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Keywords:

  • climate variability;
  • adaptive;
  • management strategy;
  • perception;
  • pests;
  • diseases incidence;
  • crops

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

The article examines the influence of local perceptions of climate variability and pest–disease incidence on crops and its management and on adaptive forest–agricultural practices. The study was conducted in the humid forest of Southern Cameroon along a resource use intensification and population gradient using a semi-structured questionnaire administrated to farmers. The results showed that the level of severity of crops–pests incidence was perceived as high, with an increase over the past 15 years. A high incidence of pests–diseases was perceived on yield/income of cocoa, cassava, and groundnuts. The results indicated that each crop has its management practices of pests–diseases both at the crop and land use level. The farmers respond positively to their perception of climate variability by anticipating cropping practices, by harvesting earlier or later, and by adapting strategies of pests–diseases with crops and land use practices that affect the sustainability of forest–agriculture.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

During the last five years, there have been unprecedented shifts in the interests of the scientific community and international policy makers with the threats of climate change and global warming. These shifts have had an increasing affect on international development and economic growth (MEA 2005:25–30). Climate change represents a nightmare scenario for the future of the people of Africa, the world's poorest continent, and the consequence could be dramatic declines in rainfall, a fall in crop yields that would make previous famines look like small tragedies, and increasing bush fires in humid forest (UK Government 2006). There are likely to be severe water shortages and serious disturbances in the rainfall patterns in many parts of the African continent. At the same time, this foreseen disproportionate impact on Africa seems to have ignored historical human–nature relationships that are recognized as the major factors in the development of human societies and their adaptation to specific climatic conditions (Instone 2003a:4–5; Nordhaus 2007:690–702). Looking from the historical perspective, for tens of thousands of years, humans were foragers, yet in a relatively short period (c. 10,000–5,000 years ago) agricultural systems appeared in several widely separated parts of the Old and New World. By 2,000 years ago, most human populations were dependent on agriculture. This subsistence shift radically transformed human ecology, social organization, demography, and even art and religion; yet we still do not have a widely agreed explanation for why (as opposed to how) it occurred (Winterhalder 1993:330–334; Winterhalder and Goland 1997).

Present consensus seems to be that while climate change may be a factor in the origins of agriculture, it is not sufficient in itself to justify the development of agriculture. These findings also suggest that even the current natural resource management (NRM) practice of slash-and-burn agriculture or “shifting cultivation” (in this article, slash-and-burn agriculture is called forest–agriculture) has a historical background, and the practices associated with it are the result of human–nature interactions with climate variability, transitions of seasons, migrations, and population pressure (Instone 2003a:10–12; Rindos 1980:1984–760, 1984; Westphal et al. 1985; Winterhalder 1993:327–330; Winterhalder and Kennett 2006:15–17).

The relationships between climate variability, transition of seasons, and the spread/incidence of pests–diseases on crops is well documented all over the world (Altieri and Nicholls 1999:75–79; MEA 2005:35–40; Weiss 1990:90–91). This is also true for how activities such as agriculture, pastoralism, hunting, honey production and fishing, and the collection of nontimber forest products are influenced by the management of local ecological knowledge and climate variability (Altieri 2002:10–14; Ellis 1995:42–44; Joshi et al. 2004:13–14; Mviena 1970:10–12; Scoones 1995:25–30). In Africa, agriculture is largely traditional and characterized by a great number of smallholdings with more or less 1 ha per household. Crop production takes place under extremely variable agroecological conditions, with annual rainfall ranging from 250 to 750 mm in the Sahel in the northwest and in the semiarid east and south, from 1,500 to 4,000 mm in the forest zones in Central and West Africa (Abate et al. 2000:640–645; FAO 1999:35–40). Besides this agroecological heterogeneity, the same agricultural research and development (R&D) processes are often implemented without understanding the contextual economic and social constraints under which local pest management strategies take place. These processes focus on either the introduction of improved crop varieties or the use of pesticides mostly adapted for cash crops and were implemented irrespective of the role of knowledge and spatial contexts of agricultural biodiversity management (Instone 2003a:9–11, 2003b:14; Penkuri and Jokinen 1999:145; Woodley 2004). Although many government extension programs encourage the use of pesticides, the majority of African farmers still rely on indigenous pest management approaches to manage pest problems (Abate et al. 2000:640–642).

