title: Monarch butterfly migration and parasite transmission in eastern North America.
abstract: Seasonal migration occurs in many animal systems and is likely to influence interactions between animals and their parasites. Here, we focus on monarch butterflies (Danaus plexippus) and a protozoan parasite (Ophryocystis elektroscirrha) to investigate how host migration affects infectious disease processes. Previous work showed that parasite prevalence was lower among migratory than nonmigratory monarch populations; two explanations for this pattern are that (1) migration allows animals to periodically escape contaminated habitats (i.e., migratory escape), and (2) long-distance migration weeds out infected animals (i.e., migratory culling). We combined field-sampling and analysis of citizen science data to examine spatiotemporal trends of parasite prevalence and evaluate evidence for these two mechanisms. Analysis of within-breeding-season variation in eastern North America showed that parasite prevalence increased from early to late in the breeding season, consistent with the hypothesis of migratory escape. Prevalence was also positively related to monarch breeding activity, as indexed by larval density. Among adult monarchs captured at different points along the east coast fall migratory flyway, parasite prevalence declined as monarchs progressed southward, consistent with the hypothesis of migratory culling. Parasite prevalence was also lower among monarchs sampled at two overwintering sites in Mexico than among monarchs sampled during the summer breeding period. Collectively, these results indicate that seasonal migration can affect parasite transmission in wild animal populations, with implications for predicting disease risks for species with threatened migrations.
authors: Odum School of Ecology, University of Georgia, Athens, Georgia 30602-2202, USA. bbartel@uga.edu
authors: Rebecca A
authors: RA
authors: Bartel
authors: Karen S
authors: KS
authors: Oberhauser
authors: Jacobus C
authors: JC
authors: De Roode
authors: Sonia M
authors: SM
authors: Altizer
references: Oecologia. 2009 Aug;161(1):67-75
references: 19418070
references: Science. 2005 Oct 28;310(5748):628-9
references: 16254175
references: Proc Biol Sci. 2005 Apr 7;272(1564):689-96
references: 15870031
references: Nature. 2000 Feb 17;403(6771):724-5
references: 10693792
references: Science. 2007 Jun 1;316(5829):1298-301
references: 17540894
references: Trends Parasitol. 2006 Oct;22(10):475-83
references: 16920027
references: Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19368-73
references: 17158217
references: Environ Entomol. 2007 Dec;36(6):1365-73
references: 18284764
references: PLoS One. 2007 Jan 31;2(1):e184
references: 17264886
references: Science. 2005 Oct 28;310(5748):676-9
references: 16195424
references: J Invertebr Pathol. 1997 Jan;69(1):79-83
references: 9028932
references: PLoS Biol. 2008 Jul 29;6(7):e188
references: 18666834
references: Proc Biol Sci. 2007 Aug 22;274(1621):2003-12
references: 17537707
references: Proc Biol Sci. 2007 Dec 22;274(1629):3141-9
references: 17939989
references: Science. 2006 Aug 11;313(5788):794-6
references: 16902129
references: Proc Natl Acad Sci U S A. 2008 May 27;105(21):7489-94
references: 18492806
references: Proc Natl Acad Sci U S A. 2006 Oct 17;103(42):15506-10
references: 17021017
references: Proc Natl Acad Sci U S A. 2003 Nov 25;100(24):14063-8
references: 14612569
references: Parasitology. 2007 May;134(Pt 5):657-68
references: 17140464
references: Proc Biol Sci. 2002 Apr 7;269(1492):671-6
references: 11934357
references: Emerg Infect Dis. 2007 Aug;13(8):1139-43
references: 17953082