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

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.

Combined effects of two arthropod herbivores and water stress on growth of Hypericum species.

The interaction between physiological stress and arthropod herbivory was studied using two perennial species of Hypericum. Seedlings of H. perforatum, a herb introduced to Australia and weedy in places, and H.