Induced defenses in herbivores and plants differentially modulate a trophic cascade

TY - JOUR

T1 - Induced defenses in herbivores and plants differentially modulate a trophic cascade

AU - van der Stap, I.

AU - Vos, M.

AU - Verschoor, A.M.

AU - Helmsing, N.R.

AU - Mooij, W.M.

N1 - Reporting year: 2007 Metis note: 4073;CEME ; CL; ES ; AFW ; PGID; file:///C:/pdfs/Pdfs2007/VanderStap_ea_4073.pdf

PY - 2007

Y1 - 2007

N2 - Inducible defenses are dynamic traits that modulate the strength of both plant–herbivore and herbivore–carnivore interactions. Surprisingly few studies have considered the relative contributions of induced plant and herbivore defenses to the overall balance of bottom-up and top-down control. Here we compare trophic cascade strengths using replicated two-level and three-level plankton communities in which we systematically varied the presence or absence of induced defenses at the plant and/or herbivore levels. Our results show that a trophic cascade, i.e., significantly higher plant biomass in three-level than in two-level food chains, occurred whenever herbivores were undefended against carnivores. Trophic cascades did not occur when herbivores exhibited an induced defense. This pattern was obtained irrespective of the presence or absence of induced defenses at the plant level. We thus found that herbivore defenses, not plant defenses, had an overriding effect on cascade strength. We discuss these results in relation to variation in cascade strengths in natural communities.

AB - Inducible defenses are dynamic traits that modulate the strength of both plant–herbivore and herbivore–carnivore interactions. Surprisingly few studies have considered the relative contributions of induced plant and herbivore defenses to the overall balance of bottom-up and top-down control. Here we compare trophic cascade strengths using replicated two-level and three-level plankton communities in which we systematically varied the presence or absence of induced defenses at the plant and/or herbivore levels. Our results show that a trophic cascade, i.e., significantly higher plant biomass in three-level than in two-level food chains, occurred whenever herbivores were undefended against carnivores. Trophic cascades did not occur when herbivores exhibited an induced defense. This pattern was obtained irrespective of the presence or absence of induced defenses at the plant level. We thus found that herbivore defenses, not plant defenses, had an overriding effect on cascade strength. We discuss these results in relation to variation in cascade strengths in natural communities.

U2 - 10.1890/07-1731.1

DO - 10.1890/07-1731.1

M3 - Article

SN - 0012-9658

VL - 88

SP - 2474

EP - 2481

JO - Ecology

JF - Ecology

IS - 10

ER -