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Anthony Joern – One of the best experts on this subject based on the ideXlab platform.

  • Grasshopper Fecundity Responses to Grazing and Fire in a Tallgrass Prairie
    Environmental Entomology, 2011
    Co-Authors: Angela N. Laws, Anthony Joern

    Grasshopper abundance and diversity vary with management practices such as fire and grazing. Understanding how grasshopper life history traits such as fecundity respond to management practices is key to predicting grasshopper population dynamics in heterogeneous environments. Landscape-level experimental fire and bison grazing treatments at the Konza Prairie Biological Station (Manhattan, KS) provide an opportunity to examine how management affects grasshopper fecundity. Here we report on grasshopper fecundity for nine common species at Konza Prairie. From 2007 to 2009, adult female Grasshoppers were collected every 3 wk from eight watersheds that varied in fire and grazing treatments. Fecundity was measured by examining female reproductive tracts, which contain a record of past and current reproductive activity. Body size was a poor predictor of fecundity for all species. Despite large differences in vegetation structure and composition with management regime (grazing and fire interval), we observed little effect of management on grasshopper fecundity. Habitat characteristics (grasshopper density, vegetation biomass, and vegetation quality; measured in 2008 and 2009) were better predictors of past fecundity than current fecundity, with species-specific responses. Fecundity increased throughout the summer, indicating that Grasshoppers were able to acquire sufficient nutritional resources for egg production in the early fall when vegetation quality is generally low. Because fecundity did not vary across management treatments, population stage structure may be more important for determining population level reproduction than management regime at Konza Prairie.

  • grasshopper orthoptera acrididae communities respond to fire bison grazing and weather in north american tallgrass prairie a long term study
    Oecologia, 2007
    Co-Authors: Jayne L. Jonas, Anthony Joern

    Because both intrinsic and extrinsic factors influence insect population dynamics, operating at a range of temporal and spatial scales, it is difficult to assess their contributions. Long-term studies are ideal for assessing the relative contributions of multiple factors to abundance and community dynamics. Using data spanning 25 years, we investigate the contributions of weather at annual and decadal scales, fire return interval, and grazing by bison to understand the dynamics of abundance and community composition in grasshopper assemblages from North American continental grassland. Each of these three primary drivers of grassland ecosystem dynamics affects grasshopper population and community dynamics. Negative feedbacks in abundances, as expected for regulated populations, were observed for all feeding guilds of Grasshoppers. Abundance of Grasshoppers did not vary in response to frequency of prescribed burns at the site. Among watersheds that varied with respect to controlled spring burns and grazing by bison, species composition of grasshopper assemblages responded significantly to both after 25 years. However, after more than 20 years of fire and grazing treatments, the number of years since the last fire was more important than the managed long-term fire frequency per se. Yearly shifts in species composition (1983-2005), examined using non-metric multidimensional scaling and fourth-corner analysis, were best explained by local weather events occurring early in grasshopper life cycles. Large-scale patterns were represented by the Palmer Drought Severity Index and the North Atlantic Oscillation (NAO). The NAO was significantly correlated with annual mean frequencies of Grasshoppers, especially for forb- and mixed-feeding species. Primary grassland drivers-fire, grazing and weather-contributing both intrinsic and extrinsic influences modulate long-term fluctuations in grasshopper abundances and community taxonomic composition.

  • sustainable management of insect herbivores in grassland ecosystems new perspectives in grasshopper control
    BioScience, 2006
    Co-Authors: David H Branson, Anthony Joern, Gregory A Sword

    Grasshoppers are insect herbivores common to grassland ecosystems worldwide. They comprise important components of biodiversity, contribute significantly to grassland function, and periodically exhibit both local and large-scale outbreaks. Because of Grasshoppers‘ potential economic importance as competitors with ungulate grazers for rangeland forage, periodic grasshopper outbreaks in western US rangeland often elicit intervention over large areas in the form of chemical control. Available information combined with alternative underlying conceptual frameworks suggests that new approaches for sustainable management of grasshopper outbreaks in US rangeland should be pursued. There are many reasons to believe that approaches to grasshopper management that aim to reduce or prevent outbreaks are possible. These habitat manipulation tactics maintain existing ecological feedbacks responsible for sustaining populations at economically nonthreatening levels. Sustainable strategies to minimize the likelihood and extent of grasshopper outbreaks while limiting the need for chemical intervention are a rational and attainable goal for managing grasslands as renewable resources.

