Although many parasites are host generalists and vectored by generalist-feeding insects, much of the foundational mathematical modeling work on parasite transmission has focused on single species host and vector systems. To embrace the complex transmission scenarios that can arise for generalist parasites, the goal of my dissertation is to develop and analyze ecologically-motivated mathematical models representing a broad scope of vector-borne parasites. Within the realm of biodiversity-disease relationships, I identify three important concepts lacking in theory: (i) the dilution effect hypothesis, (ii) transmission by multiple vector species, and (iii) the role of paratenic hosts in providing alternative transmission pathways. The first remains a highly contentious theory, relating risk of infection to loss of biodiversity, and where arguments for and against are often verbal and lacking in rigor. Accordingly, I developed a model that includes an arbitrary richness of host species and allows for flexible assumptions about the host community including how abundance is related to competency. My results show how changes in average competency and the vector to host ratio jointly determine transmission potential. The second applies to many systems and I developed a model that includes a vector community with an arbitrary richness that allowed for distinct phenologies and epidemiological traits. Here, I have shown an interplay between community ecology and epidemiology that determine parasite transmission potential, essentially a type of “vector dilution effect hypothesis”. Specifically, my results show that asynchrony in phenology can lead to an increase in parasite transmission. Lastly, using Guinea worm (Dracunculus medinensis) as a model system, I have shown that the paratenic transmission via frogs may not substantially contribute to local transmission, as frogs act as both predators and hosts, but can help sustain transmission. To effectively reduce transmission, interventions should focus on the reductions of the intermediate host (copepods, a vector for the parasite) as this would reduce transmission potential across all assumptions regarding the role paratenic hosts. Across all my chapters, I provided a framework through which we have begun to develop a set of general rules that describe how generalist parasite transmission will respond to changes in community diversity.