The Relationship Between White Nose Syndrome and Dietary PUFA Levels in Bats
Six bat species in northeastern North America spend winter hibernating in caves/mines. Hibernation is characterized by multi-day periods of torpor, when metabolic rates are reduced. Body fat levels increase from 7 to 27% in the fall, just prior to the onset of hibernation by bats. Some groups of hibernating bats in northeastern North America display abnormal behaviors and increased overwinter mortality called white nose syndrome (WNS). Large numbers of dead bats are found in hibernation sites affected by WNS. Previous research has demonstrated that the increased over-mortality is due to the depletion of depot fat reserves by February, which is in turn caused by greatly shortened torpor bouts. Published studies on hibernating mammals have revealed that moderately high levels of polyunsaturated fatty acids (PUFAs) are required in the diet during the fall for torpor. We thus predicted that bats suffering from WNS have lower levels of PUFAs in their fall diets than those that do not suffer from WNS. We tested this hypothesis by analyzing white adipose tissue (WAT) samples from: (a) little brown bats (Myotis lucifugus) collected from different hibernation sites and (b) big brown bats (Eptesicus fuscus), a species not greatly affected by WNS. Our analyses reveal that M. lucifugus populations prone to WNS have significantly less of the PUFA α-linolenic acid in their fall diets than those where WNS does not occur. The fall diets of E. fuscus contain significantly more of the PUFA linoleic acid than those of M. lucifugus from the same site. Our findings thus support the hypothesis that bats suffering from WNS have lower levels of PUFAs in their fall diets.
KeywordsWhite Adipose Tissue Ground Squirrel PUFA Content Torpor Bout PUFA Ratio
We thank Alan Hicks and Carl Hertzog for their generous assistance. This study was supported by NSF grants IOS-0818222 awarded to C.L.F., and IOS- 0840762 awarded to T.H.K. and C.L.F.
- Buckner JS (1993) Cuticular polar lipids of insects. In: Stanley-Samuelson DW, Nelson DR (eds) Insect lipids: chemistry, biochemistry, and biology. University of Nebraska Press, LincolnGoogle Scholar
- Frank CL (1992) The influence of dietary fatty acids on hibernation by golden-mantled ground squirrels (Spermophilus lateralis). Physiol Zool 65:906–920Google Scholar
- Frank CL, Storey KB (1996) The effect of total unsaturate content on hibernation. In: Geiser F, Hulbert A, Nicol SJ (eds) Adaptations to the cold. University of New England Press, ArmidaleGoogle Scholar
- Frank CL, Dierenfeld ES, Storey KB (1998) The relationship between lipid peroxidation, hibernation, and food selection in mammals. Amer Zool 38:341–349Google Scholar
- Frank CL, Hood WR, Donnelly MC (2004) The role of α-Linolenic acid (18:3) in mammalian torpor. In: Barnes M, Carey H (eds) Life in the cold: evolution, mechanisms, adaptation and application. Institute of Arctic Biology Press, FairbanksGoogle Scholar
- Kayser C (1965) Hibernation. In: Mayer W, VanGelder R (eds) Physiological mammalogy, volume II. Academic Press, New YorkGoogle Scholar
- Kunz TH, Wrazen JH, Burnett CD (1998) Changes in body mass and body composition in pre-hibernating little brown bats (M. lucifugus). Ecoscience 5:8–17Google Scholar
- Reynolds RS, Kunz T (2000) Changes in body composition during reproduction and postnatal growth in the little brown bat, Myotis lucifugus (Chiroptera: Vespertilionidae). Ecoscience 7:10–17Google Scholar
- Ruf T, Arnold W (2008) Effects of polyunsaturated fatty acids on hibernation and torpor: a review and hypothesis. Amer J Physiol 294:R1044–R1052Google Scholar
- Turner GG, Reeder D, Coleman J (2011) A five-year assessment of mortality and geographic spread of white-nose syndrome in North American bats and a look to the future. Bat Res News 52:13–27Google Scholar
- Urich K (1990) Comparative animal biochemistry. Springer, New YorkGoogle Scholar