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Title:Direct and indirect effects of native and invasive plants on mosquito ecology
Author(s):Gardner, Allison Mae
Director of Research:Allan, Brian F.; Muturi, Ephantus J.
Doctoral Committee Chair(s):Allan, Brian F.
Doctoral Committee Member(s):Berenbaum, May R.; Hanks, Lawrence M.; Hansen, Allison K.
Department / Program:Entomology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Mosquito ecology
invasive plants
Culex pipiens
ecological trap
Abstract:Container-breeding mosquitoes (Diptera: Culicidae), including the vectors of human and wildlife pathogens, interact with terrestrial plants throughout their life cycles. Inputs of leaf detritus into the aquatic habitat provide an energy base for developing larvae, and plants mediate the distribution of adult mosquitoes by influencing microclimate conditions, supplying sugar-feeding sources, and altering communities of wildlife blood-meal hosts. This dissertation examines direct and indirect effects of understory shrubs, including species both native and invasive to North America, on the ecology of Culex pipiens, an important vector of West Nile virus in the northeastern and midwestern United States. Laboratory and field bioassays demonstrated that leaf detritus from different plant species in the aquatic environment alter two key components of mosquito production (i.e., oviposition site selection and adult emergence) via the abundance and composition of bacterial flora that form on different leaf species as they decompose. In particular, an invasive plant (Lonicera maackii, Amur honeysuckle) yielded high oviposition and adult emergence rates, while in contrast, a native plant (Rubus allegheniensis, common blackberry) was identified to function as an ecological trap for Cx. pipiens, attracting gravid females to oviposit and yet deleterious to larvae yielding low emergence rates. Subsequent laboratory bioassays in which first instar larvae were exposed to mixtures of leaves from different plant species revealed that while leaf resource diversity generally yields an increase in Cx. pipiens adult emergence rates, addition of high-quality resources is not sufficient to offset the deleterious effect of R. allegheniensis leaves. I then explored two integrated vector management applications of these findings. First, a field experiment demonstrated the feasibility of exploiting a naturally-occurring ecological trap (R. allegheniensis leaves) and an artificial ecological trap (L. maackii leaves mixed with Bacillus thuringiensis var. israelensis larvicide) for attract-and-kill mosquito control in storm water catch basins, in which gravid females are lured to oviposit in a low-quality environment. This result provides experimental proof of concept for a novel integrated vector management tool that may enhance the effectiveness and sustainability of existing mosquito abatement strategies with minimal non-target effects and reduced potential to select for insecticide resistance. A second field experiment showed that removal of L. maackii decreases abundance of adult Culex spp. mosquitoes in forest fragments within a residential neighborhood. The mechanisms underlying this reduction in mosquito abundance most likely include effects of L. maackii removal on microclimate conditions and the availability of avian blood-meal hosts. Collectively, these studies reveal multiple ecological pathways by which terrestrial plants interact with, and alter the abundance, distribution, and life history characteristics of mosquitoes, and suggest landscape modification strategies that may be used to manage an important disease vector species in residential ecosystems.
Issue Date:2016-04-20
Rights Information:Copyright 2016 Allison M. Gardner
Date Available in IDEALS:2016-07-07
Date Deposited:2016-05

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