The war on pests

In the long run, using chemical weapons against weeds and bugs is a losing proposition. So, what are the hopes for Integrated Pest Management?

by Gary Gardner
araquat and Nature working in perfect Harmony," proclaims the caption of a Malaysian ads for one of the world's more common pesticides. A photo shows lush green palm trees surrounding a farmer's hut. "Groundwater, rivers, streams and lakes are not affected by paraquat," the ad assures us. "Paraquat is not harmful to our wildlife." But paraquat's harmony is likely to be lost on those who know the pesticide well: farmers with paraquat-induced organ damage, relatives of farm workers killed by paraquat, and biologists concerned about paraquat's effects on creatures from to bees to horses.
The language of the ad reflects an underlying tension at the heart of pest management today. On one hand, the adverse economic, health, and environmental effects of pesticide use are ever more apparent. All over the world, governments and farmers look increasingly to Integrated Pest Management (IPM) - a strategy meant to minimize pesticide use by relying on natural methods of pest control - to break the pesticide addiction. Nine Asian nations now run comprehensive IPM programs, sponsored by the U.N.'s Food and Agriculture Organization. The United States aims to extend the use of IPM to 75 percent of its crop area by the turn of the century. And the World Bank has teamed up with the FAO to promote IPM through a newly established IPM Global Facility,
But despite the interest in reducing pesticide use, global pesticide sales actually rose in 1994 (the most recent year for which data were available) and at the fastest rate in a decade. Further sales increases are likely, which means more poisoning of people and their land, more contaminated rivers and groundwater, and more farms whose natural pest defenses have been broken. Given these dangers, and given the interest in IPM, why are pesticide sales so strong?
The question has several answers, but the most significant is a shift in the definition of IPM over its nearly four decades of evolution. Today, the IPM faithful are an eclectic crowd, ranging from pesticide-shy organic farmers to pesticide manufacturers. IPM-ers subscribe to a diverse and contradictory set of creeds, some of which are nearly as unsustainable as a total reliance on pesticides. But practitioners who live by IPM's original message - that pesticides belong on the margins of pest management - argue that the time has come to reaffirm the strategy's founding principles.

The pesticide addiction

Pest control is as old as agriculture, but widespread use of synthetic pesticides took off only after World War II, when these chemicals came to be regarded as near-miraculous solutions to one of the toughest problems in farming. Quick and easy to apply, pesticides were relatively cheap and powerfully effective. A new, "wonder" chemical used by Allied troops during the war to combat head lice and mosquitoes was later shown to be so effective at suppressing farm pests that it raised potato yields by more than half. The chemical - DDT - quickly became a basic piece of equipment in the pest-fighting arsenal. With the advent of such controls, it was thought, crop losses to insects, weeds and diseases would soon be a thing of the past.
The farmers in Peru's Canete valley were among the first to learn otherwise. During the mid-1950s, they noticed that pesticides were losing their power over insects that attacked their cotton. Radical and continual increases in the doses seemed the only way to bring the bugs under control. What the farmers were witnessing was a kind of evolution in fast-forward: the few pests genetically equipped to survive the deadly rain became the progenitors of new generations, which inherited their protective genes. After a few cropping seasons, insects could practically swim in the chemicals that had decimated previous generations. Worse still, farmers discovered that the chemicals disrupted some basic ecological relationships on which their farming depended. Pesticides killed off predatory insects that once controlled minor cotton pests. These minor pests then exploded onto the scene, and farmers found themselves fighting a total of 13 major insect pests, instead of the seven they had previously contended with. By 1956, the region's cotton yields had hit their lowest level in more than a decade.
But pesticides were casting a pall over more than pest ecology. In 1962, Rachel Carson published Silent Spring, a best-selling exposé on pesticide use that brought to public attention what scientists had known since the 1940s. Not only were pesticides dangerous for farmers, they also threatened any creature whose food they contaminated: fish, birds and mammals - including people. DDT and other organochlorines (the most important class of pesticides at the time) are very slow to break down. When residual quantities of these substances find their way into the food chain - as happens, for instance, when sprayed insects are eaten by birds and fish - they tend to accumulate in the chain's higher links. This process of "bio-accumulation" provokes a range of toxic effects in the food chain's top predators, whether bald eagles or people. Carson explained, for example, how thinning egg shells were preventing birds of prey from brooding successfully. Today, a growing body of evidence suggests that health risks from pesticides extend beyond these immediate effects to include long-term dangers, such as breast and testicular cancer and falling sperm counts.
Despite pesticides' liabilities, their convenience and power both proved addictive, and sales continued to increase. (Sales figures are an imperfect indicator of what is actually happening on the ground - a full assessment would require data on application rates and potency - but sales are the best readily available yardstick.) Global pesticide production rose without a break between the mid-1940s and the mid-1980s. In the United States, pesticide expenditures rose more than five-fold between 1951 and 1976. By the 1990s, global sales had stagnated, but with the economic recovery of eastern Europe and continuing growth in Asia and Latin America, sales jumped again in 1994. The latter two regions account for more than a third of global sales, and are expected to drive sales growth for the rest of the decade.

