DETERRENCE OF HERBIVORY BY ZINC HYPERACCUMULATION IN THLASPI-CAERULESCENS (BRASSICACEAE)

Plants known as hyperaccumulators take up and sequester high concentra tions of potentially toxic elements from metalliferous soils. We teste d the hypothesis that zinc hyperaccumulation benefits plants by deterr ing herbivory. In laboratory feeding trials, three species of herbivor es were allowed to choose between Thlaspi caerulescens (Brassicaceae) plants grown in low-Zn and Zn-amended culture solution. Locusts (Schis tocerca gregaria), slugs (Deroceras; cavuanae), and caterpillars (Pier is brassicae) all showed significant preferences for plants with lower foliar Zn concentrations. Such differential feeding could result in s election pressures favouring the evolution of hyperaccumuIation. The f indings are also relevant to current proposals to exploit hyperaccumul ation as a means of remediating metal-contaminated soils.