Effects of Tall Fescue Endophyte Infection and Population Density on Growth and Reproduction in Prairie Voles

Abstract

The fungal endophyte (Neotyphodium coenophialum) infecting tall fesene grass (Festuca arundiuacea) can produce adverse effects when consumed by herbivores, Becent laboratory studies have produced conflicting results on effects of the endophyte on growth and reproduction of small mammals. We compared the growth and reproductive condition of prairle voles (Microtus ochrogaster) on plots of endophyte-infected and uninfected fescue to determine the effects of the endophyte under field conditions. Populations of voles on endophyte-infected plots exhibited a skewed sex ratio at low population densities. As densities increased in the second year of the study the sex ratios equalized on all grids, but female voles on the infected plots exhibited greater weights at sesxual maturity. Greater weight at sexnal maturity could be due to either a change in growth. rate or a change in the timing of reproductive maturation. No differences in the growth rates of voles were found, suggesting that the endophyte may delay the onset of sexual maturity in wild rodents.