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United States Department of Agriculture

Agricultural Research Service

Title: Natural Enemies of the Rangeland Weed Whitebrush (Aloysia Gratissima: Verbenaceae) in South America: Potential for Biological Control in the United States

Authors
item Cordo H A,
item Deloach Jr, Culver

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 3, 1994
Publication Date: N/A

Interpretive Summary: Whitebrush is a weed of rangelands of the Southwest, especially in central and southern Texas. Whitebrush is native in North America but very few insects or diseases attack it here. The site of origin of the genus is in the northern half of Argentina and Paraguay and southern Brazil where whitebrush and 10-20 other closely-related species are also native. In extensive surveys, we found 82 species of insects and four plant pathogens on these plant species in South America, in addition to the 36 species of insects previously reported by other researchers. Several of these are promising candidates for introduction into the United States as biological control agents of whitebrush, including two rust fungi, two stem-boring insects, a twig-girdling beetle, a scale insect, and the bark-feeding larva of a moth

Technical Abstract: Whitebrush, Aloysia gratissima (Gill. and Hook.) Troncoso (Verbenaceae), is a weed of rangelands in the southwestern United States. The genus Aloysia probably originated in southern South America, with the center of evolution in Argentina; A. gratissima is also native there. We traveled 81,550 km in Argentina, Paraguay, and Brazil over a six-year period searching for natural enemies that could be introduced into North America for biological control of A. gratissima and other weeds of rangelands. We found 82 species of insects and four plant pathogens on various species of Aloysia, in addition to the 36 species of insects previously reported from the plant genus. Promising candidates for further research for introduction included a new species of rust fungus, Prospodium tumefaciens Lindquist that produces stem galls, a probable new species of buprestid stem-boring beetle in the tribe Agrilini, a large crown-boring cerambycid beetle probably in the genus Calocosmus, a scale in the genus Cerococcus, an oecophorid moth Timocratica sp. that feeds on bark, and a twig girdling cerambycid near the genus Arenicia. Only the rust fungus was abundant enough in South America to cause significant damage, but the other species might cause greater damage in North America if their parasites were eliminated before release

Last Modified: 9/29/2014
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