Source: TEXAS A&M UNIVERSITY submitted to
NUTRIENT NICHES: USING NUTRITIONAL ECOLOGY TO PREDICT RANGELAND GRASSHOPPER OUTBREAKS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
0230251
Grant No.
2012-67011-19930
Cumulative Award Amt.
$74,823.00
Proposal No.
2012-01162
Multistate No.
(N/A)
Project Start Date
Aug 15, 2012
Project End Date
Aug 14, 2014
Grant Year
2012
Program Code
[A7101]- AFRI Predoctoral Fellowships
Project Director
Lenhart, P. A.
Recipient Organization
TEXAS A&M UNIVERSITY
750 AGRONOMY RD STE 2701
COLLEGE STATION,TX 77843-0001
Performing Department
Entomology
Non Technical Summary
Insect outbreaks inflict tremendous damage. Despite years of study the root causes of outbreaks are still poorly understood. Recently it has been suggested that new insights regarding outbreaks might be found by applying a new, more integrative, nutritional approach. One model system to which a nutritional approach could be applied is rangeland grasshoppers, which usually occur in communities of multiple pest species. Recent work using this approach has shown that different grasshopper species regulate their intake of key nutrients (protein/carbohydrates) in different amounts and ratios. These species-specific nutrient requirements might reduce competition. Under certain conditions, this could favor outbreaks of particular species. The goal of this research is to determine whether and how different nutrient requirements affect different grasshopper populations. I will first document the natural diet of common outbreaking rangeland grasshoppers by analyzing the gut content of field-collected grasshoppers. Second, I will identify nutrient (protein/carbohydrate) requirements for each of these species using laboratory feeding experiments. Third, I will assess how differences in species' nutrient requirements correlate with competition between grasshopper species, and the resulting population density of each. This will be explored using both greenhouse and field experiments, using species identified by the first two objectives. The expected outcome of this research is a better understanding of how host plant use and nutrient regulation relate to insect outbreaks. Insights from this study will improve our ability to predict and manage rangeland grasshopper populations.
Animal Health Component
40%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2113110101050%
1210799107050%
Goals / Objectives
The goal of this research is to determine if coexisting generalist herbivores occupy different nutrient niches and how such nutrient niches relate to grasshopper outbreaks. I propose to combine field sampling as well as laboratory, greenhouse, and field experiments to reach this goal. Specifically, I plan to address three objectives. 1) Document host plant use for a number of common rangeland grasshoppers that often show population outbreaks. 2) Determine macronutrient (protein:carbohydrate) intake targets for each of these species. 3) Assess how differences in nutrient intake correlate with inter-specific competition and population density. To evaluate progress toward achieving the project objectives several milestones are set up, which will signify the completion of a distinct phase of the research. By December of 2012, I will have determined the diet for a suite of coexisting grasshoppers at the site, analyzed, and presented the results at a national meeting. By April of 2013, I will have determined the nutrient intake targets of these same grasshopper species, and used this data, in conjunction with the host plant diet dataset, to choose 3 focal species for use in some following competition experiments. By December of 2013, I will have conducted the field cage competition study and submitted manuscripts based on the objectives 1 and 2 experiments for publication in a refereed journal. By May of 2014, I will have conducted the greenhouse competition study, written and defended my PhD dissertation, and have prepared drafts of my final manuscripts for publication in refereed journals. The expected outcomes of this research include publications in refereed scientific journals, presentations at national meetings of the Ecological Society of America and Entomological Society of America, and the completion of a PhD.
Project Methods
To determine the host plant use of coexisting rangeland grasshopper species, I will analyze the crop of individuals previously collected from a grassland in central Texas. These grasshoppers will represent the 10 most abundant species at the field site. From August to September, 2012, crop contents will be removed in the laboratory and analyzed under a microscope to identify plant species using epidermis and trichome characteristics. The percentage of each plant species in a crop will be estimated. Grasshopper species with similar diets will be identified, using Nonparametric Multidimensional Scaling (NMDS). This objective will be completed by December of 2012 and efforts to share these results will include presentation at a national meeting in 2012 and publication in a refereed journal by December 2013. To determine the protein:carbohydrate nutrient intake targets of the 10 most abundant species at the field site, a standard methodology developed in the context of the Geometric Framework approach will be used. Captive reared grasshoppers in their final nymphal instar will be fed combinations of artificial diet of known nutritional content. ANCOVA and MANCOVA techniques will be used to analyze whether food consumption is non-random, and if there are significant inter-specific differences. This objective will be completed by April, 2013 and efforts to share these results will include presentation at a national meeting in 2013 and publication in a refereed journal by December 2013. By comparing the relative effect of inter-specific competition between different species pairings, I can test the hypothesis that species with similar nutrient intake target ratios are more likely to compete. I will conduct parallel competition experiments in the greenhouse and in the field. The species used in this experiment will be chosen based on the findings of objective 1 and 2. The experiment will follow grasshopper development over several molts. I will measure and compare several estimates of fitness between individuals in monoculture, and those caged with another species to assess the relative strength of inter-specific competition. Estimates of fitness will include body size, body mass, and lipid content. Differences in survival will be tested with survival analysis. Differences in the estimates of fitness will be compared using ANOVA. The field study, during May-June of 2013, will utilize cages placed over natural plant assemblages. The greenhouse study, conducted in January of 2014, will use mesh cages supplied with a mix of 3 plant species. This design will be utilized because many rangeland grasshopper species are believed to be true generalists (meaning an individual will feed on many different host plant species within a short period of time). These experiments will run until grasshoppers reach adulthood, or until vegetation is almost completely consumed. Both experiments in this objective will be completed by May 2014 and efforts to share these results will include presentation at a national meeting in 2013 and submitted manuscripts to a refereed journal by August 2014.

