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- All Subjects: Urban
- All Subjects: Seed Beetles
- Status: Published
Description
The spread of urbanization leads to habitat fragmentation and deterioration and changes the composition of ecosystems for species all over the world. Different groups of organisms are impacted differently, and insects have experienced loss in diversity and abundance due to changing environmental factors. Here, I collected seed beetles across 12 urban and rural sites in Phoenix, Arizona, to analyze the effects of urbanization and habitat variation on beetle diversity and abundance. I found that urbanization, host tree origin, and environmental factors such as tree diversity and density had no impact on overall beetle diversity and abundance. Beetles were found to have higher density on hosts with a higher density of pods. In assessing individual beetle species, some beetles exhibited higher density in rural sites with native trees, and some were found more commonly on nonnative tree species. The observed differences in beetle density demonstrate the range of effects urbanization and environmental features can have on insect species. By studying ecosystem interactions alongside changing environments, we can better predict the role urbanization and human development can have on different organisms.
ContributorsPaduano, Gabrielle (Author) / Savalli, Udo (Thesis director) / Sweat, Ken (Committee member) / Division of Teacher Preparation (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The global spread of the Aedes aegypti mosquito, a competent disease vector, is occurring at an alarming pace. These invasive mosquitos have spread to latitudes once thought inaccessible due to thermal and hydric limitations, including Maricopa County, AZ, where strong increases in population size has occurred over the last decade. The Aedes aegypti in Maricopa County follow a highly seasonal pattern with populations all but disappearing each winter, only to return and build exponentially though the summer and fall. Maricopa County’s winters are relatively mild, which raises the question of whether further global climate change will warm conditions enough to create a broadened seasonal breeding period, or worse yet, year-round mosquito activity within desert southwest cities. This dissertation focuses on exploring the possible seasonal constraints on the egg, larva, and adult life stages of the Aedes aegypti mosquito within a suburban desert ecosystem. I explored whether climatic warming would raise temperatures enough to enable survival and development of these animals during the winter offseason. I determined that larval growth and adult flight are constrained by ambient winter temperatures in Maricopa County, explaining the currently observed winter crash in populations. However, warming by only a few degrees Centigrade could enable successful larval growth and development, as well as adult flight, even during the coldest desert months. I found that load and temperature interact to determine the flight cost of mosquitos, which can very up to six-fold, with higher temperatures likely increasing their flight performance but decreasing their distance capacities and increasing their need for fuel.
Aedes aegypti likely primarily overwinters as eggs. However, I showed that the vast majority of Aedes aegypti eggs die overwinter in Maricopa County. By manipulating humidity in eggs exposed to ambient air temperatures, I showed that desiccation, not cold temperatures, is the limiting factor in long-term survival of Aedes aegypti eggs. Together, my data suggests that humid, urban microhabitats may be essential for enabling overwinter egg survival in Maricopa County, providing a potential important pathway toward control of this disease vector.
ContributorsFox, Trevor (Author) / Harrison, Jon F (Thesis advisor) / Angilletta, Michael J (Committee member) / Benoit, Joshua B (Committee member) / Smith, Kirk (Committee member) / Arizona State University (Publisher)
Created2021