A recent study (Pimentel 2000) estimated the annual cost of damage caused by exotic species and their control in the US to be over $130 Billion/ year. Of the 4552 exotic organisms now estimated to be free-living in the United States (Office of Technology Assessment 1993), exotic and invasive plants are the largest group of invaders. Many of the 2000+ plants have become weeds infesting many different types of managed and non-managed areas including agricultural fields, natural lands, urban areas and wetlands/ waterways. As discussed in a number of recent summary publications (Coppock and Kreith 1999, Office of Technology Assessment 1993, Stolzenburg 1999, USDA-FS 1998, USDI-NPS 1996, USDI-BLM 1996) including the recent Presidential Executive Order on Invasive Species (#13112, Feb. 1999), invasive exotic plant species and other noxious weeds pose a huge and ever increasing threat to agriculture, native ecosystems and other communities throughout all of North America and the world (see Science Vol. 285: 1834, 1999). Although the total area affected and the actual economic costs are not well documented, the Bureau of Land Management estimates that over 4,600 new acres are lost to the spread of invasive weeds each day on all western public lands (USDI-BLM 1996). Clearly large-scale action is needed to arrest this spread and the negative impacts associated with exotic plant invasions. This proposal addresses the management of three specific pest plants and provides an example multi-agency effort that may be used as a model system of cooperative action for other such programs that are to be conducted in the future.

The overarching goal of this proposed effort is the development and implementation of an ecologically sound and sustainable approach to the long-term management of destructive invasive plant species. We believe that biologically-based technologies, particularly classical biological controls, offer many advantages over the use of other more costly and often disruptive methods of weed control (e.g. wide-spread herbicide application, physical removal, etc.). We are readily aware, however, that biological control is also not without risk and that the use of any exotic organisms must be developed, evaluated and used in a wise and effective manner. Therefore, biological control must be planned and implemented in a way so that it is integrated with other methods of weed management and habitat restoration practices such as revegetation of desirable species. Such an effort must be developed in a comprehensive manner and based on adequate biological, social and economic understanding of the system in question, and with the long-term ecosystem management goals associated with all involved groups.

Several years prior to this Request For Proposals (RFP), a highly diverse team of scientists, land managers, economists and others, organized the Saltcedar Consortium with the primary goal of implementing and evaluating biological control technologies for Tamarix spp. in the western US. Through a series of meetings and focused workshops, several different needs were identified for the general area of sustainable weed control that ranged from improved regulatory assessment to new implementation technology for groups responsible for controlling noxious weeds at the local level. Dispite some controversy over non-target safety effects (Simberloff and Stiling 1996, Johnson and Stiling 1998, Louda et al. 1998), biological control was felt to be the primary desired control strategy (DeLoach et al. 2000, Dudley et al. 2000), not just for saltcedar management, but for many other major invasive species problems in the western US (see Delfosse 2000). Based on the combined expertise in the Saltcedar Consortium, the group strongly believes that biological control is the only technology that has realistic ecological and economic potential to control well established invasive species (like saltcedar). All other methods of invasive plant control are either highly destructive to non-target species or are cost prohibitive to use over wide-areas. For that reason, the Consortium has worked together with USDA-APHIS and USDI-Fish and Wildlife Service (FWS) to acquire all necessary permits to move forward with saltcedar biological control. This has occurred despite some controversy associated with the threatened and endangered subspecies of the Southwestern Willow Flycatcher (swWIFL), a bird that is now nesting in saltcedar in some areas of Arizona and New Mexico. Since saltcedar and other invasive species negatively affect many other species, including dozens of threatened and endangered species, biological control was approved to proceed. This proposal focuses on the safety, use, and evaluation of biological control technologies as the central and unifying methodology to address the management of the three key invasive plant species (including saltcedar), that are discussed in detail throughout the remainder of this proposal.

As a technology, biological control of weeds has an excellent success and safety record. An estimated 30% of the >725 releases of biological control agents made world-wide have achieved a level of "success" in controlling target species with relative low project costs, high sustainability of control, and few unintended impacts (Julien and Griffiths 1999, McFadyen 1998). This has resulted in a enviable short-range benefit: cost ratio estimated at over 100:1 with even higher benefits if evaluated long-term (Coulson et al. 2000). Although some would say that inadequate monitoring has been conducted to detect non-target problems (Howarth 1983, Lockwood 1986), only eight documented examples of damage to non-target plants are recorded worldwide (Julien and Griffiths 1999). In almost all of these examples, feeding was mostly incidental and was predicted prior to release by host-specificity testing. Thus the science supporting biological control did not fail, just the decision was made to release those agents despite known test results (e.g. the well-known case of Rhinocyllus conicus on thistles (Louda et al. 1998)).

Current testing methods are rigorous, with several levels of regulatory evaluation made before an agent is approved for general field release. Although oversight is provided by USDA-APHIS with the assistance of an inter-agency Technical Advisory Group (TAG), some feel that inadequate discussion and evaluation is conducted prior to the final decisions being approved. Others feel that the regulatory burden is becoming so high that biological control may no longer be a viable technology if the regulatory requirements increase further. Neither perspective is without justification and an improved risk/ benefit assessment system needs to be developed and evaluated to resolve potential conflicts (Carruthers and Petroff 1997, Delfosse 1997). This proposal has been developed to enhance the research base, monitoring and biological assessment capabilities of the groups involved in the field evaluation of saltcedar biological control efforts and two similar exotic weed control programs. It will also provide supporting information to a interdisciplinary team that will be working to improve risk/ benefit and economic assessments for biological control regulatory activities. In that regard, the project has listed a balanced team of ecologists, biological control specialists, economists and risk assessors (see Key Personnel) to oversee a series of meetings and workshops aimed at improving the decision making methods and processes that are used to approve or reject natural enemy release decisions. This is being done to better characterize both the specific risks associated with the proposed biological control programs for the target plants under investigation in this proposal, and to help define more comprehensive benefit/ risk assessment methods for all future biological control of weeds programs.