Macroecological characteristics of bat geomycosis in the Czech Republic: results of five years of monitoring
Abstract
Infestation of hibernating bats by infectious fungus Geomyces (Pseudogymnoascus) destructans (GD) was monitored in 13 regions of the Czech Republic from 2009 to 2014 using a standardized field protocol. Although fungus mycelia were recorded in 12 bat species, only two of them (Myotis myotis, in a smaller extent also Myotis emarginatus) were infested regularly.
In total 20,268 individuals of M. myotis (by far the most infected species) were examined, 4047 of them being GD positive. The mean site positive rate varied among years from 61.3 to 71.2%, the mean total prevalence varied from 10.4 to 26.3% with considerable differences between particular regions (with total site positive rate 41.8-100%, and total prevalence 2.7-49.2%).
Despite temporal variation, the pattern of geographic (inter-regional) variation remained unchanged throughout all five winters: mean regional values were low in lowland and karstic regions (site positive rate 20-42%, prevalence 0-7%), while in mountain and submontane hibernacula and/or those situated in a dynamic relief with stone debris cover and high surface humidity they were quite high (prevalence 22-58%, site positive rate 55-100%). Contrary to our expectations, we found no significant relation between prevalence of geomycosis and the abundance of hibernating populations or cluster size.
The vast majority of observed cases showed the weakest stage of infection, severe damages (e.g. macroscopic lesions on auricles or wings) were rather exceptional. No case of mortality directly caused by GD was recorded.
The pattern of prevalence does not suggest that GD is a specialized pathogen. The considerable difference between Europe and North America in mortality associated with the WNS and its possible causes (different tactics of hibernation, habituation to skin injuries due to high ectoparasite load in Europe etc.) are discussed.