It has been shown that there is a high degree of uncertainty in the behavior of many African ecosystems. This makes it difficult to predict the levels of production that a system might yield from year to year, and how ecosystem structure may change over time (Ellis 1995:40; Scoones 1995:35–37). African farmers have learned to deal with uncertainties by using complex plant communities, that is, multispecies crops to reduce risks on yield and to influence their diverse range of social goals and definitions of well-being (Altieri and Nicholls 1999:75–77; Scoones 1995:20–22; Smith and McSorely 2000:156). Farmers often select well-adapted, stable crop varieties, and cropping systems are such that two or more crops are grown in the same field at the same time. These diverse traditional systems balance natural enemy abundance and generally keep pest numbers at low levels (Abate et al. 2000:640–644; Altieri 2002:10–13; Smith and McSorely 2000:157). As a result, pest management practice in traditional agriculture is a built-in process in the overall crop production system rather than a separate well-defined activity (Abate et al. 2000:655; Altieri 2002:15–17).

Recent studies have shown that economic and social constraints have kept pesticide use in Africa at the lowest levels among all the world regions, and these figures are not about to change (Abate et al. 2000:633; FAO 1999:15–20). Furthermore, despite the huge investment made in pest management research activities in Africa with classical biological control and breeding of host plant resistance, except for classical biological control of the cassava mealy bug, research results have not been widely adopted in field management. This could be due to African farmers facing heterogeneous conditions, not needing fixed prescriptions or one ideal variety, but instead a number of options and genotypes to choose from (Abate et al. 2000:654). Other recent studies have shown that farmers learn through experimentation concerning the management of their crops and the effects of the incidence of pests–diseases on crop yields (Altieri and Nicholls 1999:75–77; Haverkort and Rist 2004; Joshi et al. 2004:10–12; Van Mele and Van Chien 2004:72–73; Vernooy and Song 2004). Each season is an experiment during which new knowledge is obtained and new ideas are generated. The experimental process happens by considering market conditions or access, the decision to diversify the number of farms and crops, and farmers’ social and livelihood goals. In Cameroon, it has been shown that farmers’ response to uncertainty is promoted by climate variability and seasonal transitions, by anticipating or delaying the field management activities such as clearing, burning, tillage, ridging, sowing, and use of pesticides and several crop varieties (Molua and Lambi 2007:12–15). In Southern Cameroon, between 18 and 25 crop species can be found in a single mixed food crop farm (Mala 2009:106–107). The number of crop varieties of cassava (Manihot esculenta), plantain (Musa paradisiaca), and groundnuts (Arachis hypogea) is variable (three to four) and it is largely influenced by farmers’ knowledge of their biophysical qualities such as resistance to pests and diseases, good taste, and good yield in crop processing (Mala et al. 2008:101; Mala 2009:139–140).

In summary, traditional NRM decisions and practices are highly influenced by various forms of knowledge such as the bio-ecological indicators associated with the climate variability and transition of seasons (Altieri 2002:9; Joshi et al. 2004:15–17). Nevertheless, the links between these forms of knowledge and the ability to adapt management practices to uncertainty generated by climate variability has yet to be examined. This understanding is a crucial step in order to build/develop adaptive capacity in social-ecological systems (Folke et al. 2002; Prabhu 2003:10–14; Scheffer et al. 2002). More specifically, the relationships between the spatial distribution of agricultural biodiversity, the incidence and effect of pests–diseases on crop yield, the perception of climate variability, and the uncertainty conditions through which farmers adapt their agricultural practices have received little attention and remain poorly analyzed.

This study was developed to examine the consequences of local perceptions of climate variability on the ability and adaptive capacity of farmers in slash-and-burn agriculture in Southern Cameroon to use their local knowledge as well as to deal with pests–diseases on crop yield, their corrective management actions, and adaptive management in slash-and-burn agriculture. The following questions were addressed: What are the perceptions of climate variability and how do these affect management activities in slash-and-burn agriculture? What are the perceptions and management actions to deal with pest–disease problems on the main crop species? How do local agricultural biodiversity knowledge systems help farmers to respond and adapt to the incidence of pests and diseases on crops? How do the socioeconomic conditions of villages and farmers affect the management actions of pest–disease problems on the main crop species? The general hypothesis was that local perceptions of climate variability affect farmers’ pest–disease management strategies as they respond and adapt slash-and-burn agricultural practices.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

