ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: Biology
- Creators: Pratt, Stephen C
- Creators: Cease, Arianne
Description
The coordination of group behavior in the social insects is representative of a broader phenomenon in nature, emergent biological complexity. In such systems, it is believed that large-scale patterns result from the interaction of relatively simple subunits. This dissertation involved the study of one such system: the social foraging of the ant Temnothorax rugatulus. Physically tiny with small population sizes, these cavity-dwelling ants provide a good model system to explore the mechanisms and ultimate origins of collective behavior in insect societies. My studies showed that colonies robustly exploit sugar water. Given a choice between feeders unequal in quality, colonies allocate more foragers to the better feeder. If the feeders change in quality, colonies are able to reallocate their foragers to the new location of the better feeder. These qualities of flexibility and allocation could be explained by the nature of positive feedback (tandem run recruitment) that these ants use. By observing foraging colonies with paint-marked ants, I was able to determine the `rules' that individuals follow: foragers recruit more and give up less when they find a better food source. By altering the nutritional condition of colonies, I found that these rules are flexible - attuned to the colony state. In starved colonies, individual ants are more likely to explore and recruit to food sources than in well-fed colonies. Similar to honeybees, Temmnothorax foragers appear to modulate their exploitation and recruitment behavior in response to environmental and social cues. Finally, I explored the influence of ecology (resource distribution) on the foraging success of colonies. Larger colonies showed increased consistency and a greater rate of harvest than smaller colonies, but this advantage was mediated by the distribution of resources. While patchy or rare food sources exaggerated the relative success of large colonies, regularly (or easily found) distributions leveled the playing field for smaller colonies. Social foraging in ant societies can best be understood when we view the colony as a single organism and the phenotype - group size, communication, and individual behavior - as integrated components of a homeostatic unit.
ContributorsShaffer, Zachary (Author) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Janssen, Marco (Committee member) / Fewell, Jennifer (Committee member) / Liebig, Juergen (Committee member) / Arizona State University (Publisher)
Created2014
Description
Land management practices such as domestic animal grazing can alter plant communities via changes in soil structure and chemistry, species composition, and plant nutrient content. These changes can affect the abundance and quality of plants consumed by insect herbivores with consequent changes in population dynamics. These population changes can translate to massive crop damage and pest control costs. My dissertation focused on Oedaleus asiaticus, a dominant Asian locust, and had three main objectives. First, I identified morphological, physiological, and behavioral characteristics of the migratory ("brown") and non-migratory ("green") phenotypes. I found that brown morphs had longer wings, larger thoraxes and higher metabolic rates compared to green morphs, suggesting that developmental plasticity allows greater migratory capacity in the brown morph of this locust. Second, I tested the hypothesis of a causal link between livestock overgrazing and an increase in migratory swarms of O. asiaticus. Current paradigms generally assume that increased plant nitrogen (N) should enhance herbivore performance by relieving protein-limitation, increasing herbivorous insect populations. I showed, in contrast to this scenario, that host plant N-enrichment and high protein artificial diets decreased the size and viability of O. asiaticus. Plant N content was lowest and locust abundance highest in heavily livestock-grazed fields where soils were N-depleted, likely due to enhanced erosion and leaching. These results suggest that heavy livestock grazing promotes outbreaks of this locust by reducing plant protein content. Third, I tested for the influence of dietary imbalance, in conjunction with high population density, on migratory plasticity. While high population density has clearly been shown to induce the migratory morph in several locusts, the effect of diet has been unclear. I found that locusts reared at high population density and fed unfertilized plants (i.e. high quality plants for O. asiaticus) had the greatest migratory capacity, and maintained a high percent of brown locusts. These results did not support the hypothesis that poor-quality resources increased expression of migratory phenotypes. This highlights a need to develop new theoretical frameworks for predicting how environmental factors will regulate migratory plasticity in locusts and perhaps other insects.
