title: Risk of spider predation alters food web structure and reduces local herbivory in the field.
abstract: Predators can indirectly enhance plant performance via herbivore suppression, with both prey consumption and changes in prey traits (e.g. changes in foraging behaviour) contributing to the reduction in herbivory. We performed a field experiment to determine the extent of such non-consumptive effects which consisted of repeatedly placing spiders (Pisaura mirabilis) on enclosed plants (Urtica dioica) for cue deposition. Control plants were enclosed in the same way but without spiders. After cue deposition, the enclosures were removed to allow arthropods to colonize the plants and feed on them. Arthropods were removed from the plants before the subsequent spider deposition or control enclosure. During six cycles of enclosure, we quantified leaf damage on the plants. After a seventh cycle, the colonizing arthropods were sampled to determine community composition in relation to the presence/absence of spider cues. We found that the presence of chemotactile spider cues reduced leaf damage by 50 %. In addition, spider cues led to changes in the arthropod community: smaller spiders avoided plants with spider cues. In contrast, the aphid-tending ant Myrmica rubra showed higher recruitment of workers on cue-bearing plants, possibly to protect aphids. Our results show that the risk of spider predation can reduce herbivory on wild plants and also demonstrate that non-consumptive effects can be particularly strong within the predator guild.
authors: Ecosystem Analysis, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany, bucher@uni-landau.de.
authors: Roman
authors: R
authors: Bucher
authors: Florian
authors: F
authors: Menzel
authors: Martin H
authors: MH
authors: Entling
mesh_terms: D000818:Animals; D001000:Ants; D001042:Aphids; D044822:Biodiversity; D002633:Chemotaxis; D003463:Cues; D020387:Food Chain; D060434:Herbivory; D007302:Insect Repellents; D010935:Plant Diseases; D011235:Predatory Behavior; D013112:Spiders / Q000737:chemistry; D026982:Urtica dioica
chemical_list: D007302:Insect Repellents
references: Proc Natl Acad Sci U S A. 1997 Sep 30;94(20):10735-8
references: 11038581
references: Oecologia. 1978 Jan;33(1):71-86
references: 28309267
references: Ecol Lett. 2010 Oct;13(10):1199-209
references: 20602626
references: Biol Lett. 2013 Feb 23;9(1):20120948
references: 23193048
references: Am Nat. 1998 Apr;151(4):327-42
references: 18811324
references: Oecologia. 2007 Jan;150(4):611-24
references: 17091284
references: Biol Lett. 2009 Dec 23;5(6):773-6
references: 19586964
references: Oecologia. 2000 Aug;124(2):156-165
references: 28308174
references: Am Nat. 2001 Mar;157(3):262-81
references: 18707289
references: Am Nat. 2000 Feb;155(2):141-153
references: 10686157
references: Science. 1980 Nov 28;210(4473):1041-3
references: 17797495
references: Proc Natl Acad Sci U S A. 2010 Aug 31;107(35):15503-7
references: 20713698
references: Science. 2012 Jun 15;336(6087):1434-8
references: 22700928
references: Anim Behav. 2001 Jan;61(1):43-51
references: 11170695
references: Ecology. 2007 Oct;88(10):2555-62
references: 18027758