##  [Sublethal Effects of Parasitism on Ruminants Can Have Cascading Consequences for Ecosystems](/resource/sublethal-effects-parasitism-ruminants-can-have-cascading-consequences-ecosystems) 

Organization

[Washington University in St. Louis](/organization/washington-university-st-louis)

 

 

Resource Type

[Peer reviewed article](/taxonomy/term/37)

 

 

Author(s)

Amanda Koltz

David Civitello

Daniel Becker

Sharon Deem

Aimée Classen

Brandon Barton

Maris Brenn-White

Zoë Johnson

Susan Kutz

Matthew Malishev

 

 

Original Authors

Amanda Koltz

David Civitello

Daniel Becker

Sharon Deem

Aimée Classen

Brandon Barton

Maris Brenn-White

Zoë Johnson

Susan Kutz

Matthew Malishev

 

 

Resource Date:

2022

 

Page Length

10

 

 

Parasitic infections are common, but how they shape ecosystem-level processes is understudied. Using a mathematical model and meta-analysis, we explored the potential for helminth parasites to trigger trophic cascades through lethal and sublethal effects imposed on herbivorous ruminant hosts after infection. First, using the model, we linked negative effects of parasitic infection on host survival, fecundity, and feeding rate to host and producer biomass. Our model, parameterized with data from a well documented producer–caribou–helminth system, reveals that even moderate impacts of parasites on host survival, fecundity, or feeding rate can have cascading effects on ruminant host and producer biomass. Second, using meta-analysis, we investigated the links between helminth infections and traits of free-living ruminant hosts in nature. We found that helminth infections tend to exert negative but sublethal effects on ruminant hosts. Specifically, infection significantly reduces host feeding rates, body mass, and body condition but has weak and highly variable effects on survival and fecundity. Together, these findings suggest that while helminth parasites can trigger trophic cascades through multiple mechanisms, overlooked sublethal effects on nonreproductive traits likely dominate their impacts on ecosystems. In particular, by reducing ruminant herbivory, pervasive helminth infections may contribute to a greener world.