Contact-independent exposure to <i>Rhodococcus rhodochrous</i> DAP96253 volatiles does not improve the survival rate of <i>Myotis lucifugus</i> (little brown bats) affected by White-nose Syndrome.

Abstract

Since the emergence of White-nose Syndrome, a fungal disease in bats, caused by <i>Pseudogymnoascus destructans,</i> hibernating populations of little brown bats (<i>Myotis lucifugus</i>) have declined by 70-90% within <i>P. destructans</i> positive hibernacula. To reduce the impact of White-nose Syndrome to North American little brown bat populations we evaluated if exposure to volatile organic compounds produced by induced cells from <i>Rhodococcus rhodochrous</i> strain DAP96253 could improve the overwinter survival of bats infected by <i>P. destructans</i>. Two simultaneous field treatment trials were conducted at natural hibernacula located in Rockcastle and Breckinridge counties, Kentucky, USA. A combined total of 120 little brown bats were randomly divided into control groups (<i>n</i> = 60) which were not exposed to volatile organic compounds and treatment groups (<i>n</i> = 60) which were exposed to volatile organic compounds produced by non-growth, fermented cell paste composed of <i>R. rhodochrous</i> strain DAP96253 cells. Cox proportional hazard models revealed a significant decreased survival at the Rockcastle field trial site but not the Breckinridge field site. At the Breckinridge hibernacula, overwinter survival for both treatment and control groups were 60%. At the Rockcastle hibernacula, Kaplan-Meier survival curves indicated significantly increased overwinter survival of bats in the control group (43% survived) compared to the treatment group (20% survived). Although complete inhibition of <i>P. destructans</i> by volatile organic compounds produced by induced <i>R. rhodochrous</i> strain DAP96253 cells was observed <i>in vitro</i> studies, our results suggest that these volatile organic compounds do not inhibit <i>P. destructans in situ</i> and may promote <i>P. destructans</i> growth.