Date on Master's Thesis/Doctoral Dissertation

12-2012

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Committee Chair

Remold, Susanna K.

Author's Keywords

Dengue virus; Larval susceptibility

Subject

Mosquitoes as carriers of disease; Dengue viruses; Mosquitoes--Physiology

Abstract

In the course of their life cycle, mosquitoes undergo an ontogenetic niche shift; immature larval development occurs within an aquatic habitat from which adult mosquitoes subsequently disperse into the terrestrial environment. While adult female mosquitoes transmit dengue to humans, the larval stage influences dengue virus transmission significantly in several ways. The biotic and abiotic conditions in which larvae develop influence epidemiologically important aspects of adult life history and influence the geographic distribution of mosquito species. Through vertical transmission, mosquitoes may serve as reservoir hosts for dengue during periods that are unfavorable for transmission to humans. For my dissertation, I conducted research that investigated how environmental conditions experienced by larvae influence dengue transmission both directly and indirectly. In chapter 1, I experimentally infected Aedes aegypti and Aedes albopictus larvae to determine their susceptibility to dengue and evaluate the potential for horizontal transmission within the larval habitat. I found that larvae are susceptible to dengue and that horizontal transmission could be possible. In chapter 2, I tested the hypothesis that dengue infection affected mosquito fitness. The effect of infection was sex dependent; infected males took significantly longer to develop and were significantly smaller, while infection in females was cost-free. This result indicates that female larvae infected through vertical transmission are likely to be able to transmit dengue to humans as adults. In chapter 3 and 4, I investigated how resources within the larval habitat influence development and competition. Using larval detritus as a resource, I studied its utilization within the habitat, and its influence on larval development and competition. I found that larval detritus was consumed rapidly and differently from another type of invertebrate detritus. When larval detritus was the main resource within the larval habitat, Ae. albopictus significantly outcompeted Ae. aegypti; Ae. aegypti were significantly smaller and took longer to develop when reared in containers with Ae. albopictus. This result indicates that interspecific competition with Ae. albopictus significantly decreases the population growth of Ae. aegypti and may influence its ability to transmit dengue. Overall, my results further demonstrate the influential role of mosquito larvae on dengue transmission and epidemiology.

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