, Volume 784, Issue 1, pp 201–210

Parasite abundance decreases with host density: evidence of the encounter-dilution effect for a parasite with a complex life cycle

Primary Research Paper

DOI: 10.1007/s10750-016-2874-8

Cite this article as:
Buck, J.C. & Lutterschmidt, W.I. Hydrobiologia (2017) 784: 201. doi:10.1007/s10750-016-2874-8


The relationship between host density and parasitism depends on a parasite’s life history. The abundance of a directly transmitted contagious parasite should increase with host density, whereas the abundance of a directly transmitted parasite that seeks its host might decrease due to the encounter-dilution effect. For parasites with complex life cycles, previous studies have found no association between parasite abundance and host density. We tested the relationship between host density and metacercarial abundance of a trematode parasite (Posthodiplostomum minimum) in two species of centrarchid fishes (Lepomis macrochirus and L. auritus) from eight small creeks. We found that host density was negatively associated with parasite abundance. Thus, our study represents the first evidence of the encounter-dilution effect for a parasite with complex life cycle in a natural system. We also report a positive association between total P. minimum population abundance and Lepomis spp. density, indicating that at low host density, cercarial mortality could moderate the encounter-dilution effect.


Encounter-dilution Lepomis Posthodiplostomum minimum Sunfish Trematode 

Funding information

Funder NameGrant NumberFunding Note
Engineer Research and Development Center
  • DACA 42-00-C-0047
U.S. Army Corps of Engineers
  • DACA 42-00-C-0047

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Texas Research Institute for Environmental StudiesSam Houston State UniversityHuntsvilleUSA
  2. 2.Marine Science InstituteUniversity of California Santa BarbaraSanta BarbaraUSA
  3. 3.Department of Biological SciencesSam Houston State UniversityHuntsvilleUSA

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