Research and Extension Supporting Ecologically Based IPM Systems

Summary

Integrated Pest Management (IPM) has a long history of developing pest management strategies based on ecological principles. While IPM systems differ in their reliance on chemical controls, an ecological approach to IPM offers opportunities both to test ecological theory and to develop novel pest management techniques. We review ecological concepts relevant to habitat management as a tool for managing pest and natural enemy populations in annual cropping systems, and we describe a case study of the impacts of habitat management on predatory ground beetles (Coleoptera: Carabidae) in annual cropping systems. Experimental manipulation of carabid population density revealed a positive relationship between the abundance of carabids in cropland and prey removal. Provision of stable refuge habitats in annual crops increased carabid species richness and abundance. Further studies demonstrated that the presence of refuge habitats mitigated the impacts of insecticide disturbance on carabid abundance and community structure in adjacent cropland. These results were used as part of a program to educate extension agents and producers in the principles of agroecology and ecologically based pest management. We encourage extension agents and producers to test novel practices using adaptive management. In this approach, predictions are formulated regarding specific management practices and evaluated against the results. Based on these observations, management is then adapted to yield the desired outcome. Such an approach recognizes the inherent uncertainty of multifactor ecological manipulation while providing producers with methods to manage this uncertainty.     

Weed Biology,Cropping Systems,and Weed Management

SUMMARY

Weeds pose a recurrent threat to agricultural productivity in both industrialized and developing countries. Weeds respond dynamically to all cropping practices, and therefore, the design and function of cropping systems plays a central role in the composition of weed communities. The unique and challenging nature of weed communities requires more integrated approaches to weed management than are currently being employed by most growers. Integrating weed management with cropping system design and application may be an effective approach to diversifying weed management systems. Each crop-weed system is a unique mix of genetics and biology and will respond dynamically to changes in management practices. Practices such as crop rotation, tillage, cover crops, and fertility management modify weed populations. The challenge is to integrate these and other practices with the best available control tactics to generate integrated management systems. Cropping system design provides an excellent framework for developing and applying integrated approaches to weed management because it allows for new and creative ways of meeting the challenge of managing weeds. Weed science must integrate the theories and application of weed management into cropping system design based on the unique characteristics of weed communities and the available weed management options.     

Cropping Systems and Integrated Pest Management: Examples from Selected Crops

SUMMARY

Cropping systems have been central to managing associated pests for centuries. This treatment focuses on the history, concepts, and the integration of available Integrated Pest Management (IPM) tools/strategies into cropping systems. Pest assessments/diagnoses, IPM-decision-making aids, and examples of pest management in selected crops/cropping systems (wheat, soybean, corn, cotton, potato, and strawberry) as well as emerging opportunities and challenges are discussed. The evolving philosophy of IPM and the recently renewed emphasis on ecologically based pest management address the fact that significant levels of predation and/or parasitism are desirable insofar as they promote diversity and sustainability of agroecosystems. Thus, cropping systems are beginning to focus on soil and crop health as well as specific IPM and production goals. Although extensive efforts have been directed toward modeling the many interactions between crops, associated pests and the environment, the general implementation of a systems approach to integrated crop and pest management remains to be accomplished.     

Problems and Perspectives of Yam-Based Cropping Systems in Africa

SUMMARY

Yams (Dioscorea spp.) constitute an important starchy staple in sub-Saharan Africa (SSA) where food security for a growing population is a critical issue. Mixed cropping in yam based systems is the norm in the region and productivity of yams in these systems is below potential. It is concluded that there is much scope for improvement of yam based cropping systems in SSA in order to meet the needs of the region. The strategy of crop breeding to select yam varieties suitable for various cropping systems must consider a truly multidisciplinary systems approach. Further manipulation must be made to tuber dormancy to expand flexibility in field propagation in different cropping systems and improve storage and marketing. The sustainability of yam based cropping systems in SSA could improve if agronomic research was focused on strategies for improving soil fertility, weed and pest management including design of cropping systems and suitable rotations.     

Weed Thresholds

Abstract

Weed thresholds are an integral component of an integrated weed management system (IWM). In this paper we review the literature on weed thresholds and examine the theory and applicability of thresholds within the context of a systems approach to IWM. The development of empirical models describing single and multi-species thresholds are reviewed and discussed in terms of the magnitude of weed threshold values in various crops and the importance and limitations of the parameters used to calculate these values. Mechanistic weed threshold crop competition models are suggested as a means of overcoming some of the limitations of empirically based threshold models. A mechanistic approach to the development of weed threshold models is desirable since relative crop and weed responses to environmental factors, cultural practices and the dynamic nature of competition are considered. Guidelines for the application of weed thresholds within a cropping system are outlined.     

