LONG-TERM SURVIVAL OF PSEUDOGYMNOASCUS DESTRUCTANS AT ELEVATED TEMPERATURES

Abstract

White-nose syndrome is an emerging fungal disease that has devastated hibernating bat populations across eastern North America. The causal pathogen, Pseudogymnoascus destructans (PD), is a psychrophilic fungus with a known maximal growth temperature of 20 C. Although it is widely speculated that PD is primarily spread between hibernacula by the movement of bats, experimental evidence is lacking to demonstrate that PD can endure temperatures experienced by active bats for periods of time that would facilitate dispersal of viable fungus. We used an in vitro culture-based approach to study the survival of PD conidia on three artificial growth media and bat fur. The fungus was incubated at three temperatures it might realistically be exposed to on nonhibernating bats or in the environment outside of caves and mines (24 C, 30 C, and 37 C). When incubated on artificial media, we found that PD conidia were able to survive for a maximum of 150 d when exposed to temperatures of 24 C, 60 d at 30 C, and 15 d at 37 C. At all temperatures, maximal survival duration was recorded when conidia were incubated on brain–heart infusion agar with 10% volume of sheep (Ovis aries) blood. When incubated on bat fur, viable PD was recovered at 180 d, 60 d, and 5 d when exposed to temperatures of 24 C, 30 C, and 37 C, respectively. Our results suggest that viable PD conidia may be able to survive on or within the bodies of bats, which may facilitate long-distance dispersal. The long-term viability of the fungus on various fomites may differ, and therefore must be assessed for each potential substrate.