Progress 08/15/12 to 08/14/14

Outputs
Target Audience: Results of the study were disseminated in oral and poster presentations at national meetings of the Ecological Society of America, Entomological Society of America, Society for Integrative and Comparative Biology, and Gordon Conference on Plant-Herbivore interactions as well as Texas A&M University's Ecological Integrated Symposium. During these presentations results were presented to student and professional entomologists, ecologists, and other biological researchers from around the world.I was also invited to present the results at a seminar for the University of Kentucky department of biology and a forthcoming symposium at the 2014 meeting of the Entomological Society of America. Members of the public were engaged in outreach presentations tothe Brazos Valley chapter of the Texas Master Naturalists, Southwood Valley Elementary's Science Night (College Station, TX), Galatas Elementary School (Woodlands, TX), Houston-area high school students during a career fair at Texas A&M University, and to central Texaslandowners via the Texas Ecolab program. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project has allowed for extensive training from my two mentors (Drs. Spencer Behmer & Micky Eubanks) in terms of experimental design and execution, data analysis, creating effective presentations, writing manuscripts, networking with colleagues, applying for grants, teaching, and planning for my future career. I have gained a great deal of experience in community and nutritional ecology methodology. Progress was monitored through weekly lab meetings as well as frequent one-on-one meetings with either mentor. This training culminated in my graduation from Texas A&M with a Ph.D. in Entomology and my acceptance of a postdoctoral scholar position in the Department of Entomology at the University of Kentucky. During the period of this project I was engaged in many professional development activities. I attended a 4 week POWER writing studio in April 2013 offered by the Texas A&M College of Education and Human Development. I attended the department of Texas A&M Entomology's weekly seminars as well as those hosted by the Ecology and Evolutionary Biology program which features invited speakers. I attended all graduate student lunch meetings with the speakers. I have also had the opportunity to meet colleagues at meetings of the Entomological Society of America, Ecological Society of America, Gordon Conference on Plant-Herbivore interactions, and Texas A&M Ecological Integrated Symposium. How have the results been disseminated to communities of interest? Results have been disseminated at oral and poster presentations at theEntomological Society of America, Ecological Society of America, Society for Integrative and Comparative Biology, Gordon Conference on Plant-Herbivore interactions, and Texas A&M Ecological Integrated Symposium (see 'Products"), and are featured in my dissertation, a published manuscript in the journal Oikos, and three upcoming manuscripts. To reach member of other communities I have conducted outreach activities at the Brazos Valley chapter of the Texas Master Naturalists, Southwood Valley Elementary's Science Night (College Station, TX), Galatas Elementary School (Woodlands, TX), Houston-area high school students during a career fair at Texas A&M University, and to central Texaslandowners via the Texas Ecolab program. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Insect outbreaks inflict tremendous damage. Recently it has been suggested that new insights regarding outbreaks might be found by applying a new, more integrative, nutritional approach. One model system to which a nutritional approach could be applied is rangeland grasshoppers, which usually occur in communities of multiple pest species. Previous work shows that different grasshopper species regulate their intake of key nutrients (protein/carbohydrates) to different amounts and ratios. I hypothesized that these species-specific nutrient requirements might reduce competition. Under certain conditions, this could favor outbreaks of particular species. To investigate this I documented the natural diet of common rangeland grasshoppers. I found that among a suite of 11 grasshopper species, diets were highly overlapping, implying the species do compete for resources. Second, I identified nutrient (protein/carbohydrate) requirements for each of these species using laboratory feeding experiments. Nutrient requirements differed significantly between species in relation to diet and taxa. Many species with strongly overlapping diets had significantly different nutrient requirements. Third, I assessed whether differences in species’ nutrient requirements predict competitive outcomes between grasshopper species. We only found mixed support for the effect of nutrient requirements on competition, with stronger effects of grasshopper body size. However, by comparing nutrient regulation in multiple coexisting and related species we gained a greater understanding of feeding in herbivorous pest insects. At a basic level this study raises interesting questions about whether nutrient requirements adapt to host foods and how they might evolve. At the more applied level my data on optimal nutrient requirements for different grasshopper species could be compared against the nutrient content of rangeland forage, allowing more targeted control of outbreaking rangeland grasshoppers. Objective 1. My first objective was to document host plant use for a number of common rangeland grasshoppers that often show population outbreaks. This objective was completed