Oecologia

, Volume 165, Issue 4, pp 983–993

Defensive effects of extrafloral nectaries in quaking aspen differ with scale

Plant-Animal interactions - Original Paper

DOI: 10.1007/s00442-010-1799-6

Cite this article as:
Mortensen, B., Wagner, D. & Doak, P. Oecologia (2011) 165: 983. doi:10.1007/s00442-010-1799-6

Abstract

The effects of plant defenses on herbivory can differ among spatial scales. This may be particularly common with indirect defenses, such as extrafloral nectaries (EFNs), that attract predatory arthropods and are dependent on predator distribution, abundance, and behavior. We tested the defensive effects of EFNs in quaking aspen (Populus tremuloides Michx.) against damage by a specialist herbivore, the aspen leaf miner (Phyllocnistis populiella Cham.), at the scale of individual leaves and entire ramets (i.e., stems). Experiments excluding crawling arthropods revealed that the effects of aspen EFNs differed at the leaf and ramet scales. Crawling predators caused similar reductions in the percent leaf area mined on individual leaves with and without EFNs. However, the extent to which crawling predators increased leaf miner mortality and, consequently, reduced mining damage increased with EFN expression at the ramet scale. Thus, aspen EFNs provided a diffuse defense, reducing damage to leaves across a ramet regardless of leaf-scale EFN expression. We detected lower leaf miner damage and survival unassociated with crawling predators on EFN-bearing leaves, suggesting that direct defenses (e.g., chemical defenses) were stronger on leaves with than without EFNs. Greater direct defenses on EFN-bearing leaves may reduce the probability of losing these leaves and thus weakening ramet-scale EFN defense. Aspen growth was not related to EFN expression or the presence of crawling predators over the course of a single season. Different effects of aspen EFNs at the leaf and ramet scales suggest that future studies may benefit from examining indirect defenses simultaneously at multiple scales.

Keywords

Plant–animal interactionsTritrophicBiotic defenseScalingDefense hypothesis

Supplementary material

442_2010_1799_MOESM1_ESM.pdf (134 kb)
Supplementary material 1 (PDF 133 kb)
442_2010_1799_MOESM2_ESM.pdf (268 kb)
Supplementary material 2 (PDF 267 kb)

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of Biology and Wildlife, Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksUSA
  2. 2.Department of Ecology, Evolution, and Organismal BiologyIowa State UniversityAmesUSA