Matching Items (35)
Description
In order to survive, species must regulate their intake of nutrients. In desert leafcutter ant colonies, acquisition of nutrients is not only important for maintaining the health of the colony, but also for the survival of a fungus which the ants cultivate and then consume. This multi-trophic, symbiotic relationship is relatively unique to leafcutter ants and interesting to researchers due to the complexity of how the individual foragers supply nutrients to both the colony and the fungus. The objective of this experiment is to study foraging rates and variation in macronutrient preference among foragers from the same colony of the desert leafcutter ant Acromyrmex versicolor. This study asks if individual foragers vary in their preference of protein to carbohydrate ratios when compared to the overall nutrient content of the colony, and how do these individuals respond as the nutrient content of the available diets increasingly deviates from the previously determined nutritional intake target ratio between 1 Protein:6.3 Carbohydrates to 1 Protein:7.5 Carbohydrates. It was hypothesized that foragers express individualized nutritional preferences that in aggregate balance colony macronutrient consumption, and the number of individuals collecting the diets would decrease as the available nutritional diets deviated away from the colony-level intake target of approximately 1P:7C. The results show trends that support the hypothesis that the number of foraging instances and the number of foragers who exhibit individualized preference towards a certain protein to carbohydrate ratio is highest when the colony is presented with diets that are closest to the colony nutritional intake target.
ContributorsGlovsky, Taylor Ella (Author) / Fewell, Jennifer (Thesis director) / Harrison, Jon (Committee member) / School of Life Sciences (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Honeybees (Apis mellifera) are pollinators that face multiple challenges during foraging such as fungicides applied to floral sources. Fungicides are chemicals used to inhibit key fungal mechanisms like metabolism, but their effects remain relatively unknown in bees. In addition, studying the maturing bee can help us identify demographics that are more vulnerable to toxic materials like fungicides. The purpose of this study is test whether maturation and the fungicide Pristine influence the permeability of the blood-brain barrier. Specifically, we use a transportable dye to test how blood brain barrier transporter function responds to toxic insult and how it changes with age. Oral ingestion of Pristine by female workers did not have an effect on blood brain barrier permeability which suggests Pristine may have no or longer term consequences in the bee. However, blood brain barrier permeability changed with the bee's age which could be explained by the regulation of blood brain barrier transporters during natural transitions in hive task or the presence of hemolymph protein filtration
ContributorsPatel, Aamir S. (Author) / Amdam, Gro (Thesis director) / Harrison, Jon (Committee member) / Ozturk, Cahit (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Neurotoxicology has historically focused on substances that directly damage nervous tissue. Behavioral assays that test sensory, cognitive, or motor function are used to identify neurotoxins. But, the outcomes of behavioral assays may also be influenced by the physiological status of non-neural organs. Therefore, toxin induced damage to non- neural organs may contribute to behavioral modifications. Heavy metals and metalloids are persistent environmental pollutants and induce neurological deficits in multiple organisms. However, in the honey bee, an important insect pollinator, little is known about the sublethal effects of heavy metal and metalloid toxicity though they are exposed to these toxins chronically in some environments. In this thesis I investigate the sublethal effects of copper, cadmium, lead, and selenium on honey bee behavior and identify potential mechanisms mediating the behavioral modifications. I explore the honey bees’ ability to detect these toxins, their sensory perception of sucrose following toxin exposure, and the effects of toxin ingestion on performance during learning and memory tasks. The effects depend on the specific metal. Honey bees detect and reject copper containing solutions, but readily consume those contaminated with cadmium and lead. And, exposure to lead may alter the sensory perception of sucrose. I also demonstrate that acute selenium exposure impairs learning and long-term memory formation or recall. Localizing selenium accumulation following chronic exposure reveals that damage to non-neural organs and peripheral sensory structures is more likely than direct neurotoxicity. Probable mechanisms include gut microbiome alterations, gut lining
damage, immune system activation, impaired protein function, or aberrant DNA methylation. In the case of DNA methylation, I demonstrate that inhibiting DNA methylation dynamics can impair long-term memory formation, while the nurse-to- forager transition is not altered. These experiments could serve as the bases for and reference groups of studies testing the effects of metal or metalloid toxicity on DNA methylation. Each potential mechanism provides an avenue for investigating how neural function is influenced by the physiological status of non-neural organs. And from an ecological perspective, my results highlight the need for environmental policy to consider sublethal effects in determining safe environmental toxin loads for honey bees and other insect pollinators.
