The herbivory experienced by non-native invasive plants may depend on their local environments, such as herbivore abundance. In this study, I performed a common garden experiment with plants sampled from 11 populations of Arctium minus, from southern Ontario to near its northern range limit. I also compared performance and herbivory of burdock in open and understory habitats. Finally, I conducted freezing tolerance experiments with the lepidopteran seed predator Metzneria lapella, and palatability tests with plants from different populations. Results suggested that the previously described latitudinal trends in herbivore damage among populations are due to environmental differences rather than genotypic differences among populations. At a local scale, plants of open habitat were less damaged and had better performance than understory plants. Burdock has not escaped damage by herbivores in its invaded range; instead variation among sites in herbivore populations and impacts may significantly affect the invasiveness of this species.

I studied the ecological factors related to declining forest forb communities in the Lower Peninsula of Michigan during 2007 and 2008. Data on forb demography, fecundity, and deer herbivory rates were collected for endemic forbs given deer density and site-specific environmental factors. Investigations into endemic forbs were conducted at the population-, community-, and landscape-levels to detect overarching trends. Diverse and abundant forb communities were principally found in areas with available water and rich soil organic matter and were not affected by sympatric vegetation competition, canopy density, or deer densities. Deer densities were highest in lowland conifer stands, vegetated open lands, and heterogeneous landscapes, but herbivory was driven by population-level processes including the selection of specific forb species at the time of seed production. At the landscape level, soil conditions and human influence were major factors affecting the distribution of endemic forb communities. Soil conditions exhibited a non-linear, but generally positive relationship with forb diversity, and human influence negatively affected site diversity. Soil conditions and road densities were used to develop a spatial model identifying a gradient of priority-conservation areas across the study area. Conservation agencies interested in similar vegetation communities should consider anthropogenic factors, nutrient cycling, and local environmental conditions when conducting ecological research and identifying forb conservation areas.

Orientador: José Luiz Stape / Banca: Iraê Amaral Guerrini / Banca: Clayton Alcarde Alvares / Resumo: A produtividade de plantios de eucalipto no Brasil foi triplicada nas últimas quatro décadas graças, principalmente, à pesquisa intensiva, investimentos em tecnologia silvicultural, clonagem e melhoramento genético. Atualmente, existem diversas pesquisas relacionadas ao gênero Eucalyptus, mas são poucas as que abordam o tema estresse biótico por ser uma avaliação complexa e de difícil planejamento e execução. Em Piracicaba, em um sítio experimental com alta sanidade e sobrevivência, foram induzidas uma, duas e três desfolhas sucessivas, retirando-se manualmente todas as folhas da copa das árvores de 12 clones de eucalipto de extrema relevância à silvicultura brasileira. As desfolhas ocorreram aproximadamente aos 15, 19 e 23 meses de idade das árvores, e a avaliação final de perda de produtividade ocorreu aos 27 meses. O crescimento das árvores foi monitorado semanalmente, sendo possível ver o efeito das desfolhas ao longo do período. Os clones de eucalipto escolhidos para este estudo, apesar de pertencerem ao mesmo gênero, mostraram resultados bastante diferentes. O impacto das desfolhas no crescimento das árvores foi imediato e prolongado, com o crescimento próximo à zero por 50 a 120 dias após a desfolha. As desfolhas causaram redução de crescimento em DAP (Diâmetro à Altura do Peito), altura total, volume e biomassa de madeira. As árvores não desfolhadas acabaram dominando as desfolhadas. Isso causou o estiolamento das árvores desfolhadas e a redução da homogeneidade das ... / Abstract: The Brazilian Eucalyptus productivity has tripled in the last four decades, mainly because of intensive research, development of forestry and genetics. Nowadays, there are several studies related to the Eucalyptus genus, but only a few address biotic stress, as the subject is of complex evaluation, difficult planning and execution. In Piracicaba, in an experimental site with high health and survival rate, one, two and three successive