UMD Theses and Dissertations
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Item SOCIOECOLOGICAL PREDICTORS OF COMMUNITY-LED MOSQUITO CONTROL SUCCESS(2023) Tingler, Aubrey; Leisnham, Paul; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The worldwide spread of the Asian Tiger Mosquito (ATM), Aedes albopictus, demands effective and sustainable urban mosquito management, due to their disease vector capacity and potential for causing high nuisance levels. Agency-led mosquito management is often ineffective at controlling ATM or unwanted by residents. In 2016 and 2017, citizens of University Park, Maryland, USA led a town-wide campaign to encourage residents to purchase Gravid Aedes Traps (GATs), a lethal oviposition trap successful at capturing Aedes mosquitoes. This campaign resulted in significant reductions of adult female ATM in areas with >80% GAT coverage among yards. The goal of this study was to test the continued effectiveness of University Park’s citizen-led program and explore social and environmental predictors of household GAT deployment in 2021. We conducted adult trapping at 18 sites in University Park to test if current levels of GAT deployment still predicted reductions in area-wide adult female ATM, distributed an online questionnaire to gather data for testing relationships of demographic, environmental, knowledge, and attitude predictors with household GAT deployment, and conducted environmental yard surveys to assess relationships of GAT deployment with container habitat and mosquito container infestation. We found that only 24.9% (130/523) of University Park households deployed GATs in 2021, which is substantially lower than the 46.0% (439/954) of households that deployed GATs in 2017. GAT coverage in 2021 did not exceed 50% (3/6) in any adult-trapping area, well below the 80% threshold thought needed to reduce area wide adult Aedes. Nevertheless, we found a significant negative relationship between household GAT deployment and adult female ATM, indicating that GATs are still effective at controlling Aedes at lower coverages. Households that deployed GATs had lower numbers of total, but not infested, water-filled containers, suggesting GAT deployment was often a part of a household's overall effort to reduce mosquitoes alongside source reduction, but that source reduction and GATs may not limit mosquito infestation at the yard scale. Households with middle incomes, further from town greenspace were less likely to deploy GATs along with respondents who spent less time outdoors, were less favorable toward University Park's GAT Program, and could not name ATM as University Park's most common human-biting mosquito. Respondent familiarity of ATM was lower in renters than homeowners, and respondent favorability towards University Park's GAT program was lower in households with children, and with respondents that do fewer yard activities and who had resided for less time in the town. The results of this study show that a citizen-led mosquito-control program using a passive lethal oviposition trap is still effective, four years after its inception, and that there were specific social and environmental predictors of household participation. In this thesis, I will discuss these results and their implications for bottom-up, citizen-led, control of ATM and other Aedes in other residential communities and demonstrate a framework for understanding drivers of participation and success in community-led environmental management.Item UNDERSTANDING LATE SEASON FRUIT ROT PATHOSYSTEMS AND INSECT INTERACTIONS IN MID-ATLANTIC VINEYARDS(2016) Kepner, Cody; Swett, Cassandra L; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fungal fruit rots and insect pests are among the most important problems negatively affecting the yield and quality of mid-Atlantic wine. In pathogenicity trials of fungi recovered from diseased Chardonnay and Vidal blanc grapes, Alternaria alternata, Pestalotiopsis telopeae, and Aspergillus japonicus were found to be unreported fruit rot pathogens in the region. Additionally, P. telopeae and A. japonicus had comparable virulence to the region’s common fruit rot pathogens. Furthermore, a timed-exclusion field study was implemented to evaluate vineyard insect-fruit rot relationships. It was found that clusters exposed to early-season insect communities that included Paralobesia viteana had a significantly greater incidence of sour rot than clusters protected from insects all season. These results were contrary to the current assumption that fall insects are the primary drivers of sour rot in the region. This research provides diagnostic tools and information to develop management-strategies against fungal and insect pests for mid-Atlantic grape