ContributorsCease, Arianne (Author) / Harrison, Jon (Thesis advisor) / Elser, James (Thesis advisor) / DeNardo, Dale (Committee member) / Quinlan, Michael (Committee member) / Sabo, John (Committee member) / Arizona State University (Publisher)
Created2012
Description
For interspecific mutualisms, the behavior of one partner can influence the fitness of the other, especially in the case of symbiotic mutualisms where partners live in close physical association for much of their lives. Behavioral effects on fitness may be particularly important if either species in these long-term relationships displays personality. Animal personality is defined as repeatable individual differences in behavior, and how correlations among these consistent traits are structured is termed behavioral syndromes. Animal personality has been broadly documented across the animal kingdom but is poorly understood in the context of mutualisms. My dissertation focuses on the structure, causes, and consequences of collective personality in Azteca constructor colonies that live in Cecropia trees, one of the most successful and prominent mutualisms of the neotropics. These pioneer plants provide hollow internodes for nesting and nutrient-rich food bodies; in return, the ants provide protection from herbivores and encroaching vines. I first explored the structure of the behavioral syndrome by testing the consistency and correlation of colony-level behavioral traits under natural conditions in the field. Traits were both consistent within colonies and correlated among colonies revealing a behavioral syndrome along a docile-aggressive axis. Host plants of more active, aggressive colonies had less leaf damage, suggesting a link between a colony personality and host plant health. I then studied how aspects of colony sociometry are intertwined with their host plants by assessing the relationship among plant growth, colony growth, colony structure, ant morphology, and colony personality. Colony personality was independent of host plant measures like tree size, age, volume. Finally, I tested how colony personality influenced by soil nutrients by assessing personality in the field and transferring colonies to plants the greenhouse under different soil nutrient treatments. Personality was correlated with soil nutrients in the field but was not influenced by soil nutrient treatment in the greenhouse. This suggests that soil nutrients interact with other factors in the environment to structure personality. This dissertation demonstrates that colony personality is an ecologically relevant phenomenon and an important consideration for mutualism dynamics.
ContributorsMarting, Peter (Author) / Pratt, Stephen C (Thesis advisor) / Wcislo, William T (Committee member) / Hoelldobler, Bert (Committee member) / Fewell, Jennifer H (Committee member) / Gadau, Juergen (Committee member) / Arizona State University (Publisher)
Created2018
Description
Understanding how and why animals choose what to eat is one of the fundamental goals of nutritional and behavioral biology. This question can be scaled to animals that live in social groups, including eusocial insects. One of the factors that plays an important role in foraging decisions is the prevalence of specific nutrients and their relative balance. This dissertation explores the role of relative nutrient content in the food selection decisions of a species that is eusocial and also agricultural, the desert leafcutter ant Acromyrmex versicolor. A dietary choice assay, in which the relative amount of protein and carbohydrates in the available diets was varied, demonstrated that A. versicolor colonies regulate relative collection of protein and carbohydrates. Tracking the foraging behavior of individual workers revelaed that foragers vary in their relative collection of experimental diets and in their foraging frequency, but that there is no relationship between these key factors of foraging behavior. The high proportion of carbohydrates preferred by lab colonies suggests that they forage to nutritionally support the fungus rather than brood and workers. To test this, the relative amounts of 1) fungus, and 2) brood (larvae) was manipulated and foraging response was measured. Changing the amount of brood had no effect on foraging. Although decreasing the size of fungus gardens did not change relative P:C collection, it produced significant increases in caloric intake, supporting the assertion that the fungus is the main driver of colony nutrient regulation. The nutritional content of naturally harvested forage material collected from field colonies was measured, as was recruitment to experimental diets with varying relative macronutrient content. Field results confirmed a strong colony preference for high carbohydrate diets. They also indicated that this species may, at times, be limited in its ability to collect sufficiently high levels of carbohydrates to meet optimal intake. This dissertation provides important insights about fundamental aspects of leafcutter ant biology and extends our understanding of the role of relative nutrient content in foraging decisions to systems that span multiple trophic levels.