Study Area

The study site is located in the forest margins of Southern Cameroon where the Alternatives to Slash and Burn (ASB) program (ASB 2000), with their technological interventions and policy recommendations for the Congo basin, conducted research (Gockowski et al. 2005:310–315). The 15,500 km2 benchmark area covers gradients in both intensity of resource use and population density. (1) The intensity of resource use is defined by the length of fallow that increases from the Yaoundé block (3.9 years), through the Mbalmayo block (5.4 years) to the Ebolowa block (7.5 years); and (2) the population density decreases from the Yaoundé block, with 30–90 people per square kilometer, through the Mbalmayo block, with 10–30 people per square kilometer, to the Ebolowa block, with less than 10 people per square kilometer, corresponding to high, medium, and low levels of the population density gradient (Gockowski et al. 2004:7–8, 2005:310–315). The study site is illustrated in Figure 1. The climate is equatorial, and rainfalls are in a bimodal patterns ranging from 1,350 to 1,900 mm per annum and an increasing gradient from the northwest to the southeast. The climate-related constraints, such as droughts and heavy rains, affect water availability and humidity extremes. This in turn affects the development of fungal/bacterial diseases and insect pests on food and tree crops and the whole farming strategy and management of the land (Gockowski et al. 2004:15–18; Manyong et al. 1996:13–17). There is much variation between blocks for different important characteristics (Mala 2009:30–32). Market access is manageable in Ebolowa and Yaounde and manageable to good in Mbalmayo. Very few respondents in all three blocks considered market access as bad. Fifty-five percent of farmers had an estimated land area of more than 20 ha, and 65 percent had an estimated annual revenue of more than CFA350,000 (local currency) (Mala 2009:32).

figure

Figure 1. The Alternatives to Slash and Burn (ASB) Forest Margins Benchmark in Southern Cameroon (Gockowski et al. 2005)

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The most important agricultural land uses in the study area include food cropping systems such as groundnut/cassava-based mixed food crop fields, cocoa plantations, and plantain/melon-based fields. These land uses contain the crops that are susceptible to disease and pest attacks. For each of these crops, the associated diseases/pests have been identified in the literature as follows: cocoa with fruit rot; plantain with nematodes, sigatoka disease, and cigar-end diseases; groundnuts with leaf-spot disease, root rot, rust, aflaroot, and rosette-virus diseases; cassava with anthracnose, leaf spot, and tuber rots; and palm tree with blast, crown disease, vascular-wilt disease, and trunk and bud rots (Westphal et al. 1985). Both the plantain and plantain/melon-based fields are generally targeted in the longer period fallow fields and secondary forests because of the better site conditions. Input intensive horticultural monocrops and maize, intended for the fresh produce market, are frequently encountered in the Yaoundé block, which has the best access to urban markets of the three blocks. Another process associated with increasing resource use intensification and farming system diversification is the number of different field types (Gockowski and Baker 1996:7–10). ASB survey results have revealed that 62 percent of the households in the Yaoundé block had 5–8 distinct field types, versus only 28 percent in the Mbalmayo block and 44 percent in the Ebolowa block (Gockowski et al. 2004:10–11). The field management practices are greatest in the Yaoundé block. The use of purchased input-improved varieties, pesticides, and fertilizers (with annual crops) was not common in the Mbalmayo block and was nearly nonexistent for fertilizers and pesticides in the Ebolowa block. However, in the Yaoundé block, 56 percent of households used improved varieties, 39 percent used fertilizers, and 51 percent used pesticides. The tillage before planting, the use of ridges, and planting in rows was also more frequent in the Yaoundé block. The intensity of field management practices follows the resource use intensification gradient within the forest margins of Southern Cameroon. These differences are very significant for the use of improved varieties, fertilizers, fungicides, and insecticides (Gockowski et al. 2004:13).

Sampling Methods

Six villages were selected from within the humid forest benchmark area, with two in each block, to understand the decision-making processes behind the traditional practices for the management of the incidence of pests and diseases on crop species. The two top villages in terms of the higher intensity of R&D activities were selected per block. The intensity of R&D activities was measured by three categories based on the monthly duration of the interventions (three days of activities; one week of activities; and more then 10 days of activities). For each block, a matrix was used to categorize each village as low, medium, and high intensity of R&D activities, using the different criteria. In each block, the two villages with the highest rating were retained for this study.

In each selected village, five households were sampled to give a total of 30 households (5*6 = 30) for the study. These households were selected based on the criteria of their participation in the development and utilization of the innovations. These criteria included three categories: (1) farmers involved in on-farm research and testing the innovations; (2) farmers who were not directly involved in on-farm research but who have received benefits from on-farm research and have tested them; and (3) those who were not involved in any activity and who did not test any innovations. A list of names of respondents in each category was compiled to select respondents based on the estimated proportion of each group (category) over the total numbers given by the village.

Five crop species were selected from the more than 25 species for the assessment of the incidence of pests on crops and the strategies for their management. The criteria used for their selection included: (1) their economic importance; (2) the high number of cultivars per crop species; (3) the importance of crops for household consumption based on a literature review; and (4) the impact of pests on crop yields. The final selection of five-crop species retained cocoa, cassava, groundnuts, plantain, and cocoyam.

Data Collection

The data were collected through household interviews, using a semi-structured questionnaire, to analyze the relationships between the perception of climate stress, the incidence of pests–diseases on crops, and the adaptive management practices in slash-and-burn agriculture.

