The Role of Biological Control in Sustainable Agriculture

Sustainable agriculture encompasses many goals, but literally all it means is to "keep in existence; keep up; maintain or prolong." Sustainable agriculture evolved from a number of reform movements in the U.S., Canada, and Western Europe. The movement stemmed from concerns about the impacts of agriculture on nonrenewable resource depletion, soil erosion and loss of soil quality, health, food quality and safety, off-site environmental effects of agricultural chemicals, declining rural communities, decreasing farm numbers and loss of traditional agrarian values. The concerns are centered around agriculture production moving towards "industrial agriculture." With this wide set of agenda items, it is no wonder that sustainable agriculture does not have a universally accepted definition. The term sustainable agriculture means something different to almost everyone. One definition (from the Leopold Center for Sustainable Agriculture, at Iowa State University) is "the appropriate use of crop and livestock systems and agricultural inputs supporting those activities which maintain economic and social viability while preserving the high productivity and quality of [the] land". A simple, and widely accepted definition for sustainable agriculture is a system of farming that is practical for the producer to use, profitable for the individual operation and environmentally sound.

In many people's view, sustainable agriculture is a philosophy and is contrasted with "conventional agriculture" (another term that is difficult to define). Conventional agriculture usually is identified with industrialization and with high inputs, including pesticides, and is usually associated with the mainstream research and education institutions. The "alternate" as opposed to "conventional" approaches include organic farming, biological agriculture, alternative agriculture, biodynamic agriculture, permaculture and agroecology (among others), often characterized by values such as independence, decentralization, community, harmony with nature, diversity and equity. Because the sustainable agriculture philosophy is ill-defined, it often has been adopted by mainstream agriculture, which concerns many proponents of sustainable agriculture who feel such adoption threatens to dilute the concept.

These ideological interpretations of sustainability guide the creation of sustainable farming systems. The most frequently linked strategies involve reduction or elimination of processed chemicals, largely fertilizers and pesticides. Sustainable agriculture attempts to develop a farming system that is ecologically based and is not dependent on outside influences such as chemicals. This farming system should be based on the managed ecosystem, including the natural processes that suppress pest populations, and must not disrupt natural processes, especially those that destabilize the managed ecosystem. These natural processes will be supplemented by biological control organisms and products, resistant plants, and narrow-spectrum pesticides. A total systems approach is necessary for a successful ecologically-based pest management (EBPM) strategy.

EBPM strategies naturally link with sustainable agriculture strategies. Sustainable agriculture requires a systems (holistic) approach to management, requiring new research paradigms emphasizing application of whole-field and whole-farm approaches to nutrient and pest management, and team research involving farmers. This contrasts to the efficiency and substitution approaches that are emphasized in most research agendas. Effectively implementing EBPM strategies, whether in the context of sustainable or "conventional" agriculture, will require a substantial knowledge base of the ecosystem in question. Just obtaining the requisite ecosystem data over the small climatic range of a single state in the Midwest will be a large task.

Where does biological control fit into the philosophy of sustainable agriculture? Even though it would appear that biological control should be an integral component of a philosophy that espouses an ecosystem approach, insect control concerns seem to be secondary to the focus of sustainable agriculture on nutrient inputs and tillage systems. Pest management is a lower priority than getting the plants to grow well, especially during the transition or conversion period when a grower is in the process of changing from conventional to sustainable practices. Much of the literature in the area of sustainable agriculture emphasizes rotational grazing, soil fertility improvements through organic amendments, crop rotations, and no-till or ridge-till methods. Certainly these practices will have an impact--positive or negative--on the arthropod populations in the farmer's field. The effect of alternative tillage systems on both pest and natural enemy populations has been researched in some crops (MBCN Vol. II, No. 11), but not all pests or their natural enemies are greatly influenced by soil factors.

Biological control can be effective in all types of agricultural systems, including organic, sustainable, and conventional. But certain biological control approaches certainly have the potential to conform to the sustainable agriculture philosophy. The introduction and establishment of new beneficial natural enemies (classical biological control) can substantially reduce the need for synthetic pesticides. And habitat management to improve the performance of natural enemies (conservation biological control) also fits within the sustainable framework.

The success of many farmers who have embraced alternative practices indicates the potential for greater adoption of sustainable agriculture. Biological control should be an important tool in managing pest populations in sustainable production systems. However, biological control is dependent on public sector funding for research and development. This is primarily because many effective controls decrease the need for purchased inputs, reducing future commercial market potential for private companies. Also, biological control is often location- and management system-specific, so it requires intense knowledge of relatively unique conditions that may not be applicable on a widescale basis, again a problem for marketing a product. Unfortunately, public funds for development and delivery of biological control products or systems to growers are scarce, so many potential biological control methods remain largely unexploited. Until changes are made in agricultural programs and policies, increased development and utilization of biological control will be limited for both sustainable and conventional farming systems.

- Susan Mahr, University of Wisconsin - Madison

Based on a paper presented by Dennis Keeney, Director of the Leopold Center for Sustainable Agriculture, Iowa State University, at the 1996 Conference "Biological Control in the Midwest," Ames, Iowa; the National Research Council's 1989 publication Alternative Agriculture; and other sources.

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