The Illusion of Integrated Pest Management
Despite three decades of research, there is very little “I” in IPM. It’s time to start over with an achievable goal.
In 1993, the U.S. Department of Agriculture (USDA), the Environmental Protection Agency (EPA), and the Food and Drug Administration (FDA) called for a national commitment to implement Integrated Pest Management (IPM) on 75 percent of U. S. crop acreage by the year 2000. The next year, USDA announced its IPM Initiative to embrace this commitment. Seven years have passed, and farm practices have changed very little. Indeed, the only significant change is that we know less than what we thought we knew about what IPM is. Revisiting what we mean by IPM will help us understand what went wrong with the initiative.
USDA and EPA struggled to come up with a workable definition of IPM and a suitable way to assess its level of adoption. This is not surprising, given the apparent confusion among policymakers as to what IPM is all about. The most recent attempt came in October 1998, when USDA announced that a given farm should have in place a management strategy for “prevention, avoidance, monitoring, and suppression” (PAMS) of pests. To qualify as IPM under these guidelines, a farmer must use tactics in at least three PAMS components. USDA defines “prevention” as the practice of keeping a pest population from ever infesting a crop. “Avoidance” may be practiced when pest populations exist in a field, but their impact on the crop can be avoided by some cultural practice. “Monitoring” refers to regular scouting of the crop to determine the need for suppressive actions. “Suppression” is used where prevention and avoidance have failed and will typically mean application of a chemical pesticide.
The major problem with the PAMS approach is that it does not recognize the concept of integration or compatibility among pest management tactics as envisioned by the founders of IPM. Simply mixing different management tactics does not constitute IPM. Mixing the tactics arbitrarily may actually aggravate pest problems or produce other unintended effects. For example, studies have documented antagonistic relationships between genetically resistant crop cultivars and biological control agents of insect pests. It is naïve to assume that nonchemical or reduced-risk alternatives can be mixed and deployed in the same way in which pesticide “cocktails” have commonly been used in the past. Combining tactics to achieve the best long-term results requires considerable ecological finesse. Many potentially effective alternatives will provide only disappointment if they are used in the same way as conventional pesticides and are applied without good knowledge of how they affect other control agents.
A federal policy that promotes IPM without a proper understanding of IPM is doomed to failure. But just understanding IPM is not enough: Federal policy also must address how farmer adoption will be measured and provide incentives to encourage such adoption. This is not likely to happen in the foreseeable future. In view of this, we believe that the time has come for a major policy change at the federal level: Dispense with what has become an “IPM illusion” and shift the focus to a more definable goal, such as pesticide reduction (including risk reduction). Because policymakers in Washington seem to have a fuzzy view of the origin of IPM, we will begin with a brief historical account.
Shortly after World War II, when synthetic organic insecticides became available, applied entomologists in California developed the concept of “supervised insect control.” Entomologists in cotton-belt states such as Arkansas were advocating a similar approach. Under this scheme, insect control was “supervised” by qualified entomologists, and insecticide applications were based on conclusions reached from periodic monitoring of pest and natural-enemy populations. This was viewed as an alternative to calendar-based insecticide programs. Supervised control was based on a sound knowledge of the ecology and analysis of projected trends in pest and natural-enemy populations.
Supervised control formed much of the conceptual basis for the “integrated control” that California entomologists articulated in the 1950s. Integrated control sought to identify the best mix of chemical and biological controls for a given insect pest. Chemical insecticides were to be used in manner least disruptive to biological control. The term “integrated” was thus synonymous with “compatible.” Chemical controls were to be applied only after regular monitoring indicated that a pest population had reached a level (the economic threshold) that required treatment to prevent the population from reaching a level (the economic injury level) at which economic losses would exceed the cost of the artificial control measures.
