Master of Science, The Ohio State University, 2014, Environmental Science

Glyphosate is a broad-spectrum herbicide used extensively worldwide to control broadleaf weeds in agriculture. Research suggests that repeated application causes a change in soil microbial properties which could be affecting soil quality and productivity. Glyphosate tolerant (GT) soybean technology is valuable to farmers because it reduces the use of other herbicides, is as a critical for weed control in reduced tillage systems, and is generally regarded as having low environmental impacts. However, after using this technology for 10 or more years, field observations by farmers and emerging research suggest that long-term glyphosate usage is having cumulative non-target effects on soils and crops. The research of GT relative to soils and crop productivity has been mixed and often inconclusive. However, most of this research was short-term lab and field studies that did not investigate soils that had been under long-term GT cropping (10+ years). Indeed, there is now anecdotal evidence that long-term repeated application of glyphosate has a detrimental effect on GT crop yields, including non-GT crops grown in rotation with GT crops. Another aspect of GT cropping is the potential effects on soils by the GT crop residue. Nearly all of the research to date has been on glyphosate added directly to soil with little information on the effects of GT plant residue that was exposed to glyphosate. Therefore, the objective of this study was to analyze soil microbial communities during decomposition of biomass from plants grown in soil that have been exposed to glyphosate in soils with and without a history of glyphosate exposure. An experiment was designed to mimic eight years of field applications in a 24 month greenhouse study. Soybean residues from this experiment were used in an laboratory incubation study and incubated in soils with and without a history of glyphosate exposure. These soils were profiled using phospholipid fatty acid analysis to determine shifts in s (open full item for complete abstract)

Committee: Richard Dick PhD (Advisor); Warren Dick PhD (Committee Member); Olli Tuovinen PhD (Committee Member) Subjects: Ecology; Environmental Science; Microbiology; Soil Sciences

Doctor of Philosophy, The Ohio State University, 2008, Horticulture and Crop Science

Horseweed and giant ragweed are becoming more difficult to control in glyphosate-resistant soybeans due to repeated use of herbicides with the same site of action, especially glyphosate and ALS-inhibiting herbicides. Greenhouse and field dose-response studies were conducted to characterize response of giant ragweed and horseweed populations to glyphosate and the combination of glyphosate and cloransulam, respectively. Field studies were conducted to determine the most effective combination and timing of preplant herbicides for the control of multiple-resistant horseweed populations, and to determine whether glyphosate-based herbicide programs could effectively control glyphosate-resistant giant ragweed populations. The GR50 for a multiple-resistant horseweed population treated with cloransulam and glyphosate was 45 g ai/ha and 2120 g ae/ha, respectively. The level of resistance for this biotype was a factor of 31, compared to a sensitive population. In the field, horseweed survived the application of glyphosate plus cloransulam and glyphosate alone at rates up to four times the recommended rate. Combinations of paraquat, metribuzin, plus 2,4-D, and glyphosate (3360 g/ha) plus 2,4-D, controlled emerged multiple-resistant horseweed. The GR50 for glyphosate-resistant giant ragweed populations ranged from 8.3 to 23.9 kg/ha of glyphosate. The level of resistance for these populations ranged from a factor of 2.1 to 6.1, compared with a glyphosate-sensitive population. In the field, individual plants within the populations could survive single or multiple applications of glyphosate totaling 2.5 to 3.4 kg/ha. The majority of plants within each glyphosate-resistant giant ragweed population could be controlled when glyphosate (1.7 kg/ha) or fomesafen was applied postemergence, and followed with another application of glyphosate (0.84 kg/ha). Effective control required the preplant use of glyphosate and 2,4-D to control emerged plants, and cloransulam plus flumioxazin to provi (open full item for complete abstract)

Committee: Mark Loux PhD (Advisor); Steven Kent Harrison PhD (Committee Member); John Cardina PhD (Committee Member); Allison Snow PhD (Committee Member) Subjects: Agricultural Chemicals; Agriculture; Agronomy