Oswald J. Schmitz – One of the best experts on this subject based on the ideXlab platform.

  • Fear on the move: predator hunting mode predicts variation in prey mortality and plasticity in prey spatial response
    Journal of Animal Ecology, 2013
    Co-Authors: Jennifer R. B. Miller, Judith M. Ament, Oswald J. Schmitz

    Summary 1. Ecologists have long searched for a framework of a priori species traits to help predict predator–prey interactions in food webs. Empirical evidence has shown that predator hunting mode and predator and prey habitat domain are useful traits for explaining predator–prey interactions. Yet, individual experiments have yet to replicate predator hunting mode, calling into question whether predator impacts can be attributed to hunting mode or merely species identity. 2. We tested the effects of spider predators with sit-and-wait, sit-and-pursue and active hunting modes on grasshopper habitat domain, activity and mortality in a grassland system. We replicated hunting mode by testing two spider predator species of each hunting mode on the same grasshopper prey species. We observed Grasshoppers with and without each spider species in behavioural cages and measured their mortality rates, movements and habitat domains. We likewise measured the movements and habitat domains of spiders to characterize hunting modes. 3. We found that predator hunting mode explained grasshopper mortality and spider and grasshopper movement activity and habitat domain size. Sit-and-wait spider predators covered small distances over a narrow domain space and killed fewer Grasshoppers than sit-and-pursue and active predators, which ranged farther distances across broader domains and killed more Grasshoppers, respectively. Prey adjusted their activity levels and horizontal habitat domains in response to predator presence and hunting mode: sedentary sit-and-wait predators with narrow domains caused Grasshoppers to reduce activity in the same-sized domain space; more mobile sit-and-pursue predators with broader domains caused prey to reduce their activity within a contracted horizontal (but not vertical) domain space; and highly mobile active spiders led Grasshoppers to increase their activity across the same domain area. All predators impacted prey activity, and sit-and-pursue predators generated strong effects on domain size. 4. This study demonstrates the validity of utilizing hunting mode and habitat domain for predicting predator–prey interactions. Results also highlight the importance of accounting for flexibility in prey movement ranges as an anti-predator response rather than treating the domain as a static attribute.

  • herbivore physiological response to predation risk and implications for ecosystem nutrient dynamics
    Proceedings of the National Academy of Sciences of the United States of America, 2010
    Co-Authors: Dror Hawlena, Oswald J. Schmitz

    The process of nutrient transfer through an ecosystem is an important determinant of production, food-chain length, and species diversity. The general view is that the rate and efficiency of nutrient transfer up the food chain is constrained by herbivore-specific capacity to secure N-rich compounds for survival and production. Using feeding trials with artificial food, we show, however, that physiological stress-response of grasshopper herbivores to spider predation risk alters the nature of the nutrient constraint. Grasshoppers facing predation risk had higher metabolic rates than control Grasshoppers. Elevated metabolism accordingly increased requirements for dietary digestible carbohydrate-C to fuel-heightened energy demands. Moreover, digestible carbohydrate-C comprises a small fraction of total plant tissue-C content, so nutrient transfer between plants and herbivores accordingly becomes more constrained by digestible plant C than by total plant C:N. This shift in herbivore diet to meet the altered nutrient requirement increased herbivore body C:N content, the C:N content of the plant community from which Grasshoppers select their diet, and grasshopper fecal C:N content. Chronic predation risk thus alters the quality of animal and plant tissue that eventually enters the detrital pool to become decomposed. Our results demonstrate that herbivore physiology causes C:N requirements and nutrient intake to become flexible, thereby providing a mechanism to explain context dependence in the nature of trophic control over nutrient transfer in ecosystems.

  • Weather variation and trophic interaction strength: sorting the signal from the noise
    Oecologia, 2004
    Co-Authors: Ofer Ovadia, Oswald J. Schmitz

