Matching Items (7)
Filtering by
- All Subjects: Behavioral Sciences
- All Subjects: honey bee
- Creators: Pratt, Stephen
Description
How a colony regulates the division of labor to forage for nutritional resources while accommodating for changes in colony demography is a fundamental question in the sociobiology of social insects. In honey bee, Apis mellifera, brood composition impacts the division of labor, but it is unknown if colonies adjust the allocation of foragers to carbohydrate and protein resources based on changes in the age demography of larvae and the pheromones they produce. Young and old larvae produce pheromones that differ in composition and volatility. In turn, nurses differentially provision larvae, feeding developing young worker larvae a surplus diet that is more queen-like in protein composition and food availability, while old larvae receive a diet that mimics the sugar composition of the queen larval diet but is restrictively fed instead of provided ad lib. This research investigated how larval age and the larval pheromone e-β ocimene (eβ) impact foraging activity and foraging load. Additional cage studies were conducted to determine if eβ interacts synergistically with queen mandibular pheromone (QMP) to suppress ovary activation and prime worker physiology for nursing behavior. Lastly, the priming effects of larval age and eβ on worker physiology and the transition from in-hive nursing tasks to outside foraging were examined. Results indicate that workers differentially respond to larvae of different ages, likely by detecting changes in the composition of the pheromones they emit. This resulted in adjustments to the foraging division of labor (pollen vs. nectar) to ensure that the nutritional needs of the colony's brood were met. For younger larvae and eβ, this resulted in a bias favoring pollen collection. The cage studies reveal that both eβ and QMP suppressed ovary activation, but the larval pheromone was more effective. Maturing in an environment of young or old larvae primed bees for nursing and impacted important endocrine titers involved in the transition to foraging, so bees maturing in the presence of larvae foraged earlier than control bees reared with no brood.
ContributorsTraynor, Kirsten S. (Author) / Page, Robert E. (Thesis advisor) / Hölldobler, Berthold (Committee member) / Pratt, Stephen (Committee member) / Liebig, Jürgen (Committee member) / Brent, Colin (Committee member) / Baluch, Page (Committee member) / Arizona State University (Publisher)
Created2014
Description
The ability to detect and appropriately respond to chemical stimuli is important for many organisms, ranging from bacteria to multicellular animals. Responses to these stimuli can be plastic over multiple time scales. In the short-term, the synaptic strengths of neurons embedded in neural circuits can be modified and result in various forms of learning. In the long-term, the overall developmental trajectory of the olfactory network can be altered and synaptic strengths can be modified on a broad scale as a direct result of long-term (chronic) stimulus experience. Over evolutionary time the olfactory system can impose selection pressures that affect the odorants used in communication networks. On short time scales, I measured the effects of repeated alarm pheromone exposure on the colony-level defense behaviors in a social bee. I found that the responses to the alarm pheromone were plastic. This suggests that there may be mechanisms that affect individual plasticity to pheromones and regulate how these individuals act in groups to coordinate nest defense. On longer time scales, I measured the behavioral and neural affects of bees given a single chronic odor experience versus bees that had a natural, more diverse olfactory experience. The central brains of bees with a deprived odor experience responded more similarly to odorants in imaging studies, and did not develop a fully mature olfactory network. Additionally, these immature networks showed behavioral deficits when recalling odor mixture components. Over evolutionary time, signals need to engage the attention of and be easily recognized by bees. I measured responses of bees to a floral mixture and its constituent monomolecular components. I found that natural floral mixtures engage the orientation of bees’ antennae more strongly than single-component odorants and also provide more consistent central brain responses between stimulations. Together, these studies highlight the importance of olfactory experience on different scales and how the nervous system might impose pressures to select the stimuli used as signals in communication networks.
