the effective pollinators are part of the predators' diet and/or (ii) the non-consumptive effects of predator presence (e.g. dead prey) alter the behavior of effective pollinators and pollen movement among individual plants. We analyzed the direct and indirect effects of a crab-spider (Misumenops pallidus), on the pollination and reproductive success of Chloraea alpina, a Patagonian rewardless orchid. Our results indicate that most of the flower visitors do not behave as effective pollinators and most effective pollinators were not observed as prey for the crabspider. In terms of non-consumptive effects, inflorescences with and without spiders and/or dead-prey did not vary the frequency of flower visitors, nor pollinia removal or deposition. Hence, it is not surprising that M. pallidus has a neutral effect on pollinia removal and deposition as well as on fruit and seed set. Similar to other rewardless orchids, the low reproductive success of C. alpina (~6% fruit set) was associated with the limited number of visits by effective pollinators. Negative top-down effects of a flower-visitor predator on plant pollination may not be anticipated without studying the direct and indirect effects of this predator on the effective pollinators. In pollination systems where effective pollinators visited flowers erratically, such as in deceptive orchids, we expect weak or no effect of predators on plant fitness.

Neotropical Insect Galls, 2014

ABSTRACT South American temperate forests are of special conservation concern due to their highly... more ABSTRACT South American temperate forests are of special conservation concern due to their highly endemic flora and fauna, and the occurrence of unique plant-animal interactions. Yet, knowledge regarding gall inducers diversity is limited although increasing rapidly in the last two decades. Here, we performed a review of the literature, supplemented with field collected data by the authors, in order to provide the most up to date knowledge of gall inducers’ diversity associated with native woody species of the temperate forest of Chile and Argentina. We present data for 90 morphospecies of galls associated with 39 host-plant species (21 genera, 15 families), spanning insects and arachnids of at least 6 orders and nematodes. Most of this richness is associated to the best surveyed host-plant genus, Nothofagus, with up to 43 morphospecies of galls in just 8 dominant tree species. Moreover, we provide evidence that gall species richness across all woody host-plant species decreases with elevation, probably driven by decreased temperature and number of available host-plant species. However, this overall trend vary among host plant species and scales of observation. Overall, the study of gall diversity and the biotic and abiotic factors that shape their distribution in these austral forests offer an exciting and fertile field for future research. Besides emphasizing the need for more in depth taxonomic and diversity studies of the gall fauna of these forests, we propose several future lines of research that promise to further elucidate our understanding of the evolution of plant-gall interactions in these forests.

Plant-insect interactions, which are strongly mediated by chemical defenses, have the potential t... more Plant-insect interactions, which are strongly mediated by chemical defenses, have the potential to shape invasion dynamics. Despite this, few studies have quantified natural variation in key defensive compounds of invasive plant populations, or how those defenses relate to levels of herbivory. Here, we evaluated variation in the iridoid glycosides aucubin and catalpol in rosette plants of naturally occurring, introduced populations of the North American invader, Verbascum thapsus L. (common mullein; Scrophulariaceae). We examined two scales that are likely to structure interactions with insect herbivores-among populations and within plant tissues (i.e., between young and old leaves). We additionally estimated the severity of damage incurred at these scales due to insect chewing herbivores (predominantly grasshoppers and caterpillars), and evaluated the relationship between iridoid glycoside content and leaf damage. We found significant variation in iridoid glycoside concentrations among populations and between young and old leaves, with levels of herbivory strongly tracking leaf-level investment in defense. Specifically, across populations, young leaves were highly defended by iridoids (averaging 6.59 the concentration present in old leaves, and containing higher proportions of the potentially more toxic iridoid, catalpol) and suffered only minimal damage from generalist herbivores. In contrast, old leaves were significantly less defended and accordingly more substantially utilized. These findings reveal that quantitative variation in iridoid glycosides is a key feature explaining patterns of herbivory in an introduced plant. In particular, these data support the hypothesis that defenses limit the ability of generalists to feed on mullein's well-defended young leaves, resulting in minimal losses of high-quality tissue, and increasing performance of this introduced species.

by Carolina Quintero, Gilbert Adum, Carolina Laura Morales, Konstans Wells, Nicholas Berry, Maria Guiomar Nates Parra, Danilo B Ribeiro, Inge Armbrecht, Dave Goulson, Alain Dejean, T'Ai Roulston, Douglas Yu, Gábor Lövei, Guiomar Nates Parra, Gretchen Lebuhn, and Joseph Hawes

Ecology and evolution, 2014

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habit... more Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadive...

