Ecology and Evolutionary Biology Commons^™

Determining The Impact Of Post-Harvest Water Management On Chironomid Abundance, Agrochemical Biomass And Potential Trophic Biomagnification, Mason Thomas

Theses and Dissertations

Agriculture has diminished shorebirds’ natural habitat in the Mississippi Alluvial Valley. Remaining natural stopover sites are supplemented with agricultural fields during the fall and winter. This study evaluates the impact of 4 different post-harvest water management strategies on shorebird food abundance and potential agrochemical biomagnification. Chironomid samples estimated abundance, biomass, and chironomid agrochemical concentration in each field. A risk assessment of agrochemical biomagnification to shorebirds was made across all treatments. Of treatments represented on all study sites, winter treatment had greatest chironomid abundance and biomass. Models indicated that days since flood initiation, start date, and temperature are significant predictors of …

Effects Of Mass Death On Community Structure And Ecosystem Function, Abby Kimpton Jones

Theses and Dissertations

Death and decomposition are natural processes that are generally well-understood. However, large events of death, such as mass mortality events (MMEs) are increasing in frequency and their impacts on the ecosystem are largely unknown. These events may have both bottom-up effects from increased nutrient input as well as top-down effects from loss of an ecological functional group by the affected population. Different functional MMEs may result in different top-down effects, creating cascading effects. In Chapter 1, I test the hypothesis that scavenger and herbivore simulated MMEs generate novel bottom-up and top-down effects. Results indicate that MMEs have a significant effect …

Plant-Pollinator Associations In An Eastern Serpentine Savannah And The Effects Of Overbrowsing, Allyson Richins

Theses and Dissertations

Chapter 1: Native plant response to deer overbrowsing in a serpentine savannah

Plants are particularly vulnerable to physical disturbance in low productivity areas, due to a high cost of replacing lost plant tissue. In the eastern United States, serpentine grasslands are fragmented ecosystems with high concentrations of rare endemic plant species, low concentrations of soil nutrients, and uncontrolled deer overpopulation. This study assessed functional responses of native angiosperms in a rare eastern serpentine savannah to selective deer browsing. Plant count, flower count, floral area, vegetative area, and plant height of 10 serpentine plant species were compared inside and outside of …

Bee Diversity Of Three Appalachian Shale Barren Sites, Olivia C. Latham

Theses and Dissertations

Insect pollination is vital to ecosystem function. However, climate change, habitat loss, pesticides, and a variety of other anthropogenic sources are contributing to a decline in pollinator diversity. Fragile small ecosystems with a high composition of specialized plant species that rely on specific pollinators such as Appalachian shale barrens, are especially at risk of losing biodiversity. This study combines the use of active sweep net sampling of endemic shale barren forbs and passive trap methods over the course of a bloom season (April-August) in three barren sites to identify bee community populations and visitation relationships between pollinator species and endemic …

Upper Thermal Limits Vary Among And Within Native Bee Species In Relation To Season, Voltinism, And Nest Type, Kálmán K. Csigi Xiv

Theses and Dissertations

Native bees are only recently gaining attention for the extent to which they aid in pollination and ecosystem services. These services are threatened by predictions of warming temperatures if bees are not able to respond. Voltinism - the number of generations produced annually- can strongly influence thermal conditions experienced by both developing and adult bees based on emergence strategies for each voltinism type. Differences in experienced thermal conditions brought on by climate change could therefore affect upper thermal limits (UTL) in bees. This study observes UTLs across a foraging season within and among native bee species vi to elucidate the …

Natural Selection By Insect Pollinators And Seed Predators On Floral Head Traits Of Helianthus Grosseserratus (Sawtooth Sunflower), Jason Stephen Servi