Master of Science (M.S.), University of Dayton, 2024, Biology

Glyphosate, a key ingredient in roundup, is increasingly present in aquatic systems due to agricultural runoff. High doses of this toxin cause defect in organisms due to its ability to interfere with physiological processes as an endocrine disruptor. I used the mangrove rivulus fish (Kryptolebias marmoratus) to evaluate the effects of glyphosate on non-target species in aquatic environments. They are self-fertilizing amphibious hermaphrodites with the ability to escape water in times of poor quality, predation, and nesting. These fish produce genetically identical offspring, allowing us to evaluate how variation in toxicant exposure alters their phenotypes while ruling out genetic effects. I treated newly hatched larvae for 96 hours with three different concentrations of glyphosate: control (0mg/L), environmentally relevant (.01 mg/L), and high (1 mg/L), and then measured behavior, morphology, and reproductive traits at 60 and 130 days. I predicted that fish exposed to low, environmentally relevant doses would show adaptive jumping behavior, and deficits in other traits would be greater with higher glyphosate dosages. I found phenotypic changes in reproductive output, behavior, and jumping ability; none of these effects appeared to be adaptive at low or high doses of glyphosate. Deficits in reproductive output scaled with dosage while other phenotypic deficits largely did not scale with treatment; instead, they were treatment specific for each trait. For instance, I found that low doses of glyphosate led to lower anxiety (decreased thigmotaxis), impaired jumping behaviors, and hormonal imbalances while high dose exposures to glyphosate resulted in impaired anti-predator behavior and lower average egg yield per individual. This study displayed the importance of maintaining healthy ecosystems by showing even environmentally relevant concentrations of herbicide may be harmful to aquatic organisms and have lifelong consequences. Furthermore, implications of environment (open full item for complete abstract)

Committee: Karolyn Hansen (Advisor); Chelse Prather (Committee Chair); Mariela Gantchoff (Committee Chair); Jennifer Hellmann (Advisor) Subjects: Behavioral Sciences; Biology; Ecology

Bachelor of Science, Wittenberg University, 2021, Biology

Glyphosate has been shown to impact not only amphibian survival, but also their development, phenotypic response to predators, and overall behavior. Dicamba, another herbicide, was permitted for use by the EPA in 2016. However, less is known about its potential environmental impact. Being an extremely volatile chemical, dicamba poses a risk to aquatic organisms in areas that may experience runoff or overspray. It can also harm yields of neighboring crops, leading the EPA to ban dicamba use part way through this experiment in June 2020. We investigated the effects of an environmentally relevant dosage of two forms of dicamba on grey treefrog tadpole development and behavior. We also investigated how dicamba impacted the response of tadpoles to predator cues. Herbicide treatment significantly decreased growth compared to the control. The presence of predator cues also significantly decreased growth, and there was no interaction between herbicide treatment and predator treatment. Tadpoles exposed to predator cues generally had wider tails, and the introduction of dicamba caused similar morphological changes. The presence of commercial dicamba also significantly reduced startle responses, potentially increasing the risk for predation. Dicamba has the potential for sublethal impacts on the development and behavior of tadpoles, and therefore should be further studied.

Committee: Amber Burgett (Advisor); Richard Phillips (Committee Member); Doug Andrews (Committee Member) Subjects: Agricultural Chemicals; Animal Sciences; Animals; Aquatic Sciences; Biology; Environmental Science; Statistics; Zoology

Honors Theses, Ohio Dominican University, 2021, Honors Theses

From 2005-2006, it was reported that glyphosate, the active ingredient in herbicides like Roundup, was applied to 31% of corn fields and 92% of soybean fields in the United States, making it the most commonly used herbicide (24). Due to its increasing rate of usage on everyday food products, much controversy has risen in the last decade over the safety of exposure and consumption of glyphosate (24). Gastrointestinal diseases and disorders are also on the rise, with past publications supporting the correlation between such diseases and increased glyphosate residues discovered on everyday food products (18). The aim of this study was to discover if glyphosate had a detrimental effect on the in vitro growth of human gastrointestinal bacteria obtained from a probiotic medical food. After successful bacteria isolation, growth of Lactobacillus and Streptococcus thermophilus were discovered to be inhibited when exposed to high concentrations of glyphosate that mimicked residues found on food products, as well as when exposed to the concentration amount deemed as the child safety benchmark, supported by p-values <0.05.

