Indigenous and modern approaches
to IPM in Latin America
Miguel
A. Altieri and Clara I. Nicholls
Prevailing
economic policies in Latin America encourage
the production of export and/or commercial
crops, primarily in large-scale monocultures.
Pesticide expenditures in the Latin American
region increased from US$1.0 billion in 1980
to US$2.7 billion in 1990 (see Table
1).
The major recipients of pesticides were
large-scale production systems producing
sugar cane, cotton, maize, soybeans, rice,
citrus and tomatoes, especially in Brazil,
Colombia, Argentina and Mexico. Predictably,
the emphasis of the chemical-intensive
agricultural export model has intensified
ecologically-based crisis conditions and has
lead to serious environmental and health
consequences (Belloti et al., 1990).
Despite the
above trends, there are several documented
cases of alternative pest management
approaches scattered throughout the region
that have result in sustainable crop
production. These are traditional crop
protection practices (indigenous IPM systems)
developed by indigenous farmers using
traditional knowledge and local resources and
modern IPM systems developed by innovative
researchers involved in the search for more
sustainable methods of food production.
Modern
IPM Systems
Despite many
scientific advances, it is still arguable
whether ecological principles have actually
had an impact on the practice of modern IPM.
In most case, modern IPM has come to mean
Intelligent Pesticide Management, which aims
at scouting crops to monitor pest densities
in order to take action (usually an
insecticide application) when they threaten
economic viability (the economic threshold
(ET)). As long as the simplified structure of
monocultures is maintained, pest problems
will continue because the process of
ecological simplification that has been set
in motion. The IPM projects described below
are, however, a step in the right direction
as they emphasise withdrawing pesticides
allowing beneficial fauna to recover and a
more desirable level of biodiversity to
re-establish itself within agro-ecosystems.
Peru
In the mid
1950s as cotton production reached a peak in
the Canete Valley, organochlorinated
insecticides were in intensive use. Several
pests had already developed resistence to
these pesticides and heavier dosages and more
frequent applications became necessary. Six
new species of secondary pests made their
appearance and cotton yields fell sharply.
A number of
changes in pest control practices were
introduced in response to this crisis
including the banning of synthetic organic
pesticide use, the reintroduction of
beneficial insects, crop diversification
schemes, the planting of early maturing
varieties and the destruction of cotton crop
residue. Pest problems declined dramatically
and pest control costs were substantially
reduced (Hansen, 1987).
Nicaragua
In Nicaragua,
cotton also exhibited the classic pesticide
"treadmill" pattern observed
earlier in Peru. After a successful
production phase in which cotton yields
peaked in 1964-1965, pesticide-induced
ecological disruptions made themselves felt:
insecticide-resistant pests, secondary pests
and the elimination of natural enemies.
Average yields fell by 15-30% because of
insect damage despite 28 insecticide
applications per season. In 1971, a programme
started by UN-FAO began to yield information
on, amongt other things, economic thresholds,
the seasons of when natural enemies were most
abundant, and cotton phenology. This helped
researchers to identify the best time for
planting cotton and the conditions that gave
the best growth environment to the plant
allowing it to escape boll weevil and boll
worm attack. Later, a "trap
cropping" system was developed. This
consisted of planting small cotton plots at
the beginning and end of the growing seasons
to attract and concentrate weevils. Once
trapped, they were then killed off by
selective insecticides (Swezey et al., 1986).
Costa
Rica
Another case
of insecticide-induced ecological disruption
comes from the Pacific coastal plains. In
1954, over 12,000 hectraes of United Fruit
Company banana plantations were treated with
an aerial application of dieldrin granules
against banana weevil and rust thrips. This
killed off many natural enemies and led to
the appearance of other pests which had
previously been of minor significance. An
outbreak of banana stalk borer, Castiomera
humbolti was countered by more pesticide
pesticide spraying. By 1958, in spite of
increasing pesticide use, there was an
unprecedented outbreak of pests, including
six major Lepidoptera pests including
Ceramidia moth, owleye and the West Indian
bag worm that had not previously been a
problem. In 1973, the oil crisis prompted
United Fruit entomologists to stop all
insecticide sprays in the entire Golfito
banana division. Insect pests fell to below a
level where they were a threat to
profitability within one to three generations
(a period of several months) with little or
no fruit loss. Within two years, virtually
all of the former pest species had almost
disappeared from the plantations. Indeed,
pests like Ceramidia and the owleyes were
rarely seen. There were occasional small
outbreaks of larvae of the West Indian bag
worm, but their numbers did not threaten the
economic threshold. The same was true of the
banana weevil. Stopping pesticide sprays
allowed natural enemies to move in from the
surrounding jungle, colonise the area, become
more abundant and thus re-exert a natural
control over many of the pest populations
(Stephens, 1984).