    Weather can have important consequences for the structure and function of ecological communities by substantially altering the nature and strength of species interactions. We examined the role of intra- and inter-annual weather variability on species interactions in a seasonal old-field community consisting of spider predators, grasshopper herbivores, and grass and herb plants. We experimentally varied the number of trophic levels for 2 consecutive years and tested for inter-annual variation in trophic abundances. Grasshopper emergence varied between years to the extent that the second growing season was 20% shorter than the first one. However, the damage Grasshoppers inflicted on plants was greater in the second, shorter growing season. This inter-annual variation in plant abundance could be explained using the foraging-predation risk trade-off displayed by Grasshoppers combined with their survival trajectory. Decreased grasshopper survival not only reduced the damage inflicted on plants, it weakened the strength of indirect effects of spiders on grass and herb plants. The most influential abiotic factor affecting grasshopper survival was precipitation. We found a negative association between grasshopper survival and the total yearly precipitation. A finer scale analysis, however, showed that different precipitation modalities, namely, number of rainy days and average precipitation per day, had opposing effects on grasshopper survival, which were inconsistent between years. Furthermore, our results suggest that small changes in these factors should result in changes of up to several orders of magnitude in the mortality rate of Grasshoppers. We thus conclude that in this system the foraging-predation risk trade-off displayed by Grasshoppers combined with their survival trajectory and relevant weather variability should be incorporated in analytical theory, whose goal is to predict community dynamics.

Isabelle Badenhausser – One of the best experts on this subject based on the ideXlab platform.

  • enhancing grasshopper orthoptera acrididae communities in sown margin strips the role of plant diversity and identity
    Arthropod-plant Interactions, 2015
    Co-Authors: Isabelle Badenhausser, Nicolas Gross, Stephane Cordeau, L Bruneteau, M Vandier

    Grasshoppers are important components of grassland invertebrate communities, particularly as nutrient recyclers and as prey for many bird species. Sown margin strips are key features of agri-environmental schemes in European agricultural landscapes and have been shown to benefit Grasshoppers depending on the initial sown seed mixture. Understanding the mechanisms by which the sown mixture impacts Grasshoppers in sown margin strips is the aim of our study. Here, we investigated plant–grasshopper interactions in sown margin strips and the respective effects of plant identity and diversity on Grasshoppers. We surveyed plants and Grasshoppers in 44 sown margin strips located in Western France which were initially established with three sowing mixtures dominated, respectively, by alfalfa, Festuca rubra and Lolium perenne and Festuca arundinacea. Grasshopper species contrasted in their response to plant diversity and to the abundance of sown and non-sown plant species. Some grasshopper species were positively correlated with the abundance of grass and especially of a single sown plant species, F. rubra. In contrast, other grasshopper species benefited from high plant diversity likely due to their high degree of polyphagy. At the community level, these contrasted responses were translated into a positive linear relationship between grass cover and grasshopper abundance and into a quadratic relationship between plant diversity and grasshopper diversity or abundance. Since plant identity and diversity are driven by the initial sown mixture, our study suggests that by optimizing the seed mixture, it is possible to manage grasshopper diversity or abundance in sown margin strips.

  • Herbivore effect traits and their impact on plant community biomass: an experimental test using Grasshoppers
    Functional Ecology, 2015
    Co-Authors: Hélène Deraison, Isabelle Badenhausser, Lucas Borger, Nicolas Gross

    1. Using trait-based approaches to study trophic interactions may represent one of the most promising approaches to evaluate the impact of trophic interactions on ecosystem functioning. To achieve this goal, it is necessary to clearly identify which traits determine the impact of one trophic level on another. 2. Using functionally contrasting grasshopper species, we tested the ability of multiple traits (morphological, chemical and biomechanical) to predict herbivore impact on the biomass of a diverse plant community. We set-up a cage experiment in an old species rich grassland field and evaluated how multiple candidate grasshopper effect traits mediated herbivore impact on plant biomass.3. Grasshoppers had different impact on plant community biomass (consuming up to 60% of plant community biomass). Grasshopper impact was positively correlated with their incisive strength while body size or grasshopper C:N ratio exhibited low predictive ability. Importantly, the strong relationship between the incisive strength and the impact was mediated by the grasshopper feeding niche, which was well predicted in our study by two simple plant traits (leaf dry matter content, leaf C:N ratio). Feeding niche differences between Grasshoppers were explained by differences in incisive strength, highlighting the fundamental linkage between grasshopper effect traits and their niche.4. Our study contributes to the development of the trait-based approach in the study of trophic interactions by providing a first experimental test of the relationship between herbivore effect traits, their impact on plant community biomass, and in a larger extent on ecosystem functioning. By comparing the relative importance of multiple interacting grasshopper traits, our study showed that incisive strength was a key effect trait which determined grasshopper feeding niche and its relative impact on plant community biomass.