defoliations were induced, manually removing all the canopy leaves of 12 extremely relevant clones to Brazilian forestry. The defoliations occurred in approximately 15, 19 and 23 months after planting and the final evaluation of productivity occurred at 27 months. Tree growth was weekly monitored, and the effect of defoliation over time was visible. The eucalypts clones chosen for this study, despite belonging to the same genus, showed quite different results. The impact of canopy defoliation on tree growth was immediate and prolonged, with growth close to zero for 50 to 120 days following defoliation. Defoliation caused growth reduction in DBH (Diameter at Breast Height), total height, volume and wood biomass. Defoliated trees were etiolated as the non-defoliated were the dominant trees in the plot. Defoliation reduced plot homogeneity. One year after the first defoliation, the 27-month-old trees that have undergone one defoliation showed 48% lower wood biomass, in comparison with non-defoliated trees (ranging from 24 to 57% by clones). ... / Mestre

The importance of resource supply and herbivory in driving competitive interactions among species has been an important but contentious issue within ecology. These variables exhibit different effects on species competition when manipulated in isolation but interact when manipulated together. I tested the direct and interactive effects of nutrient addition and simulated grazing (clipping) on the competitive performance of primary producers and community structure of a seagrass bed in South Florida. One square meter experimental plots were established in a mixed seagrass meadow from August 2007 to July 2009. The experiment was a 3 x 3 factorial experiment: 3 fertility treatments: control, medium (2.4 mg N d-1 and 80 µg P day-1) and high (4.8 mg N d-1 and 160 µg P day-1) x 3 clipping intensities (0, 25% and 50 % biomass removal (G)) x 5 replicates for each treatment = 45 plots). Nutrient additions and simulated grazing were done every two months. Fertilization and simulated grazing decreased sexual reproduction in S. filiforme. Fertilization increased competitive dominance within the primary producers while simulated grazing counteracted this effect by removal of the dominant species. Fertilization ameliorated the negative impacts of simulated grazing while simulated grazing prevented competitive exclusion in the fertilized plots. Nutrient addition and simulated grazing both exerted strong control on plant performance and community structure. Neither bottom up nor top down influences was eliminated in treatments where both factors where present. The effects of fertilization on plant performance were marked under all clipping intensities indicating that the system is regulated by nutrient availability both in the presence or absence of grazers. Clipping effects were strong under both fertilized and unfertilized conditions indicating that the seagrass bed can be simultaneously under top-down control by grazers.

The interaction of herbivory and pollination is not well understood. Both topics on their own have been studied thoroughly, yet their interaction has not. Until the 1990s, few studies attempted to explore how herbivory might affect pollination, and vice versa.

Suppression of canopy tree recruitment beneath rapidly spreading thickets of Rhododendron maximum L. (Ericaceae) in southern Appalachian forests is an issue of major concern because of the potential impacts on forest productivity, hydrology and wildlife habitat. Many studies have investigated the causes of seedling inhibition beneath dense shrub understories, but few have uncovered specific mechanisms leading to seedling decline. In this study, I have examined the influence of the evergreen understory (R. maximum and Kalmia latifolia L.) on tree recruitment processes at multiple stages - seed rain, seed bank, and post-establishment seedling growth and survivorship. Effects of dense shrub cover on seed rain and seed bank density and composition were examined using a paired treatment design in which samples were collected beneath shrub-influenced and open understories. A second experiment investigated the influence of R. maximum and K. latifolia density on the growth and survivorship of Quercus seedlings, resource availability, and the rates / causes of seedling damage. I found that neither seed rain, nor seed bank density or species richness was inhibited by the presence of R. maximum or K. latifolia. Forest seed banks were dominated by sweet birch (Betula lenta L.), and were compositionally disparate from the overstory. Analysis of resource competition between shrubs