Pesticide Use And Crop Yields:
IPM-trained Farmers Versus Untrained Farmers

                IPM-trained Farmer         IPM-trained Farmer
                Pesticide Applications        Crop Yields
                Compared with those        Compared with those
Country         of Untrained Farmers       of Untrained Farmers
Bangladesh              N/A                      +15%
China                   -79%                     +11%
India                   -33%                     + 9%
Indonesia               -36%                     + 2%
Philippines             -50%                     + 2%
Sri Lanka               -26%                     +23%
Vietnam                 -57%                     + 8%
Source: Compiled From FAO, Intercountry Programme for the Development and Application of Integrated Pest Control in Rice in South and South-East Asia, (Rome: FAO, 1994).
Note: Yields are multi-year averages that span different years for the different country prolects.

Farming with the forces of nature

By as early as 1959, an alternative to chemical pest control had emerged. Entomologists at the University of California, looking for ways to reduce alfalfa losses to aphids, had developed the revolutionary yet biologically conservative approach now known as IPM. IPM starts from the premise that a farm is a simplified ecosystem, an assumption with happy consequences for pest management. After all, pest outbreaks are relatively rare in an undisturbed forest, desert or wetland; the interaction of diverse elements in those ecosystems prevents any one component from dominating the rest. The researchers came to see this "checks-and-balances" characteristic - largely absent from farms that rely heavily on pesticides - as a key natural resource. Why not harness nature's genius at self-regulation to control pests on the farm?
Modeling pest management on the dynamics of an ecosystem, however, is intricate business. Compared with "calendar" spraying - the traditional practice of applying pesticides on a fixed schedule - IPM is complex, employing a panoply of tools - some new, some ancient - and each one tailored to the conditions of a particular farm. One important approach involves varying the crop to disrupt pest habitats, or to provide habitat for pests' natural enemies. Such "cultural" control can take many forms. For example, several crops can be planted in the same field - a technique known as intercropping, which is practiced in some developing countries with an abundance of labor. A centuries-old cropping pattern used by indigenous Americans mingles corn, squash and beans. Or the variation can be achieved over time, by crop rotation. A common rotation in the United States involves planting corn and soybeans in alternate years.
IPM may also employ various biological tools. Farmers may, for example, augment the population of a pest's natural enemies by releasing predatory insects. Sometimes this tactic involves the introduction of a new, "exotic" species - one that does not occur naturally in the region. Such a step requires very careful testing, but it can pay huge dividends when the pest is itself exotic and the new species preys exclusively on it. The 1995 World Food Prize was awarded to Hans Rudolph Herren, a Swiss scientist who introduced Paraguayan wasps into 30 African countries to save the root crop cassava - a staple of more than 200 million Africans - from the cassava mealybug, also a native of South America. Another set of biological tools consists of certain natural toxins that can be used as pesticides. Pyrethrins, for instance, are an important group of insecticidal plant extracts. Not all such "biocides" are simple chemicals, however; some are whole organisms, usually bacteria - of which Bacillus thuringiensis, or Bt, is probably the most common. Because biocides occur in nature, they are in general more environmentally friendly than synthetic pesticides.
Common to all of these alternative tools are two very bold, yet fundamentally conservative, ideas. In the first place, IPM holds that pests should be managed, not eradicated. Rather than opting for chemicals at the first sign of trouble, IPM tolerates a certain level of pests. Farmers bent on eradication may spend more on extra pesticide than they gain in saved crops, an economically irrational strategy. More important, such overspraying makes little ecological sense: farmers risk working themselves deeper into the pesticide dilemma, by accelerating resistance among pests, or by eliminating the pests' natural enemies. Pesticides are designed for overkill - they are the atomic bombs of pest control - so the original, ecological IPM permitted them only as a last-ditch response, to be used only after safer methods had failed.
A second idea, at once novel and ancient, flows directly from the first: successful pest management, with little recourse to conventional pesticides, depends heavily on farmer skills. Because managing pests is more complex than eradicating them, and because management strategies must vary from farm to farm in order to accommodate local conditions, a trained farmer is essential. Under ecological IPM, farmers cannot get their pest management instructions off the back of a pesticide drum, or even simply from a government extension agent. They must design their own strategy, based on an intimate understanding of their own farming ecosystem.

