Bachelor of Science, Wittenberg University, 2021, Biology

Insecticide use is steadily increasing in the United States. Of these, the insecticide Sevin™ has the active ingredient carbaryl, which is a xenobiotic. This is a reverse inhibitor of acetylcholinesterase, which prevents nerve excitation causing paralysis and death in insects. Though insects are the target species, carbaryl has many routes of exposure such as run-off, inhalation, and physical contact making it easy to encounter for non-target species like aquatic life and humans. Carbaryl has been studied within in vitro models to test its effects on zebrafish. The insecticide has already been shown to act on the acetylcholinesterase (AChE) pathway, but it also has potential to act on a second pathway: the aryl hydrocarbon receptor (AhR) pathway. Zebrafish genes and genetic pathways are homologous to humans, allowing for insight on how carbaryl could be affecting humans as well. This study set out to use an in vivo model to show how carbaryl is inducing cytochrome P450 or other AhR pathway gene expression. Gene expression of carbaryl treated embryos were compared to untreated embryos to examine this possible relationship. Cyp1a and cyp1b gene expression was increased with an increase in carbaryl concentration suggesting that carbaryl may be causing induction of the AhR pathway.

Committee: Michelle McWhorter (Advisor); Matthew Collier (Committee Member); Daniel Marous (Committee Member) Subjects: Agricultural Chemicals; Biochemistry; Biology; Developmental Biology; Environmental Science; Genetics; Molecular Biology; Toxicology

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

Doctor of Philosophy, Case Western Reserve University, 2016, Civil Engineering

Regulating pesticides in residential surface soil, air, drinking water, and food is a worldwide problem since pesticides exposure can significantly impact human health. Approximate 25% of the world's nations have provided pesticide soil standards, about half have provided pesticide drinking water standards, about 44% have provided pesticide food standards, and only the U.S. has provided pesticide air standards. Most regulatory jurisdictions regulate individual pesticide exposures independently, although the total pesticide exposure risk depends on the cumulative exposure from soil, water, air, and food. Even for a single source such as soil, jurisdiction pesticide guidance values often vary by five, six, and even seven orders of magnitude. The highest of these values are almost certainly too high to protect human health, especially for children, and the exposures are increased even further by food, air, and water. For the most common pesticides, the exposure contributions from different exposure pathways have been quantified by using risk models to convert guidance values into daily maximum implied dose limits. Most jurisdictions have higher pesticide standard values is that they derived their standards independently without consideration of all exposures. Few nations have promulgated standards for all exposures and most nations regulate pesticide standard for only one or two pesticide exposures. For many nations, the sum of the daily maximum implied dose limit from each exposure was compared. Also a ranking system based on standard completeness and numerical values has been developed to quantify how conservative a country's pesticide exposure standards are for each exposure pathway, and for a person's total pesticide exposure. Nations in Europe have better performance in pesticide standard regulations. Also human health risk models and recommended standard values were developed to help regulatory jurisdictions around the world rationalize their guidance values th (open full item for complete abstract)

Committee: Aaron Jennings (Committee Chair); Brynjarsdóttir Jenný (Committee Member); Rhoads Kurt (Committee Member); Xiong Yu (Committee Member) Subjects: Civil Engineering; Environmental Engineering