and seedlings indicated that seedling performance and survivorship was a negative function of R. maximum density. Open-canopy light availability, nitrogen content in the organic horizon (litter and humus), and soil nutrient availability were potential resource-related mechanisms. Further, I found that the rates of insect herbivory on Quercus seedlings were positively correlated with R. maximum density. Kalmia latifolia had little influence on resource availability, seedling performance or herbivory rates, and does not appear to have a suppressive effect on tree seedlings. Overall, this research indicates that resource competition is the primary mechanism by which seedling suppression occurs beneath R. maximum, and that increased herbivory on seedlings may be an additional mechanism that demands further study. / Master of Science

In this thesis, I combined field, greenhouse and common-garden experiments to examine the ecological and evolutionary consequences of plant-herbivore interactions and the genetic architecture of fitness-related traits in the insect-pollinated, self-incompatible, perennial herb Arabidopsis lyrata. More specifically, I examined (1) whether damage to leaves and inflorescences affects plant fitness non-additively, (2) whether trichome production is associated with a cost in terms of reduced tolerance to leaf and inflorescence damage, (3) whether young plant resistance to a specialist insect herbivore varies among populations, and (4) whether the evolution of flowering time, floral display and rosette size is constrained by lack of genetic variation or by genetic correlations among traits. A two-year field experiment in a Swedish population showed that damage to rosette leaves and to inflorescences can affect both current and future plant performance of A. lyrata, and that effects on some fitness components are non-additive. A two-year field experiment in another Swedish population indicated that trichome-producing plants are not less tolerant than glabrous plants to leaf and inflorescence damage. In a greenhouse experiment, acceptability of young plants (5-6 weeks old) to ovipositing females and damage received by Plutella xylostella larvae varied considerably among twelve A. lyrata populations. Both oviposition and leaf damage were positively correlated with rosette size, but trichome density in the trichome-producing morph was apparently too low at this developmental stage to influence resistance to P. xylostella. In a common-garden experiment, flowering time, floral display and rosette size varied among four Scandinavian A. lyrata populations, and displayed significant additive genetic variation in some populations. Yet, strong genetic correlations between flowering start and number of flowers, and between petal length and petal width suggest that these traits may not evolve independently. Taken together, the results indicate the need to consider possible long-term and non-additive effects of herbivore damage to different plant parts, that there is no trade-off between trichome production and tolerance to herbivory, that the importance of morphological defenses against herbivory may change through plant ontogeny, and that considerable genetic variation for traits such as flowering time and floral display can be maintained in natural plant populations.

Herbivory is one of most important factors which form meadow ecosystems. These ecological communities have one of the biggest variety of species in Central Europe and their research is important in terms of management of protected species as well. Localities which has a similar importance, is also a meadow ecosystem with occurrence of Succisa pratensis, the only host plant for rare butterfly Euphydryas aurinia. Research of Succisa and its other herbivores can improve a protection of this particular butterfly. Effects of herbivores of Succisa were examined by several experiments. The first one was a field cage experiment. Its aim was to detect what kinds of herbivores (rodents and invertebrates) are involved in herbivory of leaf rosettes of Succisa and what is their impact on the fitness of these plants. The intensity of herbivory of Succisa was measured for over two vegetation seasons on the month bases. In this experiment were also examined effects of surrounding vegetation on the studied plants of Succisa. The second experiment was performed in a garden. Its aim was to clarify the role of herbivores of leaf rosettes, stalks and their interactions on the fitness of Succisa. The third experiment was concerned to true bugs, which are pre-dispersal predators of seeds of Succisa. Their effects on...

