Yet another weapon has been added to the U.S. biological control arsenal: Yahoo! News is reporting that New Mexico has joined other western states in releasing Tamarisk leaf beetles (Diorhabda elongata) to manage burgeoning populations of salt cedar (Tamarix spp.). Salt cedar is an invasive tree that causes problems in the already drought-prone western U.S. with its thirsty, water-seeking root system. Right now, this biocontrol is still in the testing phase - scientists are hoping the beetles survive the cool New Mexico winters and can multiply in the spring. There is also some concern that if the beetles have a negative effect on salt cedar, this will in turn have a negative impact on the endangered Southwestern willow flycatcher (Empidonax trailii extimus), a bird which has taken to nesting in the salt cedar that has replaced the native vegetation of its habitat.
Thanks to Jeremy at BioHabit.org for emailing the link to this report.
Update:There was a conference in Colorado on October 22 where the USDA announced a widespread project to release the leaf beetles in 13 different states next spring. You can read a brief story about it at news4colorado.com (Thanks Alex).