Invasions of tropical and subtropical aquatic plants threaten biodiversity and cause ecological and economic impacts worldwide.
An urgent question is whether native herbivores are able to inhibit the spread of these alien species thus providing biotic resistance.
The potential for biotic resistance to these plants depends on plant traits that affect palatability to herbivores, i.e., plant nutritional
quality and the presence of secondary metabolites related to anti-herbivory defenses. Studies across latitudinal gradients suggest
that aquatic plants from lower latitudes may be less nutritious and better defended than high latitude plants. Therefore, we
hypothesized that native herbivores prefer temperate plants over plants from tropical and subtropical regions which would limit the
strength of biotic resistance that native temperate herbivores can provide against alien tropical and subtropical plants. Drawing
upon the published literature we (1) investigated whether native temperate herbivores reduce the establishment or performance of
tropical and subtropical alien plants in the field, and (2) analyzed herbivore consumption of tropical and subtropical versus
temperate plants in laboratory feeding trials. In our literature survey, we found only three field studies which, in contrast to our
hypothesis, all demonstrated that the native herbivores (beavers, coots or generalist insect herbivores) significantly reduced the
success of invading tropical and subtropical plant species. The analysis of the feeding trials yielded mixed results. Ten out of twelve
feeding trials showed that (sub)tropical and temperate plants were consumed in equal amounts by both temperate and tropical
generalist ectothermic herbivores. The remaining trials showed higher consumption rate of both temperate and tropical plants by
tropical snails. Although a body of evidence suggests that tropical plants are nutritionally poor and better defended (i.e., less
palatable) compared to temperate plants, we conclude that in the majority of cases, herbivores would eat tropical plants as much as
temperate plants. Thus, in agreement with the available field studies, evidence suggests that there is potential for biotic resistance
from native generalist herbivores to tropical invasive plants in non-tropical areas.
Original languageEnglish
Pages (from-to)343-353
JournalAquatic Invasions
Issue number3
StatePublished - 2017

    Research areas

  • international

ID: 5332420