growers.Item UNDERSTANDING THE RELATIONSHIP BETWEEN THE BROWN MARMORATED STINK BUG, HALYOMORPHA HALYS (STÅL), AND ITS SYMBIONT, PANTOEA CARBEKII, WITH IMPLICATIONS FOR STINK BUG MANAGEMENT(2016) Taylor, Christopher Michael; Mitter, Charles; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Symbiotic relationships between insects and beneficial microbes are very common in nature, especially within the Hemiptera. The brown marmorated stink bug, Halyomorpha halys Stål, harbors a symbiont, Pantoea carbekii, within the fourth region of the midgut in specialized crypts. In this dissertation, I explored this insect- microbe relationship. I determined that the brown marmorated stink bug is heavily reliant on its symbiont, and that experimental removal of the symbiont from the egg mass surface prior to nymphal acquisition led to lower survival, longer development, lower fecundity, and aberrant nymphal behavior. Additionally, I determined that even when the symbiont is acquired and housed in the midgut crypts, it is susceptible to stressors. Stink bugs reared at a higher temperature showed lower survival, longer development, and a cease in egg mass production, and when bugs were screened for their symbiont, fewer had successfully retained it while under heat stress. Finally, with the knowledge that the stink bug suffers decreases in fitness when its symbiont is missing or stressed, I wanted to determine if targeting the symbiont was a possible management technique for the stink bug. I tested the efficacy of a number of different insecticidal and antimicrobial products to determine whether prevention of symbiont acquisition from the egg mass was possible, and results indicated that transmission of the symbiont from the egg mass to the newly hatched nymph was negatively impacted when certain products were applied (namely surfactants or products containing surfactants). Additionally, direct effects on hatch rate and survival were reported for certain products, namely the insect growth regulator azadirachtin, which suggests that nymphs can pick up residues from the egg mass surface while probing for the symbiont. I conclude that P. carbekii plays a critically important role in the survival of its host, the brown marmorated stink bug, and its presence on the egg mass surface before nymphal hatch makes it targetable as a potential management technique.Item Nutrient Removal by Tidal Fresh and Oligohaline Marshes in a Chesapeake Bay Tributary(2005-11-22) Greene, Sarah E; Boynton, Walter R; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Located at the interface between estuaries and surrounding uplands, tidal marshes are in position to receive and transform material from both adjacent systems. Of particular importance in eutrophic estuarine systems, tidal marshes permanently remove nutrients via two mechanisms - denitrification and long-term burial. Denitrification was measured (monthly) in two marshes in a Chesapeake Bay tributary for 7 months, using the MIMS technique. Burial of nitrogen (N) and phosphorus (P) was measured using 210Pb techniques. Strong spatial and temporal patterns emerged, and there was a Michaelis-Menten type response in denitrification rates to experimentally elevated nitrate levels. Denitrification rates measured may account for removal of 22% of N inputs to the upper estuary on an annual basis. Burial rates could account for 30% of N inputs and 60% of P inputs. Based on the cost of nutrient control technologies, Patuxent marsh nutrient removal may be valued at $10 to 30 million yr-1.Item Construction Project Organizational Structuring(2005-04-20) Salgado, Carlos; Baecher, Gregory B; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation presents an extended research study of project organizational structuring design, using Mintzberg's design parameters of organization and Lucas' IT-enabled variables on construction building project organizations. To the design parameters of unit grouping, unit size, liaison devices, planning and control systems, decision-making system and design of positions, this dissertation study simultaneously considers virtual components, technological leveling, technological matrixing, electronic linking and communications. This study used Yin's multiple case holistic design approach for this extended research study with data from major successful building construction projects to illustrate the use of this extended view and compare its findings. Based on this extended research study, this dissertation develops a practical methodology for construction project organizational structuring design. Furthermore, this dissertation applied Robbins' measures of organization structure (complexity, formalization and centralization) for corroboration.