Committee: Jessica Hall Dr. (Advisor); Janet Antwi Dr. (Committee Member) Subjects: Biology; Microbiology; Molecular Biology

Master of Science, The Ohio State University, 2020, Environment and Natural Resources

Aminomethylphosphonic acid (AMPA) is a microbial degradation product of the herbicide glyphosate, and industrial phosphonates. In addition to possible negative effects on human health, AMPA may inhibit soil microbial growth and alter the soil microbial community composition. Strong soil adsorption causes AMPA to persist in the environment, slowing degradation, and making AMPA a possible long-term environmental contaminant. Review of the research literature in Chapter 1 revealed knowledge gaps concerning the effects of AMPA on soil microorganisms in different soil types and in isolation from glyphosate. Although there have been many studies on the behavior and effects of glyphosate in different soil types, there is scarce data that isolates the effects of AMPA. Therefore, the research objectives were to (1) study the effects of AMPA on soil microorganisms, (2) investigate how soil type affects AMPA bioavailability, (3) determine if chemical extractability can be used to predict AMPA bioavailability, and (4) investigate AMPA in isolation from glyphosate. Based on the literature, the hypotheses were that (1) a higher concentration of AMPA would be found to have a greater effect on soil microorganisms, and (2) bioavailability would be less in soils with high clay, high iron and aluminum oxides, and low pH. Chapter 2 describes a 139-day incubation study on three diverse soils with no exposure to glyphosate. These soils included a sandy soil, and two high clay soils with different mineralogy. Three field relevant concentrations of AMPA, including the control, were applied directly to soil, and the effects of AMPA on soil microbial respiration and phospholipid fatty acids were analyzed. Chapter 3 describes an investigation of AMPA bioavailability using chemical extraction, and correlations of extractable AMPA with microbial responses. Total soil carbon and pH appeared to be the most important soil factors affecting response to AMPA. Based on PLFA results, AMPA w (open full item for complete abstract)

Committee: Richard Dick PhD (Advisor); Jeffory Hattey PhD (Committee Member); Roman Lanno PhD (Committee Member) Subjects: Environmental Health; Environmental Science; Microbiology; Soil Sciences

Master of Science, The Ohio State University, 2020, Evolution, Ecology and Organismal Biology

Introduced insects can compete with native species and alter population and community dynamics. To minimize these effects and potential threats to biodiversity, it is necessary to understand the mechanisms that lie behind successful colonization of novel environments by introduced species, including anthropogenic factors such as herbicides. Glyphosate, the active ingredient of Roundup, is a broad-spectrum herbicide that is commonly applied to various types of land across the world. Its application increased dramatically after the introduction of glyphosate-resistant crops, leading glyphosate to become the top-selling herbicide worldwide. Although it is so widely used, its effects on wildlife are extremely under-studied. Of the few studies examining glyphosate's effects on non-target organisms, it has been shown to affect locomotion, reproduction, memory and learning of various species of arthropods. It is necessary to understand how glyphosate may be impacting invasion success of non-native insects. The present study examines these effects on native and non-native species of crickets. Further, competition with invasive species and exposure to herbicides may reveal or emphasize existing tradeoffs between traits. For example, many crickets trade off effort devoted to reproduction and immunity. Crickets commonly face immune challenges in the wild, so it is possible that a trade-off may lie in managing exposure to agrochemicals like herbicides and investment into immune function. If present, this trade-off may be contributing to the success of non-native species competing with native species and colonizing novel environments. Therefore, in the present study, I examine the effects of glyphosate and a possible trade-off with immunity on lifespan, calling effort and fecundity in the native fall field cricket, Gryllus pennsylvanicus and the non-native Japanese burrowing cricket Velarifictorus micado. G. pennsylvanicus and V. micado occupy a similar niche and therefore are e (open full item for complete abstract)

Committee: Susan Gershman Dr. (Advisor); Ian Hamilton Dr. (Committee Member); Roman Lanno Dr. (Committee Member) Subjects: Biology; Ecology

Doctor of Philosophy, The Ohio State University, 2019, Evolution, Ecology and Organismal Biology