Neotropical Insect Galls, 2014

South American temperate forests are of special conservation concern due to their highly endemic ... more South American temperate forests are of special conservation concern due to their highly endemic fl ora and fauna, and the occurrence of unique plant-animal interactions. Yet, knowledge regarding gall inducers diversity is limited although increasing rapidly in the last two decades. Here, we performed a review of the literature, supplemented with fi eld collected data by the authors, in order to provide the most up to date knowledge of gall inducers' diversity associated with native woody species of the temperate forest of Chile and Argentina. We present data for 90 morphospecies of galls associated with 39 host-plant species (21 genera, 15 families), spanning insects and arachnids of at least 6 orders and nematodes. Most of this richness is associated to the best surveyed host-plant genus, Nothofagus , with up to 43 morphospecies of galls in just 8 dominant tree species. Moreover, we provide evidence that gall species richness across all woody host-plant species decreases with elevation, probably driven by decreased temperature and number of available host-plant species. However, this overall trend vary among host plant species and scales of observation. Overall, the study of gall diversity and the biotic and abiotic factors that shape their distribution in these austral forests offer an exciting and fertile fi eld for future research. Besides emphasizing the need for more in depth taxonomic and diversity studies of the gall fauna of these forests, we propose several future lines of research that promise to further elucidate our understanding of the evolution of plant-gall interactions in these forests.

Physiological and morphological constraints during plant ontogeny affect the expression of numero... more Physiological and morphological constraints during plant ontogeny affect the expression of numerous plant traits relevant to higher trophic levels, such as nutritional content and physical and chemical defenses. Yet we know little about how temporal variation in these traits can directly and/or indirectly mediate tri-trophic interactions, such as those between plants, their herbivores, and herbivore natural enemies. Using four distinct ontogenetic stages of Plantago lanceolata (Plantaginaceae) and the specialist herbivore Junonia coenia (Lepidoptera, Nymphalidae), we evaluated how ontogenetic changes in plant quality can: (1) directly alter plant-herbivore interactions through butterfly oviposition choice and caterpillar performance assays, and (2) indirectly alter herbivores' susceptibility to higher trophic levels through caterpillars' iridoid glycoside sequestration and immune defenses. Results showed that plant defensive traits increased over P. lanceolata development, with leaf tissues becoming tougher and plant allelochemicals (iridoid glycosides) occurring in higher amounts. Conversely, plant nutritional quality (water and nitrogen content) decreased as plants aged. These ontogenetic trajectories strongly altered both direct and indirect interactions between plants and higher trophic levels. Buckeye butterflies showed a stronger oviposition preference for younger developmental stages of P. lanceolata, laying on average 60% more eggs on juvenile than on reproductive plants. Feeding experiments with caterpillars showed that larvae feeding on juvenile plants showed faster relative growth rate and increased digestive efficiency compared with those feeding on plants in the reproductive stage. These individuals, however, acquired lower levels of sequestered chemical defenses than did those feeding on older P. lanceolata plants, potentially rendering them more susceptible to predation. Finally, host plant age altered the ability of a caterpillar to mount an immune response against simulated parasitoid eggs. Specifically, caterpillars reared on older plant life stages, and thus with higher levels of sequestered iridoid glycosides, showed a compromised immune response compared to those feeding on younger plant age classes. This study exemplifies how ontogenetic trajectories in plant traits can scale up to directly or indirectly alter tri-trophic interactions, which may have key implications for understanding temporal shifts in herbivore population and community structure.

