Evidence of induced plant defences in a pondweed

SUMMARY. 1. Palatability changes, induced by herbivore damage, have received much attention in terrestrial plant-insect research but negligible investigation in freshwater systems.
2. Potamogeton coloratus (Potamogetonaceae) and the folivorous caddis larva Triaenodes bicolor (Insecta: Trichoptera) were used to duplicate bioassay techniques common in terrestrial plant-insect research.
3. Leaves of P. coloratus were artificially damaged. Grazing on damaged leaves, and undamaged leaves from damaged plants, was compared to that on control leaves from undamaged plants up to 10 days after initial damage.
4. The palatability of damaged and undamaged leaves from damaged plants declined compared to control leaves. The differences were significant at 5 days after damage, but had recovered to approximately equal palatability after 10 days.