Experimental landscape epidemiology of La Crosse virus in the southern Appalachian Mountains
- UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
- Marcelo Schwarz Giribaldi (Creator)
- Institution
- The University of North Carolina at Greensboro (UNCG )
- Web Site: http://library.uncg.edu/
- Advisor
- Gideon Wasserberg
Abstract: The incidence of La Crosse encephalitis (LACE) (a mosquito-borne pediatric neuroinvasive infectious disease) has increased in the Appalachian region. A causal association between anthropogenic landscape change and LACE emergence has been hypothesized, but has not been studied. This potential association was the major impetus for my dissertation. My specific goals were to: (1.) Characterize, ecologically, the forest-to-field ecotone in a LACE endemic area and describe the distribution of La Crosse virus (LACV) mosquito vectors along it. (2.) Determine the effects of experimental larval habitat supplementation on the ecology of LACV vectors along forest-to-field ecotones. (3.) Determine if the vertical distribution of LACV vector differs along a forestto-urban ecotone within an urban landscape (4.) Determine if the vertical distribution of LACV vector differs along a forestto-field ecotone and if experimental larval habitat supplementation affects this vertical distribution. I determined the natural distribution of the LACV mosquitoes in the western North Carolina along forest-to-field ecotones (Aim 1) using oviposition cups and by trapping adult host-seeking and resting mosquitoes. In the second year I introduced 9 tires (Aim 2) in either the forest or the field habitats along the ecotones to determine the effect of artificial larval habitat supplementation on the ecology of these mosquitoes. I also deployed oviposition cups along three heights: 0, 4.5, and 9 m in each habitat along the forest-to-field ecotone (Aim 4) and in an urban landscape (Aim 3) to explore the vertical distribution of LACV mosquitoes along a gradient of anthropogenic land use intensity and determine the effect of container introduction along this neglected spatial dimension. Aedes triseriatus was the most abundant mosquito in the Appalachian sites followed by Ae. japonicus and Ae. albopictus. Oviposition activity decreased along the ecotone, from forest to field habitats, with Aedes triseriatus mostly found in the forest and Ae. japonicus peaking at the edge and Aedes albopictus with relatively higher abundance in the field. Tires were associated with a higher abundance of Ae. triseriatus and Ae. albopictus, but also with a decrease in Ae. japonicus. The effect of tire introduction persisted throughout all three years of the experiment. Ae. triseriatus was most commonly present in tires in the forest habitat and Ae. albopictus the tires in the field, while Ae. japonicus and Ae. hendersoni did not show a significant difference between forest and field tires. Species specific parity rates did not differ among habitats and were not impacted by tire addition. Also, Ae. triseriatus mosquitoes collected from the forest habitat were larger than those collected at the edge habitat. In terms of tire introduction effects, only Ae. japonicus was significantly affected with individuals at the control sites being larger than those collected at the tire introduction sites. In the urban landscape study (Aim 3), I only collected Ae. albopictus, Ae. triseriatus, and Ae. hendersoni eggs. Even though all three species mostly exploited the shaded forest and park habitats, only Ae. albopictus was found in the urban campus habitats of UNCG. All three mosquito species in the forest and park habitats mostly oviposited at ground level, a surprising finding for Ae. hendersoni, which typically oviposits at the canopy level. Along the forest-to-field ecotones (Aim 4), the vertical distribution in the control plots was consistent with previous studies, with Ae. triseriatus exhibiting no clear vertical affinity while Ae. hendersoni showing clear preference for ovipositing at the canopy level. Both invasive species (Ae. albopictus and Ae. japonicus), exhibited a clear preference for ovipositing at ground level. Tire introductions to either the field or the forest habitat resulted in a shift in the vertical habitat use pattern for all four species: Ae. triseriatus, Ae. albopictus, and Ae. japonicus, substantially enhanced their affinity to oviposition at ground level, while Ae. hendersoni reduced its affinity towards the canopy level and laid relatively more at mid-level heights. These findings highlight the well-known importance of container control for the purpose of source reduction and provide a broader framework of understanding regarding the scope, scale, and heterogeneity associated with these anthropogenic changes and their impact on LACV entomological risk.
Experimental landscape epidemiology of La Crosse virus in the southern Appalachian Mountains
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Created on 8/1/2021
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Additional Information
- Publication
- Dissertation
- Language: English
- Date: 2021
- Keywords
- Aedes albopictus, Aedes japonicus, Aedes triseriatus, Ecotone, Edge, La Crosse Virus
- Subjects
- Mosquitoes as carriers of disease $z Appalachian Region, Southern
- Encephalitis $z Appalachian Region, Southern $x Epidemiology
- Virus diseases $z Appalachian Region, Southern $x Epidemiology