damage, immune system activation, impaired protein function, or aberrant DNA methylation. In the case of DNA methylation, I demonstrate that inhibiting DNA methylation dynamics can impair long-term memory formation, while the nurse-to- forager transition is not altered. These experiments could serve as the bases for and reference groups of studies testing the effects of metal or metalloid toxicity on DNA methylation. Each potential mechanism provides an avenue for investigating how neural function is influenced by the physiological status of non-neural organs. And from an ecological perspective, my results highlight the need for environmental policy to consider sublethal effects in determining safe environmental toxin loads for honey bees and other insect pollinators.
ContributorsBurden, Christina Marie (Author) / Amdam, Gro (Thesis advisor) / Smith, Brian H. (Thesis advisor) / Gallitano-Mendel, Amelia (Committee member) / Harrison, Jon (Committee member) / Vu, Eric (Committee member) / Arizona State University (Publisher)
Created2016
Description
Though it is a widespread adaptation in humans and many other animals, parental care comes in a variety of forms and its subtle physiological costs, benefits, and tradeoffs related to offspring are often unknown. Thus, I studied the hydric, respiratory, thermal, and fitness dynamics of maternal egg-brooding behavior in Children's pythons (Antaresia childreni). I demonstrated that tight coiling detrimentally creates a hypoxic developmental environment that is alleviated by periodic postural adjustments. Alternatively, maternal postural adjustments detrimentally elevate rates of egg water loss relative to tight coiling. Despite ventilating postural adjustments, the developmental environment becomes increasingly hypoxic near the end of incubation, which reduces embryonic metabolism. I further demonstrated that brooding-induced hypoxia detrimentally affects offspring size, performance, locomotion, and behavior. Thus, parental care in A. childreni comes at a cost to offspring due to intra-offspring tradeoffs (i.e., those that reflect competing offspring needs, such as water balance and respiration). Next, I showed that, despite being unable to intrinsically produce body heat, A. childreni adjust egg-brooding behavior in response to shifts in nest temperature, which enhances egg temperature (e.g., reduced tight coiling during nest warming facilitated beneficial heat transfer to eggs). Last, I demonstrated that A. childreni adaptively adjust their egg-brooding behaviors due to an interaction between nest temperature and humidity. Specifically, females' behavioral response to nest warming was eliminated during low nest humidity. In combination with other studies, these results show that female pythons sense environmental temperature and humidity and utilize this information at multiple time points (i.e., during gravidity [egg bearing], at oviposition [egg laying], and during egg brooding) to enhance the developmental environment of their offspring. This research demonstrates that maternal behaviors that are simple and subtle, yet easily quantifiable, can balance several critical developmental variables (i.e., thermoregulation, water balance, and respiration).
ContributorsStahlschmidt, Zachary R (Author) / DeNardo, Dale F (Thesis advisor) / Harrison, Jon (Committee member) / McGraw, Kevin (Committee member) / Rutowski, Ronald (Committee member) / Walsberg, Glenn (Committee member) / Arizona State University (Publisher)
Created2011
Description
Selenium, a group 16 metalloid on the periodic table, is a necessary mineral for many organisms. Trace amounts of selenium are essential for normal development, antioxidant protein function, enzyme function, and hormone regulation (Burden et al., 2016). However, when selenium is found in toxic amounts in organisms, it has been found to substitute for sulfur in proteins, which can be toxic to these animals, and cause oxidative stress (Quinn et al., 2007). Using the previous research done with acute exposure to organic and inorganic selenium compounds, we hypothesized that the inorganic sodium selenate would significantly decrease learning and memory recall for both chronic and acute exposure. We also hypothesized that the consumption of organic methylseleno-L-cysteine by honey bees would decrease learning and memory recall for both the chronic and acute exposure. We further hypothesized that protein carbonyl content would be increased due to oxidative damage caused by selenium in both the sodium selenate and the methylseleno-L-cysteine treatment groups, but that the inorganic selenium compound would increase the carbonyl content more than the methylseleno-L-cysteine. To run the experiments, three tents outside had two colonies in each tent. One tent contained the sodium selenate group, another had the sucrose control, and one contained the methylseleno-L-cysteine group. The treatment groups were fed selenium in their sucrose feeders. The first part of the experiment was training the bees by using proboscis extension response (PER) to teach them to extend their proboscis to the rewarded odor and not to the unrewarded odor. This was done by pairing the rewarded odor with a sucrose reward and not pairing it with the unrewarded odor. Then their short-term and long-term memory recall was tested. The second part of the experiment was checking for oxidative damage