Herbicide resistant weeds are among the greatest threats facing modern agriculture. Glyphosate, the active ingredient in the commercial herbicide RoundUp, is the most widely applied herbicide worldwide, and 43 weed species have evolved resistance to glyphosate to date. My research addressed four key questions about the strength, mechanisms, and fitness effects of glyphosate resistance using Conyza canadensis, a representative glyphosate-resistant weed, and Arabidopsis thaliana, a model plant species. In northcentral Ohio and southern Iowa, maternal biotypes (individual plants) of Conyza canadensis, also known as horseweed or marestail, were collected from 74 locations (both agricultural and non-agricultural) in both states. Dose-response experiments were used to categorize biotypes into resistance categories based on 80% survival at 0x only (Susceptible, S), and up to 1x (equivalent to 840 g ae ha-1; R1), 8x (R2), 20x (R3), and 40x (R4). Extreme glyphosate resistance (R4 biotypes) was quite common in both states and both habitats, and non-agricultural habitats served as a refuge for R4 biotypes. Glyphosate resistance mechanisms are generally presumed to impose a fitness cost due to possible trade-offs in resource allocation to plant defense, growth, and reproduction. Nine S, eight R1, and nine R4 biotypes originally collected in Iowa were grown in a common garden experiment in Iowa over two years and two sites to test for fitness effects. Based on early rosette sizes and days to bolting, nested ANOVAs showed that R4 biotypes grew as large as, if not larger than, both S and R1 biotypes, and bolted significantly earlier. Furthermore, R1 and R4 biotypes were less likely to display disease symptoms than S biotypes. Glyphosate resistance in horseweed appears not to impose an early growth penalty, and possibly no lifetime fitness cost. Specific mechanisms of glyphosate resistance in horseweed include altered translocation and vacuolar sequestration. Recently, a Canadi (open full item for complete abstract)

Committee: Allison Snow (Advisor); Stephen Hovick (Committee Member); Kristin Mercer (Committee Member) Subjects: Agriculture; Agronomy; Biology; Ecology; Evolution and Development

Master of Science, The Ohio State University, 2018, Environment and Natural Resources

The herbicide glyphosate (N-(phosphonomethyl) glycine) was first introduced in 1974 as a non-selective, broad spectrum, post-emergent agrochemical, branded under the trade name Roundup® and intended to control weed competition in agricultural farming. It gained large popularity and increased usage in 1996 with the introduction of glyphosate resistant soybean (Glycine max) cultivars and again in 1998 with resistant corn (Zea mays) cultivars. Its widespread usage has increased the concern of unknown long-term effects on the soil rhizosphere microbial community. In the same long-term context there is also increased concern over glyphosate's toxicity and accumulation of degradation products, notably aminomethylphosphponic acid (AMPA), which accounts for the majority of detected metabolites in the soil. Chapter one of this thesis will review the current literature on the toxicity and degradability of glyphosate and AMPA in the soil. In chapter two of this thesis a long-term glyphosate greenhouse experiment was designed with two main objectives, (1) determine the effects of long-term glyphosate application for three different glyphosate formulations on glyphosate resistant (GR) soybean rhizosphere microbial communities of two different soil managements, one with and one without a history of glyphosate exposure, and (2) use stable isotope probing (SIP) to identify possible glyphosate degrading microbial functional groups in these two soil managements. The objective of chapter three was to expand on chapter two by investigating the accumulation of glyphosate and AMPA in both the rhizosphere and bulk soil of the same long-term glyphosate greenhouse experiment. Research from a greenhouse study showed that repeated application of glyphosate increased the abundance of gram-negative microorganisms relative to a single application as detected by FAMEs. Likewise a field study also showed that repeated application of glyphosate increased Fusarium fungal colonization on both corn an (open full item for complete abstract)

Committee: Richard Dick (Advisor) Subjects: Agricultural Chemicals; Agriculture; Microbiology; Soil Sciences

Doctor of Philosophy, The Ohio State University, 2015, Horticulture and Crop Science