Perspectives in Plant Ecology, Evolution and Systematics, 2013

ABSTRACT Plants frequently attract natural enemies of their herbivores, resulting in a reduction ... more ABSTRACT Plants frequently attract natural enemies of their herbivores, resulting in a reduction in tissue damage and often in enhanced plant fitness. While such indirect defenses can dramatically change as plants develop, only recently have ecologists begun to explore such changes and evaluate their role in mediating plant–herbivore–natural enemy interactions. Here we review the literature documenting ontogenetic patterns in plant rewards (i.e. extrafloral nectaries (EFNs), food bodies (FBs) and domatia) and volatile organic compounds (VOCs), and identify links between ontogenetic patterns in such traits and the attraction of natural enemies (ants). In the case of reward traits we concentrate in ant–plant studies, which are the most numerous. We report that all indirect defensive traits commonly vary with plant age but ontogenetic trajectories differ among them. Myrmecophytic species, which provide both food and shelter to their defenders, do not produce rewarding traits until a minimum size is reached. Then, a pronounced increase in the abundance of food rewards and domatia often occurs as plants develop, which explains the temporal succession or colony size increase of mutualistic ant species and, in some cases, leads to a reduction in herbivore damage and enhanced fitness as plants age. In contrast, ontogenetic patterns were less consistent in plant species that rely on VOC emissions to attract natural enemies or those that provide only food rewards (EFNs) but not nesting sites to their associated ants, showing an overall decline or lack of trend with plant development, respectively. Future research should focus on uncovering: (i) the costs and mechanisms underlying ontogenetic variation in indirect defenses, (ii) the relative importance of environmental and genetic components shaping these ontogenetic trajectories, and (iii) the consequences of these ontogenetic trajectories on plant fitness. Advances in this area will shed light on the context dependency of bottom-up and top-down controls of herbivore populations and on how natural selection actually shapes the ontogenetic trajectories of these traits.

Annals of botany, 2013

The lack of studies assessing the simultaneous expression of tolerance and resistance traits duri... more The lack of studies assessing the simultaneous expression of tolerance and resistance traits during seedling development and overall seedling defences as compared with adult plants, in general, constitutes a significant research need that can greatly improve our understanding of overall investment in defences during plant ontogeny. Using two seedling and two juvenile stages of the perennial herb Penstemon virgatus (Plantaginaceae) evaluations were made of (a) patterns of investment in constitutive chemical defences [i.e. iridoid glycosides (IGs)], and (b) simultaneous variation in the short-term ability of seedling and juvenile stages to induce resistance traits, measured as induced chemical defences, or tolerance traits, measured as compensatory re-growth following moderate levels of damage by a specialist insect herbivore. Plants were highly defended during most of their transition from seedling to early juvenile stages, reaching a constant approx. 20 % dry weight total IGs. Furth...

Journal of Chemical Ecology, 2013

Global environmental change alters the supply of multiple limiting resources that regulate plant ... more Global environmental change alters the supply of multiple limiting resources that regulate plant primary and secondary metabolism. Through modifications in resource availability, acquisition, and allocation, global change is likely to influence plant chemical defenses, and consequently species interactions that are mediated by these compounds. While many studies focus on individual global change factors, simultaneous changes in abiotic factors may interact to influence plant allelochemicals. In this study, we examined the individual and interactive effects of nitrogen enrichment and altered precipitation patterns on chemical defense compounds (iridoid glycosides) of an invasive plant, Linaria dalmatica. Plants were grown from seed in native mixed-grass prairie for 2 years. Nitrogen and water treatments were applied in each growing season over this period. Results indicate that soil water and nitrogen availability interact to shape plant chemical defense concentrations in L. dalmatica. Nitrogen addition decreased iridoid glycoside concentrations by approximately 25 % under reduced water availability, increased concentrations by 37 % in ambient water plots, and had no effect on these chemical defenses for plants growing under augmented water supply. Thus, results show differing patterns of allelochemical response to nitrogen enrichment, with respect to both the magnitude and direction of change, depending on water availability. Our study demonstrates the importance of examining multiple environmental factors in order to predict potential changes in plant chemical defenses with climate change.

Oecologia, 2012

Numerous empirical studies have examined ontogenetic trajectories in plant defenses but only a fe... more Numerous empirical studies have examined ontogenetic trajectories in plant defenses but only a few have explored the potential mechanisms underlying those patterns. Furthermore, most documented ontogenetic trajectories in plant defenses have generally concentrated on aboveground tissues; thus, our knowledge regarding whole plant trends in plant defenses throughout development or potential allocation constraints between growth and defenses is limited. Here, we document changes in plant biomass, nutritional quality and chemical defenses for below-and aboveground tissues across seven age classes of Plantago lanceolata (Plantaginaceae) to evaluate: (1) partial and whole plant ontogenetic trajectories in constitutive chemical defenses and nutritional quality, and (2) the role of resource allocation constraints, namely root:shoot (R:S) ratios, in explaining whole plant investment in chemical defenses over time. Overall investment in iridoid glycosides (IGs) signiWcantly increased, while water and nitrogen concentrations in shoot tissues decreased with plant age. SigniWcant variation in IG content between shoot and root tissues across development was observed: allocation of IGs into root tissues linearly increased from younger to older plants, while non-linear shifts in allocation of IGs during ontogeny were observed for shoot tissues. Finally, R:S ratios only weakly explained overall allocation of resources into defenses, with young stages showing a positive relationship, while older stages showed a negative relationship between R:S ratios and IG concentrations. Ontogenetic trajectories in plant quality and defenses within and among plant tissues can strongly inXuence insect herbivores' performance and/or predation risk; thus, they are likely to play a signiWcant role in mediating species interactions.