by measuring the protein carbonyl content in the bees. Three boxes were set up with the same three treatment groups as used in the tents. The treatment group bees were exposed to selenium in the sucrose feeders and in the pollen patties. After one week, the living bees were removed and frozen. They were then homogenized to extract protein. The first assay run was the protein content assay to establish a standard protein concentration for samples. Then a protein carbonyl assay was run, to determine the protein carbonyl content. Overall, the experiment found that exposure to selenium negatively impacted honey bees learning and memory recall significantly. Chronic exposure to the inorganic selenate reduced the bees' long-term memory abilities to differentiate between odors. With methylseleno-L-cysteine, it had no significant effect for the chronic exposure, but for the acute exposure, it had a significant impairment on their abilities to distinguish between the rewarded and unrewarded odors during conditioning. Our results showed that from our experiment there appeared to be no significant effect of selenium exposure on the increase of carbonylation content in the different treatment groups. This is most likely due to the fact the carbonyl content was not detectable because the protein concentration was low in the samples (approximately 3.5 mg/mL).
ContributorsWinski, Alexandra (Co-author) / Winski, Brandon (Co-author) / Smith, Brian (Thesis director) / Harrison, Jon (Committee member) / Burden, Christina (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This study illustrates the abilities of the honeybee, Apis mellifera, to learn and differentiate between patterns solely off their spatial frequencies. Patterns were chosen based off of calculations derived from the measurements of the physical construction of the apposition compound eye, which led to predictions of what the bees could theoretically see. The hypothesis was then that bees would have a visual threshold where patterns with spatial frequencies that fall below this line should be easily distinguishable, and patterns above the threshold would have scores that mimic if the bees made choices randomly. There were 9 patterns tested, all with different spatial frequencies and in the colors of black, white, and gray. The bees were tested on their learning and pattern differentiation abilities with 10 pattern comparisons, with the lower frequency of the two being associated with an unscented sucrose solution reward. The results were surprising in that the previous studies pointing towards this visual threshold were inaccurate because of some of the patterns being learning in an intermediate ability. These intermediate scores suggest that the calculations predicting what the bees could see clearly were slightly wrong because it was more likely that the bees saw those images in more of a blur, which resulted in their intermediate score. Honeybees have served as a useful model organisms over the decades with studying learning involving visual information. This study lacked in its total numbers of trials and bees tested, which could have led to incomplete results, and this showing of an intermediate score and ability. Future studies should continue in order to advance this understanding of a perceptually and cognitively advance processing animal.
ContributorsBalsino, Brandon Bartholomew (Author) / Harrison, Jon (Thesis director) / Smith, Brian (Committee member) / Duell, Meghan (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
Nutritional balance is a requirement for the survival of all species. This balance is important for complex eusocial organisms as it influences the growth and development of the colony. Leafcutter ants function as tri-trophic systems, harvesting mixed vegetation to cultivate a fungus garden that in return supplies the colony with food. Examining how the colony deals with nutrient balance is of particular interest because this species forages to provide nutrients for the fungus. There seems to be a feedback system between the fungus and the workers that influences how much of a particular macronutrient should be collected. The objective of this thesis study was to examine the foraging behavior of the desert leaf cutter ant, Acromyrmex versicolor. This study asked how nutrition, in particular the ratio of carbohydrates to proteins, influences the foraging behavior of the colony. It was hypothesized that given a choice of high protein and high carbohydrate diets the leafcutters would forage towards a balance ratio. The results from this experiment showed that A. versicolor forage towards a target ratio of protein to carbohydrate to based diets. This p:c ratio was calculated to be 1:6.2; 1 gram of protein to 6.2 grams of carbohydrate. When colonies were restricted to the high carbohydrate diet, they increased food consumption, consistent with the expectation that they would forage to reach their protein nutrient requirement, however, they reduced foraging on that diet. This suggests that ants avoid overconsuming protein, even when doing so provided more optimal carbohydrate intake. From this study I concluded that nutritional balance is a foraging goal for ant societies, similar to organisms. These results also open the question of how nutrient regulation by leafcutter ants is regulated around their mutualist relationship with another organism, the fungus.
