Date of Award:

5-2017

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Committee Chair(s)

Scott A. Bernhardt

Committee

Scott A. Bernhardt

Committee

Lee F. Rickords

Committee

Diane G. Alston

Committee

Carol D. von Dohlen

Committee

Zachariah Gompert

Abstract

Sand flies, like mosquitoes, ticks, fleas, and lice, transmit pathogens that cause disease in humans. Leishmaniasis, caused by pathogens transmitted by sand flies, kills tens of thousands of people every year. Insecticides have been used to control sand flies, but there is evidence of insecticide resistance in populations of sand flies around the world. The goal of this dissertation was to develop tools to maintain sand flies in the laboratory, develop the ability to identify insecticide-resistant populations of sand flies, and to investigate the genetic mechanisms of how sand flies become resistant to insecticides. I began by comparing live animal and artificial techniques for blood-feeding two species of sand flies, Phlebotomus papatasi and Lutzomyia longipalpis, in the laboratory, both of which are important leishmaniasis vectors. Next, I investigated how susceptible laboratory colonies of both species are to ten insecticides that are used worldwide to control sand flies. Based on my results, I determined diagnostic concentrations and diagnostic exposure times for the laboratory colonies to the ten insecticides using a known assay that has been used very little for sand flies, which allows researchers to determine if a population of sand flies is resistant to an insecticide. Finally, I tested for known mechanisms of insecticide resistance in four artificially resistant-selected colonies of sand flies, and I also looked for novel mechanisms. This dissertation is useful in that it provides researchers practical approaches to maintain sand flies to be used for further research and to determine resistance in the field. It also demonstrates that sand fly populations are homogenous, and it implies that it is challenging for a population to become resistant to insecticides. This aspect can be exploited by sand fly researchers and public health officials in effectively controlling sand fly populations, which is also beneficial for slowing the transmission of leishmaniasis.

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