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Complementarity and redundancy of interactions enhance attack rates and spatial stability in host–parasitoid food webs

Guadalupe Peralta, Carol M. Frost, Tatyana A. Rand, Raphael K. Didham, Jason M. Tylianakis
Ecology 2014 v.95 no.7 pp. 1888-1896
biodiversity, ecosystems, energy flow, food webs, herbivores, parasitism, parasitoids, predators
Complementary resource use and redundancy of species that fulfil the same ecological role are two mechanisms that can increase and stabilize process rates in ecosystems. For example, predator complementarity and redundancy can determine prey consumption rates, in some cases providing invaluable control over economically-damaging herbivore species. Even though multiple herbivores are usually attacked at different rates by multiple predators in a community, few studies have focused on these biodiversity mechanisms in entire herbivore-enemy assemblages, and even fewer take into account the pattern and relative frequency of interactions within the community, which affect overall consumption rates. Here, we use a quantitative food-web approach to study the community-wide effects of complementarity and redundancy of consumers (parasitoids) on herbivore control. By incorporating trophic interactions (links) among species as a proxy for energy flow among organisms, we test the mechanisms driving the biodiversity-functioning relationship in diverse empirical multitrophic communities. We found that complementarity of host resources used by parasitoids was the strongest predictor of parasitism rates at the community level and that redundancy in host-use patterns stabilised community-wide parasitism rates in space but not in time. These effects can potentially explain previous contradictory results from biodiversity and ecosystem functioning research. Our study shows that known mechanisms underpinning predator diversity effects can easily be extended to an entire community, providing a link between biodiversity and food-web research.