This thesis elucidates patterns and drivers of invertebrate herbivory, herbivore diversity, and community-level biomass along elevational and land use gradients at Mt. Kilimanjaro, Tanzania. Chapter I provides background information on the response and predictor variables, study system, and the study design. First, I give an overview of the elevational patterns of species diversity/richness and herbivory published in the literature. The overview illuminates existing debates on elevational patterns of species diversity/richness and herbivory. In connection to these patterns, I also introduce several hypotheses and mechanisms put forward to explain macroecological patterns of species richness. Furthermore, I explain the main variables used to test hypotheses. Finally, I describe the study system and the study design used. Chapter II explores the patterns of invertebrate herbivory and their underlying drivers along extensive elevational and land use gradients on the southern slopes of Mt. Kilimanjaro. I recorded standing leaf herbivory from leaf chewers, leaf miners and gall-inducing insects on 55 study sites located in natural and anthropogenic habitats distributed from 866 to 3060 meters above sea level (m asl) on Mt. Kilimanjaro. Standing leaf herbivory was related to climatic variables [mean annual temperature - (MAT) and mean annual precipitation - (MAP)], net primary productivity (NPP) and plant functional traits (leaf traits) [specific leaf area (SLA), carbon to nitrogen ratio (CN), and nitrogen to phosphorous ratio (NP)]. Results revealed an unimodal pattern of total leaf herbivory along the elevation gradient in natural habitats. Findings also revealed differences in the levels and patterns of herbivory among feeding guilds and between anthropogenic and natural habitats. Changes in NP and CN ratios which were closely linked to NPP were the strongest predictors of leaf herbivory. Our study uncovers the role of leaf nutrient stoichiometry and its linkages to climate in explaining the variation in leaf herbivory along climatic gradients. Chapter III presents patterns and unravels direct and indirect effects of resource (food) abundance (NPP), resource (food) diversity [Functional Dispersion (FDis)], resource quality (SLA, NP, and CN rations), and climate variables (MAT and MAP) on species diversity of phytophagous beetles. Data were collected from 65 study sites located in natural and anthropogenic habitats distributed from 866 to 4550 m asl on the southern slopes of Mt. Kilimanjaro. Sweep net and beating methods were used to collect a total of 3,186 phytophagous beetles representing 21 families and 304 morphospecies. Two groups, weevils (Curculionidae) and leaf beetles (Chrysomelidae) were the largest and most diverse families represented with 898 and 1566 individuals, respectively. Results revealed complex (bimodal) and dissimilar patterns of Chao1-estimated species richness (hereafter referred to as species diversity) along elevation and land use gradients. Results from path analysis showed that temperature and climate-mediated changes in NPP had a significant positive direct and indirect effect on species diversity of phytophagous beetles, respectively. The results also revealed that the effect of NPP (via beetles abundance and diversity of food resources) on species diversity is stronger than that of temperature. Since we found that factors affecting species diversity were intimately linked to climate, I concluded that predicted climatic changes over the coming decades will likely alter the species diversity patterns which we observe today. Chapter IV presents patterns and unravels the direct and indirect effects of climate, NPP and anthropogenic disturbances on species richness and community-level biomass of wild large mammals which represent endothermic organisms and the most important group of vertebrate herbivores. Data were collected from 66 study sites located in natural and anthropogenic habitats distributed from 870 to 4550 m asl on the southern slopes of Mt. Kilimanjaro. Mammals were collected using camera traps and used path analysis to disentangle the direct and indirect effects of climatic variables, NPP, land use, land