NATIONAL NEEDS AND PRIORITIES IN NEMATOLOGY
Nematodes are small roundworms that thrive in virtually all environments throughout the world (Fig.1). They are one of the largest and most diverse groups of multicellular organisms. Many species are economically important parasites of all agronomic crops, but other species beneficial to agriculture and the environment make up a large portion of the nematode community (Fig. 2). Scientists study nematodes because of the disease and injury that hundreds of species cause on plants and animals as well as the beneficial role of others. Nematodes that parasitize plants are a significant constraint to crop production, causing an estimated $8 billion annual loss (12%) to U. S. growers and nearly $78 billion loss globally (Fig. 3). For example, the soybean cyst nematode is the most economically damaging disease for soybean with annual losses in the North Central Region of the U.S. amounting to $267 million (Fig. 4). These economic losses in crop plants caused by nematodes undoubtedly would be many times greater if we did not use available strategies and tactics to manage nematode populations and thereby limit the losses.
The Society of Nematologists recently completed a 2-year, in-depth, assessment of the national needs and priorities in nematology research, education, and extension. A document entitled Plant and Soil Nematodes: Societal Impact and Focus for the Future, based on this study, outlines the benefits of nematology research and education and the challenges and opportunities facing this small but important discipline in the next decade. The document identifies three nematology research priorities for the future sustainability of agriculture and the biosphere. The three research priorities identified in the report to help achieve the goal of nematode management in sustainable agriculture systems are: 1) lessening the societal impact of plant parasitic nematodes (Fig.5, 2) advancing our knowledge of fundamental nematode biology (Fig. 6), and 3) promoting the use of beneficial nematodes (Fig. 7).
These three priorities were developed to address a major crisis in nematology. As the needs and demands for nematology research, extension, and education are increasing, the support for these activities is rapidly decreasing. This has created a knowledge gap between what society expects from scientists studying nematodes and the diseases they cause and what the scientists can actually deliver under the current conditions of support. Modern agriculture faces major challenges as the world's demands for food and fiber increase amidst calls for stricter measures to protect and preserve our environment and natural resources. Future development of sustainable management systems for preventing the major economical agricultural losses to nematodes must focus on strategies that limit production costs, enhance crop yields, and protect the environment. Basic information is essential for developing new management alternatives, expanding the availability of resistant crops, developing biological control tactics, enhancing the role of beneficial nematodes in soil/plant nutrient cycling, exploiting the potential biological control of plant insects with nematodes, and designing effective cropping systems to lessen the limitations placed on production of food and fiber crops by plant parasitic nematodes.
Management of plant and soil nematodes has acquired new urgency in recent years. No new nematicide has been developed since 1974 and over half of the nine principal nematicides have been removed from the market or are under review (Fig.8). Heavy reliance on pesticides to control nematodes now must be reduced by the use of economically and environmentally friendly management strategies. The transition from chemical control to alternative methods of management will require the development of an extensive knowledge base on nematode biology, ecology, and host-parasite interactions. The overall goal of nematology research, education, and outreach programs is to contribute to environmental quality and sustainable and affordable sources of high-quality food and fiber. Developing essential information about parasitic nematodes and strategies for managing them has been important in advancing agricultural production for many years. Most of the success occurred after 1943, when the discovery that inexpensive by-products of the petroleum industry could kill nematodes in the soil and greatly increase crop yields. From that beginning, scientists discovered and developed new ways to lessen the economic impact of nematodes on food and fiber production to improve the productivity of agriculture systems. The importance of nematology research can be illustrated by its impact on the production of soybeans in the United States. As with many other crops, parasitic nematodes pose a major threat to soybean production. But a $1 million investment in research to develop a single nematode-resistant variety resulted in $400 million in increased soybean profits to farmers over a six-year period (Fig. 9). Development of resistant varieties has proven to be the most const-effective and sustainable method for reducing nematode damage to food and fiber crops. However, the number of plants that are resistant to nematodes is small and limited to a few nematode species.
Today, exciting new developments are taking place in biology that could
be exploited to lessen the economic impact of plant-parasitic nematodes
in agriculture. The tools of biotechnology now provide the means to determine
the molecular basis of complex interactions between nematodes and their
hosts and apply this knowledge to develop novel resistant crops for limiting
nematode damage (Fig. 10).
Increased investments, both personnel and research support, at this time
could lead to major new discoveries, allowing specific intervention into
the parasites' life cycles, development of new diagnostic tools, creation
of superior nematode-resistant crops, and exploitation of natural enemies
for biological control of these pests. Thus, with the removal of outdated
technology and the opportunities offered through modern research, increased
funding for research, education, and information-transfer programs is urgently
needed for agricultural nematology. For copies of the full report Plant
& Soil Nematodes: Societal Impact and Focus for the Future contact
Richard Hussey, Department of Plant Pathology, University of Georgia, Athens,
GA USA 30602-7274.