during the first year of funding. I documented host plant use for each species via microscopic analysis of gut content. Gut content analysis allowed me to assign species to functional feeding (grass-, forb-, and mixed-feeders). Diets of the 11 grasshopper species examined displayed a high degree of resource utilization overlap. Comparing Pianka indices of the sampled and simulated communities revealed that niche overlap was significantly greater than the expected level of overlap. This means that, in general, species were sharing trophic niches. On average, 90% of a grasshopper species diet was composed of diet categories, i.e., plant morphospecies, which were shared by another grasshopper species. By analyzing the diets of this focal suite of species I was able to accurately compare nutrient regulation (see objective 2) to diets in the same population of grasshoppers. Previous work relied on separate diet studies in the literature at the species level, which can vary between sites. This study also resulted in a change in knowledge by providing for the first time diets for a central Texas rangeland grasshopper community. Multiple presentations at conferences have been given to disseminate these results (see ‘Products’), it constitutes a chapter in my Ph.D. dissertation (combined with objective 2), and a manuscript detailing these results is currently being prepared for submission. Objective 2. The second objective of my study was to determine macronutrient (protein:carbohydrate) intake targets for each of the species studied in objective 1. This objective was completed during the first year of funding. My study identified self-selected protein-carbohydrate intake for a suite of coexisting grasshopper species. I investigated the intake results in the context of relatedness (taxonomy), host plant range, and body size to better understand factors that might determine a species’ protein-carbohydrate preferences. I collected grasshoppers from the field as nymphs, reared each species in the laboratory, and subjected them to artificial diet experiments to determine their self-selected protein-carbohydrate intake. My laboratory feeding studies revealed that all species actively regulated for protein-carbohydrate intake. Self-selected protein-carbohydrate intake across the entire community was more carbohydrate-biased than previous studies. The ratio of protein:carbohydrate regulated for differed between species, and corresponded to differences in diet and taxa, but not body size. In the case of mixed-feeding Melanoplinae, differences could be the result of niche partitioning since there was a negative relationship among species between diet similarity and nutrient intake similarity. This study developed a change in knowledge by providing further understanding of patterns in nutrient regulation across species. I nearly doubled the number of species with known macronutrient intake targets in the most studied group: grasshoppers. I observed stark differences in the general distribution of macronutrient intake, which may be related to phylogeny, temperature/latitude, functional feeding-group differences, and perhaps competition. Multiple presentations at conferences have been given to disseminate these results (see ‘Products’), it constitutes a chapter in my Ph.D. dissertation (combined with objective 1), and a manuscript detailing these results is currently being prepared for submission. Objective 3. The third objective of my research was to assess how differences in nutrient intake correlate with inter-specific competition and population density. This objective was completed during the second year of funding. I investigated this hypothesis in greenhouse microcosms using three species of generalist grasshoppers with overlapping diets, but either similar or dissimilar nutrient intake targets. Field caught grasshopper nymphs from Central Texas were caged in either monoculture, or mixed species treatments on a standard mixed plant community with one grass and two forb species. Grasshoppers in the experimental microcosms had high mortality rates in all species treatments. Forbs were the limiting resource and all species engaged in cannibalism. Analysis of cage population decline revealed competitive differences between species, but the patterns of survival gave only mixed support for the predictions of the nutrient niche hypothesis. Mortality differences were more likely linked to body size differences between species. Nutrient requirement differences have, at most, a weak effect on interspecific interactions, at least among the species tested. Nutrient requirement differences could effect interspecific competition, but via its effect on host plant selection, and would be secondary to other factors in the field such as body size. This objective provided a change in knowledge by showing that our hypothesized “nutrient niches” may not be a strong factor shaping rangeland grasshopper communities. Although I found only found mixed support for the nutrient niche hypothesis among the species tested, this study made some considerable advances in linking findings from the geometric framework with field-relevant biology. Future work will need to focus on how nutrient intake targets relate to macronutrient content of host plants, how plant defenses complicate nutrient regulation, and compare macronutrient intake targets in a phylogenetic context. Multiple presentations at conferences have been given to disseminate these results (see ‘Products’), it constitutes a chapter in my Ph.D. dissertation, and a manuscript detailing these results is currently being prepared for submission.

