W2185: Biological Control in Pest Management Systems of Plants
Statement of Issues and Justification
Biological control has proven to be one of the most effective, environmentally sound, and cost-effective pest management approaches used to control pests. It is anticipated that biological control will play an increasingly important role in integrated pest management (IPM) programs as broad-spectrum pesticide use continues to decline. Moreover, biological control is a cornerstone of organic farming, and the production of organic commodities in the United States continues to increase at roughly 20% per year (USDA-ERS 2002). Organic farming is no longer considered a cottage industry since retail sales hit $14.6 billion in 2006. Biological control is the "the action of parasites, predators, and pathogens in maintaining another organism's density at a lower level than would occur in the absence of the natural enemies" (DeBach 1964). Two types of biological control, natural biological control and applied biological control, are often distinguished. Natural biological control is that brought about by indigenous natural enemies in the native range of a pest species. In contrast, applied biological control is achieved through human efforts or intervention, and consists of three main approaches - - importation, augmentation, and conservation. In the importation approach (generally referred to as classical biological control), exotic natural enemies are imported and released in a new area where the target pest occurs, while augmentation and conservation involve supplementing (or manipulating) natural enemies already in place, or modifying the environment, respectively, to improve the effectiveness of biological control. For a given arthropod pest or weed, a pool of natural enemies often exists which consists of vertebrates, invertebrates, and microorganisms. The fundamental problem in applied biological control is to select an appropriate species or combination of species from this pool that will bring about the desired level of pest suppression with minimal impact on nontarget species. The mission of this regional project is to facilitate research and implementation activities among the participating institutions and organizations in applied biological control.The application is a renewal request for regional project W-1185 and involves biological control of both arthropod pests and weeds. Because biological control of arthropod pests and biological control of weeds are based upon many of the same ecological principles, researchers from the two fields benefit greatly from information exchange and research collaboration. Whereas the methodologies for controlling arthropod pests and weeds may differ, the scientific issues (e.g., introduction strategies, genetics of colonization, evaluation of natural enemy impact, etc.) overlap to a great extent. That some individuals involved in this project conduct research in both arthropod pest and weed systems is further evidence of the conceptual similarities between these two fields. In 2004, the USDA strengthened its commitment to pesticide reduction with its National Road Map to Integrated Pest Management (http:www.ipmcenters/IPMRoadMap.pdf). IPM programs based largely on biological control are of great benefit to agriculture, the quality of rural life, and the consumer. Reductions in insecticide, acaricide, and herbicide applications should allow farmers and ranchers to reduce production costs and make adjustments for a more sustainable agriculture. Reduced pesticide use will enhance the quality of rural life by decreasing ground and surface water contamination, reducing effects on nontarget species (including wildlife), and increasing safety of farm workers and other rural residents. These benefits also accrue at the interface of urban and agricultural environments, where there is increasing opposition to pesticide use by stakeholders. The reduction in pesticide residues in food is also desirable, although controversy remains over the extent and public health significance of such residues. Background Information and Justification: Despite many advances in recent years, our practical and conceptual understanding of success and failure in applied biological control fall short of meeting certain current and future requirements. For example, in classical biological control, the rate of establishment of natural enemies is relatively low in the case of arthropod pests (ca. 34%) (Kimberling 2004); further research into the genetics and ecology of colonization is clearly warranted. In the future, classical biological control should ideally be able to predict (1) the appropriate species (or biotype) or combination of species (and/or biotypes) to release for control of a target pest in a given situation; and (2) the environmental impact resulting from the introduction of an exotic enemy. Nontarget impacts to plants or insects from biocontrol agents are of great concern to conservation biologists, environmentalists, and federal agencies. Since 2000, regulations on natural enemy importation and introduction have increased and are enforced by USDA-APHIS using guidelines from the North American Plant Protection Organization (NAPPO). These guidelines require researchers to provide in-depth studies complete with rigorous data on the nontarget effects of biological control agents they wish to release (Mason et al. 2005). Currently, nontarget testing and regulations involved in releasing biological control agents are the subject of serious discussions by this workgroup at their annual meeting.
Where success has been achieved in classical biological control, the underlying ecological mechanisms are not always clear. After 100 years of effort, we still do not fully understand the mechanisms by which a successful natural enemy operates in nature, or why a particular organism is successful in one situation and unsuccessful in another. Basic research in augmentation and conservation of natural enemies is also needed. In augmentation, we urgently need a coherent theory of inundative/inoculative release as well as basic efficacy data in order to more readily incorporate commercially available predators and parasitoids of arthropod pests into IPM systems. The genetics of mass production must be evaluated experimentally so that quality control procedures can become a regular practice in the commercial production of natural enemies. Advances in the nutrition of parasitoids and predators are needed. Continued commitment to conservation of natural enemies is required, including innovative ways of integrating pesticides and cultural controls with key natural enemy species. Global warming has now been accepted as a serious threat to our natural and agroecosytems (Intergovernmental Panel on Climate Change 2007). It will be imperative that biological control scientists watch for the effects of climate change on arthropod pests that have been kept in check by natural enemies. Products of biotechnology designed for pest control must also be assessed and incorporated (where appropriate) into IPM programs. In the past five years, W-1185 scientists have examined interactions between transgenic crops and biological control species, and these studies will increase as more such crops are approved. Finally, biological control scientists are providing management professionals with the sustainable and effective tools with which to manage the relentless pressure of invasive species on natural and agricultural ecosystems.
Regional Character of Project: Exotic pests continue to arrive in the western U.S., and many of these will become permanently established. For such pests, the use of classical biological control should remain a high priority. At the same time, our IPM programs must be continuously evaluated, refined, and adjusted in response to changes in newer and more specific control technologies and production practices. The most effective way to address these new pests that become quickly established and spread to other states is through regional collaboration of state and federal scientists. Experiment Stations and non-Land Grant institution members to this project accrue timely and relevant benefits to participation. Regionality is essential to implementing biological control-based solutions to our pest problems for the following reasons: 1) numerous target pests occur in three or more western states or territories; for these pests, the research effort must be coordinated and duplication minimized to effectively utilize very limited resources; 2) regional importation/quarantine facilities are critical for a coordinated response to exotic arthropod pests and weeds. These facilities are finite, there are no plans to expand them in the foreseeable future, and they serve the needs of all states and territories in the region; and 3) interstate exchange of information and exotic species/biotypes is facilitated through a regional approach. Sharing the cost of foreign exploration and quarantine is essential, as is sharing of methodological advances and our knowledge base. Without a regional project in biological control, the Western states and territories will not be able to rapidly share current information on controlling new and existing pest species, many of which have ranges over multiple states. Additionally, this group discusses emerging pest threats and forms collaborations and networks that anticipate and plan for pest arrival. Besides state to state (Experiment Station) collaborations, active participants include scientists from USDA-ARS, USDA-APHIS, USFS, and state departments of agriculture, all of which benefit from rapid information transfer and shared projects.
Transcending the coordination and cooperation on a given pest is an important shared need for advances in regulatory policy, general methodologies for release and evaluation of natural enemies, and the need to develop sound ecological theory concerning pest population dynamics, predator-prey interactions, and the genetics of colonization in biological control. For example, theoretical and experimental studies of the actual ecological mechanisms that underpin pest population regulation are being addressed in several states and among pest systems. Our members and Federal Advisors, serve on key committees that are steering efforts to minimize nontarget effects through policy management, and a website developed in 2004 for this project, serves to maintain real-time communication and continuity in this group of scientists that include members outside the western region.
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