area, levels of habitat protection and occurrence of domesticated mammals on the patterns of richness and community-level biomass of wild mammals, respectively. Results showed unimodal patterns for species richness and community-level biomass of wild mammals along elevation gradients and that the patterns differed depending on the type of feeding guild. Findings from path analysis showed that net primary productivity and levels of habitat protection had a strong direct effect on species richness and community-level biomass of wild mammals whereas temperature had an insignificant direct effect. Findings show the importance of climate-mediated food resources in determining patterns of species richness of large mammals. While temperature is among key predictors of species richness in several ectotherms, its direct influence in determining species richness of wild mammals was insignificant. Findings show the sensitivity of wild mammals to anthropogenic influences and underscore the importance of protected areas in conserving biodiversity. In conclusion, despite a multitude of data sets on species diversity and ecosystem functions along broad climatic gradients, there is little mechanistic understanding of the underlying causes. Findings obtained in the three studies illustrate their contribution to the scientific debates on the mechanisms underlying patterns of herbivory and diversity along elevation gradients. Results present strong evidence that plant functional traits play a key role in determining invertebrate herbivory and species diversity along elevation gradients and that, their strong interdependence with climate and anthropogenic activities will shape these patterns in future. Additionally, findings from path analysis demonstrated that herbivore diversity, community-level biomass, and herbivory are strongly influenced by climate (either directly or indirectly). Therefore, the predicted climatic changes are expected to dictate ecological patterns, biotic interactions, and energy and nutrient fluxes in terrestrial ecosystems in the coming decades with stronger impacts probably occurring in natural ecosystems. Furthermore, findings demonstrated the significance of land use effects in shaping ecological patterns. As anthropogenic pressure is advancing towards more pristine higher elevations, I advocate conservation measures which are responsive to and incorporate human dimensions to curb the situation. Although our findings emanate from observational studies which have to take several confounding factors into account, we have managed to demonstrate global change responses in real ecosystems and fully established organisms with a wide range of interactions which are unlikely to be captured in artificial experiments. Nonetheless, I recommend additional experimental studies addressing the effect of top-down control by natural enemies on herbivore diversity and invertebrate herbivory in order to deepen our understanding of the mechanisms driving macroecological patterns along elevation gradients. / In dieser Dissertation werden Muster und Determinanten von Herbivorendiversität, von Herbivorieraten durch Invertebraten sowie die Diversität und Gesamtbiomasse von Säugetieren entlang von Höhen- und Landnutzungsgradienten am Kilimandscharo (Tansania) untersucht. Kapitel I liefert Hintergrundinformationen zu den betrachteten Variablen, dem Untersuchungssystem und dem generellen Studiendesign: Zuerst fasse ich den aktuellen Kenntnisstand über die Muster des Artenreichtums und der Herbivorie entlang von Höhengradienten zusammen und erläutere in diesem Zusammenhang verschiedene Hypothesen, die zur Erklärung von Gradienten des Artenreichtum herangezogen werden. Ich erkläutere verschiedene Variablen, die zum Testen dieser Hypothesen erhoben wurden und stelle dar, wie diese den Artenreichtum, die Herbivorieraten und die Biomasse beeinflussen könnten. Anschließend beschreibe ich das Untersuchungssystem, sowie das generelle Design der Studie. In Kapitel II werden die Muster und Determinanten der Invertebratenherbivorie entlang von Höhen- und Landnutzungsgradienten an den südlichen Hängen des Kilimandscharos präsentiert. Auf insgesamt 55 Untersuchungsflächen, die