GREIVES, Timothy*; CLAY, Keith; DEMAS, Gregory; Indiana University Department of Biology and Center for the Integrative Study of Animal Behavior: Effects of a common fungal endophyte, Neotyphodium coenophialum, on reproductive and immune factors in prairie voles (Microtus ochrogaster)

Environmental factors can exert profound influences on animal physiology including reproduction and immunity, two factors that can strongly influence the lifetime reproductive success of an organism. The prairie vole, (Microtus ochrogaster) is an herbivore that ingests the foliage of broad leaf plants, including a common grass, tall fescue (Fescuta arundinacea). >80% of this grass in the U.S. is infected with the symbiotic fungal endophyte Neotyphodium coenophialum, which produces ergot alkaloids, chemicals that can affect physiological functions in small rodents. A limited number of laboratory studies indicate that animals ingesting diets containing high concentrations of this endophyte display impairments in both immune and reproductive function, as well as changes in reproductive hormones. Similar results have been found in livestock that graze on endophyte-infected grass. Few field studies, however, have investigated the effects on reproduction in rodents inhabiting endophyte-infected compared to unifected grasslands, and no field study has examined potential changes in immunity. To test the effects of endophyte infection on reproductive and immune function in the field, prairie voles were live-trapped from May-July 2005. Animals were sexed, weighed and blood samples were taken. Effects of residing in endophyte-infected fields on immunity were assessed by measuring total immunoglobulin-G, and complement hemolysis. In addition, testosterone levels were determined. Collectively, these results will provide insights on the effects of endophyte infection on reproductive and immune function potentially interacting to affect population dynamics.