From managing pests to managing pesticides

Caught between IPM's powerful conceptual appeal and the seductive convenience of the pesticide option, agriculture seems to have developed a kind of schizophrenia when it comes to pest control. It is true, on the one hand, that agricultural policy has grown increasingly sensitive to certain types of pesticide threats. In 1972, for instance, public health concerns led to the banning DDT in the United States - the first of many such sanctions around the world. (The U.S. ban is for domestic use; U.S. law. permits companies to manufacture and export pesticides even when they are banned or heavily restricted in the United States.) Later in that decade, oil price hikes boosted pesticide costs (since synthetic pesticides are derived from oil), further lengthening the list of pesticide liabilities. By the early 1980s, for example, Nicaraguan cotton farmers found that 26 percent of their total production costs went to pesticides - an important factor in Nicaragua's decision to develop a national IPM program, one of the first in the developing world. In the United States, pesticide costs, both in health and dollars, led two U.S. presidents, Richard Nixon and Jimmy Carter, to set up programs promoting IPM. But such policies can hardly be called adequate, given the growth of the world pesticide market. Between 1968 and 1992, a period of steadily growing interest in IPM in the United States, the amount of pesticides applied to U.S. cropland increased 125 percent.
As pesticide use grew, the original IPM philosophy began to fade - a change that was evident as early as 1979. The U.S. Congress's Office of Technology Assessment adopted a definition of IPM in which biological and cultural controls took a back seat to a mixture of tactics that essentially rationalized conventional pesticide use. In the most extreme perversion of ecological IPM, some farmers claimed to be practicing IPM simply by rotating pesticides to reduce the risk that pests would develop resistance. In the early 1980s, for example, the U.S. Agency for International Development reportedly advised Guatemalan farmers to use chemical pesticides early in the growing season, and switch to biocides as the harvest approached. In addition to slowing the development of resistance, this practice made the detection of pesticide residues less likely on Guatemalan exports to the United States. (U.S. government concern for public health apparently didn't extend to Guatemalan farm workers.)
A more common practice was to calculate an economically tolerable level of pest populations, hire scouts to determine if pests had surpassed this level, and spray if they had. Farmers concerned about risking pesticide costs found in this "scout-and-spray" approach an economical way to minimize crop losses to pests. While scout-and-spray is an improvement over traditional calendar spraying - regular use of pesticides regardless of pest levels - it still puts pesticides at the center of pest management.
Using techniques like these, revisionist IPM co-opted much of the interest in alternative pest management, without really addressing the problems of pesticide use. Some pesticides even came to be touted as IPM tools. Chlordimeform, introduced in 1966, was one of these. Chlordimeform had a lower acute toxicity than the early organochlorines, less persistence in the environment and a lower effective dosage. These relatively benign characteristics gave it a progressive image that seemed to suit a progressive pest management program like IPM. But chlordimeform was not as innocuous as originally thought. In the 1970s, Japanese researchers discovered that it was a potent carcinogen. In the late 1980s, workers at German plants that produced the chemical were developing cancer of the urinary bladder at 78 times the rate of the general population. Around the same time, in Guatemala and Nicaragua, a third of the farmers tested for the chemical were found to have unacceptably high levels of it in their systems. Because the lag between chlordimeform exposure and the appearance of tumors is roughly 25 years, the full extent of the cancer in these farmers has yet to reveal itself, but it is likely to be substantial. As with so many pesticides, this "IPM-compatible" chemical was overused, which led to a steady decline in its effectiveness. In Central America, by 1986, chlordimeform required five times as many applications per season, at double the dosage, as when it was first introduced.
In the United States, a 1993 study by the U.S. Department of Agriculture (USDA) showed how far the definition of IPM had shifted. The study covered a range of crops that accounted for roughly one-third of the country's cropland. Fruit, nut and vegetable growers were classified as practicing IPM if, at a minimum, their criteria for pesticide use involved calculating economic thresholds (that is, when it would actually pay to spray) and scouting. By using such techniques as a baseline definition, the study gave pesticides a central place in its measurement of IPM. Indeed, growers of these crops who used IPM tactics - but not pesticides - were not considered IPM practitioners under this study! While this curious definition may have resulted from the kind of data collected, rather than from an intentional, pro-pesticide bias, it nevertheless reflects the broad interpretation of IPM considered acceptable today.
Still, some of the study's findings were encouraging. Calendar spraying, once the norm for pesticide applications, was used on less than 10 percent of the acreage covered in the survey. Scouting - hardly comprehensive ecological IPM but better than calendar spraying - covered more than 60 percent of the area surveyed. A full 44 percent of fruit and nut acreage was governed by three or more cultural, biological or genetic practices in addition to scouting - a combination of tactics that approaches the ecological origins of IPM. The most encouraging result fell outside the study's definition of IPM: 17 percent of fruit and nut acreage used no pesticides at all.

