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Grantee Research Project Results

Grantee Research Project Results

Toxic Effects of Herbicides and Pesticides on Immunocompetence and Zoonotic Disease Dynamics in Wild Deer Mice (Peromyscus maniculatus)

EPA Grant Number: FP917306
Title: Toxic Effects of Herbicides and Pesticides on Immunocompetence and Zoonotic Disease Dynamics in Wild Deer Mice (Peromyscus maniculatus)
Investigators: Hanselmann, Rhea
Institution: Oregon State University
EPA Project Officer: Jones, Brandon
Project Period: September 1, 2010 through August 31, 2012
Project Amount: $74,000
RFA: STAR Graduate Fellowships (2011)
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Terrestrial Systems Animal Ecology

Description:

Objective:

This proposed research evaluates the effects of toxic compounds and management interventions commonly used in intensive agricultural systems, on health, immunity and disease risk in a zoonotic reservoir species, the deer mouse (Peromyscus maniculatus). Two central relationships will be explored: (1) the effects of agricultural management practices on the normal functioning of the host immune system, and (2) the impacts of these environmental interventions on prevalence of important zoonotic diseases.

Approach:

In a first study phase, wild deer mice will be livetrapped in experimental field plots varying in management intensity, located on area-typical silviculture and grass-seed farmlands. During a second phase, the effects of agricultural herbicides and pesticides on wild deer mice health, immunity and disease dynamics will be evaluated in large-scale experimental rodent enclosures. Blood and fecal samples, as well as numerous morphometric measurements will be collected from all animals. To assess the impact of management strategies and chemicals on health and immunity, assays will be performed to measure physiologic function (i.e., stress, condition, immune function). Prevalence of three endemic zoonotic diseases (Leptospira spp., Toxoplasma gondii, and Sin Nombre virus) will be determined using serologic assays. Gastrointestinal parasite prevalence and infection intensity will be determined using standard fecal analysis techniques. Finally, various analytical methods will be used to evaluate treatment effects.

Expected Results:

This proposed study will elucidate the potential impact of harsh management strategies and chemical compounds commonly used in intensive agricultural systems (i.e., herbicides and pesticides) on an important ecosystem service: disease abatement. Conventional agricultural methods adversely can affect wildlife populations both directly via toxicity and/or habitat loss, and indirectly via stress and/or loss of condition resulting from changes in community structure. Here, it is expected to see impaired health and immunocompetence in animals exposed to harsh management practices, when compared to those in minimally managed areas. As a result, it also is expected that disease prevalence will be higher in animals inhabiting intensively managed areas, and therefore, that intensive agricultural practices intensify infectious disease risk in the environment.

Potential to Further Environmental/ Human Health Protection

Even in species that appear relatively resilient to environmental change, anthropogenic stressors can have negative impacts on health and immunocompetence. This can make host animals more susceptible to endemic and emerging diseases, which in turn can lead to increased disease prevalence and amplify pathogen transmission in affected animal populations. Ultimately, this exacerbates the risk of disease posed to animals and humans entering impacted ecosystems. Understanding the mechanism and degree to which this occurs is fundamental to the development of plans for environmental and human health risk assessment and protection.

Supplemental Keywords:

ecosystem health, ecosystem service, wildlife health, zoonotic disease, agricultural impact, environmental stressor, anthropogenic environmental change, herbicides, pesticides

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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