Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Goddard, Jerome

Committee Member

Varela-Stokes, Andrea S.

Committee Member

Baker, Gerald T.

Committee Member

Harris, Jeffrey W.

Committee Member

Schneider, John C.

Date of Degree

5-6-2017

Document Type

Dissertation - Open Access

Major

Entomology

Degree Name

Doctor of Philosophy

College

College of Agriculture and Life Sciences

Department

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology

Abstract

Little is understood about off-host behavior and ecology of immature Amblyomma maculatum Koch (Gulf Coast tick). A more complete understanding of this tick is essential to protect human and animal health. My research focused on seasonality and distribution of immatures in Mississippi, potential suitability of some insect and human hosts to larvae, and aspects of nymphal questing behavior. A single larva was collected (third off-host collection reported) when sampling A. maculatum habitat using a novel device. Collection of this larva in November expands the stage’s known seasonality and confirmed a prediction concerning seasonality of larval A. maculatum. Low frequency of immatures (8.3%) confirmed that they’re incredibly difficult to collect off-host. Nymphal collections peaked in March, and known seasonality was extended for both nymphs and adults. I examined known records, elucidating seasonality and distribution of A. maculatum in Mississippi. Either multiple generations per year or diapause are responsible for observed bi-modal distribution of immature collections. Additionally, I compiled the most extensive host record of immature A. maculatum in Mississippi and investigated seasonality patterns using USDA plant hardiness zones. I compiled the most complete record of ticks found on arthropods. Amblyomma americanum and A. maculatum were both confirmed to crawl onto arthropods, giving support to occasional, unintentional dispersal by phoresy. There was no conclusive evidence that larval A. maculatum feed on arthropods, however data supported feeding by larval A. americanum. These results have interesting implications regarding evolution of pathogens/endosymbionts. I provided the first evidence that larval A. maculatum can attach to humans. Rickettsia parkeri, a human pathogen transmitted by this species has recently been shown to be capable of transovarial transmission. Therefore, larval A. maculatum may provide another avenue of transmission. I have demonstrated that A. maculatum are difficult to collect off-host in part because they prefer to quest low to the ground. In choice studies, 5-cm-tall stems were most likely to be occupied by nymphs released into an array of stems. Low vapor pressure deficit encouraged questing, while higher VPD and warmer temperature increased questing height. These results may have implications in understanding host-seeking behavior in other tick species as well.

URI

https://hdl.handle.net/11668/17772

Comments

water vapor||relative humidity||fall armyworm||house cricket||European honey bee||Spodoptera frugiperda||Acheta domesticus||Apis mellifera||parumapertus||Tidewater spotted fever||Rickettsia parkeri rickettsiosis||Heartwater||Ehrlichia ruminantium||Hepatozoon americanum||scapularis||Maculatum group||Neotropical||Water vapor||Ixodes||Dermacentor||critical equilibrium humidity||critical equilibrium activity||Nearctic||Boophilus||Rhipicephalus||southeast||National Tick Collection||hemolymph||americanum||nitens||variabilis||Andropogon virginicus||broomsedge||tickarium||photophase||fixed action pattern||fixed behavior||Candidatus Rickettsia andeanae

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