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National Wildlife Research Center (NWRC) |
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PROJECT GOAL: Development of new and improved wildlife management tools through research in the application of biomarkers, chemical perception, and pharmacology as well as continued delivery of high-quality analytical support for Wildlife Services research and operational activities. Project Accomplishments 2012 Analyzing Body Odor To Determine Immunization Status. Infections can alter body odor in ways
that may be useful for disease diagnosis. Since
an animal’s immune system generally activates in
response to an infection, researchers believe it may
respond similarly to an immunization, thus causing
alterations in body odors that are detectable either
by trained biosensor animals or headspace gas
chromatographic analyses. In a series of experiments,
an NWRC researcher successfully trained mice to distinguish between urine odors of rabiesvaccinated (RV) mice and non-vaccinated mice. The trained mice were also able to distinguish between urine from mice immunized with an equine WNV vaccine and urine from corresponding controls, indicating that the training was not specific to the immunizing agent. To further investigate the specificity of odors, immune system processes, and the usefulness of chemometric methods for diagnostic purposes, NWRC researchers tested the urine of mice treated with lipopolysaccharide (LPS) using a new biosensor panel of mice that was trained to detect RV mice. The trained biosensor panel did not generalize to the odors of LPS-treated mice. Chemometric analyses classified RV samples as different from control samples and LPS-treated mice as similar to RV mice. Thus, although bioassay and chemometric analyses exhibited some differences, both demonstrated that immunization alters the body’s volatile patterns in ways that can be detected by smell and/or chemometric techniques. Noninvasive Monitoring of Avian Influenza in Birds. Avian influenza viruses (AIV) pose significant hazards to agriculture and human health. Rapid and accurate detection of infected organisms is critical to monitoring and preventing the spread of AIV. To achieve this goal, NWRC researchers and collaborators trained six biosensors (inbred mice) to identify feces collected from ducks infected with low-pathogenic avian influenza based on fecal volatiles. Mice were exposed to fecal odors, but contact with feces was not allowed. The trained mice correctly discriminated the health status of individual mallards by identifying feces from postinfected periods when paired with pre-infected feces. Fecal samples were also subjected to dynamic headspace and solvent extraction analyses employing gas chromatography/mass spectrometry. Chemical analyses indicated that infection was associated with a marked increase of acetoin (3-hydroxy-2-butanone) in feces. These experiments suggest that the health status of waterfowl can be evaluated noninvasively by monitoring of volatile fecal metabolites. Furthermore, environmental monitoring using trained biosensor animals or portable instrumentation may be an effective tool for assessing an animal population’s health. Zinc Phosphide: Increasing the Acceptance of Baits. Lowering pesticide concentrations in rodenticides and other baits is important in efforts to reduce the amount of these compounds in the environment. However, lower concentrations of pesticides in the formulations can also lead to the development of bait shyness in target animals before effective dosages can be achieved. Reducing bait shyness in voles is critical to successful rodent management. In 2012, NWRC evaluated two approaches for reducing zinc phosphide bait shyness in bait formulations: (1) formulating baits with zinc phosphide encapsulated with a polymethacrylate coating to prevent oral detection of zinc phosphide and (2) suppressing the bitter taste by adding zinc sulfate and sodium cyclamate to the bait. Zinc sulfate blocks taste receptors for bitter and natural sweeteners, while the artificial sweetener, sodium cyclamate, makes the bait taste sweet even in the presence of zinc sulfate. Zinc phosphide baits formulated at a low concentration routinely produced bait shyness even when zinc sulfate and sodium cyclamate were added. However, microencapsulating zinc phosphide improved efficacy. Encapsulated zinc phosphide resulted in 80-percent vole mortality when formulated at 0.5 percent, a significantly lower concentration than the 2 percent that is currently being used. Anticoagulant Risks. The U.S. Environmental Protection Agency (EPA) has placed new regulatory restrictions on the use of some second-generation anticoagulant rodenticides in the United States, and in some situations these restrictions may be offset by the expanded use of first-generation
compounds. NWRC scientists conducted several studies with captive adult American kestrels and Eastern screech-owls that examined the toxicity of
Project
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