sowohl natürliche als auch anthropogen genutzte Habitate am Kilimandscharo in Höhenlagen zwischen 866 und 3060 Meter über Normalnull (m ü. NN) umfassten, wurden die Herbivorieraten ektophager, minierender und gallbildener Insekten an Blättern erfasst. Die Blattherbivorie war sowohl mit klimatischen Variablen [Jahresmitteltemperatur und mittlere Jahresniederschlagsmenge], der Nettoprimärproduktivität (NPP) und mit funktionellen Blattmerkmalen von Pflanzen [spezifische Blattfläche (SLA), Kohlenstoff (C) / Stickstoff (N)-Verhältnis, sowie N / Phosphor (P)-Verhältnis] assoziiert. Die Gesamtherbivorie zeigte eine unimodale Verteilung über den Höhengradienten, wurde aber sowohl von der Herbivorengilde, als auch vom Habitattyp (natürlich versus anthropogen) beeinflusst. Das C/N-Verhältnis von Blättern war die stärkste Determinante der Blattherbivorie und wurde selbst stark durch die NPP bestimmt. Herbivorieraten sanken mit steigendem C/N-Verhältnis. Das C/N Verhältnis nahm mit steigender NPP zu.- Letztere konnte fast vollständig durch Änderungen der mittleren Jahrestemperatur (MAT) und des Jahresniederschlags (MAP) entlang des Höhengradienten erklärt werden. Damit zeigt unsere Studie, dass sich durch klimatische Faktoren und Energie, welche ihrerseits die Blattchemie beeinflussen und so Variationen in der Blattherbivorie entlang großer Klimagradienten ergeben. In Kapitel III werden die Muster im Artenreichtum phytophager Käfer entlang der Höhen- und Landnutzungsgradienten untersucht und die direkten und indirekten Effekte von klimatischen Faktoren (MAT, MAP), NPP und funktionellen Pflanzenmerkmalen (funktionelle Dispersion, SLA, C/N - und N/P - Verhältnisse) auf diese Muster analysiert. Die entsprechenden Daten wurden auf 65 Untersuchungsflächen, die sowohl natürliche als auch anthropogene Habitate entlang eines Höhengradienten am Kilimandscharo von 866 bis 4550 m ü. NN abdeckten, erhoben. Mittels Kescher wurden insgesamt 3186 phytophage Käfer aus 21 Familien gesammelt und in 304 Morphospezies eingeteilt. Der Artenreichtum phytophager Käfer zeigte eine komplexe, zweigipflige Verteilung entlang der Höhen- und Landnutzungsgradienten. Eine Pfadanalyse ergab, dass sowohl die MAT, als auch NPP positiven direkte bzw. indirekte Effekt auf die Artendiversität phytophager Käfer hatte. Die NPP war positiv mit der funktionellen Dispersion von Blattmerkmalen, ein Maß für die Diversität der Nahrungsressourcen, korreliert. Letztere hatte einen positiven Effekt auf die Diversität der Käfer. Die starken direkten und indirekten Effekte von Klima auf die Diversität und Abundanz von phytophagen Käfern, lassen vermuten dass der Klimawandel in den nächsten Dekaden großen Änderungen der Struktur von phytophagen Käfergemeinschaften bewirken wird. In Kapitel IV untersuchen wir den Effekt von Klima, NPP und anthropogener Störung auf den Artenreichtum und die Gesamtbiomasse von Großwild. Dazu wurden auf 66 Untersuchungsflächen, welche natürliche und anthropogene Habitate in Höhenstufen zwischen 870 und 4550m ü. NN umfassten, Daten zum Artenreichtum un der Abundanz von Großwild mittels Kamerafallen erfasst. Mittels einer Pfadanalyse wurden die direkten und indirekten Effekte von klimatischen Variablen, NPP, Landnutzung, Größe und Schutzstatus der Flächen, sowie der Präsenz von domestizierten Säugetieren auf den Artenreichtum und die Biomasse von Großwild untersucht. Artenreichtum und Gesamtbiomasse dieser endothermen Organismen zeigten eine unimodale Verteilung über den Höhengradienten. Verschiedene Nahrungsgilden zeigten unterschiedliche Muster. Es konnte gezeigt werden, dass NPP und der Schutzstatus der Fläche, aber nicht die Temperatur einen direkten, positiven Einfluss auf den Artenreichtum und die Gesamtbiomasse des Großwildes hatte. Die vom Klima abhängige Nahrungsressourcenverfügbarkeit ist also eine wichtige Determinante im Artenreichtum von Großwild. Die Temperatur hingegen, die den Artenreichtum verschiedener ektothermer Organismen entscheidend prägt, hatte keinen direkten Einfluss auf den Artenreichtum des Großwildes Dafür reagiert das Großwild besonders sensibel auf anthropogene Einflüsse, was wiederum die Wichtigkeit von Schutzgebieten unterstreicht. Obwohl die