Oecologia

, Volume 120, Issue 4, pp 632–640

Is the increased vigour of invasive weeds explained by a trade-off between growth and herbivore resistance?

  • Anthony J. Willis
  • Matthew B. Thomas
  • John H. Lawton
Article

DOI: 10.1007/s004420050899

Cite this article as:
Willis, A., Thomas, M. & Lawton, J. Oecologia (1999) 120: 632. doi:10.1007/s004420050899

Abstract

Blossey and Nötzold (1995) recently hypothesised that the increased vigour of certain invasive plant species has been at the expense of defences against natural enemies. A prediction of their evolution of increased competitive ability (EICA) hypothesis is that invasive genotypes are relatively poorly defended. We tested this prediction with herbivore bioassays and with direct quantification of plant secondary metabolites comparing non-indigenous genotypes of Lythrum salicaria L. (purple loosestrife) with indigenous forms. The herbivore bioassays revealed no significant intra-specific variation in herbivore resistance between indigenous and non-indigenous hosts. The phenolic content of L. salicaria leaves was significantly higher in indigenous genotypes, as predicted by the EICA hypothesis. The average phenolic content of leaves (regardless of their origin) was, however, low, implying that the role of plant phenolics in purple loosestrife anti-herbivore defence is probably limited. It is suggested that the EICA hypothesis, as tested in the current study, does not explain the increased vigour of L. salicaria in non-indigenous habitats.

Key wordsLythrumWeedHerbivore resistancePlant defenceTrade-off

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Anthony J. Willis
    • 1
  • Matthew B. Thomas
    • 1
  • John H. Lawton
    • 1
  1. 1.Leverhulme Unit for Population Biology and Biological Control, NERC Centre for Population Biology and CABI Bioscience, Imperial College at Silwood Park, Ascot, Berks, SL5 7PY, UKGB