CABI - Biocontrol News and Information 26(1) March News

Biocontrol News and Information

March 2005, Volume 26 No. 1

IPM Systems

This section covers integrated pest management (IPM) including biological control, and techniques that are compatible with the use of biological control or minimize negative impact on natural enemies.

IPM in Honduran Subsistence Agriculture: a Multi-Focal Perspective

In many Central American countries, agrochemicals are commonly used in both subsistence and intensive agriculture. For resource-poor farmers, reliance on pesticides for pest management can engender significant costs, and can also instigate pest problems in their production systems. In an effort to discourage farmers from irrational pesticide use, various institutions have introduced them to the key principles of integrated pest management (IPM). Several IPM methods offer cheap and sustainable pest management options, considered attractive to resource-poor farmers. IPM technologies include conservation biological control which encourages the use of indigenous natural enemies for suppression or prevention of pest outbreaks. Since many natural enemies have ecological requirements beyond the field edge, the success of conservation biological control depends upon the wider landscape in which fields are embedded. In Central America, slash-and-burn agriculture, deforestation and inappropriate management of natural resources have affected this landscape considerably and can compromise IPM to varying extents. Quantifying the contribution of the agro-landscape will therefore help us explain farmers' degree of success in adopting IPM within their respective field settings.

The successful adoption of many IPM technologies depends on farmer knowledge and on enabling ecological conditions in their field settings. Where farmers' knowledge is deficient, adoption of such technologies can be increased through delivering essential information to farmers by means of IPM training workshops. This information can contain both technical and non-technical components. Connecting farmers' knowledge with the ecological conditions of their production systems can help explain farmers' actions, including their adoption of IPM. This understanding could also help identify needs for IPM extension and the limits of some IPM technologies like conservation biological control.

In our research we proposed to investigate the potential for conservation biological control in Honduran small-scale maize cropping systems. Influential factors for success of conservation biological control were identified relating in-field natural control to the specificities of the agro-landscape. Our work also set out to assess the importance of farmer knowledge in determining farmer pest management behaviour, specifically their exploitation of the available potential for biological control within their respective field settings. Farmer knowledge systems were validated by comparing them to ecological conditions as observed within the farming environment. Lastly, we quantified the effect of IPM training history on farmer knowledge and pest management behaviour.

Fieldwork was conducted during 2002/03 in rain-fed, hillside areas of southeastern Honduras, where local small-scale farmers cultivate maize as their primary staple crop. In the region, fall armyworm (FAW) (Spodoptera frugiperda) is a key pest of maize.

We took a threefold approach.

Firstly, we quantified pest severity and dynamics within farmers' fields and related those to the abundance and diversity of natural enemies as observed.
Secondly, we measured the contribution of the agro-landscape to in-field conservation biological control and the associated potential for sustainable pest management. Agro-landscape composition was assessed through combining aerial imagery analysis with in-situ vegetation classification.
Lastly, adoption of IPM practices was evaluated through farmer surveys, conducted in communities that were typified by differences in training history and historical pest severity. Farmers' appreciation of key biological and ecological concepts was determined and related to their associated pest management behaviour. Linkages with the ecological characteristics of the farming environment were explored.

Pest Severity and Natural Control

FAW infestation levels were low during both years, and remained below the action threshold (30% plants infested) in most farm plots. FAW infestation appeared influenced by abiotic conditions (altitude, weather) and natural enemies. Levels of FAW parasitism and disease incidence were low, while the arthropod predator complex was extremely diverse and abundant. Infestation patterns indicated that earwigs, carabid beetles and spiders significantly impacted FAW population establishment and growth. Fire ants (Solenopsis spp.), a key predator in many maize-growing systems, seem to be of lesser importance in hillside agriculture.

Agro-Landscape Contribution

In-field natural control was linked to features of the broader agro-landscape. Abundance levels of several natural enemies were related to the composition of the surrounding landscape mosaic. Some natural enemies, such as earwigs and fire ants, were associated with early successional habitats (grasslands, shrublands, etc.). Others however, including spiders and carabid beetles, reached high abundance levels in fields located within later successional environments (broadleaved/pine forest). Although the composition of the agro-landscape affected natural enemy abundance and diversity, it generally did not compromise the suppressive potential of the in-field natural enemy.

