Monarch butterfly migration and parasite transmission in eastern North America

• Type of Material: Article
• Authors: Rebecca A. Bartel, University of Georgia; Karen S. Oberhauser, University of Minnesota Twin Cities; Jacobus De Roode, Emory University; Sonia M. Altizer, University of Georgia
• Language: English
• Date: 2011-02-01
• Publisher: Wiley
• Publication Version: Final Published Version
• Copyright Statement: © 2011 by the Ecological Society of America.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1890/10-0489.1
• Title of Journal or Parent Work: Ecology
• Volume: 92
• Issue: 2
• Start Page: 342
• End Page: 351
• Grant/Funding Information: J. C. de Roode was supported by a Marie Curie Outgoing International Fellowship and Emory University.; The National Science Foundation (ISE‐0104600), the Xerces Society, the University of Minnesota Extension Service, and Monarchs in the Classroom provided financial support for the MLMP.; inancial support was provided to R. Bartel by a National Institutes of Health NRSA award and to S. Altizer by a National Science Foundation grant (DEB‐0643831).
• Keywords: Larva; Butterflies; North America; Apicomplexa; Animal Migration; Animals; Time Factors; Host-Parasite Interactions; Asclepias
• Research Categories: Biology, Ecology; Biology, Plant Physiology; Biology, Parasitology; Biology, Virology

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.