The Importance of Biodiversity in Agroecosystems

SUMMARY

This article identifies the important functions and benefits of biodiversity in agriculture, for sustainable crop production and food security. After clarifying impacts from the decline of biodiversity in agriculture, the article summarizes principles, practices and policies for biodiversity conservation and enhancement in farming systems and in landscapes. Some of the strategies identified build upon valuable local experiences and knowledge in traditional farming practices, while others take advantage of recent scientific findings in agroecology and ecosystem health. The analysis suggests the value of adopting an agroeco-systems approach, beyond a focus on genetic resource conservation alone-to implement other biodiversity-enhancing methods in farms, such as integrated ecological pest and soil management. Attention is also given to the challenges by conflicting agricultural policies that contribute to the decline of biodiversity in farming systems, and potential of reforming such policies. The practices and approaches reviewed in this analysis show effective ways to link biodiversity conservation and sustainable agriculture.     

Nature Farming Practices for Apple Production in Japan

Summary

Apples were grown in a study using nature farming practices, including organic fertilizer to supply nutrients, microbial inocu-lants for biocontrol of pest insects, and low- or non-pesticides measures. When low- or non-pesticide measures were adopted, the numbers of pest insects increased accordingly; however, the populations of beneficial organisms and natural predators of pest insects also increased. Even though the reduction in pesticide use caused some fruit damage, the enhanced biocontrol of pest insects by increased numbers of natural predator insects more than compensated for the damage. Thus, low- or non-pesticide nature farming practices were cost-effective because they increased biocontrol of pest insects and decreased the amount of pesticide needed and the cost of application.     

Smallholder farmers' knowledge,perceptions and management of pea weevil in north and north-western Ethiopia

Pea weevil (Bruchus pisorum L.) is one of the most serious insect pests of field pea (Pisum sativum L.) in Ethiopia. A survey of 400 farmers was conducted in four main pea-growing districts in north and north-western Ethiopia. The objectives were to assess farmers' knowledge and perceptions of pea weevil, to examine their current pest management practices and to identify challenges to pea weevil control, so that participatory integrated pest management for smallholder farmers in Ethiopia can be developed. The results revealed that most (71%) of the farmers surveyed had knowledge about pea weevil and were able to identify damaged seeds based on common visible symptoms of weevil infestation. However, most farmers did not know that pea weevil attacks plants in the field, but rather considered it a storage pest. The results also showed that farmers' cultural practices influence the incidence and spread of pea weevil and that most farmers did not check seed for pea weevil symptoms before planting. Only a minority of farmers (19%) harvested peas early and some harvested late, unintentionally promoting infestation and carryover of weevils. In addition, most farmers (74%) were not aware of the source and means of weevil spread on their farm and some did not clean up fallen and shattered peas during harvesting and threshing. The majority (63%) of the farmers surveyed relied on chemical insecticides, namely actellic dust and phostoxin, to treat harvested peas in storage. However, the results revealed a knowledge gap in that farmers were well aware of the problem of pea weevil, but lacked knowledge of cultural practices affecting pea weevil and of problems in the use of pesticides. This highlights the need for farmer training and for development of participatory integrated pest management methods for pea weevil.     

Integrated Pest Management Control of Varroa destructor (Acari: Varroidae), the Most Damaging Pest of (Apis mellifera L. (Hymenoptera: Apidae)) Colonies

Varroa destructor is among the greatest biological threats to western honey bee (Apis mellifera L.) health worldwide. Beekeepers routinely use chemical treatments to control this parasite, though overuse and mismanagement of these treatments have led to widespread resistance in Varroa populations. Integrated Pest Management (IPM) is an ecologically based, sustainable approach to pest management that relies on a combination of control tactics that minimize environmental impacts. Herein, we provide an in-depth review of the components of IPM in a Varroa control context. These include determining economic thresholds for the mite, identification of and monitoring for Varroa, prevention strategies, and risk conscious treatments. Furthermore, we provide a detailed review of cultural, mechanical, biological, and chemical control strategies, both longstanding and emerging, used against Varroa globally. For each control type, we describe all available treatments, their efficacies against Varroa as described in the primary scientific literature, and the obstacles to their adoption. Unfortunately, reliable IPM protocols do not exist for Varroa due to the complex biology of the mite and strong reliance on chemical control by beekeepers. To encourage beekeeper adoption, a successful IPM approach to Varroa control in managed colonies must be an improvement over conventional control methods and include cost-effective treatments that can be employed readily by beekeepers. It is our intention to provide the most thorough review of Varroa control options available, ultimately framing our discussion within the context of IPM. We hope this article is a call-to-arms against the most damaging pest managed honey bee colonies face worldwide.     