ContributorsSmith, Nathan Edward (Author) / Fewell, Jennifer H (Thesis advisor) / Harrison, Jon F (Committee member) / Pavlic, Ted (Committee member) / Cease, Arianne (Committee member) / Hoelldobler, Bert (Committee member) / Arizona State University (Publisher)
Created2023
Description
The migratory grasshopper (Melanoplus sanguinipes) is one of the most economically important grasshoppers in the western rangelands of the United States (US), capable of causing incredible amounts of damage to crops and rangelands. While M. sanguinipes has been the focus of many research studies, areas like field nutritional physiology and ecology, and interactions between nutritional physiology and biopesticide resistance have very little research. This dissertation presents a multifaceted approach through three research-driven chapters that examine the nutritional physiology of M. sanguinipes and how it interacts with an entomopathogenic fungus for grasshopper management, as well as the challenges of using biopesticides for grasshopper management. Using the Geometric Framework for Nutrition (GFN), I established baseline macronutrient intake for M. sanguinipes, both in laboratory and field populations. Through this work, I found that field and lab populations can exhibit different protein (p) to carbohydrate (c) ratios, or Intake Targets (ITs), but that the field populations had ITs that matched the nutrients available in their environment. I also used the GFN to show that infections with the fungal entomopathogen Metarhizium robertsii DWR2009 did not alter ITs in M. sanguinipes. Although, when confined to carbohydrate- or protein-biased diets, infected grasshoppers had a slightly extended lifespan relative to grasshoppers fed balanced protein:carbohydrate diets. Interestingly, in a postmortem for the grasshopper, the fungus was only able to effectively sporulate on grasshoppers fed the 1p:1c diets, suggesting that grasshopper diet can have substantial impacts on the spread of fungal biopesticides throughout a population, in the absence of any inhibitory abiotic factors. Lastly, I examined the major barriers to fungal and microsporidian biopesticide usage in the United States, including low efficacy, thermal and environmental sensitivity, non-target effects, unregistered or restricted use, and economic or accessibility barriers. I also explored potential solutions to these challenges. This dissertation's focus on Melanoplus sanguinipes and Metarhizium roberstii Strain DWR2009, generates new information about how nutritional physiology and immunology intersect to impact M. sanguinipes performance. The methodology in each of the experimental chapters provides a framework for examining other problematic grasshopper species, by determining baseline nutritional physiology, and coupling nutrition with immunology to maximize the effectiveness of biological pesticides.
ContributorsZembrzuski, Deanna (Author) / Cease, Arianne (Thesis advisor) / Harrison, Jon (Committee member) / Angilletta, Michael (Committee member) / Jaronski, Stefan (Committee member) / Arizona State University (Publisher)
Created2023
Description
Vector control plays an important role in the prevention and control of mosquito-borne diseases (MBDs). As there are no (prophylactic) drugs and/or vaccines available for many arboviral diseases (such as zika, chikungunya, Saint Louis encephalitis, Ross River virus), the frontline approach to prevent or reduce disease morbidity and mortality is through the reduction of the mosquito vector population size and/or reducing vector-human contact using insecticides. Frontline tools in malaria (an MBD caused by a parasite) control and elimination have been drugs (targeting the malaria parasite) and insecticides (targeting the vectors) through indoor residual spraying (IRS) (spraying the internal walls and sometimes the roofs of dwellings with residual insecticides to kill adult mosquito vectors), and long-lasting insecticidal nets (LLINs), while arboviral vectors are frequently targeted using outdoor fogging and space spraying (indoor or outdoor spraying of insecticides to kill adult mosquito vectors). Integrative and novel vector control efforts are urgently needed since the aforementioned tools may not be as effective against those mosquito species that are resistant to insecticides and/or have a different (or changed) behavior allowing them to avoid existing tools. In Chapters 2 and 3, I investigate mosquito vector surveillance in Arizona by (i) discussing the species composition and public health implications of the State’s mosquito fauna, and (ii) comparing the effectiveness of 4 different carbon dioxide (CO2) sources in attracting different mosquito species on the Arizona State University Tempe Campus. In Chapters 4 and 5, I investigate a novel vector control tool by (i) completing a literature review on using electric fields (EFs) to control insects, and (ii) presenting novel data on using Insulated Conductor Wires (ICWs) to generate EFs that prevent host-seeking female Aedes aegypti from entering spaces. In Chapter 6, I discuss the non-target effects of chemical malaria control on other arthropods, including other biological and mechanical infectious disease vectors. Overall, this dissertation highlights the important role that the development of novel surveillance and vector control tools could play in improved mosquito control, which ultimately will reduce disease morbidity and mortality.
ContributorsJobe, Ndey Bassin (Author) / Paaijmans, Krijn (Thesis advisor) / Cease, Arianne (Committee member) / Hall, Sharon (Committee member) / Huijben, Silvie (Committee member) / Arizona State University (Publisher)
Created2024
Description
An insect society needs to share information about important resources in order to collectively exploit them. This task poses a dilemma if the colony must consider multiple resource types, such as food and nest sites. How does it allocate workers appropriately to each resource, and how does it adapt its recruitment communication to the specific needs of each resource type? In this dissertation, I investigate these questions in the ant Temnothorax rugatulus.
