Modeling the Spread of Pseudogymnoascus Destructans in Texas and Mexican Karst Regions

Abstract

White-nose Syndrome (WNS) is caused by a fungus that has led to deaths of millions of North American bats since it was first documented in New York 2006. Since the first cases were recorded, WNS has spread rapidly across North America, and is now present in 34 US states and 7 Canadian provinces. The disease is caused by the introduced fungal pathogen Pseudogymnoascus destructans. Often, the presence of P. destructans is detected in a cave environment before signs of WNS manifest in the resident bat population – making expansion of the fungus a more reliable assessment of epidemic spread than expansion of manifested WNS. We generated a predictive model to assess the potential spread of P. destructans, the fungal causal agent of WNS, through Texas karst systems based on external features that correlate with suitable internal microclimates for fungal growth. An analysis of 43 cave microclimates across the state of Texas reveals a pattern of thermal suitability for P. destructans that correlates significantly with landscape (elevation, lithology) and external climate (mean surface temperature and precipitation). Applications of this model to external climatic variables from 2019 show seasonally varying patterns of suitability for fungal growth in select regions of Texas karst systems. Similar work conducted in Mexico surveyed 4 caves in 2 areas of varying climate and elevation. Results from these surveys show that microclimates of Mexican caves are likely able to sustain the growth of P. destructans and could act as stepping stones for the fungus, allowing it to travel southward. The resulting work will inform researchers and natural resource managers of areas of significant concern while monitoring the spread of WNS.