Multitrophic Assessment of Copper Contamination Using Watercress (<Emphasis Type="Italic">Nasturtium officinale</Emphasis>) and the Mustard Beetle (<Emphasis Type="Italic">Phaedon viridis</Emphasis><Emphasis Type="Bold">)</Emphasis>

Copper is an active component of some commercial algaecides and is commonly found in low concentrations in contaminated aquatic systems. Unintended consequences of algaecide application include macrophyte bioaccumulation and possible trophic level bioamplification especially by specialist herbivores. Trophic level effects of copper contamination were observed through feeding trials using the mustard beetle (Phaedon viridis). Several metals, including copper, interfere with the myrosinase enzyme system responsible for the watercress (Nasturtium officinale) allelopathic defense against herbivory. The mustard beetle is a specialist herbivore that has evolved a detection system that is stimulated by the products of the glucosinolate-myrosinase system. Because copper interferes with myrosinase enzymes, mustard beetles were expected to avoid copper-contaminated plants. While larvae exhibited a slight preference for contaminated plants, adult mustard beetles in this experiment exhibited a statistically significant preference for plants uncontaminated with copper.