« Previous Abstract"Methodology for collecting, storing, and analyzing human milk for volatile organic compounds"    Next AbstractAquatic food production modules in bioregenerative life support systems based on higher plants »

Ecology

Title:		Dual-guild herbivory disrupts predator-prey interactions in the field
Author(s):		Blubaugh CK; Asplund JS; Eigenbrode SD; Morra MJ; Philips CR; Popova IE; Reganold JP; Snyder WE;
Address:		"Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina, 29678, USA. Department of Entomology, Washington State University, Pullman, Washington, 99164, USA. Department of Plant, Soil, and Entomological Sciences, University of Idaho, 875 Perimeter Drive, Moscow, Idaho, 83844, USA. Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, 99164, USA"
Journal Title:		Ecology
Year:		2018
Volume:		99
Issue:		5
Page Number:		1089 - 1098
DOI:		10.1002/ecy.2192
ISSN/ISBN:		0012-9658 (Print) 0012-9658 (Linking)
Abstract:		"Plant defenses often mediate whether competing chewing and sucking herbivores indirectly benefit or harm one another. Dual-guild herbivory also can muddle plant signals used by specialist natural enemies to locate prey, further complicating the net impact of herbivore-herbivore interactions in naturally diverse settings. While dual-guild herbivore communities are common in nature, consequences for top-down processes are unclear, as chemically mediated tri-trophic interactions are rarely evaluated in field environments. Combining observational and experimental approaches in the open field, we test a prediction that chewing herbivores interfere with top-down suppression of phloem feeders on Brassica oleracea across broad landscapes. In a two-year survey of 52 working farm sites, we found that parasitoid and aphid densities on broccoli plants positively correlated at farms where aphids and caterpillars rarely co-occurred, but this relationship disappeared at farms where caterpillars commonly co-occurred. In a follow-up experiment, we compared single and dual-guild herbivore communities at four local farm sites and found that caterpillars (P. rapae) caused a 30% reduction in aphid parasitism (primarily by Diaeretiella rapae), and increased aphid colony (Brevicoryne brassicae) growth at some sites. Notably, in the absence of predators, caterpillars indirectly suppressed, rather than enhanced, aphid growth. Amid considerable ecological noise, our study reveals a pattern of apparent commensalism: herbivore-herbivore facilitation via relaxed top-down suppression. This work suggests that enemy-mediated apparent commensalism may override constraints to growth induced by competing herbivores in field environments, and emphasizes the value of placing chemically mediated interactions within their broader environmental and community contexts"
Keywords:		Animals *Aphids *Brassica Herbivory Host-Parasite Interactions *Hymenoptera Pieris rapae Brassica oleracea Brevicoryne brassicae Diaeretiella rapae agroecology crosstalk facilitation parasitism tri-trophic interactions;
Notes:		"MedlineBlubaugh, Carmen K Asplund, Jacob S Eigenbrode, Sanford D Morra, Matthew J Philips, Christopher R Popova, Inna E Reganold, John P Snyder, William E eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2018/02/22 Ecology. 2018 May; 99(5):1089-1098. doi: 10.1002/ecy.2192"