Common ragweed (Ambrosia artemisiifolia) is a weed problem in many places throughout the world. Though it seldom dominates the landscape, common ragweed seems to be able to exploit diverse habitats. Common ragweed is primarily outcrossing and has a high rate of gene polymorphisms, leading to high genetic diversity. This high level of genetic diversity likely plays a major role in the evolution of herbicide-resistant biotypes. Whole-plant bioassays of herbicide dose-response in the greenhouse were used to characterize resistance levels to glyphosate, cloransulam-methyl, and fomesafen herbicides. Additional studies were conducted to provide insight into potential mechanisms that may contribute to the development of resistance to glyphosate in an Ohio ragweed biotype, including 5 enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene sequencing, quantitative PCR of the EPSPS gene, EPSPS enzyme immunoblot and activity/inhibition assays, 31P nuclear magnetic resonance (NMR) studies of glyphosate-treated tissues, and whole-plant absorption and translocation studies using 14C-labeled glyphosate. A single common ragweed population from Clinton County, Ohio exhibited multiple resistance to herbicides at dosages that exceeded the rate required to kill herbicide-sensitive common ragweed biotypes from 4- to 30 fold for glyphosate, > 1000 fold for cloransulam-methyl, and 14- to > 100 fold for fomesafen. This is the first report of a common ragweed biotype with multiple resistance to herbicides from three site-of-action (SOA) groups. Sequencing data indicated the gene coding for EPSPS has a high mutation rate in all studied common ragweed biotypes, but it typically does not code for an altered amino acid sequence in the glyphosate binding area. Additional studies identified alleles of EPSPS coding for proline-to-serine and proline-to-threonine substitutions at amino acid number 106 (based upon the mature maize EPSPS numbering scheme). Previous studies by other authors h (open full item for complete abstract)

Committee: Mark Loux (Advisor); S. Kent Harrison (Committee Member); David Mackey (Committee Member); James Metzger (Committee Member); Anne Dorrance (Committee Member) Subjects: Agricultural Chemicals; Agriculture; Agronomy; Molecular Biology; Plant Biology

Master of Science, Miami University, 2014, Zoology

Animals living in terrestrial agroecosystems are faced with both natural and anthropogenic stressors simultaneously. Consequently, important interactions between animals that comprise agricultural food webs can be disrupted. The wolf spider, Pardosa milvina, is a common generalist predator in fields where glyphosate−based herbicides (Roundup®) are sprayed during warm summer months. I conducted laboratory and field experiments that explored the effects of both herbicide presence and environmental temperature on Pardosa foraging success. Spiders ate more crickets in high temperatures, and especially increased consumption during the first three hours of foraging. Herbicide presence induced superfluous prey killing by spiders, and under field conditions spiders were more likely to return and scavenge on dead prey. These results suggest that herbicide and temperature both affect the foraging of Pardosa. Further, my data show that glyphosate−based herbicides used in the field may have little effect on Pardosa's role in agricultural food webs and biocontrol.

Committee: Ann Rypstra PhD (Advisor); Richard Lee PhD (Committee Member); Michelle Boone PhD (Committee Member) Subjects: Animals; Biology; Ecology; Zoology

MS, University of Cincinnati, 2013, Arts and Sciences: Biological Sciences

Human-mediated selection can lead to rapid evolution in very short time scales. The evolution of herbicide resistance in agricultural weeds is an excellent example of this phenomenon, but despite this, over 60% of herbicide resistance studies are basic descriptions of the phenotype rather than an examination of the genetic basis and/or evolutionary processes underlying the trait. Using the tools of artificial selection and RNA-seq, we assessed both the evolutionary response and the potential for gene expression differences of selection lines of the common morning glory, Ipomoea purpurea, that differ in their level of resistance to the herbicide glyphosate. We found that the species rapidly responded to artificial selection—susceptible lines exhibited more damage and had fewer leaves as well as a higher proportion of individuals that died post-spray compared to resistant lines. We identified 19 differentially expressed genes (DEGs) between the selection lines—one of which, a cytochrome P450, belongs to a large plant family of genes involved in xenobiotic detoxification. The DEGs also broadly implicated receptor-like kinases, which were down-regulated in the resistant lines, and other growth and defense genes, which were up-regulated in resistant lines.

Committee: Ronald Debry Ph.D. (Committee Chair); Regina Baucom Ph.D. (Committee Member); Joshua Gross Ph.D. (Committee Member); Stephanie Rollmann Ph.D. (Committee Member) Subjects: Evolution and Development

