Chytrid infection dynamics in cricket frogs on military and public lands in the midwestern United States

The pathogenic chytrid fungus Batrachochytrium dendrobatidis (hereafter, Bd) is a causal agent in amphibian decline and extinction events. Sampling for Bd in the Midwestern United States has largely been opportunistic and haphazard, so little information exists on the true occurrence and prevalence of the disease. We repeatedly tested Cricket Frogs Acris blanchardi or A. crepitans at 54 wetlands in 2009 and 15 wetlands in 2011 on both public and military lands to estimate Bd occurrence and prevalence rates between different land-use types, sampling seasons (spring, summer, autumn) and sampling years. We found Bd occurred in 100% of wetlands we sampled in 2009 and 2011, and overall prevalence was 22.7% in 2009 and 40.5% in 2011. Batrachochytrium dendrobatidis prevalence in 2011 was significantly higher than in 2009 and was significantly higher during the spring season than in the summer or autumn. We also found Bd prevalence was not significantly different on military versus public-use sites and was most affected by the average 30-d maximum temperature prior to sampling. This study provides data on the occurrence and prevalence of Bd in the United States and fills an important gap in the Midwest, while also corroborating prior research findings of increased prevalence in the cooler spring season.