Journal of Chemical Ecology, 2011

Herbivore-induced plant responses can significantly change as a function of plant developmental s... more Herbivore-induced plant responses can significantly change as a function of plant developmental stage and previous history of damage. Yet, empirical tests that assess the combined role of multiple damage events and age-dependent constraints on the ability of plants to induce defenses within and among tissues are scarce. This question is of particular interest for annual and/or short-lived perennial plant species, whose responses to single or multiple damage events over a growing season are likely to interact with ontogenetic constraints in affecting a plant's ability to respond to herbivory. Using Plantago lanceolata and one of its specialist herbivores, Junonia coenia, we examined the effect of plant ontogeny (juvenile vs. mature developmental stages) and history of damage (single and multiple damage events early and/or late in the season) on plant responses to leaf damage. Plant responses to herbivory were assessed as induced chemical defenses (iridoid glycosides) and compensatory regrowth, in both aboveand below-ground tissues. We found that constitutive concentration of iridoid glycosides markedly increased as plants matured, but plant ability to induce chemical defenses was limited to juvenile, but not mature, plant stages. In addition, induced defenses observed 7 d following herbivory in juvenile plants disappeared 5 wk after the first herbivory event, and mature plants that varied considerably in the frequency and intensity of damage received over 5 wk, did not differ significantly in their levels of chemical defenses. Also, only small changes in compensatory regrowth were detected. Finally, we did not observe changes in below-ground tissues' defenses or biomass a week following 50% removal of leaf tissues at either age class or history of damage. Together, these results suggest that in P. lanceolata and perhaps other systems, ontogenetic trajectories in plant growth and defenses leading to strong age-dependent induced responses may prevail over herbivore-induced indirect interactions.

Neotropical Entomology, 2010

Ormiscodes amphimone (Fabricius) is a phytophagous moth species known to severely defoliate woody... more Ormiscodes amphimone (Fabricius) is a phytophagous moth species known to severely defoliate woody species in Chile and Argentina. Here we document new records of O. amphimonehost associations emphasizing the role of Nothofagus pumilio as its primary host in our study area. This new record for Argentina is highly signifi cant given the economic importance of N. pumilio as a timber resource and the potential of O. amphimone to generate extensive outbreaks.

Biodiversity and Conservation, 2010

Anthropogenic habitat disturbance can have profound effects on multiple components of forest biot... more Anthropogenic habitat disturbance can have profound effects on multiple components of forest biotas including pollinator assemblages. We assessed the effect of small-scale disturbance on local richness, abundance, diversity and evenness of insect pollinator fauna; and how habitat disturbance affected species turnover across the landscape and overall diversity along a precipitation gradient in NW Patagonia (Argentina). We evaluated the effect of disturbance on overall pollinator fauna and then separately for bees (i.e. Apoidea) and non-bee pollinators. Locally, disturbed habitats had significantly higher pollinator species richness and abundances than undisturbed habitats for the whole pollinator assemblage, but not for bees or non-bees separately. However, significant differences in species richness between habitats vanished after accounting for differences in abundance between habitat types. At a local scale Shannon-Weaver diversity and evenness did not vary with disturbance. A b diversity index indicated that, across forest types, species turnover was lower between disturbed habitats than between undisturbed habitats. In addition, rarefaction curves showed that disturbed habitats as a whole accumulated fewer species than undisturbed habitats at equivalent sample sizes. We concluded that small patches of disturbed habitat have a negligible effect on local pollinator diversity; however, habitat disturbance reduced b diversity through a homogenization of the pollinator fauna (in particular of bees) across the landscape.

