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Title: Apparent competition drives community-wide parasitism rates and changes in host abundance across ecosystem boundaries

Author
item FROST, CAROL - Canterbury Christchurch College
item PERALTA, GUADALUPE - Canterbury Christchurch College
item Rand, Tatyana
item DIDHAM, RAPHAEL - University Of Western Australia
item VARSANI, ARVIND - Canterbury Christchurch College
item TYLIANAKIS, JASON - Canterbury Christchurch College

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2016
Publication Date: 8/31/2016
Citation: Frost, C.M., Peralta, G., Rand, T.A., Didham, R.K., Varsani, A., Tylianakis, J.M. 2016. Apparent competition drives community-wide parasitism rates and changes in host abundance across ecosystem boundaries. Nature Communications. 7:12644. doi:10.1038/ncomms12644.

Interpretive Summary: Insects can have pervasive indirect effects on other insects, even if they never encounter one another in a common space. In particular, pairs of unrelated insect prey species can be linked by a shared predator, and information about shared predation has been used successfully to predict predator impact on a given prey species such as a crop pest. However, it remains unclear whether these predictions can be scaled up to entire food webs spanning diverse communities of plant feeding insects (herbivores) which live in different habitat types that are linked by predator movement between them. Here we show that attack rates on entire herbivore communities can be predicted remarkably accurately from host abundance and quantitative interaction data alone. Moreover, we successfully predicted changes in community-wide attack rates across edges between natural and managed forests. These findings show that predator-prey interactions propagate through food webs in important and predictable ways, with broad implications for invasion biology and biological control of pest herbivores in mosaic landscapes.

Technical Abstract: Species have pervasive indirect effects on other species, even if they never encounter one another in nature. Pairs of unrelated prey species that share a common predator can be linked by ‘apparent competition’, and information about shared predators has been used successfully to predict simple pairwise indirect interactions. However, it remains unclear whether these predictions can be scaled up to whole networks of indirect interactions in quantitative food webs spanning diverse communities in different habitat types spatially-coupled by predator movement. Here we show that attack rates by parasitoids on entire herbivore assemblages can be predicted remarkably accurately from host abundance and quantitative interaction data alone. Moreover, we successfully predicted changes in community-wide attack rates across edges between natural and managed forests. These findings show that species effects propagate across networks in important and predictable ways, with broad implications for invasion biology and biological control of pest herbivores in mosaic landscapes.