Exploratory Study of Ectoparasites of Medical & Veterinary Importance in Alabama

Abstract

Ectoparasites play a critical role in affecting the health and economic prosperity of both human and animal populations. This thesis presents a study focusing on two prominent ectoparasites within Auburn, Alabama: horn flies (Diptera: Muscidae: Haematobia irritans irritans) and mosquitoes (Diptera: Culicidae: Culex erraticus). The objective of this study was to elucidate the efficacy of a novel vaccine for cattle against Haematobia irritans irritans and to determine the viral profile within Culex erraticus found within the Auburn Fisheries. This thesis encompasses a comprehensive literature review, field collections, RNA extractions, Next Generation Sequencing, and live animal investigations. The goals were to determine the physiological effects vaccinated cattle play in feeding behavior of Haematobia irritans irritans and gather information on the viral profile of Culex erraticus found in the Auburn Fisheries. Both horn flies and mosquitoes are ectoparasites that can have major economic consequences in the livestock industry, but also play a negative role in a medical (human and veterinary) context by spreading disease. Findings revealed vaccinating heifers against thrombostasins altered horn fly feeding based upon smaller blood meal volumes in the midguts of horn flies that fed on vaccinated animals versus ones that fed on control animals. This is done by measuring the blood volume of horn fly mid guts after a 12 hour starve followed by a 25-minute feeding challenge. Consistent with this finding, horn fly mortality was higher in flies feeding on vaccinated heifers during a 3- day cage challenge compared to flies feeding on control animals during the same challenge. This suggests vaccination induced a negative energy balance in flies that resulted in a shorter life spans. The viral profile of Culex erraticus has yet to be determined, but high quality Culex RNA samples have been successfully sequenced and the resulting sequence data set is currently undergoing bioinformatic analysis. The knowledge gained from this research provides important support for the commercialization of the vaccine which would provide novel tools for cattle producers to use against horn flies. Furthermore, full sequencing of the Culex erraticus will result in characterization of viruses found in mosquitoes which is vital information needed to develop sustainable management practices for mitigating the negative effects of these ectoparasites on both human and animal populations. By generating this knowledge, we will be better able to manage and protect not only our livestock, but ourselves as well.