Ecological Entomology, 2018

Sit and wait predators hunting on flowers are considered to be exploiters of plantepollinator mut... more Sit and wait predators hunting on flowers are considered to be exploiters of plantepollinator mutualisms. Several studies have shown that plantepollinator interactions can be highly susceptible to the impact of a third trophic level, via consumptive (direct) and non-consumptive (indirect) effects that alter pollinator behavior and, ultimately, plant fitness. However, most flowering plants attract a wide array of flower visitors, from which only a subset will be effective pollinators. Hence, a negative effect of an ambush predator on plant fitness should be expected only when: (i) the effective pollinators are part of the predators' diet and/or (ii) the non-consumptive effects of predator presence (e.g. dead prey) alter the behavior of effective pollinators and pollen movement among individual plants. We analyzed the direct and indirect effects of a crab-spider (Misumenops pallidus), on the pollination and reproductive success of Chloraea alpina, a Patagonian rewardless orchid. Our results indicate that most of the flower visitors do not behave as effective pollinators and most effective pollinators were not observed as prey for the crabspider. In terms of non-consumptive effects, inflorescences with and without spiders and/or dead-prey did not vary the frequency of flower visitors, nor pollinia removal or deposition. Hence, it is not surprising that M. pallidus has a neutral effect on pollinia removal and deposition as well as on fruit and seed set. Similar to other rewardless orchids, the low reproductive success of C. alpina (~6% fruit set) was associated with the limited number of visits by effective pollinators. Negative top-down effects of a flower-visitor predator on plant pollination may not be anticipated without studying the direct and indirect effects of this predator on the effective pollinators. In pollination systems where effective pollinators visited flowers erratically, such as in deceptive orchids, we expect weak or no effect of predators on plant fitness.

Neotropical Insect Galls, 2014

ABSTRACT South American temperate forests are of special conservation concern due to their highly... more ABSTRACT South American temperate forests are of special conservation concern due to their highly endemic flora and fauna, and the occurrence of unique plant-animal interactions. Yet, knowledge regarding gall inducers diversity is limited although increasing rapidly in the last two decades. Here, we performed a review of the literature, supplemented with field collected data by the authors, in order to provide the most up to date knowledge of gall inducers’ diversity associated with native woody species of the temperate forest of Chile and Argentina. We present data for 90 morphospecies of galls associated with 39 host-plant species (21 genera, 15 families), spanning insects and arachnids of at least 6 orders and nematodes. Most of this richness is associated to the best surveyed host-plant genus, Nothofagus, with up to 43 morphospecies of galls in just 8 dominant tree species. Moreover, we provide evidence that gall species richness across all woody host-plant species decreases with elevation, probably driven by decreased temperature and number of available host-plant species. However, this overall trend vary among host plant species and scales of observation. Overall, the study of gall diversity and the biotic and abiotic factors that shape their distribution in these austral forests offer an exciting and fertile field for future research. Besides emphasizing the need for more in depth taxonomic and diversity studies of the gall fauna of these forests, we propose several future lines of research that promise to further elucidate our understanding of the evolution of plant-gall interactions in these forests.

Plant-insect interactions, which are strongly mediated by chemical defenses, have the potential t... more Plant-insect interactions, which are strongly mediated by chemical defenses, have the potential to shape invasion dynamics. Despite this, few studies have quantified natural variation in key defensive compounds of invasive plant populations, or how those defenses relate to levels of herbivory. Here, we evaluated variation in the iridoid glycosides aucubin and catalpol in rosette plants of naturally occurring, introduced populations of the North American invader, Verbascum thapsus L. (common mullein; Scrophulariaceae). We examined two scales that are likely to structure interactions with insect herbivores-among populations and within plant tissues (i.e., between young and old leaves). We additionally estimated the severity of damage incurred at these scales due to insect chewing herbivores (predominantly grasshoppers and caterpillars), and evaluated the relationship between iridoid glycoside content and leaf damage. We found significant variation in iridoid glycoside concentrations among populations and between young and old leaves, with levels of herbivory strongly tracking leaf-level investment in defense. Specifically, across populations, young leaves were highly defended by iridoids (averaging 6.59 the concentration present in old leaves, and containing higher proportions of the potentially more toxic iridoid, catalpol) and suffered only minimal damage from generalist herbivores. In contrast, old leaves were significantly less defended and accordingly more substantially utilized. These findings reveal that quantitative variation in iridoid glycosides is a key feature explaining patterns of herbivory in an introduced plant. In particular, these data support the hypothesis that defenses limit the ability of generalists to feed on mullein's well-defended young leaves, resulting in minimal losses of high-quality tissue, and increasing performance of this introduced species.

by Carolina Quintero, Gilbert Adum, Carolina Laura Morales, Konstans Wells, Nicholas Berry, Maria Guiomar Nates Parra, Danilo B Ribeiro, Inge Armbrecht, Dave Goulson, Alain Dejean, T'Ai Roulston, Douglas Yu, Gábor Lövei, Guiomar Nates Parra, Gretchen Lebuhn, and Joseph Hawes

Ecology and evolution, 2014

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habit... more Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadive...

