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Anurag A. Agrawal - One of the best experts on this subject based on the ideXlab platform.
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specialist versus Generalist insect herbivores and plant defense
Trends in Plant Science, 2012Co-Authors: Anurag A. AgrawalAbstract:There has been a long-standing hypothesis that specialist and Generalist insects interact with plants in distinct ways. Although many tests exist, they typically compare only one species of each, they sometimes confound specialization and feeding guild, and often do not link chemical or transcriptional measures of the plant to actual resistance. In this review, we synthesize current data on whether specialists and Generalists actually differ, with special attention to comparisons of their differential elicitation of plant responses. Although we find few consistencies in plant induction by specialists versus Generalists, feeding guilds are predictive of differential plant responses. We outline a novel set of predictions based on current coevolutionary hypotheses and make methodological suggestions for improved comparisons of specialists and Generalists.
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Specialist versus Generalist insect herbivores and plant defense
Trends in Plant Science, 2012Co-Authors: Jared G. Ali, Anurag A. AgrawalAbstract:There has been a long-standing hypothesis that specialist and Generalist insects interact with plants in distinct ways. Although many tests exist, they typically compare only one species of each, they sometimes confound specialization and feeding guild, and often do not link chemical or transcriptional measures of the plant to actual resistance. In this review, we synthesize current data on whether specialists and Generalists actually differ, with special attention to comparisons of their differential elicitation of plant responses. Although we find few consistencies in plant induction by specialists versus Generalists, feeding guilds are predictive of differential plant responses. We outline a novel set of predictions based on current coevolutionary hypotheses and make methodological suggestions for improved comparisons of specialists and Generalists. © 2012 Elsevier Ltd.
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specificity of induced resistance in wild radish causes and consequences for two specialist and two Generalist caterpillars
Oikos, 2000Co-Authors: Anurag A. AgrawalAbstract:Agrawal, A. A. 2000. Specificity of induced resistance in wild radish: causes and consequences for two specialist and two Generalist caterpillars. ‐ Oikos 89: 493‐500. Inducible plant resistance against herbivores is becoming a paradigm of plant‐herbivore ecology. Fundamental to understanding induced resistance and its evolutionary ecology is specificity of ‘‘induction’’ and ‘‘effects’’. Specificity in the induction of resistance refers to whether plant damage by various herbivores causes the same response in plants. Specificity in the effects of induced resistance refers to whether induction has the same consequences (i.e., reduced preference or performance) for various herbivores. I examined both specificity of induction and effect employing four lepidopteran herbivores and wild radish plants, a system for which fitness benefits and costs of induction have been documented for the plant. Variation in the specificity of induction and effects of induced plant resistance was found; however, this variation was not associated with diet specialization in the herbivores (i.e., specialists vs Generalists). Induction caused by Plutella (specialist) and Spodoptera (Generalist) resulted in general resistance to all of the herbivores, induction caused by Pieris (specialist) induced resistance only to Spodoptera (Generalist) and Pieris, and plant damage by Trichoplusia (Generalist) failed to induce resistance and reduce the performance of any of the herbivores. To the contrary, plants damaged by Trichoplusia supported enhanced growth of subsequently feeding Trichoplusia compared to uninduced controls. These results add a novel level of complexity to interactions between plants and leaf chewing caterpillars. Within the same guild of feeders, some herbivores cause strong induced resistance, no induced resistance, or induced susceptibility. Similarly, caterpillar species were variable in the level to which induced resistance affected their performance. Such interactions limit the possibility of pairwise coevolution between plants and herbivores, and suggest that coevolution can only be diffuse.
Rob George - One of the best experts on this subject based on the ideXlab platform.