Expanding the Context of Weed Management

Abstract

Concerns about current weed control practices have increased the consideration of new weed management strategies. In recent times, weed control practices for major crops have been influenced greatly by the availability of selective herbicides. Herbicides are critical tools, but weed science must integrate more components to create weed management systems. Changes in weed management can be attained within the framework of existing cropping systems. However, for the longer term, new methods and approaches to weed management are needed. Weed scientists need to play a central role in the development of new cropping systems to make weed management an integral component of the system. This volume contains a series of review articles and original research that presents innovative approaches to weeds and weed management. It is our hope that these papers will stimulate discussion on a broader view of weeds and weed management.     

Could movement of neonates from non-host plants affect the potential of polyculture to reduce crop colonisation by pest insects?

Existing and impending constraints to the use of synthetic pesticides, along with changing legislation in favour of an integrated approach to pest management, are driving uptake of ‘alternative’ approaches to pest control. Polyculture is one such approach, often relying upon the presence of non-host plants within the crop to reduce colonisation by pest insects. The diamondback moth, Plutella xylostella (L.), is known to oviposit on non-host plants and the present study showed that neonates were able to move relatively large distances, enabling them to relocate from non-host natal plants to nearby hosts. Although fewer larvae were found on host plants when they hatched on non-hosts, it is concluded that even a low level of re-location of neonates could potentially reduce the potential for polyculture to control this pest. It is proposed that non-host oviposition and neonate movement could explain why polyculture sometimes fails in controlling pest insects.     

Integrating Agroecological Processes into Cropping Systems Research

Summary

Agroecology is defined as the application of ecological concepts and principles to the design and management of sustainable agroecosystems. By viewing cropping systems as agroecosystems, an understanding of the value of the emergent qualities of systems can become a guiding element in research design. A framework for applying this approach in cropping systems research in proposed. A protocol for researching the conversion to sustainable agriculture involves three levels of investigation. The first focuses on improving the efficiency of conventional farming inputs and practices in ways that reduce both their amounts and the environmental impacts of their use. The second focuses on substituting conventional inputs and practices with alternatives that meet broader environmental standards, such as certified organic. Since the problems addressed at these two levels continue to present themselves, a third level is proposed whereby the agroecosystem is redesigned so as to operate on the basis of a new set of ecological processes. At this third level, the emergent qualities of the system itself help prevent problems. Such an approach promotes the conversion to sustainability.     

Knowledge-Based Decision Support Strategies

Abstract

Research and application of site-specific farming has focused on technological advancements that enable site-specific field operations. The current emphasis on technological tools of site-specific farming, rather than the development of new crop and pest management systems that integrate and optimize the use of these new tools, limits our abilities to realize the full potential and promise of site-specific management. The objective of this paper is to introduce a conceptual framework that integrates spatial and temporal data, information, knowledge, and wisdom into a knowledge-based decision support strategy (KBDSS). Our goal is to stimulate researchers, engineers, farmers, and other agri-business personnel to refocus their approach to site-specific resource management. Moreover, this knowledge-based decision support strategy must embrace questions of economic, environmental, and social sustainability as well as create an opportunity for people to share information and experiences in addressing emerging issues in crop production. Current strategies emphasize data collection and information management followed by an immediate action. We argue that implementation of decisions derived using only data and information circumvents knowledge and wisdom, often leading to inappropriate resource management. A successful KBDSS will incorporate a better understanding of interdependence among factors affecting or affected by a site-specific decision. We believe that the KBDSS outlined in this paper is a first step in improving integration of weed biology, enhancing the utility of bioeconomic models, shaping farmer/advisor relationships, and recognizing the importance of long-term learning and experience-building within the landscape.     