ContributorsJernigan, Christopher (Author) / Smith, Brian H. (Thesis advisor) / Newbern, Jason (Committee member) / Harrisoin, Jon (Committee member) / Rutowski, Ronald (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2018
Description
Division of labor is a hallmark for social insects and is closely related to honey bee morphology and physiology. Vitellogenin (Vg), a precursor protein in insect egg yolk, has several known functions apart from serving as a nutrient source for developing eggs. Vg is a component in the royal jelly produced in the hypopharyngeal glands (HPG) of worker bees which is used to feed both the developing brood and the queen. The HPG is closely associated with divisions of labor as the peak in its development corresponds with the nursing behavior. Independent of the connection between Vg and the HPG, Vg has been seen to play a fundamental role in divisions of labor by affecting worker gustatory responses, age of onset of foraging, and foraging preferences. Similar to Vg, the number of ovarioles in worker ovaries is also associated with division of labor as bees with more ovarioles tend to finish tasks in the hive and become foragers faster. This experiment aims to connect HPGs, ovaries, and Vg by proposing a link between them in the form of ecdysone (20E). 20E is a hormone produced by the ovaries and is linked to ovary development and Vg by tyramine titers. By treating young emerged bees with ecdysone and measuring HPG and ovary development over a trial period, this experiment seeks to determine whether 20E affects division of labor through Vg. We found that though the stress of injection caused a significant decrease in development of both the ovaries and HPG, there was no discernable effect of 20E on either of these organs.
ContributorsChin, Elijah Seth (Author) / Wang, Ying (Thesis director) / Page, Robert (Committee member) / Cook, Chelsea (Committee member) / School of Molecular Sciences (Contributor) / W. P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Honeybees require the use of their antennae to perceive different scents and pheromones, communicate with other members of the colony, and even detect wind vibrations, sound waves, and carbon dioxide levels. Limiting and/or removing this sense makes bees much less effective at acquiring information. However, how antennal movements might be important for olfaction has not been studied in detail. The focus of this work was to evaluate how restriction of antennae movements might affect a bee’s ability to detect and perceive odors. Bees were made to learn a certain odor and were then split up into a control group, a treatment group that had their antennae fixed with eicosane, and a sham treatment group that had a dot of eicosane on their heads in such a way that it would not affect antennae movements but still add the same amount of weight. Following a period of acclimation, the bees were tested with the conditioned odor, one that was perceptually similar to it, and to a dissimilar odor. Using proboscis-extension duration and latency as response measures, it became clear that both antenna fixation and sham treatments affected the conditioned behavior. However, these treatment effects did not reach statistical significance. Briefly, both fixation of antennae as well as the sham treatment reduced the discriminability of the conditioned and similar odors. Although more data can be collected to more fully evaluate the significance of the treatments, the behavior of the sham group could indicate that mechanoreceptive hairs on the head play an important role in olfaction. It is also possible that there are other factors at play, possibly induced by the fixed bees’ increased stress levels.
ContributorsHozan, Alvin Robert (Author) / Smith, Brian H (Thesis advisor) / Lei, Hong (Committee member) / Cook, Chelsea (Committee member) / Arizona State University (Publisher)
Created2021
Description
Pollinator populations globally have declined at concerning rates in recent years, which is problematic given that roughly a third of all food production depends on them. Managed honey bee colony losses in particular have alarmed beekeepers and scientists, especially in the United States. Widespread agrochemical use has been implicated as one of the major causes of these colony losses. While the lethal effects of agrochemicals often receive the most attention, sublethal effects can occur at lower doses and can substantially weaken colonies over time. Impaired associative learning ability is a sublethal effect of a number of agrochemicals, and is particularly concerning, as it may hinder the abilities of bees to forage for food or find their way back to the colony. Here, I focus on the fungicide Pristine® (active ingredients: 25.2% boscalid, 12.8% pyraclostrobin), which is sprayed on honey bee-pollinated crops during bloom and is known to poison bee mitochondria at ppm levels. First, I show that Pristine® impairs performance on an associative learning assay in the laboratory. Next, I show that Pristine® alters carbohydrate absorption in honey bees, providing a possible mechanism underlying this impaired learning performance. Finally, I demonstrate that Pristine® interacts with high temperatures to induce homing failure in exposed bees. My results raise concerns that this common fungicide may not be safe for pollinators and will be relevant to policymakers as they make decisions surrounding the regulation of fungicide use in agriculture.