Data on perceptions of the effects of climate variability on slash-and-burn agricultural practices based on local indicators were collected. A list of indicators was proposed to farmers for analysis and validation and eventual retention. Six indicators were retained and covered the following variables: (1) abundance of insects; (2) severity of crop pests–diseases; (3) appearance of new crop pest–disease species; (4) disappearance of certain plant/crop species; (5) occurrence of extreme rainfall events or heavy rains; (6) occurrence of extreme drought events or severity of drought. The evaluation was based on three categories or levels in terms of the agricultural calendar (low effects, medium effects, and high effects) with four periods: today, 5 years ago, 10 years ago, and 15 years ago. The perception of the impacts of the selected local indicators of climate variability on the implementation of field management activities was assessed at three levels (low, medium, and high).

Following this, data on the perception of the effects of pests–diseases on crop yield/income for the five most important crops (cocoa, plantain, cassava, cocoyam, and groundnuts) were collected. The assessment was based on three categories: low effects on yield/income; medium or manageable effects on yield/income; and high effects on yield/income. In addition, the management actions to mitigate the effects of pests–diseases on crop yield/income were recorded. Five actions were proposed to farmers who then discussed the relevance of each and validated them. Seven categories of action were used: nothing/no action; use of modern pesticides; abandonment of crop varieties; introduction of new crop varieties and tree species; introduction of improved varieties; introduction of new cropping practices; and use of local pesticides. The adaptive local responses to the management of crop pests–diseases were recorded: rotation of crops between season/years; abandonment of a field to become fallow and opening of a new farm; modern farming methods such as the use of modern or local pesticides, insecticides, and fertilizers; and improved local varieties.

Data Analysis

Data were computed in Excel, and descriptive statistics were calculated using XLStat2007 (XLStat, Barcelona, Spain). The calculations were made based on the number of persons participating in the household survey over the total number of observations. For the calculation of the percentages, the minimum number of people who participated in the household discussions was considered, with generally three to five people per household. The number of responses per variable was expressed as percentage of total number of respondents, that is, a total of 124 respondents with respectively 45 respondents in Ebolowa, 42 respondents in Mbalmayo, and 37 respondents in Yaoundé.

Frequency and contingency tables were prepared to analyze the relationships between the crop pest–disease management strategies and perception of village market access, perception of climate variability/stress, farmer's financial and natural capitals, and history of land uses. Several types of relationships were investigated including between perceptions of current climate variability and pest management strategies; between pest–disease management strategies and farmer's financial and physical capital; between pest management strategies and former land use in the cropping–fallow–forest conversion cycles; and between perceptions of climate variability and the implementation of field activities.

The results are based on data collected from household census within 30 households with the responses of the individual members of the households. Where perceptions were tested for the different years up to 15 years ago, it should be considered that the assessment for the current year would be more accurate than perceptions from memory for periods of 10–15 years ago.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

Perception of Climate Variability/Stress

The surveyed farmers had different perceptions of changes in different factors used as indicators of climate variability (Table 1). (1) Perception of abundance of insects is that about 40 percent of the respondents considered this to be low, throughout the 15 years, but about 60 percent of the respondents had different opinions of the medium to high abundance. (2) Perception of severity of crop pests–diseases was high 15 years ago (65 percent of respondents), low (47 percent) to medium (50 percent) 10 to 15 years ago, and currently low (87 percent). (3) Perception of appearance of new plant species (invader species not used) was high (67 percent) 15 years ago, low (40 percent) to medium (43 percent) 10 to 15 years ago but stable since the last 5 years (30 percent) with a current low appearance (44 percent). About 56 percent of the respondents had different opinions of the medium to high assessment of appearance of new plant species. (4) Disappearance of certain plant species is that the perception was high 15 years ago (56 percent), but this high rating decreased sharply to the present (21 percent), and 58 percent of respondents considered it as currently low (58 percent). (5) About the extreme rainfall events or heavy rains, the perception was that 15 years ago, the high or extreme rainfall events were few (low) (61 percent), and this changed to low to medium 10 years ago (50–43 percent, respectively), to medium 5 years ago (63 percent), and to the current low (47 percent) to medium (47 percent). (6) About extreme drought events, the perception 15 years ago was that it was low (71 percent), which then changed to low to medium 10 years ago, to the current medium perception (53 percent).

Table 1. Perception of indicators of climate variability
Indicators of climate variabilityCategoriesFrequency of perception by time period (% of 124 respondents within a specific period)
Y-0Y-5Y-10Y-15
  1. Legend: Y-0, current year; Y-5, 5 years ago; Y-10, 10 years ago; Y-15, 15 years ago.

