Year of Graduation

2019

Document Type

Thesis

Major

Biology

Directing Professor

Elizabeth Gleim & Morgan Wilson

Abstract

Understanding tick phenology is crucial to understanding disease ecology and for reducing risk of tick-borne disease in human and animal populations. Although phenological studies have been conducted in other parts of Virginia, tick activity and species abundance in Southwest Virginia has been under-studied. Importantly, there has been an unexplained, disproportionately high increase in the number of Lyme disease cases in western Virginia over the past ten years. In order to better understand the unusually high Lyme incidence and overall tick ecology in this region, monthly collections were performed at 12 collection sites in Southwest Virginia over a 12-month period. Tick species collected within this study included Amblyomma americanum, Amblyomma spp., Ixodes scapularis, Ixodes spp., Dermacentor variabilis, Dermacentor albipictus, Haemaphysalis leporispalustris, and Haemaphysalis longicornis. Polymerase chain reactions and sequencing were performed to identify Ixodes scapularis nymphs and all larvae. All other species/life stages were identified morphologically. Our results generally correspond to other studies examining tick abundance and/or phenology across Virginia with one important exception which was that I. scapularis nymphs exhibited higher activity in Southwest Virginia compared to other geographic regions of the state. This suggests that their questing behaviors may be distinctive from other populations within the state. Because I. scapularis is the primary vector of Lyme disease and nymphs are the most commonly associated life stage with pathogen transmission to humans, this increased activity of I. scapularis nymphs may be contributing to the higher case incidence of Lyme disease in this region.

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