ContributorsFarris, Megan Alexandra (Author) / Fewell, Jennifer (Thesis director) / Harrison, Jon (Committee member) / Smith, Nate (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
Lactate is a commonly known biochemical that is usually produced under anaerobic conditions. This makes it a useful marker for examining the possibility that Drosophila melanogaster undergoes natural hypoxic states during development due to the rate of growth. To analyze this observation and its potential for explaining developmental changes, a lactate assay was used to quantify lactate produced across time points in the third larval instar and across early adulthood. Lactate assay results showed near-zero lactate levels for both larvae and adults. There were confounding factors present in larval lactate assays which made analysis difficult. However, the results of the adult lactate assays seem to indicate an inability to produce large amounts of lactate regardless of time point in adulthood, suggesting that adults do not naturally experience hypoxia during or after eclosion.
ContributorsWiertek, Marcellina Emilia (Author) / Harrison, Jon (Thesis director) / Angilletta, Michael (Committee member) / Talal, Stav (Committee member) / Historical, Philosophical & Religious Studies (Contributor) / Historical, Philosophical & Religious Studies, Sch (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
All organisms perform best at a balanced point of intake where nutrients are ingested in specific amounts to confer optimal performance. However, when faced with limited nutrient availability, organisms are forced to make decisions which prioritize intake of certain macronutrients. While intake regulation has been more thoroughly studied in omnivores and carnivores, no research exists regarding lipid regulation in generalist herbivores. Traditionally, proteins and carbohydrates were thought to be the most important macronutrient for herbivore intake; however the large differences in lipid nutritional content between different plant species offers lots of potential for regulation of an important macronutrient. We studied whether generalist herbivores can regulate lipid intake, using the migratory locust (Locusta migratoria). Though herbivore protein and carbohydrate intake is well studied, less research studies regulation of lipid intake. We tested this by offering choice diets of varying carbohydrate and lipid content makeup and measuring consumption of each diet choice to determine overall carbohydrate and lipid intake. Four different lipid sources were used in order to control for taste or texture related confounds; canola oil, sunflower oil, grapeseed oil, and a lab designed synthetic oil based on the four most abundant fatty acids in common plant oils. On three out of four diet sources, groups evidences strong regulation of narrow intake target, with little disparity in overall intake of carbohydrate and lipid content between various choice diet treatments. Groups feeding on canola oil and sunflower oil based diets displayed the best regulation based on their having small disparities in intake between treatments, while those feeding on grapeseed oil based diets displayed wide variation in feeding behavior between treatments. Groups feeding on the synthetic oil based diet choice unexpectedly consumed much more carbohydrates than lipids when compared to all other groups. In conclusion, generalist herbivores are capable of regulating lipid intake.
ContributorsChahal, Aunmolpreet Singh (Author) / Harrison, Jon (Thesis director) / Talal, Stav (Committee member) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Foraging honey bees are challenged to balance the energetic costs of thermoregulating and load-carriage at the same time when flying in hot environments. Honey bees can reduce metabolic rate and wingbeat frequency in response to heat, but the kinematic strategies they use while carrying loads are unknown. I observed honey bees (Apis mellifera) carrying a range of nectar loads (0 to 80% of their own body weight in nectar) when flying at 25 and 40°C air temperatures, and found that hotter honey bees decreased their wingbeat frequency (from 230 to 195 Hz) and increased their stroke amplitude (from 90 to 98°) to generate increasing aerodynamic power as they carry heavier nectar loads. The bees flying at 40°C air temperature carrying heavier loads did increase their wingbeat frequency compared to the unloaded individuals. Despite the kinematic changes, both the hot and cold honey bees were able to generate sufficient power to carry loads of roughly equal mass. Bees flying at 40°C air temperature produced more power than their cooler counterparts, suggesting a more efficient mechanism of load carriage.
ContributorsWeisman, Ethan (Author) / Harrison, Jon (Thesis director) / Glass, Jordan (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / Department of Psychology (Contributor)
Created2023-05