Brazil
By 1970, total
soybean production had reached 2.278 x 106
tons, especially in the states of
Parana and Rio Grande do Sul, covering and
area of about 5.5 x 106 has. As
soybean acreage increased, so did the number
of insect pests. In 1974, Brazil adopted an
IPM programme that relied primarily on
monitoring pest damage, establishing economic
thresholds and the application of specific
insecticides. This IPM programme was so
successful that between 1974 and 1982
insecticide applications fell by 80-90%. In
the 1980s, this programme was expanded to
include the use of Nuclear Polyhedrosis Virus
against the velvetbean caterpillar. This
virus is host specific and it can be readily
mass-produced by farmers themselves by
collecting sick larvae that, when macerated
and filtered, can be applied in a water
solution (Campanhola et al., 1995).
Colombia
During the
late 1970s and early 1980s, it would have
been considered as usual to made some 20 to
30 pesticide applications in an tomato
growing area that covered about 2,000
hectares. An IPM programme in the Cauca
Valley implemented in 1985 succeeded in
reducing the number of pesticide applications
to two or three. This saved over US$ 650 per
hectare. Use of a microbial insecticide
derived from Bacillus thuringiensis
combined with the release of natural enemies
such as Trichogramma spp., and the
encouragement of natural populations of the
parasite Apanteles spp., were
particularly effective in reducing the major
pest Scrobipalpula absoluta, a leaf
miner/fruit borer (Belloti et al., 1990).
Chile
In 1972,
populations of two aphid species (Sitobium
avenae and Metopolophium dirhodum)
were detected in cereal fields. Despite the
presence of resident natural enemies, these
aphids reached outbreak proportions. As a
result over 120,000 hectares of wheat were
sprayed aerially with insecticides. In 1975,
the aphids and the Barley Yellow Dwarf Virus
they transmit were responsible for the loss
of about 20% of national wheat production. In
1976, the Chilean government’s
agricultural research center, in conjunction
with the FAO, initiated a pest management
programme. As part of the strategy, several
aphidophagous insects and parasitoids were
introduced against the aphids. Five species
of predators were introduced from South
Africa, Canada and Israel, and nine species
of parasitoids of the families Aphidiidae and
Aphelinidae were brought from Europe,
California, Israel and Iran. In 1975, more
than 300,000 Coccinellidae were mass-reared
and released, and from 1976 to 1981 more than
4x106 parasitoids were distributed
throughout the cereal areas of the country.
Aphid populations were maintained below the
threshold where they could inflict economic
damage by the action of biological control
agents (Zuñiga, 1986).
Cuba
Since the
trade relations with the socialist bloc
collapsed in 1990, pesticide imports to the
island have dropped by more than 60 percent.
Because of this, the Cuban government adopted
an IPM policy which focused on biological
control in its search for techniques that
would enable biologically sophisticated
management of agro-ecosystems (Rosset and
Benjamin, 1994). Key components of their
strategy are the Centers for the Production
of Entomophagae and Entomopathogens (CREEs),
where the centralised, "artesanal"
production of biocontrol agents takes place.
By the end of 1992, 218 CREEs had been built
throughout Cuba and were providing services
to the State, cooperatives, and individual
farmers.
CREEs produce
a number of entomopathogens (Bacillus
thuringiensis, Beauvaria bassiana,
Metarhizium anisoplae, and Verticillium
lecanaii), as well as one or more
species of Trichogramma wasps.
Their production depends on what crops are
being grown in the area.
Conclusions
The array of
both proven and promising IPM technologies
developed by innovative researchers and
indigenous farmers, offer considerable
potential for reducing agrochemical use and
for improving agricultural sustainability.