Abundance of insectsLow40.340.339.539.5
Medium12.950.046.021.0
High46.89.714.539.5
Severity of crop pests–diseasesLow87.046.846.810.5
Medium6.550.050.025.0
High6.53.23.264.5
Appearance of new plant species (invader species not used)Low43.640.47.37.3
Medium26.629.842.725.8
High29.829.850.066.9
Disappearance of certain plant speciesLow58.241.814.57.3
Medium20.931.648.437.1
High20.926.637.155.6
Extreme rainfall events or heavy rainsLow46.820.250.061.3
Medium40.362.942.723.4
High12.916.97.315.3
Extreme drought events or severity of droughtLow23.443.546.071.0
Medium53.243.539.514.5
High23.413.014.514.5

Relationship between Perceptions of Climate Variability and Field Management Activities

Farmers use different field management activities to deal effectively with specific events that relate to climate variability (Table 2). None of the field management activities are highly effective to deal with abundant insects, but patch clearing, weeding, and harvesting the crops are medium effective. Crop harvesting is highly effective and patch clearing is medium effective to deal with the appearance of new invasive plant species. Most field management activities are highly efficient to deal with extreme rainfall events, but crop harvesting and sowing and planting (medium) and patch clearing (low) are less effective. Tillage, ridging, sowing and planting, and harvesting are considered highly effective actions to deal with extreme drought events.

Table 2. Relationship between perception of current climate variability/stress and efficiency of field management activities
Indicators of climate variabilityField management activities
CLBUTIRISPUPWEHA
  1. Legend: CL, patch clearing; BU, burning; TI, tillage; RI, ridging; SP, sowing and planting; UP, use of pesticides; WE, weeding; HA, harvesting; Efficiency of field management activity: Low = (*); Medium = (**); High = (***).

Abundance of insects***********
Appearance of new invasive plant species***********
Extreme rainfall events or heavy rains********************
Extreme drought events or severity of drought****************

Relationship between Pest–Disease Management Strategies and Perceptions and Characteristics of Farmers and Farms

Importance of different pest–disease management strategies used by farmers

A high number of farmers (82 percent) follow a crop strategy whereby a field is abandoned to become fallow and a new patch is cleared for cultivation (Table 3). A few farmers (15 percent) use modern farming methods (i.e., use chain saws to cut trees, improved seeds, and modern pesticides and fertilizers), and the rest (3 percent) rotate crops between seasons/years.

Table 3. The relationship between farmers’ pest–disease management strategies and their perceptions of climate variability/stress, village access to markets, farmer's financial and natural capital, and the former land use on the farm
 Local pest–disease management strategy for crops
Abandon field to become fallow and open a new farmUse of modern farming methodsRotate crops between seasons/years
Number of respondents using strategy
(102)(18)(4)
Current perception of climate variability/stress (% of respondents)
Low14.70.025.0
Medium14.7100.025.0
High70.60.050.0
Perception of village access to markets (% of responses)
Poor4.00.00.0
Acceptable85.00.025.0
Good11.0100.075.0
Farmer's financial capital (% of respondents)
CFA200,000–250,00013.50.025.0
CFA250,000–300,00013.50.025.0
CFA300,000–350,0000.00.00.0
> CFA350,00073.0100.050.0
Farmer's natural capital (% of respondents)
5–10 ha12.047.025.0
10–15 ha8.00.025.0
15–20 ha0.00.00.0
More than 20 ha80.053.050.0
Former land use (% of respondents)
Secondary forest49.050.0100.0
Virgin forest17.00.00.0
Mixed food crops farms17.00.00.0
Cucumeropsis farms17.050.00.0
Influence of current perceptions of climatic variability

A majority of farmers (71 percent) following a crop management strategy whereby a field is abandoned to become fallow and a new patch is cleared for cultivation, perceive that climate variability or stress is high (Table 3). All the farmers (100 percent) using modern farming methods to local pests–diseases perceive that climate variability or stress is medium. Fifty percent of the farmers using rotation of crops between seasons/years as a means to manage pests–diseases perceive that climate variability or stress is high.

Influence of access to markets

A high majority of farmers (85 percent) following a crop strategy whereby a field is abandoned to become fallow and a new patch is cleared for cultivation perceive that market access is acceptable (Table 3). All the farmers (100 percent) using modern farming methods to manage local pests–diseases perceive that market access is good, while 75 percent of farmers rotating crops between seasons/years perceive that market access is good.