Farmers' Actions and the Farming Environment

Although farmers had a limited understanding of pest biology and ecology, they correctly assessed pest severity in their farm plots. Most farmers considered FAW to be of low or sporadic importance and few farmers felt a need to adopt curative pest management techniques. Farmers' agroecological understanding was surprisingly broad. Natural enemies most commonly enumerated included vertebrate and invertebrate predators. Evidence was weak for farmers' appreciation of the role of parasitoids and entomopathogens. Conspicuous and culturally important insects were more often mentioned, thereby confirming earlier findings in the same region. (In 1993, Jeffery Bentley an anthropologist then at the Panamerican School of Agriculture (Zamorano) noted that farmers have an extensive knowledge of various phenomena. He determined that folk knowledge was largely built on the principles of cultural importance and ease of observation.) Farmers' understanding of biological control was consequently related to the ecological specificities of their farming environment. Farmers' appreciation of natural enemies was related to their respective in-field abundance. It was found that abundant, conspicuous natural enemies were better known than species that were less common. IPM training significantly influenced farmer knowledge. Trained farmers had more extensive agroecological knowledge and were likely to try out new technologies. Training had the additional impact as key agroecological concepts were spread through the community through friendship, work or family ties. Since both trained and untrained farmers perceived no acute need for pest management intervention in maize, they responded in a rational manner and did not apply pesticides.

Conclusions

Our research found that subsistence production systems are characterized by high abundance and diversity of natural enemies, which adequately affect pest population dynamics. In-field natural enemy abundance is directly related to the extra-field environment. Even though alterations in agro-landscape composition and management lead to shifts in the natural enemy community, its suppressive potential was rarely compromised. Such findings could facilitate the design of multi-functional landscapes and the promotion of more drastic measures for environmental mitigation. Landscapes can ultimately be designed where natural resources (soil, water, etc.) are conserved while resilience of the maize cropping system is maintained. Landscape management could thereby modify the extra-field environment without negative impacts on pest abundance in this subsistence cropping system.

We also discovered that farmer knowledge is adapted to the agroecological conditions of the farming environment. Ecological processes occurring at a field level are being observed by farmers, and individual experiences are consequently propelled through the community. When introduced to new concepts and theories (through IPM workshops), farmers tend to cross-check acquired information by using their field settings as a touchstone environment. In the case of Honduran small-scale maize cropping, many of the key agroecological processes were easily observable and farmer knowledge reflected in-field conditions. In cases however where inconspicuous ecological processes (parasitism, insect disease) determine pest dynamics, IPM extension would need to supplement existing farmer knowledge systems with key agroecological concepts. Our work highlighted the linkages between farmer knowledge, within-field ecology and the larger agro-landscape and how those elements operate together in determining farmer practices and facilitating IPM adoption. Ultimately, our research showed that, by introducing farmers to IPM and key agroecological concepts, irrational use of pesticides could be prevented.

By: Kris A.G. Wyckhuys and
Robert J. O'Neil, Department of Entomology,
Purdue University, Smith Hall,
901 W. State Street, West Lafayette,
IN 47907-2089, USA.
Email: kwyckhuy@purdue.edu
Web: www.entm.purdue.edu/bclab

Organic Cotton in Peru: a Retrospective and Future Look

Efforts have been underway over the past few years to produce organic cotton in Peru. This has not been an easy venture and a more detailed analysis of the Peruvian socioeconomic and agroecological context is required for future development, particularly concerning pest management systems.

Socioeconomic Context

In Peru, the organic cotton processing plants, which export to the USA, Europe and Japan, provide incentives for organic cotton production, paying an organic certification based on international standards. At a national level, a future Law for the Support and Promotion of Organic and Ecological Agriculture is under discussion, and enterprises which process and export organic cotton are working with farmers and some NGOs, with the following main objectives:

Maintain and develop sustainable agricultural systems, reducing damage to the environment and human health caused by agrochemicals, by efficient pest management.
Improve the economic conditions of the small producers, generating ecosystem diversity and taking advantage of market opportunities.