The challenge will now be how to incorporate
local knowledge and skills as well as
innovative IPM research into the research
agenda of national and international
organizations. The other challenge will be
how to mobilise such organizations in order
to help scale-up such initiatives as we have
described here making a wider eco-regional
impact possible. At the political level it is
clear that a true reduction and/or
elimination of pesticide use in the
agro-export sector will require major
political reforms that deal with the reasons
why farmers turn to chemicals. These include
government pesticide subsidies, the corporate
control of agricultural enterprises, research
serving the needs of the private sector and
internationally set, unrealistic, cosmetic
standards (Nicholls and Altieri, 1997).
Miguel
A. Altieri and Clara I. Nicholls,
ESPM Division of Insect Biology, University
of California, Berkeley, USA
References
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Campos, L.S., Klein-Koch, C., Gold. C.S. and
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farmers. Westview Press, Boulder,
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- Altieri, M.A., 1994. Biodiversity
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S.L., 1990. Trends in pesticide use
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America. In: Mengech, A.N. et
al. (eds). Integrated pest management in the
tropics: current status and future prospects.
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Latin America. University of Texas
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Journal of Sustainable Development and World
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upset and recuperation of natural control of
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Table 1.Selected examples of
multiple cropping systems that effectively
prevent insect-pest outbreaks in Latin
America (after Altieri, 1994).
| Multiple
cropping System |
Pest(s)
regulated |
Factor(s)
involved |
Country |
| Cassava
intercropped with cowpeas |
Whiteflies
Aleurotrachelus socialis and Trialeurodes
variabilis |
Changes in
plant vigor and increased abundance
of natural enemies |
Colombia |
| Corn
intercropped with beans |
Leafhoppers (Empoasca
kraemeri), leaf beetle (Diabrotica
balteata) and fall armyworm (Spodoptera
frugiperda) |
Incr ease in
beneficial insects and interference
with colonization |
Colombia |
| Corn
intercropped with beans |
Corn leafhopper
(Dalbulus maidis) |
Interference
with leafhopper movement |
Nicaragua |
| Cucumbers
intercropped with maize and broccoli |
Flea beetles (Acalymma
vitata) |
? |
Costa Rica |
| Corn-bean-squash |
Caterpillar (Diaphania
hyalinata) |
Enhanced
parasitization |
Mexico |
| Corn-beans |
Stalk borer (Diatraea
lineolata) |
? |
Nicaragua |
Table 2. Selected examples
of cropping systems in which the presence of
weeds enhances the biological control of
specific crop pests (after Altieri, 1994).
| Cropping
systems |
Weed species |
Pest(s)
regulated |
Factor(s)
involved |
Country |
| Beans |
Goosegrass (Eleusine
indica) and red sprangletop (Leptochloa
filiformis) |
Leafhoppers (Empoasca
kraemeri) |
Chemical
repellency or masking |
Colombia |
| Brussels
sprouts |
Natural weed
complex |
Imported
cabbage butterfly (Pieris rapae)
and aphids (Brevicoryne brassicae) |
Alteration of
colonization background and increase
of predators |
Chile |
| Corn |
Natural weed
complex |
Heliothis
zea Spodoptera frugiperda |
Enhancement of
predators |
Colombia |
| Corn |
Natural weed
complex |
Dalbulus
maidis |
Interference
with |
Nicaragua |
| Soybean |
Broodleaf weeds
and grasses |
Epilachna
varivestis |
Enhancement of
parasites |
Mexico Colombia
|
| Soybean |
Cassia
obtusifolia |
Nezara
viridula, Anticarsia gemmatalis |
Increased
abundance of predators |
Brasil |
| Soybean |
Crotalaria
usaramoensis |
Nezara
viridula |
Enhancement of
tachinid parasite (Trichopoda sp.) |
Brasil |
| Sweet potatoes |
Morning glory
Ipomoea asarifolia |
Argus tortoise
beetle (Chelymorpha cassidea) |
Provision of
alternate host for the parasite
Emersonella sp. |
Costa Rica |
| Vineyards |
Natural weed
complex |
Grape mealy bug
Pseudococcus affinis |
Enhance natural
enemies |
Chile |