Muster im Artenreichtum und in Ökosystemfunktionen entlang großer klimatischer Gradienten bereits gut dokumentiert sind, ist das Wissen über die zu Grunde liegenden Prozesse nach wie vor unzureichend. Mit meinen drei Studien über die Muster und Determinanten der Herbivorendiversität, der Herbivorieraten und der Großwildbiomasse trage ich somit zur Verbesserung des mechanistischen Verständnisses solcher makroökologischer Muster bei. Wie die Pfadanalysen zeigten, wurden sowohl der Artenreichtum die Biomasse als auch ökologische Prozesse direkt oder indirekt vom Klima beeinflusst. Es ist somit zu erwarten, dass der vorhergesagte Klimawandel ökologische Muster, biotische Interaktionen, Energie- und Nährstoffkreisläufe in terrestrischen Ökosystemen wesentlich umstrukturieren wird, wobei natürliche Systeme wahrscheinlich besonders sensibel auf den Klimawandel reagieren werden. Meine Ergebnisse demonstrieren auch den Einfluss von Landnutzung auf Artenreichtum und ökologische Prozesse. Da der anthropogene Druck auf die natürlichen Ökosysteme des Kilimandscharos immer weiter zunimmt, sollten objektive Biodiversitätsmaße implementiert werden mit denen man Veränderungen in den Ökosystemen und in Ökosystemldienstleistungen schnell detektieren kann. Meine Ergebnisse basieren auf Beobachtungsdaten, die von bestimmten Nebenfaktoren im Feld beeinflusst werden können. Dennoch ist es mir gelungen mit korrelativen Methoden, Organismen in ihrem biotischen und abiotischen Interaktionsumfeld zu untersuchen – ein Szenario, welches in einem rein experimentellen Aufbau in dieser Form wahrscheinlich nicht geschaffen werden kann. Über weiterführende Experimente könnte jedoch zum Beispiel der Einfluss von Prädatoren auf die Herbivorendiversität und Herbivorieraten quantifiziert werden, welches unser Verständnis über die Determinanten makroökologischer Muster noch vertiefen würde.

Field studies were conducted over two growing seasons to evaluate the effect of different levels of third instar European corn borer, Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), on whole-plant dry matter in corn grown for silage. Mean (± SEM) whole-plant dry matter was significantly greater by 18.8% in uninfested control plants than in plants with an infestation level of 6 larvae/plant in 2004. Whole-plant dry matter in 2005 was significantly greater by 10.5% in control plants than in plants with an infestation level of 5 larvae/plant. Economic injury levels were calculated for each year using regression equations between whole-plant dry matter and European corn borer infestation level. Plant growth stage and infestation level had no effect on percent acid detergent fiber, neutral detergent fiber, and crude protein values for either year. Greenhouse studies were conducted to examine the relationship between aboveground herbivory by European corn borer and belowground herbivory by root knot nematode, Meloidogyne incognita Chitwood (Tylenchida: Heteroderidae), in corn. Two experiments were conducted to measure belowground herbivory by M. incognita in juvenile penetrations and eggs/root system. In the first experiment, the main effects interaction was not significant for either M. incognita juvenile penetrations or eggs/root system. Overall mean juvenile penetrations/root system across all three growth stages, at infestation levels of 1 and 3 larvae/plant were significantly less than in the non-infested control. In addition, overall mean eggs/root system at an infestation level of 3 larvae/plant were significantly less than in the control. In the second experiment, the main effects interaction was significant for both juvenile penetrations and eggs/root system. At the 8 and 10 leaf growth stages, juvenile penetrations/root system at infestation levels of 1 and 3 larvae/plant were significantly less than in the control. In addition, eggs/root system at an infestation level of 3 larvae/plant were significantly less than in the control, at all growth stages. In the reciprocal study, which examined the effect of different M. incognita inoculation levels on European corn borer stalk tunneling, no significant effect of inoculation level on European corn borer stalk tunneling was found. / Ph. D.