The NGOs are involved in developing and promoting agricultural research, particularly in the area of pest management, and in some cases support the strengthening of farmers' organizations.

On a general level, the effect of fluctuations in the world market can be marked, generating a certain amount of instability in the production system for organic cotton in Peru. Also, the small-scale farmers are disadvantaged by their economic conditions and the characteristics of existing interrelationships. However, the organic cotton system continues to be dynamic, as demonstrated by the new proposed projects in Pucallpa and Chincha.

Agroecological Context

Cotton is grown in two distinct areas of Peru: the desert coast and the tropical rainforest. Along the coast, organic cotton is grown mainly in the Ca�ete Valley, but has also been produced in Arequipa, and is now recently being promoted in the Chincha Valley.

Tang�is cotton (Gossypium barbadense), a long-staple variety with white fibre, is cultivated in these areas, south of Lima. Pest management is based on the principles of integrated pest management (IPM), although clearly in these cases synthetic chemical pesticides are excluded. Pest management continues to be one of the bottlenecks and is one of the topics receiving most attention within agroecological research.

According to Vreeland (1999), on the northern coast, despite its prohibition by state law between 1930 and 1990, small producers continue to grow native coloured cotton (brown and green), using a traditional cropping system with perennial and associated crops, certified but in small quantities. Since prehispanic times, a specific plant whose scientific name is Lippia alba (according to Ceroni [2002]), has been sown and burnt, and the smoke repels the cotton stainer Dysdercus peruvianus.

In the rainforest, some farmers grow a native cotton, �spero (Gossypium barbadense), a short-staple variety with white and light brown fibre. The farmers in the area surrounding Tarapoto grow cotton in a traditional cropping system with maize, beans and bananas as associated crops, and without the use of agrochemicals. Due to the resistance of the native variety and the biodiversity of the area, the few pests which do exist are at a manageable level. New projects for organic white cotton are projected for Pucallpa, in this case as an alternative to the illicit production of coca.

Cotton Pests in Peru

Tang�is cotton has a variety of pests. According to Gonz�lez (2000) the main pests are earthworms, a stem borer weevil (Eutinobothrus gossypii), the cotton aphid (Aphis gossypii), and Lepidoptera such as Anomis texana, Alabama argillacea, Heliothis virescens, Pococera atramentalis, Bucculatrix thurberiella and Pectinophora gossypiella. Additional pests are the Peruvian boll weevil Anthonomus vestitus) and the cotton stainer (Dysdercus peruvianus), Mescinia peruella (Lepidoptera) and to a lesser extent some thrips, mealybugs, mites and a leafhopper (Empoasca kraemeri).

In organic cotton, these pests are controlled by cultural methods (elimination of secondary hosts, sowing in moist soils, suitable irrigation management, destruction of damaged organs, periods of fallow, crop rotation); legal measures (sowing and harvesting dates, elimination of crop residues, compliance with quarantine requirements); biological control (mainly facilitating the development of beneficial fauna under natural conditions); and the use of sex pheromones for the control of the pink bollworm. The overall aim is to implement a system of prevention rather than control (Mor�n et al., 1999).

One of the comparative advantages for the development and management of organic cotton in Peru is the absence of the cotton boll weevil Anthonomus grandis, the Colombian pink bollworm Sacadodes pyralis, and the Ecuadorian worm Catarata lepisma. SENASA (Servicio Nacional de Sanidad Agraria) considers the cotton boll weevil an exotic pest of quarantine importance, and its introduction and establishment in cotton-producing areas would cause considerable losses to Peruvian agriculture, decreasing yields and returns, which would result in an increase in cotton imports to satisfy the national industry. The new methodologies of 'knowledge transfer' are also beneficial. Some technicians have run farmer field schools, emphasizing knowledge of the life cycles of pests, methods for conserving biological control agents, etc. (CABI Bioscience, 2000).

These are important aspects to consider for generating greater synergies and promoting organic cotton in Peru, without losing sight of three important aspects: the need for coherent policies, the sustainable management of natural resources and promotion of the production and consumption of sustainable products; all these in relation to the strategies for sustainable development within the European Union (Van Houtte, 2004).