  • Sown grass strip – A stable habitat for Grasshoppers (Orthoptera: Acrididae) in dynamic agricultural landscapes
    Agriculture Ecosystems and Environment, 2012
    Co-Authors: Isabelle Badenhausser, Stephane Cordeau

    This study assessed the benefits of sown grass strips on grasshopper communities in intensive farmland, and the effects of farming practices and landscape context. Results showed that sown grass strips were high quality habitats for Grasshoppers compared to grasslands. Farming practices influenced grasshopper densities in sown grass strips while landscape context affected more the species richness of Grasshoppers. Sown mixture and cutting export option were the main factors driving grasshopper density. Mixtures composed of grasses without legumes were the best, as well as hay export compared to no export. Increased grasshopper species richness occurred in sown grass strips located in landscapes with low grassland field availability and high connectivity. Enhanced use of sown grass strips by Grasshoppers can be seen as a direct effect of establishment and management options, but also as an effect of the rarity and instability of other grassland habitats in agricultural landscapes.

Brian Dennis – One of the best experts on this subject based on the ideXlab platform.

Alexandre V Latchininsky – One of the best experts on this subject based on the ideXlab platform.

  • locust and grasshopper management
    Annual Review of Entomology, 2019
    Co-Authors: Long Zhang, Alexandre V Latchininsky, Michel Lecoq, David Hunter

    Locusts and Grasshoppers (Orthoptera: Acridoidea) are among the most dangerous agricultural pests. Their control is critical to food security worldwide and often requires governmental or international involvement. Although locust and grasshopper outbreaks are now better controlled and often shorter in duration and reduced in extent, large outbreaks, often promoted by climate change, continue to occur in many parts of the world. While some locust and grasshopper control systems are still curative, the recognition of the damage these pests can cause and the socioeconomic consequences of locust and grasshopper outbreaks have led to an increasing paradigm shift from crop protection to preventive management. Effective preventive management strategy relies on an improved knowledge of the pest biology and ecology and more efficient monitoring and control techniques.

  • market basket analysis of grasshopper orthoptera acrididae assemblages in eastern wyoming a 17 year case study using associative analysis for ecological insights into grasshopper outbreaks
    Ecological Entomology, 2017
    Co-Authors: Douglas I Smith, Michael F Curran, Alexandre V Latchininsky

    1. This study utilised an associative analysis (AA) technique named market basket analysis (MBA) to investigate whether particular grasshopper (Orthoptera: Acrididae) species associations are common during outbreaks (>9.6 Grasshoppers m⁻²) that last >3 years. This study is the first of its kind to use MBA on animal communities. 2. A subset of the 17 years of grasshopper density data from the Wyoming Grasshopper Survey Dataset was used to explore associations among grasshopper species. 3. Associations of certain species were found with over 80% confidence. Life‐history traits of those species commonly found together were examined and compared (a posteriori), creating opportunities to hypothesise certain ecological relationships (e.g. interspecific competition, indirect mutualism) for future studies. 4. This case study shows that further MBA analysis of grasshopper assemblages should prove useful in discovering ecological relationships of grasshopper species during outbreaks. Preliminary examples are demonstrated.

  • Laboratory Bioassays of Vegetable Oils as Kairomonal Phagostimulants for Grasshoppers (Orthoptera: Acrididae)
    Journal of Chemical Ecology, 2007
    Co-Authors: Alexandre V Latchininsky, Scott P. Schell, Jeffrey A. Lockwood

    Vegetable oils have kairomonal attractant properties to Grasshoppers primarily due to the presence of linoleic and linolenic fatty acids. These fatty acids are dietary essentials for Grasshoppers and, once volatilized, can be detected by the insects’ olfactory receptors. A laboratory bioassay method has been developed to identify vegetable oils that have fatty acid profiles similar to Grasshoppers and that induce grasshopper attraction and feeding. Such oils could be useful kairomonal adjuvants and/or carriers for acridicide formulations. Three sets of laboratory bioassays demonstrated that the addition of a standard aliquot of different vegetable oils resulted in varying degrees of grasshopper feeding on otherwise neutral substrates. Addition of olive oil stimulated the greatest feeding in all three sets of assays, regardless of the age of the tested insects. Furthermore, addition of canola or flax oils markedly enhanced grasshopper feeding. These three oils—i.e., olive, canola, and flax oil—proved to be the best performing grasshopper stimulants. A second group of oils included rapeseedflax mix and rapeseed oils; however, their performance was not as consistent as oils in the first group—especially with regard to nymphal feeding. A third group of oils consisted of soybean, corn, peanut, and sunflower oil. Theoretical expectations regarding these oils varied wildly, suggesting that the results of a single bioassay should be cautiously interpreted as being negative.