Beginning success of biological control of saltcedars (Tamarix spp.) in the southwestern USA

摘要

Saltcedars, Tamarix spp., exotic, invading deciduous shrubs or small trees from Asia and the Mediterranean area, have become the most damaging weeds of riparian areas in the western USA. We and our cooperators have obtained highly successful initial control of saltcedar by introducing the north Asian leaf beetle (Diorhabda sp., China/Kazakhstan ecotype) at five sites north of the 38th parallel, but they failed to establish farther south. In 2001, we discovered southern-adapted Diorhabda beetles on saltcedar and began testing them. In 2004, we released 2408 Greek beetles at Big Spring, TX; by September 2004, they had defoliated two trees, by 2005, 210 trees (0.8 ha) and by 2006, 7.3 ha of the saltcedar stand and 1.4 ha at Cache Creek, California, andhad begun defoliating saltcedar at Pecos and Imperial, TX. The Uzbek beetles are increasing rapidly at Lake Meredith, TX and Fukang, China beetles at Artesia, NM, but the Greek and Tunisian beetles have not established near Kingsville in south Texas. Wehave revised the taxonomy of the five Tamarix-feeding Diorhabda ecotype/sibling species and predicted their climatic affinities in North America, correlated depletion of stored carbohydrates by beetle defoliation with plant death, developed pheromone attractants, remote sensing, improved release methods and a model of beetle dispersal and estimated possible damage to beneficial T. aphylla (Linnaeus) Karsten (athel) in the open field.