In Chapter 1, I summarize relevant past work on food and nest recruitment. Then I describe T. rugatulus and its recruitment behavior, tandem running, and I explain its suitability for these questions. In Chapter 2, I investigate whether food and nest recruiters behave differently. I report two novel behaviors used by recruiters during their interaction with nestmates. Food recruiters perform these behaviors more often than nest recruiters, suggesting that they convey information about target type. In Chapter 3, I investigate whether colonies respond to a tradeoff between foraging and emigration by allocating their workforce adaptively. I describe how colonies responded when I posed a tradeoff by manipulating colony need for food and shelter and presenting both resources simultaneously. Recruitment and visitation to each target partially matched the predictions of the tradeoff hypothesis. In Chapter 4, I address the tuned error hypothesis, which states that the error rate in recruitment is adaptively tuned to the patch area of the target. Food tandem leaders lost followers at a higher rate than nest tandem leaders. This supports the tuned error hypothesis, because food targets generally have larger patch areas than nest targets with small entrances.
This work shows that animal groups face tradeoffs as individual animals do. It also suggests that colonies spatially allocate their workforce according to resource type. Investigating recruitment for multiple resource types gives a better understanding of exploitation of each resource type, how colonies make collective decisions under conflicting goals, as well as how colonies manage the exploitation of multiple types of resources differently. This has implications for managing the health of economically important social insects such as honeybees or invasive fire ants.
In Chapter 1, I summarize relevant past work on food and nest recruitment. Then I describe T. rugatulus and its recruitment behavior, tandem running, and I explain its suitability for these questions. In Chapter 2, I investigate whether food and nest recruiters behave differently. I report two novel behaviors used by recruiters during their interaction with nestmates. Food recruiters perform these behaviors more often than nest recruiters, suggesting that they convey information about target type. In Chapter 3, I investigate whether colonies respond to a tradeoff between foraging and emigration by allocating their workforce adaptively. I describe how colonies responded when I posed a tradeoff by manipulating colony need for food and shelter and presenting both resources simultaneously. Recruitment and visitation to each target partially matched the predictions of the tradeoff hypothesis. In Chapter 4, I address the tuned error hypothesis, which states that the error rate in recruitment is adaptively tuned to the patch area of the target. Food tandem leaders lost followers at a higher rate than nest tandem leaders. This supports the tuned error hypothesis, because food targets generally have larger patch areas than nest targets with small entrances.
This work shows that animal groups face tradeoffs as individual animals do. It also suggests that colonies spatially allocate their workforce according to resource type. Investigating recruitment for multiple resource types gives a better understanding of exploitation of each resource type, how colonies make collective decisions under conflicting goals, as well as how colonies manage the exploitation of multiple types of resources differently. This has implications for managing the health of economically important social insects such as honeybees or invasive fire ants.
ContributorsCho, John Yohan (Author) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Liebig, Jürgen R (Committee member) / Amazeen, Polemnia G (Committee member) / Rutowski, Ronald L (Committee member) / Arizona State University (Publisher)
Created2019
Description
The flexibility and robustness of social insect colonies, when they cope with challenges as integrated units, raise many questions, such as how hundreds and thousands of individual local responses are coordinated without a central controlling process. Answering such questions requires: 1. Quantifiable collective responses of colonies under specific scenarios; 2. Decomposability of the collective colony-level response into individual responses; and 3. Mechanisms to integrate the colony- and individual-level responses. In the first part of my dissertation, I explore coordinated collective responses of colonies in during the alarm response to an alarmed nestmate (chapter 2&3). I develop a machine-learning approach to quantitatively estimate the collective and individual alarm response (chapter 2). Using this methodology, I demonstrate that colony alarm responses to the introduction of alarmed nestmates can be decomposed into immediately cascading, followed by variable dampening processes. Each of those processes are found to be modulated by variation in individual alarm responsiveness, as measured by alarm response threshold and persistence of alarm behavior. This variation is modulated in turn by environmental context, in particular with task-related social context (chapter 3). In the second part of my dissertation, I examine the mechanisms responsible for colonial changes in metabolic rate during ontogeny. Prior studies have found that larger ant colonies (as for larger organisms) have lower mass-specific metabolic rates, but the mechanisms remain unclear. In a 3.5-year study on 25 colonies, metabolic rates of colonies and colony components were measured during ontogeny (chapter 4). The scaling of metabolic rate during ontogeny was fit better by segmented regression or quadratic regression models than simple linear regression models, showing that colonies do not follow a universal power-law of metabolism during the ontogenetic development. Furthermore, I showed that the scaling of colonial metabolic rates can be primarily explained by changes in the ratio of brood to adult workers, which nonlinearly affects colonial metabolic rates. At high ratios of brood to workers, colony metabolic rates are low because the metabolic rate of larvae and pupae are much lower than adult workers. However, the high colony metabolic rates were observed in colonies with moderate brood: adult ratios, because higher ratios cause adult workers to be more active and have higher metabolic rates, presumably due to the extra work required to feed more brood.