Publications

  • Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2014 Citation: Lenhart, P.A. 2014 Nutrient niches: An investigation of nutritional ecology in a generalist herbivore community Dissertation. Texas A&M University.
  • Type: Conference Papers and Presentations Status: Submitted Year Published: 2014 Citation: Lenhart, P.A. 2014 Combining nutrition and community ecology of grasshoppers to benefit ecosystems and people Annual Meeting of the Entomological Society of America. Portland, Oregon.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Clissold, F.J., Richardson, A., Lenhart, P.A., Behmer, S.T., and Simpson, S.T. 2014. Is the ability to gain carbohydrate driving the evolution and ecology of an insect herbivore, the grasshopper? Annual meeting of the Society for Integrative and Comparative Biology, Austin, Texas
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Behmer, S.T., and Eubanks, M.D. 2013 Competition between generalist herbivores: effects of nutrient regulation and body size Annual Meeting of the Entomological Society of America. Austin, Texas.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Behmer, S.T., and Eubanks, M.D. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores 98th annual Ecological Society of America meeting. Minneapolis, Minnesota.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2012 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2012 Diet breadth and macronutrient regulation reveal how generalist herbivores coexist Annual Meeting of the Entomological Society of America. Knoxville, Tennessee
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores Student Research Week, Texas A&M University, College Station, Texas
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores Ecological Integrated Symposium, Texas A&M University, College Station, Texas
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores Plant-Herbivore Interactions Gordon Research Conference, Ventura, California
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2014 Citation: Lenhart P.A., Eubanks M.D., and Behmer S.T. 2014. Water stress in grasslands: the dynamic response of plants and insect herbivores. Oikos. doi: 10.1111/oik.01370


