Dissertation
Mechanisms driving increased prey consumption with increasing predator diversity
Washington State University
Doctor of Philosophy (PhD), Washington State University
08/2009
DOI:
https://doi.org/10.7273/000005925
Abstract
Theory predicts that greater prey diversity will both foster the emergence of complementary predator feeding patterns and weaken any negative effects of intraguild predation. Thus, a positive relationship between predator diversity and improved prey suppression might be realized when several prey species are present, if a diversified prey base allows complementarity among predators to be realized. In two 2005 field cages experiments in Othello, WA, I examined the effects of including multiple prey species on predator diversity by simultaneously manipulating presence or absence of multiple prey (one or two species) and predator diversity (monoculture or polyculture). We found the strength of aphid suppression always increased with greater predator biodiversity, but this effect was independent of prey species diversity or identity. This suggests that the benefits of predator diversity for prey suppression were mediated by interactions within the predator community, such that a diverse resource base was not necessary to yield a positive relationship between predator biodiversity and effective herbivore suppression. The strength of herbivore suppression often improves with greater predator biodiversity, but controversy remains about the mechanism(s) underlying such results. Positive diversity effects might result from partitioning of the prey resource, with different predator species attacking different subsets of the prey population, a release from intra-specific competition, or facilitation. In two 2007 field cage experiments I manipulated diversity, and also density, among a community of predators, and measured the impact of these manipulations on densities of aphid prey. Predator polycultures exerted the strongest aphid suppression, and only among polycultures did aphid suppression increase across all predator density levels. In addition, we found that multi-predator effects were approximately additive, consistent with a release from intra-specific competition in high diversity predator treatments. Taken together, our results provide compelling empirical evidence that, in this system, weaker interspecific than intraspecific competition underlay stronger prey suppression with greater predator biodiversity.
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Details
- Title
- Mechanisms driving increased prey consumption with increasing predator diversity
- Creators
- Gretchen Beth Snyder
- Contributors
- William E. Snyder (Chair)STEPHEN L CLEMENT (Committee Member)Sanford D Eigenbrode (Committee Member)Jeb Owen (Committee Member) - Washington State University, Department of Entomology
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Entomology
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 102
- Identifiers
- 99901055033601842
- Language
- English
- Resource Type
- Dissertation