Crop Protection Strategies For Subsistence Farmers

Miguel A Altieri

• Publisher: CRC Press
• Year: 2019
• eBook ISBN: 9780429723070
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

Top-down approaches to pest management, relying on agrochemical inputs that can be scarce, expensive, ecologically toxic, or inaccessible, have repeatedly failed to solve pest problems that affect small farmers in developing countries. Crop Protection Strategies for Subsistence Farmers offers an alternative. Drawing on examples from Latin Am

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Designing and Improving Pest Management Systems for Subsistence Farmers

Miguel A. Altieri

Introduction

Traditional and/or peasant agriculture is a prominent rural activity in most parts of the developing world. For example, in Latin America there are about nine million peasant production units located mostly in marginal environments and exhibiting low productivity (Ortega 1986). Nevertheless, their contribution to regional food security is crucial since they produce most of the maize, beans, potatoes and other staple foods. This small farm sector has been bypassed by agricultural modernization, mainly because new technologies were not made available to small farmers on favorable terms and hence often they were not suited to the agroecological and socioeconomic conditions (de Janvry 1981). Pest management innovations are no exception (Altieri 1984 and 1985).

Critics of top-down rural development programs charge past IPM programs with a lack of understanding and appreciation of the agroecological, cultural and socio-economic milieu they operated in, exclusion of the small farmer as both collaborator and beneficiary, and inept promotion of inappropriate technology (Matteson et al. 1984). As a result the development and extension of improved and adaptable IPM technology for small farmers in developing countries is being re-examined. Among the various efforts to devise better crop protection methods it is possible to distinguish three main approaches:

1. Rescuing, understanding and applying traditional farming knowledge to solving agricultural and pest problems
2. Involving farmers in the design, conduction and evaluation of technologies through participatory research methods
3. Use of agroecological principles and techniques to design agroecosystems that enhance natural and biological control processes

The purpose of this chapter is to offer a conceptual foundation based on the above three approaches for examining and optimizing small farming systems in terms of crop production and protection concerns.

Ethnoecology and the Improvement of IPM in Small Farming Systems

Interest in how traditional peasant farmers in developing countries perceive and modify their environment has recently increased among academic institutions. Researchers from a variety of disciplines (i.e., anthropology, human ecology, entomology, agronomy, soils, agroecology, ethnobiology, etc.) are engaged in describing farmers' rationale, strategies to minimize risk, local resource use, cropping systems design and management, folk taxonomies, etc. Most of these studies have documented that in most areas where cultural traditions and social organization have not been drastically changed, farmers are excellent preceptors of their environment and make successful management decisions designed to overcome production constraints (Brokensha et al. 1980, Klee 1980).

Evaluations on how traditional farmers perceive pest problems and on the various indigenous control methods employed are few. The scattered information is mostly observational/anecdotal and does not provide quantitative details about the effects of various cultural control practices on pest dynamics or about the ecological mechanisms involved in the regulation of specific pests. Nevertheless by assembling most of the current literature on the subject, it is possible to offer a synthesis of current knowledge along with an ecological basis to develop a theory on indigenous methods of pest control.

Knowledge About Pests and Folk Taxonomies

Classification of animals, especially insects and birds, is widespread among farmers and indigenous groups (Bulmer 1965). In their survey of pest control practices used by local farmers in the Philippines, Litsinger et al. (1980) found that farmers had local names in separate dialects in each location for most pests attacking rice, corn and grain legumes. Farmers were not aware of some pests considered as problems by entomologists, and consequently did not attempt control measures.

Insects and related arthropods have major roles as crop pests, causes of disease, food, medicinals, and are important in myth and folklore. In many regions, agricultural pests are tolerated because they also constitute agricultural products; that is, traditional agriculturalists may consume plants and animals that would otherwise be considered pests. In Indonesia, a grasshopper pest in rice is trapped at night and eaten (with salt, sugar, and onions) or sold as bird food in the market. Ants, some of which may be major crop pests, are one of the most popular insect foods gathered in tropical regions (Brown and Marten 1986).

