Monday, December 10, 2007 - 9:17 AM

Pollutant uptake by the invasive weed saltcedar, and effects on biological control

Mary A. Sorensen,, University of California, Riverside, Department of Entomology, Riverside, CA and John T. Trumble,, University of California - Riverside, Department of Entomology, Riverside, CA.

The invasive weed saltcedar (Tamarisk ramosissima) has replaced native riparian vegetation in many watersheds in California and throughout the United States. Saltcedar occurs in many areas contaminated by anthropogenic pollutants known to be harmful to insects, yet saltcedar pollutant uptake and its effect on saltcedar biological control have not been investigated. Using greenhouse studies, we examined saltcedar uptake of five contaminants (perchlorate, selenium, hexavalent chromium, manganese, and nickel) and examined the effect of each pollutant on growth and survival of the saltcedar biological control agent Diorhabda elongata. Saltcedar foliage accumulates perchlorate and selenium to high levels, and chromium is phytotoxic to saltcedar at a concentration of 10 mg/L or greater in the growing water. Diorhabda elongata larval growth was unaffected by perchlorate, but was significantly inhibited by selenium. To our knowledge, this is the first report of an anthropogenic pollutant reducing the effectiveness of an agent imported for biological control.

Species 1: Coleoptera Chrysomelidae Diorhabda elongata