Neotropical Insect Galls, 2014

South American temperate forests are of special conservation concern due to their highly endemic ... more South American temperate forests are of special conservation concern due to their highly endemic fl ora and fauna, and the occurrence of unique plant-animal interactions. Yet, knowledge regarding gall inducers diversity is limited although increasing rapidly in the last two decades. Here, we performed a review of the literature, supplemented with fi eld collected data by the authors, in order to provide the most up to date knowledge of gall inducers' diversity associated with native woody species of the temperate forest of Chile and Argentina. We present data for 90 morphospecies of galls associated with 39 host-plant species (21 genera, 15 families), spanning insects and arachnids of at least 6 orders and nematodes. Most of this richness is associated to the best surveyed host-plant genus, Nothofagus , with up to 43 morphospecies of galls in just 8 dominant tree species. Moreover, we provide evidence that gall species richness across all woody host-plant species decreases with elevation, probably driven by decreased temperature and number of available host-plant species. However, this overall trend vary among host plant species and scales of observation. Overall, the study of gall diversity and the biotic and abiotic factors that shape their distribution in these austral forests offer an exciting and fertile fi eld for future research. Besides emphasizing the need for more in depth taxonomic and diversity studies of the gall fauna of these forests, we propose several future lines of research that promise to further elucidate our understanding of the evolution of plant-gall interactions in these forests.

Physiological and morphological constraints during plant ontogeny affect the expression of numero... more Physiological and morphological constraints during plant ontogeny affect the expression of numerous plant traits relevant to higher trophic levels, such as nutritional content and physical and chemical defenses. Yet we know little about how temporal variation in these traits can directly and/or indirectly mediate tri-trophic interactions, such as those between plants, their herbivores, and herbivore natural enemies. Using four distinct ontogenetic stages of Plantago lanceolata (Plantaginaceae) and the specialist herbivore Junonia coenia (Lepidoptera, Nymphalidae), we evaluated how ontogenetic changes in plant quality can: (1) directly alter plant-herbivore interactions through butterfly oviposition choice and caterpillar performance assays, and (2) indirectly alter herbivores' susceptibility to higher trophic levels through caterpillars' iridoid glycoside sequestration and immune defenses. Results showed that plant defensive traits increased over P. lanceolata development, with leaf tissues becoming tougher and plant allelochemicals (iridoid glycosides) occurring in higher amounts. Conversely, plant nutritional quality (water and nitrogen content) decreased as plants aged. These ontogenetic trajectories strongly altered both direct and indirect interactions between plants and higher trophic levels. Buckeye butterflies showed a stronger oviposition preference for younger developmental stages of P. lanceolata, laying on average 60% more eggs on juvenile than on reproductive plants. Feeding experiments with caterpillars showed that larvae feeding on juvenile plants showed faster relative growth rate and increased digestive efficiency compared with those feeding on plants in the reproductive stage. These individuals, however, acquired lower levels of sequestered chemical defenses than did those feeding on older P. lanceolata plants, potentially rendering them more susceptible to predation. Finally, host plant age altered the ability of a caterpillar to mount an immune response against simulated parasitoid eggs. Specifically, caterpillars reared on older plant life stages, and thus with higher levels of sequestered iridoid glycosides, showed a compromised immune response compared to those feeding on younger plant age classes. This study exemplifies how ontogenetic trajectories in plant traits can scale up to directly or indirectly alter tri-trophic interactions, which may have key implications for understanding temporal shifts in herbivore population and community structure.