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the effect of communication skills training for Generalist palliative care providers on patient reported outcomes and clinician behaviors a systematic review and meta analysis
Journal of Pain and Symptom Management, 2017Co-Authors: Lucy E Selman, Lisa Jane Brighton, Amy Hawkins, Christine F Mcdonald, Suzanne Obrien, Vicky Robinson, Shaheen A Khan, Rob GeorgeAbstract:Abstract Context As most end-of-life care is provided by health care providers who are Generalists rather than specialists in palliative care, effective communication skills training for Generalists is essential. Objectives To determine the effect of communication training interventions for Generalist palliative care providers on patient-reported outcomes and trainee behaviors. Methods Systematic review from searches of 10 databases to December 2015 (MEDLINE, EMBASE, PsycINFO, ERIC, CINAHL, CENTRAL, Web of Science, ICTRP, CORDIS, and OpenGrey) plus hand searching. Randomized controlled trials of training interventions intended to enhance Generalists' communication skills in end-of-life care were included. Two authors independently assessed eligibility after screening, extracted data, and graded quality. Data were pooled for meta-analysis using a random-effects model. PRISMA guidelines were followed. Results Nineteen of 11,441 articles were eligible, representing 14 trials. Eleven were included in meta-analyses (patients n = 3144, trainees n = 791). Meta-analysis showed no effect on patient outcomes (standardized mean difference [SMD] = 0.10, 95% CI −0.05 to 0.24) and high levels of heterogeneity (chi-square = 21.32, degrees of freedom [df] = 7, P = 0.003; I 2 = 67%). The effect on trainee behaviors in simulated interactions (SMD = 0.50, 95% CI 0.19–0.81) was greater than in real patient interactions (SMD = 0.21, 95% CI −0.01 to 0.43) with moderate heterogeneity (chi-square = 8.90, df = 5, P = 0.11; I 2 = 44%; chi-square = 5.96, df = 3, P = 0.11; I 2 = 50%, respectively). Two interventions with medium effects on showing empathy in real patient interactions included personalized feedback on recorded interactions. Conclusions The effect of communication skills training for Generalists on patient-reported outcomes remains unclear. Training can improve clinicians' ability to show empathy and discuss emotions, at least in simulated consultations. Personalized feedback on recorded patient interactions may be beneficial. Registration number CRD42014014777.
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a systematic review of end of life care communication skills training for Generalist palliative care providers research quality and reporting guidance
Journal of Pain and Symptom Management, 2017Co-Authors: Lisa Jane Brighton, Amy Hawkins, Christine F Mcdonald, Suzanne Obrien, Vicky Robinson, Shaheen A Khan, Rob George, Jonathan Koffman, Irene J HigginsonAbstract:Abstract Context End-of-life care (EoLC) communication skills training for Generalist palliative care providers is recommended in policy guidance globally. Although many training programs now exist, there has been no comprehensive evidence synthesis to inform future training delivery and evaluation. Objectives To identify and appraise how EoLC communication skills training interventions for Generalist palliative care providers are developed, delivered, evaluated, and reported. Methods Systematic review. Ten electronic databases (inception to December 2015) and five relevant journals (January 2004 to December 2015) were searched. Studies testing the effectiveness of EoLC communication skills training for Generalists were included. Two independent authors assessed study quality. Descriptive statistics and narrative synthesis are used to summarize the findings. Results From 11,441 unique records, 170 reports were identified (157 published, 13 unpublished), representing 160 evaluation studies of 153 training interventions. Of published papers, eight were of low quality, 108 medium, and 41 high. Few interventions were developed with service user involvement ( n = 7), and most were taught using a mixture of didactics ( n = 123), reflection and discussion ( n = 105), and role play ( n = 86). Evaluation designs were weak: n = 85) relied on staff self-reported outcomes to assess effectiveness, and 49% did not cite psychometrically validated measures. Key information (e.g., training duration, participant flow) was poorly reported. Conclusions Despite a proliferation of EoLC communication skills training interventions in the literature, evidence is limited by poor reporting and weak methodology. Based on our findings, we present a CONSORT statement supplement to improve future reporting and encourage more rigorous testing.
William E Snyder - One of the best experts on this subject based on the ideXlab platform.
