Health survey of two subspecies of bent-winged bats: southern bent-winged bat (Miniopterus orianae bassanii) and eastern bent-winged bat (Miniopterus orianae oceanensis)
AuthorHolz, Peter Harry
AffiliationVeterinary and Agricultural Sciences Collected Works
Document TypePhD thesis
Access StatusOpen Access
© 2018 Peter Harry Holz
Australian bent-winged bats are small, cave-roosting, insectivorous bats. There are two subspecies: the southern bent-winged bat (Miniopterus orianae bassanii) which occurs only in south-western Victoria and south-eastern South Australia, and the eastern bent-winged bat (M. orianae oceanensis) which is more common and widespread, being distributed along the east coast of Australia. In the last 50 years, the population of southern bent-winged bats has declined to the point where the subspecies was listed as critically endangered in 2007. The cause of the population decline is not clear. This project compared the health status of both bent-winged bat subspecies to investigate the role that disease may have on the southern bent-winged bat population decline. Morphometric data was gathered for the two subspecies. Southern bent-winged bats were heavier, but forearm length was not significantly different. This suggests that southern bent-winged bats may require more energy to fly and forage than eastern bent-winged bats. Oral swabs were tested by PCR for adenoviruses, coronaviruses, filoviruses, henipaviruses, herpesviruses and lyssaviruses. Six novel herpesviruses (five betaherpesviruses and one gammaherpesvirus) were identified, with the greatest infection prevalence occurring in Victorian southern bent-winged bats. No other viruses were detected. Both bat subspecies and their environment were sampled for Pseudogymnoascus destructans, the fungus that causes white nose syndrome, which has killed millions of bats in North America. All results were negative. Bats and their environment were sampled for Histoplasma capsulatum, a potential human pathogen associated with bat caves. A prevalence of 0-19% was detected on the bats, but environmental results were negative, indicative of a low zoonotic risk. A large number of fungi were found on the skin and fur of bats, most of which were environmental or plant associated, and none of which were likely to be of significant pathogenicity for bats. A risk assessment for the introduction of P. destructans into Australia concluded that it is very likely/almost certain that P. destructans will enter Australia, and likely that bats will be exposed to the fungus over the next ten years. Eight cave-dwelling bats from southern Australia are the ones most likely to be affected. The risk was assessed as medium for the southern bent-winged bat, as any increase in mortality could impact its long term survival. The risk to the other species was deemed to range from low to very low, due to their wider distribution and/or more stable populations. Bats were examined for the presence of bat flies, mites, ticks, Riouxgolvania beveridgei (previously associated with skin nodules in bent-winged bats), Polychromophilus melanipherus and haemoplasmas. While all parasites were present in both subspecies, prevalence varied seasonally and by location group, Victorian southern bent-winged bats having a significantly greater prevalence of infection with ticks, R. beveridgei and P. melanipherus. Twenty-seven southern bent-winged bats and one eastern bent-winged bat were opportunistically necropsied and examined histologically. Trauma was the most common cause of death in the southern bent-winged bats, which mostly occurred at one site where infrastructure is positioned around a key breeding cave. In response to these findings, management actions were implemented to reduce mortality rates. The single eastern bent-winged bat examined had a severe dermatitis caused by the mite, Notoedres muris. No association was found between any of the infectious and parasitic agents surveyed and body weight, blood parameters or any signs of ill health. However, Victorian southern bent-winged bats had a greater prevalence of herpesviruses, ticks, R. beveridgei and P. melanipherus infections, possibly indicative of some type of chronic stress impacting the immune system of this population.
Keywordssouthern bent-winged bat; Miniopterus orianae bassanii; eastern bent-winged bat; Minopterus orianae oceanensis; Pseudogymnoascus destructans; Histoplasma capsulatum; Polychromophilus melanipherus; Riouxgolvania beveridgei
- Click on "Export Reference in RIS Format" and choose "open with... Endnote".
- Click on "Export Reference in RIS Format". Login to Refworks, go to References => Import References