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PLoS One

Title:		Drought and root herbivory interact to alter the response of above-ground parasitoids to aphid infested plants and associated plant volatile signals
Author(s):		Tariq M; Wright DJ; Bruce TJ; Staley JT;
Address:		"Division of Biology, Faculty of Natural Sciences, Imperial College London, Silwood Park Campus, Ascot, United Kingdom. m.tariq06@imperial.ac.uk"
Journal Title:		PLoS One
Year:		2013
Volume:		20130719
Issue:		7
Page Number:		e69013 -
DOI:		10.1371/journal.pone.0069013
ISSN/ISBN:		1932-6203 (Electronic) 1932-6203 (Linking)
Abstract:		"Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores), their parasitoids, and a dipteran species (root herbivore).We tested the hypotheses that: (1) high levels of drought stress and below-ground herbivory interact to reduce the performance of parasitoids developing in aphids; (2) drought stress and root herbivory change the profile of volatile organic chemicals (VOCs) emitted by the host plant; (3) parasitoids avoid ovipositing in aphids feeding on plants under drought stress and root herbivory. We examined the effect of drought, with and without root herbivory, on the olfactory response of parasitoids (preference), plant volatile emissions, parasitism success (performance), and the effect of drought on root herbivory. Under drought, percentage parasitism of aphids was reduced by about 40-55% compared with well watered plants. There was a significant interaction between drought and root herbivory on the efficacy of the two parasitoid species, drought stress partially reversing the negative effect of root herbivory on percent parasitism. In the absence of drought, root herbivory significantly reduced the performance (e.g. fecundity) of both parasitoid species developing in foliar herbivores. Plant emissions of VOCs were reduced by drought and root herbivores, and in olfactometer experiments parasitoids preferred the odour from well-watered plants compared with other treatments. The present work demonstrates that drought stress can change the outcome of interactions between herbivores feeding above- and below-ground and their parasitoids, mediated by changes in the chemical signals from plants to parasitoids. This provides a new insight into how the structure of terrestrial communities may be affected by drought"
Keywords:		"Animals Aphids/*physiology *Droughts Female *Herbivory Host-Parasite Interactions Male Olfactory Perception Oviposition Plant Roots/*parasitology/*physiology Stress, Physiological *Volatile Organic Compounds;"
Notes:		"MedlineTariq, Muhammad Wright, Denis J Bruce, Toby J A Staley, Joanna T eng Research Support, Non-U.S. Gov't 2013/07/31 PLoS One. 2013 Jul 19; 8(7):e69013. doi: 10.1371/journal.pone.0069013. Print 2013"