ContributorsGuo, Xiaohui (Author) / Fewell, Jennifer H (Thesis advisor) / Kang, Yun (Thesis advisor) / Harrison, Jon F (Committee member) / Liebig, Juergen (Committee member) / Pratt, Stephen C (Committee member) / Pavlic, Theodore P (Committee member) / Arizona State University (Publisher)
Created2021
Description
In many social groups, reproduction is shared between group members, whocompete for position in the social hierarchy for reproductive dominance. This
reproductive conflict can lead to different means of enforcing reproductive differences,
such as dominance displays or limited control of social hierarchy through antagonistic
encounters. In eusocial insects, archetypal colonies contain a single, singly-mated fertile
queen, such that no reproductive conflict exists within a colony. However, many eusocial
insects deviate from this archetype and have multiply-mated queens (polyandry), multiple
queens in a single colony (polygyny), or both. In these cases, reproductive conflict exists
between the matrilines and patrilines represented in a colony, specifically over the
production of sexual offspring. A possible outcome of reproductive conflict may be the
emergence of cheating lineages, which favor the production of sexual offspring, taking
advantage of the worker force produced by nestmate queens and/or patrilines. In extreme
examples, inquiline social parasites may be an evolutionary consequence of reproductive
conflict between nestmate queens. Inquiline social parasitism is a type of social
parasitism that is usually defined by a partial or total loss of the worker caste, and the
“infiltration” of host colonies to take advantage of the host worker force for reproduction.
It has been hypothesized that these inquiline social parasites evolve through the
speciation of cheating queen lineages from within their incipient host species. This “intra-
specific” origin model involves a foundational hypothesis that the common ancestor of
host and parasite (and thus, putatively, the host at the time of speciation) should be
functionally polygynous, and that parasitism evolves as a “resolution” of reproductive
conflict in colonies. In this dissertation, I investigate the hypothesized role of polygyny in the evolution of inquiline social parasites. I use molecular ecology and statistical
approaches to validate the role of polygyny in the evolution of some inquiline social
parasites. I further discuss potential mechanisms for the evolution and speciation of social
parasites, and discuss future directions to elucidate these mechanisms.
ContributorsDahan, Romain Arvid (Author) / Rabeling, Christian (Thesis advisor) / Amdam, Gro V (Committee member) / Fewell, Jennifer H (Committee member) / Pratt, Stephen C (Committee member) / Rüppell, Olav (Committee member) / Arizona State University (Publisher)
Created2021
Description
Eusocial insect colonies have often been imagined as “superorganisms” exhibiting tight homeostasis at the colony level. However, colonies lack the tight spatial and organizational integration that many multicellular, unitary organisms exhibit. Precise regulation requires rapid feedback, which is often not possible when nestmates are distributed across space, making decisions asynchronously. Thus, one should expect poorer regulation in superorganisms than unitary organisms.Here, I investigate aspects of regulation in collective foraging behaviors that involve both slow and rapid feedback processes. In Chapter 2, I examine a tightly coupled system with near-instantaneous signaling: teams of weaver ants cooperating to transport massive prey items back to their nest. I discover that over an extreme range of scenarios—even up vertical surfaces—the efficiency per transporter remains constant. My results suggest that weaver ant colonies are maximizing their total intake rate by regulating the allocation of transporters among loads. This is an exception that “proves the rule;” the ant teams are recapitulating the physical integration of unitary organisms.
Next, I focus on a process with greater informational constraints, with loose temporal and spatial integration. In Chapter 3, I measure the ability of solitarily foraging Ectatomma ruidum colonies to balance their collection of protein and carbohydrates given different nutritional environments. Previous research has found that ant species can precisely collect a near-constant ratio between these two macronutrients, but I discover these studies were using flawed statistical approaches. By developing a quantitative measure of regulatory effect size, I show that colonies of E. ruidum are relatively insensitive to small differences in food source nutritional content, contrary to previously published claims.
In Chapter 4, I design an automated, micro-RFID ant tracking system to investigate how the foraging behavior of individuals integrates into colony-level nutrient collection. I discover that spatial fidelity to food resources, not individual specialization on particular nutrient types, best predicts individual forager behavior. These findings contradict previously published experiments that did not use rigorous quantitative measures of specialization and confounded the effects of task type and resource location.
ContributorsBurchill, Andrew Taylor (Author) / Pavlic, Theodore P (Thesis advisor) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Cease, Arianne (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2022