Effect of Nutrient Quality and Leaf Age of Water Hyacinth,Eichhornia crassipes, on the Development of Its Co-Evolved Herbivore,Eccritotarsus catarinensis(Hemiptera: Miridae)

Abstract

Specialist herbivores have evolved adaptations to overcome plant defensive chemicals and thus prefer younger leaves with their higher nutritional value, whereas generalist herbivores are unable to overcome these chemical defences, and opt for older leaves which have fewer nutrients, but are less defended (Center & Wright 1990). Plants such as the invasive aquatic weed Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae) (water hyacinth) continuously produce young, unfurling leaves that require high concentrations of digestibility-reducing chemicals in their tissues to ensure protection against herbivory (Center & Wright 1990). These defensive chemicals are products of secondary metabolism (Berenbaum 1995) and ensure that young leaves are typically unpalatable to herbivores and resistant to disease (Center & Wright 1990).