IPM extended the concept of integrated control to all classes of pests and was expanded to include tactics other than just chemical and biological controls. Artificial controls such as pesticides were to be applied as in integrated control, but these now had to be compatible with control tactics for all classes of pests. Other tactics, such as host-plant resistance and cultural manipulations, became part of the IPM arsenal. IPM added the multidisciplinary element, involving entomologists, plant pathologists, nematologists, and weed scientists. In the United States, IPM was formulated into national policy in February 1972 when President Nixon directed federal agencies to take steps to advance the concept and application of IPM in all relevant sectors. In 1979, President Carter established an interagency IPM Coordinating Committee to ensure development and implementation of IPM practices.
Illusion of success
There is now a growing awareness that IPM as envisioned by its initial proponents is not being practiced to any significant extent in U.S. agriculture. According to estimates by the Consumers Union, true IPM is probably being practiced on only 4 to 8 percent of the U.S. crop acreage. Globally, the percentage is probably even lower. This is true almost three decades after President Nixon’s directive, which, among other things, stimulated major IPM research and extension programs in the land grant colleges of agriculture (LGCA).
Much of what is being billed as modern IPM is really nothing more than a reinvention of the supervised control of 50 years ago. Today, pest consultants typically monitor crops and determine when to treat with a pesticide–often as the primary or only tactic. This approach is sometimes derisively referred to as “integrated pesticide management.” In many situations, pest consultants do not even practice supervised control because they may not monitor at all, or if they do, there is no effort to monitor natural-enemy populations. Pesticides are the “magic bullet” for the risk-averse farmer and pest consultant; these materials are easy to apply, provide a quick fix, and require little or no ecological understanding of the target system. Many pest consultants are also employed by the pesticide industry and thus have a built-in conflict of interest. There is not much economic incentive to try (much less integrate) alternative methods, even when these are available. Also, alternative methods often require relatively more effort to implement as well as greater ecological understanding of the target system.
Finally, there is virtually no integration of tactics. Integration is critical both within a class of pests and among classes of pests. For example, an insecticide should not destroy natural enemies of insect pests, nor should a fungicide destroy microbial antagonists of plant pathogens (vertical integration); the same insecticide should not destroy insects that suppress weeds, nor should the same fungicide destroy predatory mites that help control other mites and smaller insect pests (horizontal integration). This was the original meaning of the term “integration.” Unfortunately, in U.S. agriculture today there is usually no “I” in the IPM.
This does not mean that the IPM movement was a complete failure. Considerable benefit was passed on to farmers in the form of models for predicting pest occurrence, plans to monitor pests, and treatment guidelines for use in supervised control. As a result, there has been some pesticide reduction in certain crops. However, little benefit was passed on in terms of truly integrated programs as envisioned by the founders of IPM. In some ways, the chief beneficiaries of the IPM movement have been research scientists, extension agents, and government bureaucrats instead of the farmers. The IPM movement was successful in that it generated the fuel (that is, funding) needed to operate the research engines of mission-oriented scientists, not to mention the research engines of other scientists engaged in curiosity-driven research that could be justified by the national need for IPM. But complete IPM programs did not result, largely because not enough research effort was devoted to vertical and horizontal integration of tactics that could be implemented by the farmer.
Problems with implementation
The implementation of IPM is hampered in several ways. The monitoring schemes developed for pest and natural enemy populations may be too sophisticated and expensive to be a practical tool for the pest consultant. In other cases, they may be too simplistic to be used in making rational decisions on how to harmonize tactics for best immediate and long-term results. Predicting pest and natural enemy population trends is difficult because of “chaos” in agro-ecosystems (that is, the extreme sensitivity to initial conditions). Economic thresholds and injury levels have proven to be primarily of academic interest; in practice, they can become operationally intractable. Because of the complexity of crop systems and the site-specific nature of many pest problems, relying on predetermined static treatment thresholds is problematic. Dynamic thresholds are needed. But developing a dynamic threshold for a single pest can take years of field research, which is a disincentive for LGCA scientists. What’s more, the concept of economic threshold may not apply to many pest problems. For example, there is no threshold in the case of a single weed that can produce enough seed to infest the entire field or for a pathogen population that cannot be monitored in any practical way.