Master of Science, The Ohio State University, 2011, Soil Science

Glyphosate [N-(phosphonomethyl)glycine] is the most widely used herbicide in the world. First sold in 1974 under the trade name Roundup, its use has increased dramatically in recent years with the introduction of genetically modified, glyphosate resistant (GR) crops. There is growing anecdotal evidence in the Midwestern United States of potassium (K) deficiency in corn, which appears to be related to the adoption of GR soybeans grown in rotation with corn. It is possible that the use of glyphosate in GR cropping systems is creating a selection pressure in soil microbial communities which could affect soil K dynamics. The first objective of Chapter 1 was to determine the effect of rates of glyphosate on microbial respiration. The second thesis objective of Chapter 1 was to determine the effect of glyphosate on microbial community structure, exchangeable, non-exchangeable, and microbial K in soils that had no, limited, or high amounts of glyphosate exposure under field conditions. The objectives of Chapter 2 were to determine the effect of foliar glyphosate applied to GR soybean on: 1) the rhizosphere soil microbial community composition, 2) exchangeable, non-exchangeable, and microbial K; and 3) leaf concentration K. In an incubation experiment, the addition of glyphosate was shown to significantly increase microbial respiration rates. The magnitude and duration of rates of respiration were greater in soils with a previous history of glyphosate applications, indicating that previous exposure to glyphosate may be associated with an increase in organisms able to metabolize glyphosate. In a second experiment, glyphosate was applied repeatedly to soils over a 180 day period. There were no significant shifts in soil microbial community structure based on ester linked fatty acid methyl ester (EL-FAME) analysis. In addition, glyphosate application did not significantly affect microbial biomass K. In a third experiment, glyphosate resistant soybeans grown in the greenhouse w (open full item for complete abstract)

Committee: Richard Dick PhD (Advisor); Brian McSpadden Gardener PhD (Committee Member); Ed McCoy PhD (Committee Member) Subjects: Agronomy; Environmental Science; Soil Sciences

Doctor of Philosophy, The Ohio State University, 2010, Soil Science

This dissertation is comprised of three separate studies in soil science and fertility. The first component concerns the use of swine manure on a leguminous crop. Recent environmental pressure has been placed to limit the practice of applying animal manures to fields planned for soybean [Glycine max (L.) Merr] production because of the perceived hazard of excessive NO3 movement offsite. The objective is to evaluate the impact of manure application to soybean fields on soil NO3-N, N uptake and soybean crop productivity. A field experiment was established in the spring of 2007 and 2008. Liquid swine (Sus scrofa domestica) manure was applied at three different N rates (based upon manure analysis and estimated availability) using two application methods (surface application or injection). Commercial fertilizer treatments (same equivalent rates) were also included as positive controls. Soil samples to 60 cm and tissue samples were collected throughout the growing season. Even though N application did result in higher soil NO3- levels for some treatments, applications rates that were less than or equal to 135 kg ha-1 represented a lower risk of possible NO3-N movement. Nitrogen supplied via manure and commercial fertilizer resulted in larger N uptake than the controls, but grain yield was not improved. This reveals that despite the fact that soybeans can fix their own N, soybeans will absorb soil inorganic-N as a net N sink. The second chapter of the dissertation explores the interactions of foliar-applied manganese and the herbicide glyphosate on glyphosate-resistant weeds. Glyphosate is a metal chelating agent that interacts with cations essential to plant growth, and previous studies have shown interactions with Mn resulting in decreased herbicide efficacy and manganese metabolism issues. This study measured the effects of different formulations of glyphosate and manganese combinations as well as timing of the application. Of six site-years, one instance of manganese a (open full item for complete abstract)

Committee: Robert Mullen PhD (Advisor); Edward McCoy PhD (Committee Member); Peter Thomison PhD (Committee Member); Mark Loux PhD (Committee Member) Subjects: Agricultural Chemicals; Agriculture; Agronomy; Soil Sciences

Master of Science, The Ohio State University, 2010, Evolution, Ecology, and Organismal Biology

