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Updated: May 18, 2026
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Published on: November 1, 2017
Warming and nitrogen affect size structuring and density dependence in a host-parasitoid food web
Claudio de Sassi1, Phillip P A Staniczenko, Jason M Tylianakis
1School of Biological Sciences, University of Canterbury, Christchurch, New Zealand. cdesassi@gmail.com
Summary
Climate change and nitrogen deposition alter food webs by increasing host availability and size. Parasitoids then target larger hosts, changing food web structure through density and trait effects.
Area of Science:
- Ecology
- Food web dynamics
- Climate change impacts
Background:
- Body size structures ecological communities and food webs.
- Climate change and nitrogen deposition can alter resource availability and quality, impacting food webs from the bottom-up.
- Effects on host-parasitoid food webs, especially size relationships, remain understudied.
Purpose of the Study:
- To investigate how climate warming and nitrogen deposition affect host-parasitoid food web structure.
- To explore the role of consumer and resource density and body size in these altered food webs.
- To understand the combined density- and trait-mediated effects on food web interactions.
Main Methods:
- Utilized a field experiment with factorial warming and nitrogen treatments.
- Assembled host-parasitoid food webs under these manipulated conditions.
- Employed a Bayesian modelling approach to analyze density and body size relationships.
Main Results:
- Warming and nitrogen deposition increased resource (host) availability and quality (size).
- Parasitoid feeding behavior shifted, with a preference for abundant and larger hosts.
- Food web interactions became less even, concentrating on high-quality hosts.
Conclusions:
- Climate-mediated bottom-up effects significantly alter food web structure.
- Both density- and trait-mediated effects contribute to these alterations.
- Host size emerges as a critical factor in climate-driven food web changes.
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