IPM proves itself

Revisionist IPM has not entirely displaced the approach's original ecological vision. One of the greatest IPM successes to date - the Indonesian experience, beginning in the late 1980s - confirms IPM's viability as both an ecological and a social program. In 1986, two years after the country had achieved its long-standing goal of self-sufficiency in rice production, Indonesia's paddies were decimated by the brown planthopper. Originally a secondary pest, the planthopper cost the country over $1 billion in rice losses during the 1970s, after pesticides eliminated its predators. Now it was back with a vengeance: in one year, it destroyed enough rice to feed 3 million people. The failure of pesticides and pest-resistant crop strains forced the government to search for a new solution. Indonesia chose IPM, and became the first country to implement the strategy on a broad basis.
Two elements of Indonesia's policy ensured that it would be strong and ecologically based. In the first place, pesticides were relegated to the sidelines; 57 of them were banned for use on rice and pesticide subsidies were eliminated - saving the government $120 million annually. Although the banned chemicals could still be used on other crops - and rice farmers not participating in the IPM program could get their banned pesticides under the table - the policy demonstrated a clear government commitment to ecological IPM.
In addition, the new policy was rooted firmly in comprehensive, participatory farmer training. More than 200,000 farmers attended the 10- to 12-week training sessions at the country's Farmer Field Schools. This grass-roots approach distinguished the program from its precursors. Nicaragua's IPM program, for example, focused the training on technicians rather than farmers; the program collapsed when the technicians were dismissed after government budget cuts. The Indonesian training was also collegial. Instructors abandoned the top-down approach of formal education and built their training around actual farmer experiences. Since many of the instructors were not farmers themselves, they were expected to cultivate a plot of land, to learn firsthand the challenges of Indonesian rice farming. This unorthodox approach to education - dubbed "trainer unlearning" by world Resources Institute analyst Lori Ann Thrupp - was key to successful dissemination of IPM in Indonesia.
The reduction in subsidies cut pesticide applications from an average of 4.5 per season to 2.2. Farmer training cut applications further, to 0.8 per season - only 18 percent of the pre-IPM level. Farmers benefitted economically, too: trained farmers spent half as much on inputs as their untrained compatriots. And despite warnings of massive crop failures as the rice sector pulled away from pesticides, production increased 12 percent in the four years following the new policy. Moreover, support for the program is widespread: local authorities, such as village heads and district administrators have endorsed the policy, in some cases using discretionary funds to help implement it. Their enthusiasm is matched by that of the farmers themselves, whose energies have made the program self-perpetuating. A survey of 400 field schools showed that 60 to 70 percent of the trained farmers' groups spontaneously gave training to other farmers. Clearly, the new policy is socially sustainable.
Ecological IPM is enjoying other successes as well. FAO's nine-country Asian IPM programs are similar to Indonesia's, and have shown equally impressive results. In the seven countries for which data are available, trained farmers' pesticide applications and expenditures were down substantially, while yields were up across the board. And in the United States, the USDA has not shown itself bound by the assumptions of that 1993 study. The Department's IPM research grants program, which funded virtually no studies of biological control between 1983 and 1991, allotted 42 percent of its grants to that area in 1993, and 26 percent to research on cultural control.

