Master of Science, Miami University, 2024, Biology

Ephemeral wetlands, which are dominated by amphibians, have been destroyed to make room for agriculture, which increases the risk of contamination from pesticide use. One of the most widely used insecticides in the US is the neonicotinoid, imidacloprid. While the direct effects of imidacloprid on amphibians are sublethal, indirect effects may be conferred through disruptions in the food web. These effects may be dependent on the structure of the community. The objective of this study was to determine the effects of imidacloprid in communities that differ in food web structure (communities without amphibians; communities with northern leopard frogs [Lithobates pipiens]; communities with northern leopard frogs and spotted salamanders [Ambystoma maculatum]) on biomass of each tropic level and amphibian outcomes at metamorphosis. This experiment was conducted in outdoor mesocosms located in Oxford, Ohio. My study demonstrated that the trophic position of amphibians affected the impact of imidacloprid–negatively impacting salamanders, while having no or positive effects on anurans. Anurans had positive effects on other community members when imidacloprid was present. My research demonstrated how the complexity of the food web can alter the impact of an insecticide on biomass produced and the movement of resources from the aquatic to terrestrial systems.

Committee: Michelle Boone (Advisor); Michael Vanni (Committee Member); Hank Stevens (Committee Member) Subjects: Aquatic Sciences; Biology; Ecology; Freshwater Ecology; Wildlife Conservation

Doctor of Philosophy (PhD), Ohio University, 2022, Biological Sciences (Arts and Sciences)

Amphibian species are declining globally, and are now one of the most threatened taxon, with over one-third of global amphibian species being listed by IUCN as Threatened, Endangered, or Critically Endangered. Foremost, the effects of climate change are pervasive across both terrestrial and aquatic systems, and synergies with other threats are actively contributing to current declines and local or global extinctions. Whether a species will be able to buffer itself against novel climate conditions and interactions with other environmental stressors will largely depend on their ability to respond through physiological and behavioral plasticity. Assessing these responses and their demographic consequences is particularly challenging for species with complex life cycles, such as amphibians, for which environmental variation can have different effects on demographic parameters across life stages. Environmental variation during development can have profound, variable effects on an organism's phenotype, fitness, morphology, and physiological attributes. As such, carryover effects from one life stage to another occur when an individuals' early life experiences affect their fitness, performance, and demographic parameters at a later life stage. Aquatic stressors, such as temperature regimes, predation risk, pool hydroperiod, and exposure to contaminants often have sublethal impacts on the developmental environment of larval amphibians, which can affect morphology, behavior, and physiology throughout development and into later life stage. My doctoral research uses a range of meso- and microcosm experiments with larval and juvenile wood frogs (Rana sylvatica) to investigate (1) whether the innate plasticity of pond-breeding amphibians allows them to demographically compensate for negative carryover effects of various environmental stressors experienced during the larval stage and (2) how particular stressors may interact and cause synergistic, additive, or antagonistic effe (open full item for complete abstract)

Committee: Viorel Popescu (Advisor) Subjects: Conservation; Ecology; Wildlife Conservation

Doctor of Philosophy, The Ohio State University, 2016, Entomology

The unifying thesis of my dissertation is that the biology of a honey bee colony cannot be understood apart from the landscape in which it lives; this influence of landscape applies especially to honey bee foraging biology and toxic exposure, and consequently to apicultural outcomes. In Chapter 1, I present and elaborate this thesis in the context of existing literature and lay out the scope of my dissertation accordingly. In Chapter 2, I describe a study in which I collaborated with volunteer beekeepers to measure the success of honey bee colonies surrounded by different types of landscape in Ohio, USA. The results of this study showed that the most successful colonies tended to be those surrounded by agricultural land as opposed to those in forested or urban landscapes, which was contrary to the prevailing opinion that agricultural landscapes are too dominated by crop monocultures and too contaminated with pesticides to support healthy honey bees. This led me to hypothesize that the relationship between honey bee success and landscape is driven mainly by the availability of certain key floral taxa that, in Ohio, occur most abundantly in the interstices of the agricultural landscape. Chapter 3 further pursues the question of whether honey bees prefer agricultural or urban land use by setting up a foraging choice test between these two landscape types. Using a combination of dance language analysis and pollen identification, I monitored the spatial and taxonomic patterns of honey bee foraging at an apiary located on the interface of urban and agricultural land use. The results indicate a strong and consistent preference for the agricultural landscape, corroborating the results of Chapter 1 with an independent data set and using different lines of evidence. In Chapter 4, I turn my attention to the issue of toxic exposure, constructing a critical review of existing approaches to modeling toxic exposure in honey bees. All existing approaches suffer from seriou (open full item for complete abstract)

Committee: Reed Johnson (Advisor); Casey Hoy (Committee Member); Mary Gardiner (Committee Member); Karen Goodell (Committee Member) Subjects: Biology; Ecology; Entomology; Toxicology