Influence of farmer's financial capitals

A majority of these farmers (73 percent) following a crop strategy whereby a field is abandoned to become fallow and a new patch is cleared for cultivation have annual financial revenue of more than CFA350,000 (Table 3). All farmers (100 percent) using modern farming methods have an annual financial revenue of more than CFA350,000. Fifty percent of farmers using rotation of crops between seasons/years have an annual financial revenue of more than CFA350,000, while 50 percent have an annual financial revenue of less than CFA300,000.

Influence of farmer's physical capitals

A high majority of the farmers (80 percent) following a crop strategy whereby a field is abandoned to become fallow and a new patch is cleared for cultivation have a natural capital of more than 20 ha (Table 3). A relative majority of farmers (53 percent) using modern farming methods have natural capital of more than 20 ha, while 47 percent of them have a natural capital of less than 10 ha each. Fifty percent of farmers using rotation of crops between seasons/years have a natural capital of more than 20 ha.

Influence of former land uses

A relatively high majority of farmers (49 percent) following a crop strategy whereby a field is abandoned to become fallow and a new patch is cleared for cultivation use secondary forests as former land use (Table 3). Fifty percent of farmers using modern farming methods to manage local pests–diseases use secondary forests as former land use and 50 percent use Cucumeropsis farms as former land use. All the farmers (100 percent) using rotation of crops between seasons/years use secondary forests as former land use.

Perception and Management of Pest–Disease Problems on the Main Crop Species

Perception of incidence of pests–diseases on crops yield/income

The perceptions of farmers varied regarding the effect of the incidence of pests–diseases on the yield/income for the different crop species over time (Table 4; see section on methodologies for the typical pests–diseases for the different crop species). (1) The effects of crop pests–diseases on cocoa yield/income were initially (15 years ago) perceived as mainly medium but have since been perceived as high (75 percent of responses 10 years ago and 87 percent since then); (2) the perceptions for plantain yield/income were a low-to-medium effect of pests–diseases 15 years ago, a medium-to-low effect 10 years ago but during the last years farmer perceptions varied between more or less equal ratings of low to high. (3) For groundnuts, the perceived effects of pests–diseases on yield/income are overall low over the 15 years, but 10 years ago, more people perceived them to be medium, and over the last 5 years, some respondents (30+%) considered the effects to be high. (4) Cassava yield/income, according to the respondents, was initially low to medium but has since increased from medium to high 10 years ago, and then from high to medium for the last 5 years. During the last 5 years, the rating of high has increased from 63 percent to 73 percent. (5) Cocoyam yield/income is perceived to be little affected by pests–diseases (overall about 70 percent), but the perceived high effect has increased from 0 percent to 27 percent over the 15 years. The general trend is that the perception of the effects of pests–diseases on yield and income has increased over the past 15 years, particularly in cocoa and cassava.

Table 4. Valuation/perception of the effects of pests–diseases on the yield of the main agricultural crop species
Main cropsCategoriesPeriod of time
Y-0Y-5Y-10Y-15
Frequency of responses (% of 124 respondents within a specific period)
  1. Legend: Y-0, current year; Y-5, 5 years ago; Y-10, 10 years ago; Y-15, 15 years ago.

CocoaLow0.06.53.222.6
Medium12.96.521.848.4
High87.187.075.029.8
PlantainLow30.026.632.348.4
Medium33.043.653.240.3
High37.029.814.50.0
GroundnutsLow45.037.937.959.7
Medium21.027.448.436.3
High34.034.713.74.0
CassavaLow6.50.07.054.0
Medium20.137.154.036.5
High73.462.939.09.5
CocoyamLow70.270.071.073.4
Medium12.913.025.026.6
High16.917.04.00.0
Management actions to mitigate the impacts of main crop pests–diseases on yield

The general trend in terms of management actions is to only take action for cocoa and to take no action in the case of cocoyam, groundnuts, plantain, and cassava (Table 5), but there is a change over time toward taking some forms of action. Although eight management actions have been used for cocoa, modern pesticides are mostly used alone, although sometimes they are used together with improved farming activities and lately also with improved cocoa varieties. Fifteen years ago, no action was the main response (82 percent of responses) for plantain, but the “no action” has decreased with introduction of improved farming methods and/or improved varieties increasing in importance with other actions (eight in total) also being tried by some farmers. For groundnuts, 85 percent of farmers followed a “no action” approach, but because more farmers changed to other actions with only 55 percent of the farmers currently following the “no action,” they have changed mainly to the use of modern pesticides, and the introduction of new crop varieties and tree species, and improved farming methods. The “no action” was followed by 76 percent of the cassava farmers 15 years ago; this decreased to 36 percent of the farmers. Although they tried nine different actions, the current important actions are the introduction of new crop varieties and tree species and to some extent the introduction of improved farming methods. Fifteen years ago, 91 percent of the farmers used the “no action” approach with cocoyam, but currently only 65 percent of the farmers follow this approach and more farmers have changed to modern pesticides, with some also introducing improved varieties and improved farming methods. Although there has been an increase in the use of a combination of two or more modes of pest–disease management, such actions are used by very few farmers (except in the case of cocoa).