Farmers’ knowledge, perceptions and management of vegetable pests and diseases in Botswana

Vegetable farmers’ knowledge and perceptions of pests, diseases and pest management practices were investigated by interviewing 112 growers in Botswana between April and June 2004. Most of the farmers grew brassicae crops, Swiss chard and tomato, and considered arthropod pest problems as the major constraint to vegetable production. Bagrada hilaris Burm., Plutella xylostella L. and Brevicoryne barassicae L. were the most serious pests on brassicas, with red spidermites (Tetranychus spp.) being the most serious pests on tomato. Ninety-eight percent of farmers relied heavily on the use of synthetic pesticides to control these pests. Their decision to apply pesticides was mostly on noticing the presence of a pest or disease. An integrated pest management programme is needed to reduce over reliance on pesticides.     

Current and Potential Role of Transgenic Crops in U.S. Agriculture

SUMMARY

Transgenic crop cultivars with resistance to insects, pathogens, and herbicides offer growers powerful new pest management tools. We reviewed the observed and potential farm-level impacts of transgenic cultivars, including those with regulatory approval and commercial availability as well as those still being researched and developed. Direct grower benefits, such as yield and production increases and decreased management costs, have led to rapid and extensive adoption of Bt corn and cotton, herbicide-resistant cotton, soybean, and canola, and virus-resistant papaya. Other transgenic crops, including Bt sweet corn and potato, and herbicide-resistant sugar beet and corn, have not been adopted despite strong agronomic and pest management performance, largely because growers fear there will be no market for their harvests. Despite inconsistent adoption of transgenic cultivars, demonstrated benefits of the technology encourage ongoing efforts to incorporate pest management traits into a wider variety of crops, including broccoli, tomato, lettuce, grape, citrus, pineapple, raspberry, peanut, wheat, barley, and rice. Potential impacts of these upcoming transgenic cultivars range from a decrease in weed management costs for lettuce and tomato growers, to the defense of stone fruit, grape, and citrus against devastating new pests.     

Large-scale sugarcane farmers' knowledge and perceptions of Eldana saccharina Walker (Lepidoptera: Pyralidae), push–pull and integrated pest management

A push–pull strategy for controlling Eldana saccharina Walker is being promoted as part of an area-wide integrated pest management (AW-IPM) programme in the South African sugar industry. Understanding farmers' perceptions of pests and pest management can improve rates of adoption of pest management strategies, in particular for knowledge-intensive practices such as AW-IPM. Fifty-three large-scale sugarcane farmers were interviewed using a semi-structured questionnaire. Respondents recognised the threat which E. saccharina posed, and 83% had heard of push–pull and IPM. Ecozone delineations played a more important role in adoption decisions than demographic and general enterprise factors such as farmer age, experience and land tenure, supporting the suggestion that experiential learning activities with small, local groups of farmers are suitable for introducing new pest management strategies. Notwithstanding good basic knowledge of E. saccharina, push–pull and IPM which farmers demonstrated, there is still a need for more detailed and practical knowledge on the implementation of push–pull at farm level. This knowledge should be made available to farmers in a hands-on manner with an emphasis on locally-oriented field days and model farms. Eldana saccharina may not be a priority for all farmers in the region where surveys were conducted. However, farmers should not be allowed to become complacent about this pest, as its range is increasing. These results will be used to formulate future push–pull and AW-IPM dissemination activities amongst large-scale sugarcane farmers in South Africa.     

Plant Parasitic Nematodes in Rice-Wheat Based Cropping Systems in South Asia

Summary

Rice-wheat based cropping systems in South Asia are among the most highly evolved production systems in the world. The productivity growth of these systems in South Asia is declining due to several factors including the biotic stresses of plant parasitic nema-todes. This article reviews the research on rice and wheat nematodes in a cropping systems perspective and identifies nematodes that have wide host ranges and are greatly influenced by the crop rotations and sequences. These polyphagous nematodes can cause significant damage to rice and (or) wheat crops, either alone or in combination with other microorganisms. The research projects on pest management in the region lack inter-disciplinarity and it is important for nematologists to become integral members of interdisciplinary teams on improving the productivity and sustainability of the rice-wheat cropping systems.     