In his studies of Kabba farmers in Nigeria, Atteh (1984) not only found that farmers could identify the pests affecting their crops, but that also they could rank the pests according to the degree of damage they caused to crops. In addition, further research revealed that for each pest farmers had knowledge of:

1. The history of the pest, including dates when the pest was noticed, when it became a menace, peak periods of occurrence in the past, and type of damage done;
2. The biology of the pest, including the life cycle of the pest, its breeding behavior, and ecological and climatic conditions facilitating or discouraging increase in numbers;
3. The bionomics of the pest—the feeding preferences and the severity of damage done to plants attacked.

A good example of farmers knowledge of the biology and bionomics of pests is the case of the variegated grasshopper Zonocerus variegatus, in southern Nigeria. Richards (1985) found that local farmer knowledge was equivalent to that of his scientific team concerning the grasshoppers' food habits, life cycle, mortality factors, degree of damage to cassava, and the egg-laying behavior and egg-laying sites of the females.

Farmers were aware that, numerous as these insects are, they congregate under only a few shaded areas on the farm or in an area to lay eggs at a particular period, and that these eggs are kept in pods and inserted an inch or so below the soft ground surface.

Farmers had discovered on their own that the egg-laying sites can be marked and the egg pods dug up. Once exposed to the hot sun the eggs die. They had in fact tried this as a control measure. Farmers had also established a close relationship between the presence of a weed (Eupatorium odoratum) and the advance and severity of the pest (Page and Richards 1977).

In this particular case farmers' knowledge added facts to that of the researchers in regard to the dates, severity and geographical extent of some of the outbreaks, plus the fact that the grasshopper was eaten and sold and was of special importance to women, children, and poor people. Thus the final control recommendation by scientists, clearing the egg-laying sites from a block of farms, did not require most farmers to learn new concepts, and for some the practice was nothing new (Richards 1985).

Indigenous Pest Control Methods

Traditional farmers rely on a variety of management practices to deal with agricultural pest problems. Two main strategies can be distinguished. One is the use of direct, non-chemical pest control methods (i.e., cultural, mechanical, physical and biological practices). The second is reliance on built-in pest control mechanisms inherent to the biotic and structural diversity of complex farming systems commonly used by traditional farmers (Brown and Marten 1986). Farmers also use a variety of other management practices that, although targeted for other farm purposes, significantly impact pest dynamics.

Traditional farmers throughout the world use a series of mechanical, cultural and biological measures to control pests (Brown and Marten 1986, Atteh 1984, Litsinger et al. 1980, Altieri 1985). Table 1.1 summarizes the main strategies as well as specific practices. This ensemble of cultural practices can be grouped into three main strategies, depending on which element of the agroecosystem is manipulated:

Manipulation of Crops in Time Farmers often carefully manipulate the timing of planting and harvest and use crop rotations to avoid pests. These techniques obviously require considerable ecological knowledge of pest phenology. Although these techniques often have other agronomic benefits (e.g., improved soil fertility), the farmers sometimes explicitly mention that they are done to avoid pest damage. For example, in Uganda farmers utilize time of planting to avoid stem borers and aphids in cereals and peas respectively. Many farmers are aware that planting out of synchrony with neighboring fields can result in heavy pest pressure and therefore use a kind of "pest satiation" to avoid extensive damage (mungbeans in the Philippines, Litsinger et al. 1980; rice in Indonesia, Prasadja and Ruhendi 1981). In the central Andes, a potato fallow rotation is carefully observed, apparently to avoid buildup of certain insects and nematodes (Brush 1983). Perhaps the most common way in which farmers manipulate the temporal permanence of agroecosystems is through the traditional pattern of slash and burn or shifting cultivation.

Manipulation of Crops in Space Farmers often manipulate plot size, plot site location, density of crops and crop diversity to achieve several production purposes, although most are aware of the links between such practices and pest control.