Progress 08/15/13 to 08/14/14

Outputs
Target Audience: During the current reporting period results of the study were disseminated in oral presentations at national meetings of the Ecological Society of America and Entomological Society of America. During these presentations results were presented to student and professional entomologists, ecologists, and other biological researchers from around the world.Members of the public were engaged in an outreach presentation tothe Galatas Elementary School (Woodlands, TX). Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? During the current reporting period I have received extensive training from my two mentors (Drs. Spencer Behmer & Micky Eubanks) in terms of experimental design and execution, data analysis, creating effective presentations, writing manuscripts, networking with colleagues, applying for grants, teaching, and planning for my future career. I have gained a great deal of experience in community and nutritional ecology methodology. Progress was monitored through weekly lab meetings as well as frequent one-on-one meetings with either mentor. This training culminated in my graduation from Texas A&M with a Ph.D. in Entomology and my acceptance of a postdoctoral scholar position in the Department of Entomology at the University of Kentucky. During the period of this project I have also engaged in professional development activities. I attended the department of Texas A&M Entomology's weekly seminars as well as those hosted by the Ecology and Evolutionary Biology program which features invited speakers. I attended all graduate student lunch meetings with the speakers. I have also had the opportunity to meet colleagues at meetings of the Entomological Society of America and Ecological Society of America. I also engaged the curator of the Texas A&M entomology collection to identify and curate unidentified grasshopper specimens, which built on my previous experience with biological collections. How have the results been disseminated to communities of interest? Results have been disseminated at oral and poster presentations at meetings of theEntomological Society of America, Ecological Society of America, and Society for Integrative and Comparative Biology (see 'Products"), and are featured in my dissertation, a published manuscript in the journal Oikos, and three manuscripts currently in prep. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Insect outbreaks inflict tremendous damage. Recently it has been suggested that new insights regarding outbreaks might be found by applying a new, more integrative, nutritional approach. One model system to which a nutritional approach could be applied is rangeland grasshoppers, which usually occur in communities of multiple pest species. Previous work shows that different grasshopper species regulate their intake of key nutrients (protein/carbohydrates) to different amounts and ratios. I hypothesized that these species-specific nutrient requirements might reduce competition. Under certain conditions, this could favor outbreaks of particular species. To investigate this I documented the natural diet of common rangeland grasshoppers. I found that among a suite of 11 grasshopper species, diets were highly overlapping, implying the species do compete for resources. Second, I identified nutrient (protein/carbohydrate) requirements for each of these species using laboratory feeding experiments. Nutrient requirements differed significantly between species in relation to diet and taxa. Many species with strongly overlapping diets had significantly different nutrient requirements. Third, I assessed whether differences in species’ nutrient requirements predict competitive outcomes between grasshopper species. We only found mixed support for the effect of nutrient requirements on competition, with stronger effects of grasshopper body size. However, by comparing nutrient regulation in multiple coexisting and related species we gained a greater understanding of feeding in herbivorous pest insects. At a basic level this study raises interesting questions about whether nutrient requirements adapt to host foods and how they might evolve. At the more applied level my data on optimal nutrient requirements for different grasshopper species could be compared against the nutrient content of rangeland forage, allowing more targeted control of outbreaking rangeland grasshoppers. Objective 1.My first objective was to document host plant use for a number of common rangeland grasshoppers that often show population outbreaks. This objective was completed during the first year of funding. I documented host plant use for each species via microscopic analysis of gut content. Gut content analysis allowed me to assign species to functional feeding (grass-, forb-, and mixed-feeders). Diets of the 11 grasshopper species examined displayed a high degree of resource utilization overlap. Comparing Pianka indices of the sampled and simulated communities revealed that niche overlap was significantly greater than the expected level of overlap. This means that, in general, species were sharing trophic niches. On average, 90% of a grasshopper species diet was composed of diet categories, i.e., plant morphospecies, which were shared by another grasshopper species. By analyzing the diets of this focal suite of species I was able to accurately compare nutrient regulation (see objective 2) to diets in the same population of grasshoppers. Previous work relied on separate diet studies in the literature at the species level, which can vary between sites. This study also resulted in a change in knowledge by providing for the first time diets for a central Texas rangeland grasshopper community. Multiple presentations at conferences have been given to disseminate these results (see ‘Products’), it constitutes a chapter in my Ph.D. dissertation (combined with objective 2), and a manuscript detailing these results is currently being prepared for submission. Objective 2.The second objective of my study was to determine macronutrient (protein:carbohydrate) intake targets for each of the species studied in objective 1. This objective was completed during the first year of funding. My study identified self-selected protein-carbohydrate intake for a suite of coexisting grasshopper species. I investigated the intake results in the context of relatedness (taxonomy), host plant range, and body size to better understand factors that might determine a species’ protein-carbohydrate preferences. I collected grasshoppers from the field as nymphs, reared each species in the laboratory, and subjected them to artificial diet experiments to determine their self-selected protein-carbohydrate intake. My laboratory feeding studies revealed that all species actively regulated for protein-carbohydrate intake. Self-selected protein-carbohydrate intake across the entire community was more carbohydrate-biased than previous studies. The ratio of protein:carbohydrate regulated for differed between species, and corresponded to differences in diet and taxa, but not body size. In the case of mixed-feeding Melanoplinae, differences could be the result of niche partitioning since there was a negative relationship among species between diet similarity and nutrient intake similarity. This study developed a change in knowledge by providing further understanding of patterns in nutrient regulation across species. I nearly doubled the number of species with known macronutrient intake targets in the most studied group: grasshoppers. I observed stark differences in the general distribution of macronutrient intake, which may be related to phylogeny, temperature/latitude, functional feeding-group differences, and perhaps competition. Multiple presentations at conferences have been given to disseminate these results (see ‘Products’), it constitutes a chapter in my Ph.D. dissertation (combined with objective 1), and a manuscript detailing these results is currently being prepared for submission. Objective 3.The third objective of my research was to assess how differences in nutrient intake correlate with inter-specific competition and population density. This objective was completed during the second year of funding. I investigated this hypothesis in greenhouse microcosms using three species of generalist grasshoppers with overlapping diets, but either similar or dissimilar nutrient intake targets. Field caught grasshopper nymphs from Central Texas were caged in either monoculture, or mixed species treatments on a standard mixed plant community with one grass and two forb species. Grasshoppers in the experimental microcosms had high mortality rates in all species treatments. Forbs were the limiting resource and all species engaged in cannibalism. Analysis of cage population decline revealed competitive differences between species, but the patterns of survival gave only mixed support for the predictions of the nutrient niche hypothesis. Mortality differences were more likely linked to body size differences between species. Nutrient requirement differences have, at most, a weak effect on interspecific interactions, at least among the species tested. Nutrient requirement differences could effect interspecific competition, but via its effect on host plant selection, and would be secondary to other factors in the field such as body size. This objective provided a change in knowledge by showing that our hypothesized “nutrient niches” may not be a strong factor shaping rangeland grasshopper communities. Although I found only found mixed support for the nutrient niche hypothesis among the species tested, this study made some considerable advances in linking findings from the geometric framework with field-relevant biology. Future work will need to focus on how nutrient intake targets relate to macronutrient content of host plants, how plant defenses complicate nutrient regulation, and compare macronutrient intake targets in a phylogenetic context. Multiple presentations at conferences have been given to disseminate these results (see ‘Products’), it constitutes a chapter in my Ph.D. dissertation, and a manuscript detailing these results is currently being prepared for submission.