The growing pesticide deficit

While these developments are encouraging, they have hardly begun to put pesticides on the margins of pest management. And the dangers that prompted the development of IPM nearly 40 years ago continues to hang over us. More than 900 species of insects, weeds and plant pathogens, for example, are now resistant to at least one pesticide - up from 182 in 1965. At least 17 insect species have shown some resistance to all major insecticide classes. A decade ago, there were only a dozen herbicide-resistant weeds; today, there are 84.
The health and ecological effects are still with us, as well. In some areas, the persistent organochlorines have been replaced with chemicals that break down more rapidly and are sprayed in smaller quantities. But these newer pesticides often have a higher acute toxicity, so they pose a greater immediate danger to farmers. Meanwhile, official estimates of pesticide poisonings - more than a million annually, according to a 1988 WHO report - are probably woefully understated. One survey of hospitals and clinics in Nicaragua's department of Leon found that documented cases of pesticide poisoning rose from fewer than 200 in 1983 to more than 1,200 in 1987. The study's author, Douglas Murray of Colorado State University, credits the sixfold increase mainly to improvements in reporting procedures, since the country's pesticide imports remained flat in all but one of those six years.
Meanwhile, the task of developing new pesticides grows more difficult every year. Today, a new pesticide can require 10 years to move from conception to crop. In Europe, where many of the major chemical companies are based, research and design costs per new product rose from an average 25 million ECU in 1975 to 125 million ECU in 1992. (The ECU, Or European Currency Unit, is a way of averaging the values of the European Union currencies.) The growing expense results from the challenge of developing compounds that meet increasingly demanding toxicological and environmental standards: the cost of European chemical companies' research into just these two areas rose twelvefold in the same 17-year period. In the United States, home to many of the other major chemical companies, pesticide R&D claims a full 12 percent of pesticide revenues. These costs have helped drive a trend toward consolidation in the industry, but even giant companies find it difficult to profit from pesticides without penetrating the global market as broadly as possible. In effect, regulations designed m make pesticides safer are pressuring companies to push pesticides more aggressively than ever.
At the same time, the slow development of new pesticides means that the market share for products whose patents have expired - already at 50 percent - continues to rise, particularly in the developing world. These older products, including organochlorines such as DDT, continue to expose users, consumers, and agroecosystems to the well-documented dangers identified by Rachel Carson and others.
Despite these problems, cutting-edge research continues to pursue "silver bullet" solutions that disregard the ecological dimension of the problem and further co-opt the IPM concept. A case in point is the genetic engineering of corn, cotton and potatoes to contain the toxin produced by the Bt bacterium. In spray form, Bt is harmless to humans and higher animals, yet effective in managing a variety of insects. The spray also breaks down quickly after application, but these transgenic crops will produce the toxin constantly until they are harvested. That will accelerate the development of resistance which could mean the loss of one of IPM's best biological tools.

The future of pest management

In 1991, some 350,000 Indonesian farmers mobilized to defeat an infestation of the white rice stemborer by collecting egg masses, setting traps and nurturing beneficial insects. Such cooperative action, borne of the increased skill and confidence that training confers, demonstrates the strong social legacy of Indonesia's IPM program. A return to IPM's original definition - which insists on only minimal, last-ditch use of pesticides - could set the stage for similar events worldwide.
But that won't happen until more people see beyond the pesticide mystique. Of course, much of the hype that clouds the issue emanates from the pesticide producers, who often promote their products as "IPM-friendly." WRI's Thrupp identifies pesticide marketing - especially the sales pitches of pesticide company field staff - as a key obstacle to the dissemination of ecologically-based IPM. Greater regulation of such activities could help curb some of these excesses. A place to start would be stepped-up enforcement of the FAO's Code of Conduct on the Distribution and Use Of Pesticides, which prohibits misleading or unsubstantiated advertising. A sampling of pesticide ads undertaken by the Pesticide Action Network of North America shows a number of clear violations of the Code's provisions.
IPM must overcome major financial obstacles as well. Development programs and farm credit organizations sometimes require pesticide use as a condition for aid. Such practices lock farmers - sometimes even entire countries - into a system fraught with unnecessary risk. Advocates of IPM need to reach out to financiers as well as farmers: once lenders understand that IPM offers long-term stability, they will find it a more attractive investment
A portion of that investment should go toward pure research, to improve our understanding of IPM's potential with various crops and pests, in various regions. IPM has been most successful in managing insects: today, more work is needed on integrated methods for dealing with weeds and pathogens. But currently, most pest control research - apart from pesticide R&D - is devoted to breeding pest-resistant crop varieties. This genetic work is essential - and perfectly compatible with IPM - but it should be accompanied by work on the broad ecological issues of pest management. One way of funding a larger research agenda might be by taxing pesticide sales, which totaled $25 billion in 1994.
But the biggest challenge may simply be conceptual. There is no question that IPM is radical by the standards of conventional agriculture. After all, IPM insists that farming is essentially a natural process - and that the people best able to manage it are farmers.

Gary Gardner is a research associate at the Worldwatch Institute. His article "From Oasis to Mirage: The Aquifers that Won't Replenish" appeared in toe May/June 1995 issue of World Watch..