• Overplanting: One of the most common methods of dealing with pests is planting at a higher density than one expects to harvest. This strategy is most effective in dealing with pests that attack the plant during early stages of growth. When infested plants are detected, they are carefully removed long before actual death so as to avoid contaminating healthy plants.
• Farm plot location: In Nigeria many farmers, linked by kinship ties, age grouping or friendship, locate their farm plots lying contiguous to each other but leaving room for the expansion of each farm in a particular direction. In accounting for this practice, farmers reported that all pests in the area will discover and concentrate on an isolated farm. Plots are therefore grouped together to spread pest risk among many farmers (Atteh 1984). Conversely, in tropical America, Brush (1983) reports that farmers deliberately use small isolated plots to avoid pests. In many areas farmers carefully use environmental indicators in site location. For example, in Belize, areas where "tiger bush" grows are avoided since they indicate probable future pest problems, especially weeds.
• Selective weeding: Studies conducted in traditional agroecosystems show that peasants deliberately leave weeds in association with crops, by not completely clearing all weeds from their cropping systems. This "relaxed" weeding is usually seen by agriculturalists as the consequence of a lack of labor and low return for the extra work; however, a closer look at farmer attitudes toward weeds reveals that certain weeds are managed and even encouraged if they serve a useful purpose. In the lowland tropics of Tabasco, Mexico, there is a unique classification of noncrop plants according to use potential on one hand and effects on soil and crops on the other. According to this system farmers recognized 21 plants in their cornfields classified as malmonte (bad weeds), and 20 as buen monte (good weeds) that serve as food, medicines, ceremonial materials, teas, soil improvers, etc. (Chacon and Gliessman 1982). Similarly, the Tarahumara Indians in the Mexican Sierras depend on edible weed seedlings (Amaranthus, Chenopodium and Brassica) from April through July, a critical period before maize, bean, cucurbits, and chiles mature in the planted fields in August through October. Weeds also serve as alternate food supplies in seasons when the maize crops are destroyed by frequent hailstorms. In a sense the Tarahumara practice a double crop system of maize and weeds that allows for two harvests: one of weed seedlings or quelites early in the growing season (Bye 1981). Some of these practices have important insect pest control implications since many weed species play important roles in the biology of herbivorous insects and their natural enemies in agroecosystems. Certain weeds, for example, provide alternate food and/or shelter for natural enemies of insect pests during the crop season but more importantly during the off season when prey/hosts are unavailable (Altieri and Whitcomb 1979).

TABLE 1.1 Pest management strategies and specific practices used by traditional farmers throughout the developing world.

* Strategy	Practices
Mechanical and physical	Scarectrs, sound devices Wrapping of fruits, pods Painting stems, trunks with lime or other materials Destroying ant nests Digging out eggs/larvae Hand picking Removal of infested plants Selective pruning Application of materials (ash smoke, salt, etc.) Burning vegetation
Cultural practices	Intercropping Overplanting or varying seeding rates Changing planting dates Crop rotation Timing of harvest Mixing crop varieties Selective weeding Use of resistant varieties Fertilizer management Water management

Manipulation of Crop Diversity The practice of multicropping and/or mixed cropping is intricately related to traditional agriculture (Toledo et al. 1985). Although most farmers use intercropping because of labor and land shortages or other agronomic purposes, the practice has obvious pest control effects (Altieri and Letourneau 1982). Many farmers know this and use polycultures as a play-safe strategy to prevent build-up of specific pests to unacceptable levels, or to survive in cases of massive pest damage. For example, in Nigeria, farmers are aware of the severe damage done to the sole crop of cassava by the variegated grasshopper after all other crops have been harvested. To reduce this damage farmers deliberately replant maize and random clusters of sorghum on the cassava plot until harvest time (Atteh 1984).

In his surveys of traditional maize cropping systems in Tlaxcala, Trujillo (1987) found that certain crop associations would reduce populations of the pestiferous scarab beetle Macrodactylus sp., while others would increase them. In a survey of insect communities associated with maize grown associated with other annual crops and with trees or shrubs in Indonesia, it was found that pest damage and abundance of natural enemies varied considerably between fields. It was clear that pest dynamics varied significantly between systems depending on insect species, locat...

Table of contents

• Cover
• Half Title
• Series Page
• Title
• Copyright
• Contents
• Preface
• 1 Designing and Improving Pest Management Systems for Subsistence Farmers
• 2 Steps Toward an Alternate and Safe Pest Management System for Small Farmers in the Philippines
• 3 A Farming Systems Approach to Insect Pest Management for Upland and Lowland Rice Farmers in Tropical Asia
• 4 Implementation of IPM for Small-Scale Cassava Farmers
• 5 Effects of Cassava Intercropping and Varietal Mixtures on Herbivore Load, Plant Growth, and Yields: Applications for Small Farmers in Latin America
• 6 Human Interactions in Classical Biological Control of Cassava and Mango Mealybugs on Subsistence Farms in Tropical Africa
• About the Book and Editor
• About the Contributors
• Index