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Oecologia

Title:		Avoidance of intraguild predation leads to a long-term positive trait-mediated indirect effect in an insect community
Author(s):		Frago E; Godfray HC;
Address:
Journal Title:		Oecologia
Year:		2014
Volume:		174
Issue:		3
Page Number:		943 - 952
DOI:		10.1007/s00442-013-2799-0
ISSN/ISBN:		1432-1939 (Electronic) 0029-8549 (Linking)
Abstract:		"Intraguild predation among natural enemies is common in food webs with insect herbivores at their base. Though intraguild predation may be reciprocal, typically one species suffers more than the other and frequently exhibits behavioural strategies to lessen these effects. How such short-term behaviours influence population dynamics over several generations has been little studied. We worked with a model insect community consisting of two species of aphid feeding on different host plants (Acyrthosiphon pisum on Vicia and Sitobion avenae on Triticum), a parasitoid (Aphidius ervi) that attacks both species, and a dominant intraguild predator (Coccinella septempunctata) that also feeds on both aphids (whether parasitized or not). As reported previously, we found A. ervi avoided chemical traces of C. septempunctata. In population cages in the laboratory, application of C. septempunctata extracts to Vicia plants reduced parasitism on A. pisum. This did not increase parasitism on the other aphid species, our predicted short-term trait-mediated effect. However, a longer term multigenerational consequence of intraguild predator avoidance was observed. In cages where extracts were applied in the first generation of the study, parasitoid recruitment was reduced leading to higher population densities of both aphid species. S. avenae thus benefits from the presence of a dominant intraguild predator foraging on another species of aphid (A. pisum) on a different food plant, a long-term, trait-mediated example of apparent mutualism. The mechanism underlying this effect is hypothesized to be the reduced searching efficiency of a shared parasitoid in the presence of cues associated with the dominant predator"
Keywords:		"Animals Aphids/*parasitology *Behavior, Animal Coleoptera/chemistry Cues Female *Food Chain Host-Parasite Interactions Male *Pheromones Population Density Population Dynamics Predatory Behavior Triticum Vicia faba Wasps/*physiology;"
Notes:		"MedlineFrago, Enric Godfray, H Charles J eng Research Support, Non-U.S. Gov't Germany 2013/10/15 Oecologia. 2014 Mar; 174(3):943-52. doi: 10.1007/s00442-013-2799-0"