Doctoral Dissertations

Date of Award

8-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Ecology and Evolutionary Biology

Major Professor

Michael J. Blum

Committee Members

Paul R. Armsworth, Michael McKinney, Joshua A. Lewis

Abstract

The push and pull of urban expansion and counter-urbanization in cities can lead to complex, dynamic social-ecological landscapes. Across urban landscapes, social-ecological features reshape the interfaces between built environments, people, animals, and vector-born pathogens in ways that amplify zoonotic disease risk. My aim in this dissertation was to evaluate and contextualize how social-ecological factors can influence the dynamics of hosts, vectors, and the pathogens they carry across the greater New Orleans (Louisiana, USA) area. The social-ecological investigations I undertook examined multiple host taxa and disease systems, considering exposure risk at multiple scales: within hosts, host-to-host, and vector-landscape interactions. I first considered if and how vertical transmission can sustain Trypanosoma cruzi infection within urban rodent reservoir populations. Utilizing an existing archive of T. cruzi positive rodents, I determined infection status for 66 embryos from 3 rodent species (Norway rats, roof rats, and house mice) to test for evidence of vertical transmission from mother to offspring. I found that 15/66 embryos (22.7%) were infected with T. cruzi and that multiple genotypes of T. cruzi can pass from mother to offspring. Next, I compared Angiostrongylus cantonensis prevalence in 3728 gastropods to rodents collected at 73 rodent trapping sites to explore primary host to secondary host transmission of A. cantonensis and if infection in different host species is influenced by a common set of social-ecological factors. I found that gastropods and rodents respond differently to factors like vacancy, unmaintained vegetation, and flooding history, highlighting the complexity of multi-host transmission cycles in urban landscapes. Finally, I examined social-ecological predictors of mosquito diversity and demography. Social-ecological modelling revealed that abundances of vector mosquitoes respond to urban heat and tree cover and may remain stable over time despite seasonal climate variability.

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