Mainstream post-World War II entomologists blazed the trails with the new synthetic organic insecticides but became preoccupied with treating the symptom rather than developing an ecological understanding of pest-antagonist relationships. Other pest disciplines seem to have followed the same trail. Plant pathologists and weed scientists have been slow to develop a good ecological understanding of naturally occurring antagonistic agents of pathogens and weeds. Soil fumigation–an ecological blunt instrument–is still used for “management” of nematodes and soil-borne pathogens in certain crops. In short, there is minimal vertical integration of tactics; horizontal integration is in its infancy. The pest disciplines have failed to integrate on behalf of the farmer. Or to quote Philip H. Abelson in his Science editorial of August 8, 1997: “. . . society has problems; universities have departments.”
Pest consultants typically have a B.S. or M.S. degree in an agricultural discipline. Some are trained in pest management. At best, most are able to diagnose pest problems and determine when to treat with a pesticide. However, their training is simply inadequate for dealing with the ecological complexity and challenge of IPM. The research, extension, and regulatory agencies have been slow (or unable) to recognize this problem, and the LCGAs have failed to assume proper responsibility for a job that should be part of their mission.
A fundamental shift in federal policy relative to IPM is in order. We suggest the following for the immediate future.
- Set aside the Clinton administration’s IPM Initiative and concentrate instead on the percentage of crop acreage that is under supervised control. Once 75 percent of U.S. crop acreage is under supervised control, policymakers can set a goal for the next step: the vertical integration of tactics (first-level IPM). Although this can be done by executive order, it would be better for Congress to act. Executive orders are usually unfunded mandates and may expire at the end of a president’s term. IPM needs financial support and a long-term commitment.
- Shift the debate to pesticide reduction, with particular emphasis on compounds that pose significant hazards to humans and the environment and/or destroy naturally occurring antagonists of pests. Pesticide reduction can be quantified and analyzed statistically, whereas IPM cannot. We also have to pay attention to “phantom reductions.” For example, switching to a different pesticide may make it possible to reduce the amount of pesticide applied, but certain compounds (such as synthetic pyrethroids) may pose greater environmental risk even though less is applied. Reducing the risk associated with pesticide use (risk reduction) must therefore also be considered.
- Increase funding for research on naturally occurring antagonists of pests in agro-ecosystems, including ways to exploit crop plants that favor the antagonists. Increased funding is especially critical for antagonists of plant pathogens, weeds, and nematodes. Priority should be given to field-oriented research projects that seek to establish the relative importance of the suite of antagonists that exist in a given crop system and integrate the more important antagonists with the standard artificial control tactics for that system.
- Reassess the academic strategy in the LGCAs for training the next generation of pest consultants. A new model is required to address the simultaneous need for field scouts to assess pest populations and determine when to treat and for broadly trained, interdisciplinary specialists to deal with the challenge of IPM and the complexity of crop systems. In the latter case, a doctoral degree in plant health is in order. This would be a professional nonresearch degree comparable to the D.V.M., D.D.S., and M.D. degrees. The University of Florida recently announced such a program.
It is tempting to simply admit defeat and drop the IPM acronym from production agriculture. However, this would probably add to the confusion that already exists. Although true IPM has yet to be substantially realized in U.S. agriculture, it does remain a worthy goal for the early part of the 21st century. This goal is attainable in principle but will most likely require innovative partnerships among scientists, extension agents, pest consultants, progressive farmers, farm workers, and consumers to see it to fruition. The focus should be at the local or grassroots level. The federal government should be a facilitator by providing as much incentive as possible, while not getting in the way of innovation.
Lester E. Ehler (firstname.lastname@example.org) is professor of entomology at the University of California, Davis. Dale G. Bottrell (email@example.com) is professor of entomology at the University of Maryland, College Park.