Perspectives in Plant Ecology, Evolution and Systematics, 2013

ABSTRACT Plants frequently attract natural enemies of their herbivores, resulting in a reduction ... more ABSTRACT Plants frequently attract natural enemies of their herbivores, resulting in a reduction in tissue damage and often in enhanced plant fitness. While such indirect defenses can dramatically change as plants develop, only recently have ecologists begun to explore such changes and evaluate their role in mediating plant–herbivore–natural enemy interactions. Here we review the literature documenting ontogenetic patterns in plant rewards (i.e. extrafloral nectaries (EFNs), food bodies (FBs) and domatia) and volatile organic compounds (VOCs), and identify links between ontogenetic patterns in such traits and the attraction of natural enemies (ants). In the case of reward traits we concentrate in ant–plant studies, which are the most numerous. We report that all indirect defensive traits commonly vary with plant age but ontogenetic trajectories differ among them. Myrmecophytic species, which provide both food and shelter to their defenders, do not produce rewarding traits until a minimum size is reached. Then, a pronounced increase in the abundance of food rewards and domatia often occurs as plants develop, which explains the temporal succession or colony size increase of mutualistic ant species and, in some cases, leads to a reduction in herbivore damage and enhanced fitness as plants age. In contrast, ontogenetic patterns were less consistent in plant species that rely on VOC emissions to attract natural enemies or those that provide only food rewards (EFNs) but not nesting sites to their associated ants, showing an overall decline or lack of trend with plant development, respectively. Future research should focus on uncovering: (i) the costs and mechanisms underlying ontogenetic variation in indirect defenses, (ii) the relative importance of environmental and genetic components shaping these ontogenetic trajectories, and (iii) the consequences of these ontogenetic trajectories on plant fitness. Advances in this area will shed light on the context dependency of bottom-up and top-down controls of herbivore populations and on how natural selection actually shapes the ontogenetic trajectories of these traits.

Annals of botany, 2013

The lack of studies assessing the simultaneous expression of tolerance and resistance traits duri... more The lack of studies assessing the simultaneous expression of tolerance and resistance traits during seedling development and overall seedling defences as compared with adult plants, in general, constitutes a significant research need that can greatly improve our understanding of overall investment in defences during plant ontogeny. Using two seedling and two juvenile stages of the perennial herb Penstemon virgatus (Plantaginaceae) evaluations were made of (a) patterns of investment in constitutive chemical defences [i.e. iridoid glycosides (IGs)], and (b) simultaneous variation in the short-term ability of seedling and juvenile stages to induce resistance traits, measured as induced chemical defences, or tolerance traits, measured as compensatory re-growth following moderate levels of damage by a specialist insect herbivore. Plants were highly defended during most of their transition from seedling to early juvenile stages, reaching a constant approx. 20 % dry weight total IGs. Furth...

Journal of Chemical Ecology, 2013

Global environmental change alters the supply of multiple limiting resources that regulate plant ... more Global environmental change alters the supply of multiple limiting resources that regulate plant primary and secondary metabolism. Through modifications in resource availability, acquisition, and allocation, global change is likely to influence plant chemical defenses, and consequently species interactions that are mediated by these compounds. While many studies focus on individual global change factors, simultaneous changes in abiotic factors may interact to influence plant allelochemicals. In this study, we examined the individual and interactive effects of nitrogen enrichment and altered precipitation patterns on chemical defense compounds (iridoid glycosides) of an invasive plant, Linaria dalmatica. Plants were grown from seed in native mixed-grass prairie for 2 years. Nitrogen and water treatments were applied in each growing season over this period. Results indicate that soil water and nitrogen availability interact to shape plant chemical defense concentrations in L. dalmatica. Nitrogen addition decreased iridoid glycoside concentrations by approximately 25 % under reduced water availability, increased concentrations by 37 % in ambient water plots, and had no effect on these chemical defenses for plants growing under augmented water supply. Thus, results show differing patterns of allelochemical response to nitrogen enrichment, with respect to both the magnitude and direction of change, depending on water availability. Our study demonstrates the importance of examining multiple environmental factors in order to predict potential changes in plant chemical defenses with climate change.