Phragmites australis, the common reed, is an invasive macrophyte in many eastern North American wetlands. Reed often rapidly forms dense, near-monotypic stands by replacing native vegetation, which lowers plant diversity and alters wetland habitat structure. Accordingly, herbicides such as imazypr-based Habitat® and glyphosate-based AquaNeat® are often applied to reed stands in an attempt to control its establishment and spread. Although these herbicides are apparently not toxic to benthic organisms, they may indirectly affect them by altering available habitat structure via increased detrital litter, increased light penetration to surface waters and increased water temperature. Understanding the impacts of widespread herbiciding on benthic communities, as well as the impact of different herbicides on habitat conditions, should help wetland managers design control plans to reduce reed and conserve system biodiversity. I compared gastropod (i.e., snails) and epiphyton communities, and habitat conditions among large, replicated plots of unsprayed Phragmites, glyphosate-sprayed Phragmites, imazapyr-sprayed Phragmites and unsprayed Typha angustifolia (narrow-leaf cattail) in early the summer 2008 in a Lake Erie coastal marsh. I studied gastropods because they can greatly influence trophic structure in freshwater systems by consuming benthic algae and by serving as prey to sportfish. Moreover, I included Typha angustifolia in the study because it is another invasive plant common to many Lake Erie coastal wetlands. Relative abundances of gastropods were similar among treatments on 24 June and 30 June, but differed on 8 July. On 8 July, Fossaria spp. were particularly abundant in herbicide-treated plots, and Promenetus umbilicatellus was abundant in AquaNeat®- treated plots. Snail densities were greater in plots containing metaphyton (filamentous green algae) than in plots without metaphyton, and juvenile and small snails were abundant in metaphyton mats. Metaphyton presen (open full item for complete abstract)

Committee: Joseph R. Holomuzki PhD (Advisor); Stuart A. Ludsin PhD (Committee Member); G. Thomas Watters PhD (Committee Member) Subjects: Ecology

Master of Science, The Ohio State University, 1986, Zoology

Not available.

Committee: Theodore Bookhout (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2005, Horticulture and Crop Science

Studies were conducted at the plant, population, and community level to address questions concerning (1) seed germination in Alliaria petiolata (2) weed community composition and structure in response to tillage, rotation and herbicide, and (3) variation in Abutilon theophrasti. Alliaria petiolata seeds are dormant at maturity, requiring approximately 90 to 105 days cold-moist stratification at 4 to 5 °C for germination to occur. Mechanically scarified, and H2O2 and H2SO4 treated seeds germinated within 35 days when GA3 was applied exogenously. The composition of the weed-seedbank community was characterized 35 years after the implementation of a long-term study involving cropping sequence (continuous corn, corn-soybean, corn-oat-hay) and tillage system (conventional-, minimum-, and no-tillage). Values of S, J, and H' recorded for all combinations of the three-crop sequence were typically greater than the values of S, J, and H' reported for either the one and two-crop rotations. As the intensity of soil disturbance decreased, values for S increased. Mean germinable weed seed density was greatest in the no-tillage treatments across rotations and years. Results suggest that the weed seed community in a corn-oat-hay rotational system differs in structure and composition from communities associated with continuous corn and corn-soybean systems. There is concern that the widespread use of genetically-modified glyphosate-tolerant crops (GTCs) will alter agricultural weed community dynamics with respect to glyphosate-tolerance and emergence phenology. Species associated with individual tillage and rotation treatments were not different from species recorded in the same plots prior to the exclusive use of GTCs and glyphosate, suggesting that significant changes in weed community composition and structure have not occurred. Abutilon theophrasti is a noxious weed in modern row-crop agriculture. This study characterized the morphological, phonological, and genetic variation ve (open full item for complete abstract)

Committee: John Cardina (Advisor) Subjects: Agriculture, Agronomy

Doctor of Philosophy, Miami University, 2010, Zoology

Animals use chemical cues for signaling between species. However, anthropogenic chemicals can interrupt this natural chemical information flow, affecting predator- prey interactions. I explored how a glyphosate-based herbicide influenced the reactions of Pardosa milvina, a common wolf spider in agricultural systems, to its predators, the larger wolf spider, Hogna helluo and the carabid beetle, Scarites quadriceps. First, I tested the effects of exposure to herbicide and chemical cues from these predators on the activity, emigration, and survival of P. milvina in laboratory and mesocosm field experiments. In the presence of H. helluo cues in the laboratory, P. milvina always decreased activity and increased time to emigration. However, in the presence of S. quadriceps cues, these spiders only decreased activity and increased time to emigration when herbicide was also present. Presence of predator cues and herbicide did not affect the emigration of P. milvina from field mesocosms, but survival was highest for spiders exposed to S. quadriceps cues alone and lowest for those exposed to herbicide alone. Secondly, I tested the effects of predator cues, herbicide and prey availability on foraging and reproduction in female P. milvina. Spiders offered more prey captured and consumed more, while those exposed to H. helluo cues consumed less. Availability of prey and exposure to predator cues and herbicide in foraging trials had interactive effects on P. milvina's subsequent reproductive success. In the low prey treatments, exposure to predator cues and herbicide each reduced reproductive success. In the high prey treatments, exposure to herbicide reduced reproductive success for spiders also exposed to S. quadriceps cues, but increased reproductive success for spiders also exposed to H. helluo cues. Finally, I exposed juvenile P. milvina to S. quadriceps cues and herbicide but found no effect of either on the spider's growth and development. Together, these results indicate (open full item for complete abstract)