Publications

  • Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2014 Citation: Lenhart, P.A. 2014 Nutrient niches: An investigation of nutritional ecology in a generalist herbivore community Dissertation. Texas A&M University.
  • Type: Conference Papers and Presentations Status: Submitted Year Published: 2014 Citation: Lenhart, P.A. 2014 "Combining nutrition and community ecology of grasshoppers to benefit ecosystems and people" Annual Meeting of the Entomological Society of America. Portland, Oregon.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Behmer, S.T., and Eubanks, M.D. 2013 Competition between generalist herbivores: effects of nutrient regulation and body size Annual Meeting of the Entomological Society of America. Austin, Texas.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Behmer, S.T., and Eubanks, M.D. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores 98th annual Ecological Society of America meeting. Minneapolis, Minnesota.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Clissold, F.J., Richardson, A., Lenhart, P.A., Behmer, S.T., and Simpson, S.T. 2014. Is the ability to gain carbohydrate driving the evolution and ecology of an insect herbivore, the grasshopper? Annual meeting of the Society for Integrative and Comparative Biology, Austin, Texas
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2014 Citation: Lenhart P.A., Eubanks M.D., and Behmer S.T. 2014. Water stress in grasslands: the dynamic response of plants and insect herbivores. Oikos. doi: 10.1111/oik.01370