Oecologia, 2012

Numerous empirical studies have examined ontogenetic trajectories in plant defenses but only a fe... more Numerous empirical studies have examined ontogenetic trajectories in plant defenses but only a few have explored the potential mechanisms underlying those patterns. Furthermore, most documented ontogenetic trajectories in plant defenses have generally concentrated on aboveground tissues; thus, our knowledge regarding whole plant trends in plant defenses throughout development or potential allocation constraints between growth and defenses is limited. Here, we document changes in plant biomass, nutritional quality and chemical defenses for below-and aboveground tissues across seven age classes of Plantago lanceolata (Plantaginaceae) to evaluate: (1) partial and whole plant ontogenetic trajectories in constitutive chemical defenses and nutritional quality, and (2) the role of resource allocation constraints, namely root:shoot (R:S) ratios, in explaining whole plant investment in chemical defenses over time. Overall investment in iridoid glycosides (IGs) signiWcantly increased, while water and nitrogen concentrations in shoot tissues decreased with plant age. SigniWcant variation in IG content between shoot and root tissues across development was observed: allocation of IGs into root tissues linearly increased from younger to older plants, while non-linear shifts in allocation of IGs during ontogeny were observed for shoot tissues. Finally, R:S ratios only weakly explained overall allocation of resources into defenses, with young stages showing a positive relationship, while older stages showed a negative relationship between R:S ratios and IG concentrations. Ontogenetic trajectories in plant quality and defenses within and among plant tissues can strongly inXuence insect herbivores' performance and/or predation risk; thus, they are likely to play a signiWcant role in mediating species interactions.

Journal of Chemical Ecology, 2011

Herbivore-induced plant responses can significantly change as a function of plant developmental s... more Herbivore-induced plant responses can significantly change as a function of plant developmental stage and previous history of damage. Yet, empirical tests that assess the combined role of multiple damage events and age-dependent constraints on the ability of plants to induce defenses within and among tissues are scarce. This question is of particular interest for annual and/or short-lived perennial plant species, whose responses to single or multiple damage events over a growing season are likely to interact with ontogenetic constraints in affecting a plant's ability to respond to herbivory. Using Plantago lanceolata and one of its specialist herbivores, Junonia coenia, we examined the effect of plant ontogeny (juvenile vs. mature developmental stages) and history of damage (single and multiple damage events early and/or late in the season) on plant responses to leaf damage. Plant responses to herbivory were assessed as induced chemical defenses (iridoid glycosides) and compensatory regrowth, in both aboveand below-ground tissues. We found that constitutive concentration of iridoid glycosides markedly increased as plants matured, but plant ability to induce chemical defenses was limited to juvenile, but not mature, plant stages. In addition, induced defenses observed 7 d following herbivory in juvenile plants disappeared 5 wk after the first herbivory event, and mature plants that varied considerably in the frequency and intensity of damage received over 5 wk, did not differ significantly in their levels of chemical defenses. Also, only small changes in compensatory regrowth were detected. Finally, we did not observe changes in below-ground tissues' defenses or biomass a week following 50% removal of leaf tissues at either age class or history of damage. Together, these results suggest that in P. lanceolata and perhaps other systems, ontogenetic trajectories in plant growth and defenses leading to strong age-dependent induced responses may prevail over herbivore-induced indirect interactions.

Neotropical Entomology, 2010

Ormiscodes amphimone (Fabricius) is a phytophagous moth species known to severely defoliate woody... more Ormiscodes amphimone (Fabricius) is a phytophagous moth species known to severely defoliate woody species in Chile and Argentina. Here we document new records of O. amphimonehost associations emphasizing the role of Nothofagus pumilio as its primary host in our study area. This new record for Argentina is highly signifi cant given the economic importance of N. pumilio as a timber resource and the potential of O. amphimone to generate extensive outbreaks.

Biodiversity and Conservation, 2010

Anthropogenic habitat disturbance can have profound effects on multiple components of forest biot... more Anthropogenic habitat disturbance can have profound effects on multiple components of forest biotas including pollinator assemblages. We assessed the effect of small-scale disturbance on local richness, abundance, diversity and evenness of insect pollinator fauna; and how habitat disturbance affected species turnover across the landscape and overall diversity along a precipitation gradient in NW Patagonia (Argentina). We evaluated the effect of disturbance on overall pollinator fauna and then separately for bees (i.e. Apoidea) and non-bee pollinators. Locally, disturbed habitats had significantly higher pollinator species richness and abundances than undisturbed habitats for the whole pollinator assemblage, but not for bees or non-bees separately. However, significant differences in species richness between habitats vanished after accounting for differences in abundance between habitat types. At a local scale Shannon-Weaver diversity and evenness did not vary with disturbance. A b diversity index indicated that, across forest types, species turnover was lower between disturbed habitats than between undisturbed habitats. In addition, rarefaction curves showed that disturbed habitats as a whole accumulated fewer species than undisturbed habitats at equivalent sample sizes. We concluded that small patches of disturbed habitat have a negligible effect on local pollinator diversity; however, habitat disturbance reduced b diversity through a homogenization of the pollinator fauna (in particular of bees) across the landscape.