Theses and Dissertations

Flowering plants must invest energy and resources to produce floral displays that are attractive to pollinators, but these same displays may also attract detrimental insects. How floral traits are shaped by the preferences of both pollinators and herbivores/seed predators is not fully understood. Using Helianthus grosseserratus (sawtooth sunflower) as my study species, I investigated these conflicting selective pressures on floral head traits through a 2-year study in a large, unbroken tract of mesic prairie in Wisconsin. In the first season, I followed individual heads over time and recorded insect visitation patterns and phenological changes to floral head traits. I also …

Upper Thermal Limits Differ Among Component Species In A Host-Parasitoid-Hyperparasitoid System, Kanchan A. Joshi

Theses and Dissertations

Among the predicted impacts associated with global climate change, warming is of special interest because the rates of physiological processes are temperature-dependent. Insects and other ectotherms are likely to be affected due to their limited ability to control body temperature. In this study, I measured the tolerance to extreme high temperatures, i.e., critical thermal maximum (CT_max), of component species in a tri-trophic system, including an herbivore (Manduca sexta), a primary larval parasitoid (Cotesia congregata) and a hyperparasitoid (genus Silochalcis). For wild insects, the parasitoid had the lowest CT_max, the hyperparasitoid had …

Environmental Impacts On Life History In Container Breeding Mosquitoes, Kathleen May Westby

Theses and Dissertations

In this dissertation I explore different ways that the environment impacts life history in mosquitoes in ways that may alter vectorial capacity. In chapter I, I tested if short-term sugar deprivation experienced after exposure to La Crosse virus altered infection rates in Aedes albopictus and if sugar treatment and virus infection status altered blood feeding behavior and fecundity. I found no evidence that sugar deprivation impacted infection rates or fecundity. Sugar deprivation did increase blood feeding. There was no effect of infection status on blood feeding or fecundity. In chapter II, I tested for effects of seasonal cues (temperature and …

Behavioral Responses Of Male Parasitic Wasps To Plant Cues: A Comparison Of Two Host-Plant Complex Sources Of Cotesia Congregata (Say), Megan Ayers

Theses and Dissertations

Prior exposure to plants cues can enhance assortative mating in insects. We hypothesized that, as previously reported for females, males of Cotesia congregata would display inherent responses to plant cues that could be modified by postemergence experience and further, that males originating from two different host-plant complexes (HPCs) would display different behavioral responses to these HPCs. In no-choice contact assays with a non-host plant, searching responses of males and females increased sharply at Day 2 and remained stable through Day 4. In no-choice assays with potential host plants, males searched longer on catalpa than tobacco; responses were not modified by …

Speed And Resolution In The Age Of Technological Reproducibility, Shawn Taylor

Theses and Dissertations

The rate of acceleration of the biologic and synthetic world has for a while now, been in the process of exponentially speeding up, maxing out servers and landfills, merging with each other, destroying each other. The last prehistoric relics on Earth are absorbing the same oxygen, carbon dioxide and electronic waves in our biosphere as us. A degraded .jpeg enlarged to full screen on a Samsung 4K UHD HU8550 Series Smart TV - 85” Class (84.5” diag.). Within this composite ecology, the ancient limestone of the grand canyon competes with the iMax movie of itself, the production of Mac pros, …

Responses Of The Catalpa Sphinx, Ceratomia Catalpae, And Its Primary Parasitoid, Cotesia Congregata, To Varying Levels Of Iridoid Glycosides In Catalpa, Jessica L. Bray

Theses and Dissertations

The catalpa sphinx, Ceratomia catalpae, is a specialist on Catalpa trees, which produce iridoid glycosides (IGs). Whereas some trees are defoliated every year, others escape herbivory. Caterpillar populations are either heavily parasitized by the braconid wasp, Cotesia congregata, or remain unparasitized. We hypothesized that these patterns could be explained by variable IG concentrations among trees and insect responses to these chemicals. IG concentrations varied among trees. Percent defoliation was positively related to IG concentration. In comparisons of insect responses to relatively high or low IG concentrations, moths preferred to oviposit on trees with high IG concentrations. Caterpillars did …