The war on pests
by Gary Gardner
In the long run, using chemical weapons against weeds and bugs is a
losing proposition. So, what are the hopes for Integrated Pest Management?
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
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
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
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
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
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
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
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
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
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..