Agroecology in Action
isidoro
revised 07-30-00

 

 

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
- Altieri, M.A., Trujillo, J, Campos, L.S., Klein-Koch, C., Gold. C.S. and Quezada, J.R., 1989. El control biológico clásico en América Latina en su contexto histórico. In: Manejo Integrado de Plagas (Costa Rica), 12: 82-107.
- Altieri, M.A., 1993. Crop protection strategies for subsistence farmers. Westview Press, Boulder, USA.
- Altieri, M.A., 1994. Biodiversity and pest management in agroecosystems. Haworth Press, New York.
- Belloti, A.C., Cardona, C. and Lapointe, S.L., 1990. Trends in pesticide use in Colombia and Brazil. In: Journal of Agricultural Entomology 7: 191-201.
- Campanhola, C., de Moraes, J. and De Sa, L., 1995. Review of IPM in South America. In: Mengech, A.N. et al. (eds). Integrated pest management in the tropics: current status and future prospects. John Wiley and Sons, New York.
- Hansen, M., 1987. Escape from the pesticide treadmill: alternatives to pesticides in developing countries. Institute for Consumer Policy Research, Consumers Union, New York.
- Murray, D., 1994. Cultivating crisis: the human costs of pesticides in Latin America. University of Texas Press, Texas.
- Nicholls, C. and M.A. Altieri, 1997. Conventional agricultural development models and the persistence of the pesticide treadmill in Latin America. In: International Journal of Sustainable Development and World Ecology 4: 93-111.
- Rosset, P. and Benjamin, D., 1994. The greening of Cuba: a national experiment in organic agriculture. Ocean Press, Sydney.
- Stephens, C.S., 1984. Ecological upset and recuperation of natural control of insect pests in some Costa Rican banana plantations. In: Turrialba 34: 101-105.
- Swezey, S.L., Murray. D.L. and Daxl, R.G., 1986. Nicaragua’s revolution in pesticide policy. In: Environment 28: 6-9.
- Zuñiga, E., 1986. Control biológico de los afidos de los cereales en Chile. I. Revisión histórica y líneas de trabajo. In: Agric. Tec. 46: 475-477.

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