Table 5. The importance of different modes of pest–disease management for the main crops
Main cropsCategoriesPeriod of time
Y-0Y-5Y-10Y-15
Frequency of responses (% of 124 respondents within a specific period)
  1. Legend: Y-0, current year; Y-5, 5 years ago; Y-10, 10 years ago; Y-15, 15 years ago.

CocoaLow0.06.53.222.6
Medium12.96.521.848.4
High87.187.075.029.8
PlantainLow30.026.632.348.4
Medium33.043.653.240.3
High37.029.814.50.0
GroundnutsLow45.037.937.959.7
Medium21.027.448.436.3
High34.034.713.74.0
CassavaLow6.50.07.054.0
Medium20.137.154.036.5
High73.462.939.09.5
CocoyamLow70.270.071.073.4
Medium12.913.025.026.6
High16.917.04.00.0

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

We started this article by challenging the prescriptive solutions for pests–diseases in crop management in Africa based on the use of pesticides and of improved varieties that have touched only a very few number of farmers living in various heterogeneous conditions (Abate et al. 2000:635). Reversing this trend requires the understanding of the strategies used by farmers to manage crop pests–diseases where climate variability promotes uncertainty. The results of the study show that the six local indicators used to capture farmers’ perception of climate variability fluctuate too much (Table 1), and this confirms the high degree of uncertainty that characterizes the behavior of climate and that influences human life-style, field management activities, and the agricultural calendar (Mala et al. 2010:178–179). The results also show that the local crop pests–diseases management strategies are dynamic processes that take place each farming season; it is an outcome of combined learning, reasoning, and the perception of future events that link field management activities to planning of crop uses both for household consumption and income generation (Joshi et al. 2004:12; Mala 2009). It indicates that each farming season is an experiment in which new knowledge is obtained and new ideas are generated from the field management activities. This confirms previous studies that have shown that traditional agroecological knowledge takes place under specific biophysical climate and socioeconomic context by considering market conditions or access, the decision to diversify the number of farms and crops, and farmers’ social and livelihood goals (Altieri and Nicholls 1999:72; Den Biggelaar 1996:9–12; Mala 2009:142–152; Van Mele and Van Chien 2004:72).

Although the results show that the perception of climate variability influences pest–disease management via related field management activities, the occurrence of heavy rains could affect the proper use of pesticides and may also result in the anticipation or delay of the field management activities such as clearing, burning, and tillage. These activities are often perceived as the ones that mitigate the spread of weeds considered as host of vectors of pests–diseases on crops (Molua and Lambi 2007; Westphal et al. 1985). However, the respondents’ crop pest–disease management strategies are also influenced by their heterogeneous socioeconomic context, characterized by their ability to fill both their consumption needs and their market preferences (Mala 2009:130–150). This ability is based on the management of a range of crop varieties with diverse qualities. As illustration, up to 25 crop species can be found in a single mixed food crop farm in the study area with cassava (M. esculenta), plantain (M. paradisiaca), and groundnuts (A. hypogea) having a high number of crops varieties per farm varying from three to four; this is also largely influenced by farmers’ knowledge of their biophysical qualities such as resistance to pests and diseases, good taste, and good yield in crop processing (Mala 2009:145–150; Mala et al. 2008:100). This confirms the fact that African farmers face heterogeneous conditions, not needing fixed prescriptions or one ideal variety but a number of options and genotypes to choose from (Abate et al. 2000:654–655; Altieri 2002:11; Joshi et al. 2004).

The perception of high incidence/effects of pest–disease problems on the yield of cocoa, plantain, and cassava is more significant than on the other crops (Table 4). These results suggest the more the economic importance of a crop, the more it is affected by pests–diseases. This is justified by the increased demand for crop production in Africa correlated with increased population pressure that has necessitated agricultural expansion as well as an increase in plant material movement that in turn has facilitated the accidental introduction of local and foreign pests–diseases (Abate et al. 2000:655; Fomekong et al. 2008:366). Even if a high number of farmers indicate that they do not take any action for several of these crops in the case of pests–diseases, this should be taken with caution. This time is probably the one taken by the farmers to learn from the behavior of their crops in the plots. At the farm level, it seems that each crop has its own specific management practices to mitigate pests–diseases that is determined not only by the perception of climate variability but also by the knowledge of crop behavior and the experiences in farming. These pest–disease management practices are based on one or more management actions ranging from the use of modern or local pesticides, abandonment of varieties, introduction of improved varieties of specific crop species or new varieties and tree crop species, and introduction of new farming practices. The use of these combinations illustrates the complexity of local management and the challenge to avoid prescriptive solutions for pest–disease management in the study area. This is because farmers live in specific biophysical conditions of land availability and rainfall regimes, and socioeconomic conditions with the level of market sophistication and organization and market access that also determine their relying on traditional land use practices and particularly the use of intercropping systems (Abate et al. 2000:656–657; Altieri 2002:18–20; Gockowski et al. 2004:8–10, 2005:310–312; Westphal et al. 1985:130–160).