Managing storage pests of maize: Farmers' knowledge,perceptions and practices in western Kenya

Insect pests are a key constraint to effective utilization of cereal crops in sub-Saharan Africa (SSA), with damage caused by these pests in the stores of particular concern. Although a number of approaches have been advanced for control of storage pests of maize, uptake remains a challenge, with effectiveness of some approaches being questionable. We conducted a survey in western Kenya among 330 respondents using face to face interviews and focus group discussions to evaluate farmers' practices, knowledge and perceptions of storage pests of maize, and their current practices in managing such pests as a basis for development of efficient integrated pest management (IPM) approaches for the pests. Majority of the respondents stored maize in traditional granaries, with less than 10% of them using modern improved facilities, mainly due to inability to afford these. Majority of the respondents also cited attack of their stored grains by a number of insect pests, causing about 40% grain losses. The larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), sawtoothed grain beetle, Oryzaephilus surinamensis (L) (Coleoptera: Silvanidae), and maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), were perceived as the most common and damaging pests. Farmers' perceptions of pests were positively and significantly influenced by level of education and farming experience, indicating that education and experience build farmers' understanding of storage pests. Storing maize in unshelled form seemed to result in less pest attack, although majority of the respondents stored their maize in shelled form. Moreover, local maize varieties were perceived to be resistant to pests. The farmers applied various control methods, with sun-drying being the most popular practice. Usage of pesticides was minimal, mainly due to high costs, lack of information, and unavailability of appropriate and effective products. There were also other cultural methods applied, such as use of smoke and insecticidal plants. The respondents decried lack of training and extension services on storage pests and their management, underscoring the need to develop extension services. The underlying mechanisms of the perceived pest resistance in local varieties of maize and cultural pest management methods need to be established for exploitation in development of effective IPM approaches. There is also need to address the challenges hindering uptake of modern storage and control approaches.     

Factors determining adoption of integrated pest management by vegetable growers in Nakhon Ratchasima Province,Thailand

Widespread use of highly toxic pesticides primarily for agricultural purpose has generated increasing concerns about the negative impact of pesticides on human health and the environment. Integrated pest management (IPM) usually seeks to minimize the use of pesticides and can be utilized to solve pest problems while minimizing risks to people and the environment. A total of 220 vegetable farmers in Nakhon Ratchasima Province of Thailand was interviewed with the objective of investigating the factors determining their adoption or non-adoption of IPM practices. The findings demonstrated that farmers had different uncompromising reasons for determining the use of IPM for their insect pest management. Higher costs of insecticides (91%), adverse effects of insecticides on human health and the environment (80%), and a greater risk of insect pests developing resistance to insecticides (28%) were the primary reasons for the adoption of IPM by vegetable growers in the study area. The reasons for the rejection of IPM practice were unsuitability of IPM for a large farm (52%), implementation difficulties (80%) and a greater belief in synthetic insecticides and their efficacy for target pest control (39%). A comparison between the IPM and the non-IPM farmers showed a significant difference (P < 0.01) in farmers' knowledge of pest management, which influenced IPM adoption or non-adoption. The IPM farmers had greater knowledge about identifying natural enemies and their beneficial role in controlling insect pests, about plant extracts and their efficacy in controlling insect pests and about sticky traps and their efficacy in monitoring natural enemies and controlling insect pests. For example, 24% of IPM farmers had knowledge of natural enemies whereas it was only 4% for the non-IPM farmers. A logistic regression model was fitted which showed that lower cost of pest management, better knowledge on IPM after training and availability of extension services were the factors which influenced farmers' adoption of IPM practice. The non-IPM farmers rejected adoption of IPM due to the common belief that natural enemies would not be effective in controlling insect pests and yields of vegetables would not be increased by practicing IPM.     

Restoring the Land Productivity of Eroded Land through Soil Water Conservation and Improved Fertilizer Application on Pothwar plateau in Punjab Province,Pakistan

Abstract

Crop production in a rainfed area is constrained by inappropriate management of soil and water by the resource-poor farmers. The present study addresses this issue through integration of practices for soil water conservation (SWC) and soil fertility enhancement as well. Extensive experimentation on wheat-maize was undertaken for two years (2004?2006) on the fields of eight farmers representing two soil types; Rajar (Typic Ustorthent; USDA soil taxonomy) and Guliana (Udic Haplustalf; USDA soil taxonomy) in the Gujar Khan Tehsil of Rawalpindi District, Pakistan. Four treatments consisting of: no SWC +farmer’s rate of fertilizer application (FP), no SWC+improved fertilizer application (IF), SWC practices i.e., deep plowing, bund improvement, plowing across contour+FP (SWC+FP) and SWC+IF. Wheat and maize grain yields in SWC and IF were statistically higher than in the treatments with no SWC and FP, respectively. Compared with the control without any treatment, increase in water use efficiency of both maize and wheat crop was higher in SWC+IF followed by IF alone. On the average, Guliana soil series showed better response to all treatments than Rajar soil. The integrated application of SWC and IF practices increased crop yields in the rainfed area.