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Eating their way to the top? Mechanisms underlying the success of invasive insect Generalist predators
Biological Invasions, 2010Co-Authors: David W. Crowder, William E SnyderAbstract:Insect Generalist predators have been introduced outside of their native range intentionally to improve biological control, or accidentally during commerce, and can subsequently become invasive. Invasive insect Generalist predators (IIGP) have widespread impacts on invaded communities because they consume both herbivores and other predators. Also, they often reach higher densities than and displace similar native species. Reflecting the complexity of their ecological roles, a wide variety of mechanisms might contribute to invasive success by IIGP. These species often drive resources to lower levels than do natives, leading to intense resource competition and sometimes competitive exclusion of other predators. The broader range of resources used by many IIGP can heighten their competitive advantage, particularly when IIGP exploit modified habitats. In either case, IIGP improve herbivore suppression by depressing prey densities below pre-invasion levels. Coexistence among native and invasive Generalists is fostered when species differ substantially in their niche requirements. In this case, a larger proportion of the total prey population is subject to attack post- than pre-invasion, which strengthens prey suppression. On the other hand, some IIGP feed heavily on other predators, at times leading to a weakening of prey suppression. Future research should continue to explore the roles of competition and niche partitioning on larger spatial scales, and in both the native and invasive ranges of IIGP. Additionally, combining data from empirical studies with theory might be an effective way to predict the spread and community impacts of IIGP invasions.
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interactions between specialist and Generalist natural enemies parasitoids predators and pea aphid biocontrol
Ecology, 2003Co-Authors: William E Snyder, Anthony R IvesAbstract:Most biological control systems involve a diverse community of natural enemies. We investigated how specialist and Generalist natural enemies differ as biological control agents of pea aphids (Acyrthosiphon pisum), and how interactions among natural enemies affect successful control. In alfalfa, pea aphids are attacked by a specialist parasitoid wasp, Aphidius ervi, and a guild of Generalist predators primarily made up of Nabis and Orius bugs, coccinellid and carabid beetles, and web-building spiders. In three field experiments, we manipulated the parasitoid, then the Generalist predator guild, and finally both classes of natural enemy, and recorded resulting impacts on pea aphid population control. The parasitoid caused little immediate reduction in aphid population growth but caused a large decline after a delay corresponding to the generation time of the parasitoid. In contrast, the Generalist guild caused an immediate decline in the aphid population growth rate. However, the Generalists did not exert density-dependent control, so aphid densities continued to increase throughout the experiment. The third field experiment in which we simultaneously manipulated parasitoids and predators investigated the possibility of “nonadditive effects” on aphid control. Densities of parasitoid pupae were 50% lower in the presence of Generalist predators, indicating intraguild predation. Nonetheless, the ratio of parasitoids to aphids was not changed, and the impact of the two types of natural enemies was additive. We constructed a stage-structured model of aphid, parasitoid, and predator dynamics and fit the model to data from our field experiments. The model supports the additivity of parasitoid and predator effects on aphid suppression but suggests that longer-term experiments (32 d rather than 20 d) would likely reveal nonadditive effects as predation removes parasitoids whose response to aphid densities occurs with a delay. The model allowed us to explore additional factors that could influence the additivity of parasitoid and predator effects. Aphid density-dependent population growth and predator immigration in response to aphid density would likely have little influence on the additivity between parasitism and predation. However, if a parasitoid were to show a strong Type II functional response, in contrast to A. ervi whose functional response is nearly Type I, interactions with predators would likely be synergistic. These analyses reveal factors that should be investigated in other systems to address whether parasitism and predation act additively on host densities. Corresponding Editor: E. Evans.
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Generalist predators disrupt biological control by a specialist parasitoid
Ecology, 2001Co-Authors: William E Snyder, Anthony R IvesAbstract:Two broad classes of arthropod natural enemies attack insect herbivores: specialists and Generalists. The tight dynamical linkage of specialist natural enemies and their prey may make the specialists able to respond numerically to, and perhaps suppress, herbivore outbreaks. Because Generalist predators may attack not only herbivores, but also the herbivores' specialist natural enemies, Generalist predators may disrupt control of herbivore populations rather than contribute to it. We examined interactions between pea aphids (Acyrthosiphon pisum), a specialist parasitoid wasp (Aphidius ervi) that attacks the aphids, and a common Generalist predator, carabid beetles (primarily Pterostichus melanarius). In two field experiments in alfalfa, we manipulated carabid densities to measure their direct (through predation) and indirect (through intraguild predation on A. ervi) impact on aphid population dynamics. The first experiment was initiated when plants were short (following cutting), and carabid predation of a...