Progress 08/15/12 to 08/14/13

Outputs
Target Audience: During the current reporting period results of the study were disseminated in oral and poster presentations at national meetings of the Ecological Society of America, Entomological Society of America, and Gordon Conference on Plant-Herbivore interactions as well as the Texas A&M University's Ecological Integrated Symposium. During these presentations results were presented to student and professional entomologists, ecologists, and other biological researchers from around the world. Members of the public were engaged in outreach presentations tothe Brazos Valley chapter of the Texas Master Naturalists and to central Texaslandowners via the Texas Ecolab program. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project has allowed for extensive training from my two mentors (Drs. Spencer Behmer & Micky Eubanks) in terms of experimental design and execution, data analysis, creating effective presentations, writing manuscripts, networking with colleagues, applying for grants, teaching, and planning for my future career. I have gained a great deal of experience in community and nutritional ecology methodology. Progress has be monitored through weekly lab meetings as well as frequent one-on-one meetings with either mentor. During the period of this project I have also engaged in many professional development activities. I attended a 4 week POWER writing studio in April 2013 offered by the Texas A&M College of Education and Human Development. I've attended the department of Entomology's weekly seminar series which features invited speakers, as well as all graduate student lunch meetings with the speakers. I have also had the opportunity to meet colleagues at recent meetings of the Entomological Society of America, Ecological Society of America, Gordon Conference on Plant-Herbivore interactions, and Texas A&M Ecological Integrated Symposium. How have the results been disseminated to communities of interest? Results have been disseminated at oral and poster presentations at theEntomological Society of America, Ecological Society of America, Gordon Conference on Plant-Herbivore interactions, and Texas A&M Ecological Integrated Symposium (see 'Products"), and are featured in the recently submitted manuscript, and two upcoming manuscripts. What do you plan to do during the next reporting period to accomplish the goals? During the next reporting phase I will execute the greenhouse competition experiment, submit manuscripts based on objective1 and 2 datasets (grasshopper diet and nutrient intake regulation), defend my PhD dissertation, and prepare drafts of all final manuscripts for publication.

Impacts
What was accomplished under these goals? To date I have successfully completed objectives 1, 2, and part of objective 3. In 2011 and 2012 I assessed the host plant use in 11 common species of grasshopper at the field site and determined the protein:carbohydrate intake targets for these same grasshoppers. The results of these objectives have been presented at several national meetings (see 'Products') and are currently on track to be submitted for publication before 2014. Using this dataset I identified three species for use in the competition experiments: two species with similar nutrient requirements ( Melanoplus femurrubrum, M. differentialis), and one with a dissimilar nutrient requirement (M. discolor). I have conducted the caged field competition experiment from objective 3. A separate field experiment using this field site and focusing on the effect of drought on plant content and grasshopper communities has recently been submitted for publication.

Publications

  • Type: Journal Articles Status: Submitted Year Published: 2013 Citation: Lenhart P.A., Eubanks M.D., and Behmer, S.T. Water stress in grasslands: the dynamic response of plants and insect herbivores. Ecology.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Behmer, S.T., and Eubanks, M.D. 2013 Competition between generalist herbivores: effects of nutrient regulation and body size Annual Meeting of the Entomological Society of America. Austin, Texas.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Behmer, S.T., and Eubanks, M.D. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores 98th annual Ecological Society of America meeting. Minneapolis, Minnesota.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2012 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2012 Diet breadth and macronutrient regulation reveal how generalist herbivores coexist Annual Meeting of the Entomological Society of America. Knoxville, Tennessee.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores Ecological Integrated Symposium, Texas A&M University, College Station, Texas
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Lenhart, P.A., Eubanks, M.D., and Behmer, S.T. 2013 Diet breadth and macronutrient regulation in coexisting generalist herbivores Plant-Herbivore Interactions Gordon Research Conference, Ventura, California