Herbivory on a chemically defended plant as a predation deterrent in Hyalella aztecaJournal Article
Overview
abstract
SUMMARY 1. We investigated whether a population of the freshwater amphipod, Hyalella azteca, which consumed plants with defensive secondary compounds, reduced predation as reported for terrestrial and marine systems.2. Field observations in Montezuma Well, U.S.A., indicated a strong association between the emergent macrophyte, Berula erecta and H. azteca. We hypothesised that this geographically isolated population of sedentary amphipods was able to consume roots of the chemically defended B. erecta as a deterrent against predation. Berula erecta is in the family Apiaceae, which commonly produce coumarins that deter herbivory in terrestrial systems.3. Hyalella azteca consumed roots of B. erecta at a significantly greater rate than alternative macrophyte substrata in Montezuma Well. Additionally, H. azteca moulted at a significantly higher rate when consuming B. erecta compared with a diet of periphyton.4. Two insect predators (Telebasis salva and Belostoma bakeri) with different feeding strategies were used to assess the effects of a B. erecta diet on predation rates in the laboratory and in Montezuma Well. Hyalella azteca was preyed on at a significantly lower rate by both predators when given a strict diet of B. erecta roots compared with a diet of periphyton.5. This is the first experimental evidence that predation on a freshwater herbivore, H. azteca, was reduced when it consumed a chemically defended plant.
