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Title: ASSESSMENT OF RISK TO NATIVE FRANKENIA SHRUBS FROM AN ASIAN LEAF BEETLE, DIORHABDA ELONGATA DESERTICOLA (COLEOPTERA: CHRYSOMELIDAE), INTRODUCED FOR BIOLOGICAL CONTROL OF SALTCEDARS (TAMARIX SPP.) IN THE WESTERN UNITED STATES

Author
item Lewis, Phillip
item Deloach Jr, Culver
item Herr, John
item DUDLEY, TOM - UNIVERSITY CA - BERKELEY
item Carruthers, Raymond

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2002
Publication Date: 5/1/2003
Citation: Lewis, P.A., DeLoach, C.J., Herr, J.C., Dudley, T.L., Carruthers, R.I. Assessment of risk to native Frankenia shrubs from an Asian leaf beetle, Diorhabda elongata deserticola (Coleoptera: Chrysomelidae), introduced for biological control of saltcedars (Tamarix spp.) in the western United States. Biological Control. 2003. v. 27. p. 148-166.

Interpretive Summary: Saltcedar is an exotic tree that has invaded river systems throughout the southwestern U.S. and causes major damage to natural areas and decreases water supplies for recreation and agriculture. USDA-ARS researchers have been investigating the potential to release a small beetle in the U.S. that specifically attacks saltcedar. This insect was intensively tested in the laboratory and in outdoor cages to see if it would impact certain native shrubs, one of which is an endangered species. It was found that the beetle could grow on some of these plants if forced to feed on them. However, if given the choice, the adult beetles would select only saltcedar to feed and to reproduce. We anticipate that this insect will reproduce and cause significant damage to saltcedar trees, but will not cause any harm to native plants.

Technical Abstract: Exotic, invasive saltcedars, Tamarix ramosissima Ledebour, distributed throughout the west, and T. parviflora DC. in California, are causing great damage to natural riparian areas, to water supplies, and to agriculture. The biology and host range of a leaf beetle, Diorhabda elongata deserticola Chen, from central Asia, indicate that it is a safe and potentially effective biological control agent. We here report that species of the somewhat related native North American shrubs, Frankenia spp., appear to be at little risk from the introduction of D.e. deserticola. In laboratory, greenhouse and outdoor cages, both at Temple, TX and Albany, CA, 0 to 27% of larvae were able to complete their development (compared to 53-56% on Tamarix host species) on four North American species of Frankenia, depending on the species tested and the growing conditions of the plants. However, adults were not attracted to, did not feed upon, and only very rarely laid eggs on Frankenia spp. Forced closer contact with Frankenia in smaller cages, and even removing all Tamarix host plants, did not increase adult selection of Frankenia plants nor oviposition on them. Adults from a generation reared on Frankenia did not increase their selection for this plant. D.e. deserticola, therefore, appears sufficiently host-specific for field release in North America. This is the first biocontrol agent introduced into the U.S. for biological control of saltcedar.