Anthony R Ives - One of the best experts on this subject based on the ideXlab platform.
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interactions between specialist and Generalist natural enemies parasitoids predators and pea aphid biocontrol
Ecology, 2003Co-Authors: William E Snyder, Anthony R IvesAbstract:Most biological control systems involve a diverse community of natural enemies. We investigated how specialist and Generalist natural enemies differ as biological control agents of pea aphids (Acyrthosiphon pisum), and how interactions among natural enemies affect successful control. In alfalfa, pea aphids are attacked by a specialist parasitoid wasp, Aphidius ervi, and a guild of Generalist predators primarily made up of Nabis and Orius bugs, coccinellid and carabid beetles, and web-building spiders. In three field experiments, we manipulated the parasitoid, then the Generalist predator guild, and finally both classes of natural enemy, and recorded resulting impacts on pea aphid population control. The parasitoid caused little immediate reduction in aphid population growth but caused a large decline after a delay corresponding to the generation time of the parasitoid. In contrast, the Generalist guild caused an immediate decline in the aphid population growth rate. However, the Generalists did not exert density-dependent control, so aphid densities continued to increase throughout the experiment. The third field experiment in which we simultaneously manipulated parasitoids and predators investigated the possibility of “nonadditive effects” on aphid control. Densities of parasitoid pupae were 50% lower in the presence of Generalist predators, indicating intraguild predation. Nonetheless, the ratio of parasitoids to aphids was not changed, and the impact of the two types of natural enemies was additive. We constructed a stage-structured model of aphid, parasitoid, and predator dynamics and fit the model to data from our field experiments. The model supports the additivity of parasitoid and predator effects on aphid suppression but suggests that longer-term experiments (32 d rather than 20 d) would likely reveal nonadditive effects as predation removes parasitoids whose response to aphid densities occurs with a delay. The model allowed us to explore additional factors that could influence the additivity of parasitoid and predator effects. Aphid density-dependent population growth and predator immigration in response to aphid density would likely have little influence on the additivity between parasitism and predation. However, if a parasitoid were to show a strong Type II functional response, in contrast to A. ervi whose functional response is nearly Type I, interactions with predators would likely be synergistic. These analyses reveal factors that should be investigated in other systems to address whether parasitism and predation act additively on host densities. Corresponding Editor: E. Evans.
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Generalist predators disrupt biological control by a specialist parasitoid
Ecology, 2001Co-Authors: William E Snyder, Anthony R IvesAbstract:Two broad classes of arthropod natural enemies attack insect herbivores: specialists and Generalists. The tight dynamical linkage of specialist natural enemies and their prey may make the specialists able to respond numerically to, and perhaps suppress, herbivore outbreaks. Because Generalist predators may attack not only herbivores, but also the herbivores' specialist natural enemies, Generalist predators may disrupt control of herbivore populations rather than contribute to it. We examined interactions between pea aphids (Acyrthosiphon pisum), a specialist parasitoid wasp (Aphidius ervi) that attacks the aphids, and a common Generalist predator, carabid beetles (primarily Pterostichus melanarius). In two field experiments in alfalfa, we manipulated carabid densities to measure their direct (through predation) and indirect (through intraguild predation on A. ervi) impact on aphid population dynamics. The first experiment was initiated when plants were short (following cutting), and carabid predation of a...
Jared G. Ali - One of the best experts on this subject based on the ideXlab platform.
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Specialist versus Generalist insect herbivores and plant defense
Trends in Plant Science, 2012Co-Authors: Jared G. Ali, Anurag A. AgrawalAbstract:There has been a long-standing hypothesis that specialist and Generalist insects interact with plants in distinct ways. Although many tests exist, they typically compare only one species of each, they sometimes confound specialization and feeding guild, and often do not link chemical or transcriptional measures of the plant to actual resistance. In this review, we synthesize current data on whether specialists and Generalists actually differ, with special attention to comparisons of their differential elicitation of plant responses. Although we find few consistencies in plant induction by specialists versus Generalists, feeding guilds are predictive of differential plant responses. We outline a novel set of predictions based on current coevolutionary hypotheses and make methodological suggestions for improved comparisons of specialists and Generalists. © 2012 Elsevier Ltd.