Committee: Ann Rypstra PhD (Advisor); Michelle Boone PhD (Committee Member); Thomas Crist PhD (Committee Member); Maria Gonazlez PhD (Committee Member); David Gorchov PhD (Committee Member) Subjects: Zoology

MS, Kent State University, 2008, College of Arts and Sciences / Department of Biological Sciences

Emergent plant litter is a major source of energy and carbon in wetland food webs. Detritus and the associated microbes are eaten by invertebrates, thereby transferring the carbon and energy to higher trophic levels. Monocultures of an invasive common reed, Phragmites australis, can alter wetland food webs and decrease native plant diversity. Therefore, stands are often controlled by cutting and/or herbiciding. The processes of decomposition were studied using leaves of herbicided and non-herbicided Phragmites and non-herbicided native wool grass, Scirpus cyperinus, using litterbags in wetland mesocosms. Leaf mass loss, percent organic content, C:N ratios, fungal biomass, bacterial numbers and biomass, and invertebrate community composition (total numbers, abundance of functional feeding groups and dominant taxa, richness) were examined on ten dates over the course of 293 days. There were no differences in invertebrate communities or most chemical characteristics between herbicided and non-herbicided Phragmites leaf litter, and both litter types decayed at similar rates (0.0047 k-1 and 0.0051 k-1, respectively). However, herbicided Phragmites litter had higher fungal and bacterial biomass than non-herbicided Phragmites litter. In contrast, Scirpus litter decayed much more slowly (0.0029 k-1) and had higher organic content remaining than either Phragmites litter. At the end of the study, over 44% of the Scirpus litter remained but only 13 - 14% of Phragmites litter remained. Significant differences were found in microbial communities between Scirpus and Phragmites litter, where Phragmites litter generally had higher fungal and bacterial biomass. Invertebrate richness was also higher on Phragmites than Scirpus litter. Furthermore, there were non-significant trends that total invertebrates, detritivores and collector-gatherers were higher on Phragmites than Scirpus litter by the last sampling date (25 May 2007). Principle components analysis also showed high positive c (open full item for complete abstract)

Committee: Laura Leff PhD (Advisor); Ferenc de Szalay PhD (Advisor); Oscar Rocha PhD (Committee Member) Subjects: Biology; Botany; Ecology; Entomology; Environmental Science; Microbiology

Master of Science (MS), Bowling Green State University, 2006, Photochemical Sciences

Marine biofouling is a worldwide problem for all seagoing vessels. It causes a roughness of a ship's hull, a decrease in its speed and maneuverability and thereby increasing fuel consumption and emission of waste products into the atmosphere. As long as 2000 years ago, people attempted to prevent biofouling by covering ship's hulls with copper and lead sheets. Since then a large variety of methods have been tried but none proved ideal. The current research project tests incorporation a glyphosate-based biocide into a model marine coating to prevent the formation of biofilms – one of the first steps in marine fouling and thereby block biofouling process. This work describes a synthetic route for a novel compound – acrylated glyphosate – and characterization by chemical, analytical and physical methods. Polymerization, photopolymerization and copolymerization experiments proved the novel compound efficiently polymerizes and copolymerizes during reasonably short time intervals (120sec-10 min). Biological assays based on the Kirby-Bauer test and monitoring of growth inhibition showed that the acrylated glyphosate derivative, as well as its polymer, possess strong herbicidal activity against model and common biofouling organisms. Incorporation of acrylated glyphosate into model acrylic resin yielded a highly cross-linked coating which proved to be toxic toward the microorganisms. Release experiments showed no leaching of copolymerized acrylated glyphosate from the coating over 21 days. This indicates that the compound, incorporated into the backbone structure of the iv coating, retains herbicidal activity against common fouling organisms. Therefore, acrylated glyphosate is a promising component for antifouling coatings for seagoing vessels.

Committee: Douglas Neckers (Advisor) Subjects: Chemistry, Polymer