ContributorsDesJardins, Nicole (Author) / Harrison, Jon F (Thesis advisor) / Smith, Brian H (Thesis advisor) / DeGrandi-Hoffman, Gloria (Committee member) / DeNardo, Dale (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2023
Description
Dominance behavior can regulate a division of labor in a group, such as that between reproductive and non-reproductive individuals. Manipulations of insect societies in a controlled environment can reveal how dominance behavior is regulated. Here, I examined how morphological caste, fecundity, group size, and age influence the expression of dominance behavior using the ponerine ant Harpegnathos saltator. All H. saltator females have the ability to reproduce. Only those with a queen morphology that enables dispersal, however, show putative sex pheromones. In contrast, those with a worker morphology normally express dominance behavior. To evaluate how worker-like dominance behavior and associated traits could be expressed in queens, I removed the wings from alate gynes, those with a queen morphology who had not yet mated or left the nest, making them dealate. Compared to gynes with attached wings, dealates frequently performed dominance behavior. In addition, only the dealates demonstrated worker-like ovarian activity in the presence of reproductive individuals, whereas gynes with wings produced sex pheromones exclusively. Therefore, the attachment of wings determines a gyne’s expression of worker-like dominance behavior and physiology. When the queen dies, workers establish a reproductive hierarchy among themselves by performing a combination of dominance behaviors. To understand how reproductive status depends on these interactions as well as a worker’s age, I measured the frequency of dominance behaviors in groups of different size composed of young and old workers. The number of workers who expressed dominance scaled with the size of the group, but younger ones were more likely to express dominance behavior and eventually become reproductive. Therefore, the predisposition of age integrates with a self-organized process to form this reproductive hierarchy. A social insect’s fecundity and fertility signal depends on social context because fecundity increases with colony size. To evaluate how a socially dependent signal regulates dominance behavior, I manipulated a reproductive worker’s social context. Reproductive workers with reduced fecundity and a less prominent fertility signal expressed more dominance behavior than those with a stronger fertility signal and higher fecundity. Therefore, dominance behavior reinforces rank to compensate for a weak signal, indicating how social context can feed back to influence the maintenance of dominance. Mechanisms that regulate H. saltator’s reproductive hierarchy can inform how the reproductive division of labor is regulated in other groups of animals.
ContributorsPyenson, Benjamin (Author) / Liebig, Jürgen (Thesis advisor) / Hölldobler, Bert (Committee member) / Fewell, Jennifer (Committee member) / Pratt, Stephen (Committee member) / Kang, Yun (Committee member) / Arizona State University (Publisher)
Created2022
Description
Social animals benefit from the aggregation of knowledge and cognitive processing power. Part of this benefit comes from individual heterogeneity, which provides the basis to group-level strategies, such as division of labor and collective intelligence. In turn, the outcomes of collective choices, as well as the needs of the society at large, influence the behavior of individuals within it. My dissertation research addresses how the feedback between individual and group-level behavior affects individuals and promotes collective change. I study this question in the context of seed selection in the seed harvester ant, Pogonomyrmex californicus. I use both field and laboratory studies to explore questions relating to individual behavior: how forager decision-making is affected through information available in the nest and at the seed pile; how workers interact with seeds in the nest; and how forager preferences diverge from each other’s and the colony’s preference. I also explore the integration between individual and colony behavior, specifically: how interactions between the foraging and processing tasks affect colony collection behavior; how individual behavior changes affect colony preference changes and whether colony preference changes can be considered learning behavior. To answer these questions, I provided colonies with binary choices between seeds of unequal or similar quality, and measured individual, task group, and colony-level behavior. I found that colonies are capable of learning to discriminate between seeds, and learned information lasts at least one month without seed interaction outside of the nest. I also found that colony learning was coordinated by foragers receiving updated information from seeds in the nest to better discriminate and make choices between seed quality during searches for seeds outside of the nest. My results show that seed processing is essential for stimulating collection of novel seeds, and that foraging and processing are conducted by behaviorally and spatially overlapping but distinct groups of workers. Finally, I found that foragers’ preferences are diverse yet flexible, even when colonies are consistent in their preference at the population level. These combined experiments generate a more detailed and complete understanding of the mechanisms behind the flexibility of collective colony choices, how colonies incorporate new information, and how workers individually and collectively make foraging decisions for the colony in a decentralized manner.
ContributorsBespalova, Ioulia Ivanovna (Author) / Fewell, Jennifer (Thesis advisor) / Hölldobler, Bert (Committee member) / Liebig, Jürgen (Committee member) / Pinter-Wollman, Noa (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2020