At the landscape level, the three pest–disease management strategies used within the cropping–fallow–forest conversion cycle, including the abandonment of field to become fallow and clearing up of patches, the use of appropriate farming methods, and the rotation of crops, are all influenced by farmers’ knowledge of land ownership, level of income, and perception of access to market (Table 5). There also exist collective strategies to break the cycles of insect or disease outbreaks as illustrated by the farming of melon seed (Cucumeropsis manii), which is done once every two years; this period is necessary to break the biological cycle of insect pests such as Dysderus voelkeri (Hem Dysdercus Voelkeri iptera: Pyrrhocoridae) and Dacus bivitattus (Diptera: Tephritedae) that attack melon seed fruits and cause high yield loss (Fomekong et al. 2008:369). The results suggest that the farmers respond positively to their perception of pests–diseases on crops by adopting both adaptive management strategies and field management practices that generally keep pest numbers at low levels and to maintain a threshold of agricultural and forest sustainability outcomes.

The abandonment of fields to become fallow plus opening of new farms seems to be the shared and common pest management strategies among farmers with different levels of land ownership, income, access to market, and with various levels of incidence of crops on yield and income. This can be related to the resource use intensification gradient within the forest margins. To deal with pest management within the study area, three scenarios could be drawn following the heterogeneity of resource use that differentiate the blocks defined by the length of fallow that increases from Yaoundé block (3.9 years), then to Mbalmayo block (5.4 years) and to Ebolowa block (7.5 years). Except for the market access that is perceived to be manageable for all blocks, the heterogeneity of market access constraints, estimated annual revenue, land ownership, local climate variability indicators, and the knowledge of the ability of crops to adapt and the alternative solutions for food consumption and income generation after a loss in a field are critical factors to integrate in order to build the adaptive capacity of pest–disease management strategies under climate variability/stress and eventually climate change scenarios specific for each block within forest margins of the benchmark area of Southern Cameroon.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

The objective of this article was to explore the relationships between local perceptions of climate variability, pest–disease incidence on crops and its management actions, and adaptive forest–agricultural practices. The perceptions of climate variability have been captured based on six local indicators; the values given by respondents fluctuate considerably, and there were no discernable patterns. Five main crop species (cocoa, cassava, plantain, cocoyam, and groundnuts) have been used to identify three pest–disease management strategies both at the landscape and farm level (field pest management) including the abandonment of fields to become fallow plus opening of new farms and rotation of land use between years/seasons for the higher production and the use of modern farming methods. Each of the main crops seems to have its own pest–disease management strategy based on a range of management actions that were not isolated from the whole management of the farm. The socioeconomic context of respondents including their perception of market access, estimated annual income, and estimated land ownership affect the adoption of management strategies both at landscape and farm level. The results confirm that local agricultural biodiversity knowledge determines the perception of climate variability and farmers’ response and adaptation to the incidence of pests–diseases under uncertainty engendered by climate variability.

Several gaps have been identified in the article in terms of methodology and research areas needed. This was an exploratory study with extractive processes of data analyses, thus, it is difficult to generate appropriate solutions. The information generated can guide the improvement of our methodology in terms of linking knowledge generated to participatory action research. It seems to be an appropriate framework to refine the identification of local indicators of climate variability such as insects, which are good indicators of the change in the environment, and to understand under which conditions it is possible to improve local crop pest–disease management practices. Additional research is also needed to understand how farmers respond and adapt their consumption needs and income generation in case of major crop yield losses and to capture the role that alternative forest products can play in the replacement of the losses. Lastly, it is also important to understand how the different regimes of heavy rains and extreme drought affect the forest–agricultural field management activities.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography

The authors would like to thank the European Union, the START/NORAD Fellowship program, and CIFOR who funded the study.

References Cited

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  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography
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Biography

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. References Cited
  10. Biography
  • William Armand Mala (PhD) is a forest ecologist with 15 years of field experience in Africa. His work has focused on landscape mosaics and forest agriculture interfaces, community managing forests, participatory action research, knowledge systems and innovation systems approaches, and adaptive comanagement.