Year of Publication

2011

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture

Department

Entomology

First Advisor

Dr. Stephen L. Dobson

Abstract

Wolbachia are maternally inherited, obligate, intracellular bacteria inducing a form of sterility known as cytoplasmic incompatibility. Wolbachia based strategies have been proposed for the control of disease vectors. One example is to use a population replacement strategy to drive into natural population a novel Wolbachia that modifies the age structure of a vector population, reducing disease transmission.

In this research, the effects of a life-shortening stain of Wolbachia (popcorn Wolbachia) are transferred into the mosquitoes Aedes albopictus (Chapter Two and Three) and A. aegypti (Chapter Four and Five). In Chapter Two, the Wolbachia symbiosis significantly reduced fecundity and egg hatches in A. albopictus, with Wolbachia being highly pathogenic in this mosquito species. In Chapter Three, the relationship between popcorn Wolbachia and its host (in a triple-infected mosquito strain) varied with the mosquito diet. Feeding on mouse blood was associated with the loss of infection, whereas the infection was maintained in human blood-fed mosquito lines. Egg viability of triple infected mosquito was reduced only with mouse blood.

In Chapter Four, the reduced competitiveness (e.g., low survival and increased developmental time) of infected A. aegypti immatures was associated with popcorn Wolbachia, relative to uninfected individuals in low food condition. In Chapter Five, the decreased survival of immature A. aegypti was associated with popcorn Wolbachia in the presence of potential predators (i.e., older A. aegypti or A. albopictus larvae). Using a novel behavioral assay, a delayed larval reaction to light avoidance was observed to be associated with the infection, suggesting Wolbachia effects on immature host behaviors.

In Chapter Six, popcorn Wolbachia and wAlbB infected A. aegypti showed similar reproduction potential. No reduced level of CI or mating competitiveness was observed in wAlbB infected males. The results suggest the wAlbB infection in A. aegypti can be an additional agent for Wolbachia-based control strategies.

In Chapter Seven, a filtering system using commercially available sieves was able to separate immature mosquitoes from water, preventing escape of mosquitoes. In Chapter Eight, an inexpensive artificial blood feeding was designed for feeding multiple mosquito cages. The results support the use of these tools to facilitate mass rearing of mosquitoes.

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