S1034: Biological Control of Arthropod Pests and Weeds
Statement of Issues and Justification
Statement of Problem:The growing emphasis on environmental and food safety issues has intensified interest in the development of biological controls as a means for controlling pests. The effective use of natural enemies in biological control programs is contingent upon understanding their ecology and that of their targets, their interaction with production practices, and the most effective means of using them. Further exotic pests continue to pose threats to American agriculture and well being, making continued efforts in importation biological control relevant and necessary. At the same time, target and non-target effects of these introductions must be documented to assure the continued value and safety of importation biological control. Resident populations of natural enemies do not always provide adequate levels of pest suppression. In such circumstances, it may be necessary to release native or introduced natural enemies. Success of this option, however, is dependent on effective production, distribution, and release technologies for the natural enemies to be so used (Ridgway, 1998). This proposal addressed each of the aspects of biological control noted above and places them in the overall context of the Southern Region.
Justification:
A component of the Southern Region Strategic Plan is to: Discover and develop effective pathogens, parasites, predators, and other biologically based techniques such as host plant resistance, naturally derived pesticides, and male sterility techniques to mitigate or manage pest populations (SAAESD 2000, NAS 1996). Furthermore, the Plan recognizes the need to: Create biocontrol techniques and integrate them with crop protection chemicals. The Experiment Station Directors ranked biologically based pest management technologies as the second most critical need for Agriculture in the Southern Region, underscoring the importance of work in this discipline. The mild climate of the southern U.S. supports a great diversity of pest arthropods and plants. Moreover, a moderate climate coupled with extensive international exchange in the Region creates ideal circumstances for the incursion and persistence of injurious invasive species.
The need for environmentally and economically sustainable production systems is growing as social pressure for safe food and fiber increases. In 1993, the Clinton Administration announced its goal of having integrated pest management (IPM) practiced on at least 75% of the production acreage in the U.S. by 2000. Biological control constitutes a cornerstone of IPM, and its use must be broadened and fine-tuned to effectively achieve widespread IPM implementation (Lynch et al. 1996). In addition, the passage of the Food Quality Protection Act in 1996 is requiring progressively more detailed review of existing pesticides, and will reduce the variety of pesticides available for use. Simultaneously, the more target specific pesticides now being developed are costlier than their broad-spectrum predecessors and will add economic burdens to growers as they will have to use combinations of more expensive insecticides to achieve results comparable to those formerly attained with conventional broad-spectrum materials. Therefore, the need for developing biological control programs for pests in a wide variety of situations is more acute than ever.
The Southern Region has a strong record of research and implementation in biological control. The four predecessors of this proposed Multistate Research Project tackled a variety of these problems and successfully effected various target pest populations in this region. The proposed project will build on this history and continue the work as well integrating it with novel and expanding technologies relative to crop production and environmental protection. Coordinated regional efforts will be fundamental to the success of this work, because many of the issues, which will be, addressed span large geographic areas and the extent of biological control efficacy may likewise vary across the region. Both formal and informal collaboration is inherent among the project participants, many of whom have worked together in previous regional projects for most of their careers. Examples of their collaboration include joint research projects and publications, grant and project reviews, information and equipment exchanges, extension and other kinds of training activities, and symposia at scientific societies.
Pest management research in the Southern Region has a strong historical emphasis on biological control, and this is reflected in the associated expertise and excellent facilities. This emphasis continues today and is reflected in the number of active projects addressing biological control of arthropods and/or plants. Further participation in the project will be encouraged and likely achieved through direct contact with participants. Thus, there is considerable work on biological control under way in the Southern Region that underscores the continuing need for regional cooperation and coordination. The proposed project would provide an effective mechanism for continuing and expanding such integration efforts as has previously been established. It could also provide a means for surveying and communication the extensive range of ongoing research and extension activities.
Invasive species can be exceptionally destructive in the Southern Region. Many high profile invasions have occurred with severe economic and ecological effects. Included in this lengthy list are the red imported fire ant, Solenopsis invicta; the B and Q biotypes of the sweet potato whitefly, Bemisia tabaci; the tropical soda apple, Solanum viarum; hydrilla, Hydrilla verticillata; and the Formosan termite, Coptotermes formosanus. In addition, the threat of new invasions in this region is persistent.
The full extent of damage by many of the invasive species is difficult to document (Pimentel et al. 2000). For example, the red imported fire ant invades many habitats, disturbing wildlife and native ants, damaging crops, disrupting extant biological control, and inflicting physical harm to humans and animals. The complete ecological and environmental costs of this ants damage have yet to be fully ascertained, but it is widely acknowledged that they are substantial, with estimates in excess of US $1 billion dollars per annum (Pimentel et al. 2000). Similarly, tropical soda apple is currently found in Mississippi, Alabama, Georgia, South Carolina, Tennessee, and extensively in Florida (NAPIS 2000). This spined plant is highly disruptive in grazing areas and is spreading across the southeastern U.S. Although its spread has been slowed by herbicide based eradication efforts, this work is dependent on the ability of individuals across the region and beyond to find and correctly identify the plants. Because tropical soda apple can also grow in uncultivated and isolated areas, there is reason to suspect that the plant is more widespread than is presently acknowledged. Such a situation with dispersed targets with risk of being undetected, is well suited to the use of biological control agents that have the capacity to locate plants independent of human intervention.
Non-invasive native pests also cause extensive damage in crops and other habitats. Management of these pests by natural enemies can provide benefits ranging well beyond the locations of immediate human concern, as well as providing more proximate assistance for pest managers. This can be particularly important for highly mobile and polyphagous species such as the tarnished plant bug, Lygus lineolaris, or the beet armyworm, Spodoptera exigua. Further chemical or other treatment of infestations of natural areas by pests may not be economically or environmentally feasible. In these circumstances, biological control may be the only possible means of control.
The advent of new technology, most notably transgenic insect resistant crops and increasingly selective herbicides, has created numerous opportunities to more adequately integrate biological control into crop production systems. It has also enhanced the need for biological control, as new pests have emerged. For example, although the widespread use of Bt-transgenic cotton varieties has contributed to reduced insecticide inputs, it has also increased the problems with heteropteran pests (e.g., stink bugs, plant bugs, leaf-footed bugs) in the southeastern U.S. as insecticide spraying for lepidopteran pests has declined (Williams 1998). Thus, cotton producers are by necessity increasing their spray regimens to handle this new and difficult suite of pests. In addition, currently available selective insecticides are more costly and growers cannot always afford to target each individual or closely related species when the pest complex is diverse. Development of biological control in low or targeted spray environments would be an invaluable component of IPM in these systems and would strengthen the sustainability and adoption of environmentally sound tools.
The proposed project will evaluate the effects of established natural enemies on non-target organisms and will enable the development of a significant database to support meaningful risk assessment protocols for future biological control programs. It is anticipated that natural enemies will be discovered and targeted for control of melaleuca, Brazilian peppertree, kudzu, tropical soda apple, water hyacinth, Chinese tallow, Chinese privet, tarnished plant bug, brown citrus aphid, bromeliad weevil, red imported fire ant, muscoid flies, mole crickets, and weevils. Understanding the interactions between pest management technology, conventional and novel, and natural enemies will lead to a more effective integration of biological control in pest management systems. Assessing lethal and sublethal effects of pesticides at the individual and population levels will permit effective integrated use of pesticides and biological control. In addition, quantifying the effect of indigenous natural enemies will permit the development of biologically based IPM programs for crop/animal systems.
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