Integrated Pest Management: Concepts and Strategies

This publication provides an overview of the basic concepts of integrated pest management (IPM) to aid in management decision-making. As an introduction to IPM, the intended audience of this article includes new farmers, consultants, and all those involved in pest management. It can be used in conjunction with specific pest management recommendations to make well-informed decisions that utilize the principles of IPM.

IPM is a process of holistic evaluation and implementation of pest management strategies in food production systems, landscapes, and urban environments. The goal of IPM is not to eradicate pests entirely but to maintain population levels below economically relevant levels. Effective implementation of IPM programs can reduce costs of management to growers as well as the impact of management on the ecosystem by minimizing the use of pesticides.

The concept of integrated control was introduced in the mainstream in 1959,¹ based on the recognition of problems caused by heavy reliance on chemical control measures. Since then, the use of IPM has varied wildly based on geographic location and the cropping systems.^2-6 This article discusses the strategies, concepts, and benefits of IPM that apply to the management of pests in crop production, landscapes, and urban settings.

Basics of IPM

The principal component of IPM is use of multiple control tactics to manage pests while reducing costs for producers and/or minimizing the use of pesticides in some cases. Some of the available tools in integrated management are discussed below. In many cases, multiple control measures can be used to reduce pest numbers below an economic level or prevent them from ever reaching those levels. An important component of IPM is that it does not preclude the use of pesticides, but rather encourages the use of alternate control tactics combined with periodic sampling to minimize the need to use pesticides. IPM can be used to manage a single pest or a group of pests in a single crop, an ecosystem, or an entire production community.

Levels of Integration in IPM^7,8

The level of integration that a production system can achieve is often dependent on the scale of production. The higher levels of IPM integration require systematic change on a community-wide basis. As IPM is adopted into more sustainable agricultural practices, the following levels of integration have been proposed to classify degrees of integration:

• Level 1 integration: Individual pest species or species complexes.
• Level 2 integration: Community of pest species (insects, pathogens, weeds)
• Level 3 integration: Ecosystem (crop and non-crop host plants and other components)
• Level 4 integration: Farming community (including social and economic components)

The levels of integration in IPM are intended to allow producers to consider the extent to which integrated management is implemented. True integrated management takes into consideration a vast range of biotic and abiotic factors; however, IPM can be practiced at varying levels.

Types of Control

• Cultural control involves the use of farm management strategies and resistant plant varieties to minimize the impact of certain pests. Examples include rotating corn production with other crops to prevent corn rootworm from completing its life cycle, using landscape varieties resistant to disease, or sanitation to prevent household pest pressure.
• Biological control focuses on protecting beneficial species in the field as well as introducing beneficial species in some cases to reduce densities of target pests. Examples include reducing broad-spectrum pesticide use to promote populations of beneficial predators in the field or landscapes or introducing lady beetles to greenhouses to control aphid populations.
• Mechanical control is any physical measure taken to trap pest species, exclude them from the area, or eliminate them. Examples include using a grease band on fruit trees to prevent wingless female moths from laying eggs on developing trees in spring, using trap crops to exclude pests from cultivated fields, or discing weeds to eliminate them.
• Chemical control is typically a last resort in integrated management systems but can still be used in the context of IPM. The goal of chemical control is to use products that specifically target a pest (as/when possible) while also reducing the number of sprays by using periodic sampling and action thresholds. An example includes using pesticides that specifically target lepidopteran pests (i.e., spinosad, B.t.) with minimal impact on natural enemies.
• Behavioral control often involves the use of chemicals but does not involve directly killing the pest species. It is the alteration of pest behavior such as mating, aggregation, or host identification via the use of pheromones and semiochemicals. Pheromones are intraspecific chemical cues used by insects, and semiochemicals are more broadly defined as chemicals that convey signals from one organism to another. Both can be synthetically produced and used to alter the behavior of pest species. An example includes introducing mating disruption pheromones to reduce populations of pest species in the field.

Economic Injury Levels and Economic Thresholds

Two of the most important concepts in making integrated management decisions are the economic injury level (EIL) and economic threshold (ET). The EIL is defined as the lowest acceptable pest density that results in economic damage and is specific to individual pest species and crops.^1,9 The amount of damage caused at the EIL causes profit loss equal to the cost of management. The ET is set below the EIL and is the point at which management is implemented to prevent the pest density from reaching the EIL.^1,9 EILs and ETs are set by conducting research on the relationship between specific pest densities, yield losses related to crop damage from pests, and the cost of management

Steps in Developing an IPM Program

Below are some typical steps in implementing an IPM program:

1. Identify pests: Identifying pests is a critical step in developing managing strategies. In many cases, a single pest is of primary concern; however, many pests can be managed in similar ways (for instance, several stink bug species cause similar damage to fruiting structures of crops and can be managed as a species complex). Identifying all the pests that require management can promote the use of strategies that are effective in preventing a range of pests.
2. Determine acceptable injury level (EIL and ET): Research-based economic injury levels and economic thresholds are available for many major pests and can be found in crop production and management guides.
3. Monitor pest population levels: Achieved/accomplished through trapping or scouting of managed areas. Degree day models are predictive tools involving simple calculations using high and low daily temperatures to determine when pest species may be emerging and can sometimes help to optimize the timing of sampling efforts.
4. Evaluate management options: Determine all available control methods for the pest or groups of pests. Prevention or exclusion of target pests is often the first line of defense, then biological or chemical control can be used if pest levels still reach economic levels.
5. Develop and implement an IPM program: Pest exclusion or prevention should be used whenever possible, for all previously identified pests. These strategies must be used prophylactically. If populations still reach previously determined threshold levels, implement one or more of all the other available control strategies. Chemical management should be supplemental and used if all other strategies fail. Chemical applications should be made at the determined acceptable level of injury or ET.
6. Monitor management effectiveness: Continue to monitor pest population levels after control implementation. This is a critical portion in IPM as it can inform the use of additional management strategies.
7. Evaluate the program: Evaluate the effectiveness of each step in the IPM implementation process to determine strengths and shortcomings for future management.

Benefits and Limitations of IPM

The main benefits of integrated management are a potential decrease in management costs, reduction in the use of pesticides, and adoption of more sustainable management practices by minimizing reliance on chemical control alone. The use of multiple control tactics can minimize selection pressure from reliance on pesticides only, which can slow or prevent the development of pesticide resistance. In areas of high IPM adoption such as California, there is documented reduction in pesticide residues on products as well as in surface waters.¹⁰ A decrease in pesticide residue is attributed to an overall decrease in use, but also to the use of newer pesticides that do not persist as long in the environment. Integrated chemical management ideally narrows the spectrum of activity to a specific pest or group of pests and can increase populations of natural enemies. Protecting natural enemies ultimately can keep target pest numbers below action thresholds and reduce the overall number of chemical applications. IPM adoption has been associated with a net increase in returns and yields in many cases.^6,11,12 For instance, IPM adoption in tomato production resulted in net profits $123-$234/ac higher than in conventional production, while simultaneously reducing the overall use of pesticide.¹²

Unfortunately, in some cases, pesticide usage increased, or overall pesticide cost in IPM programs increased.⁶ Reasons for these increases may, in part, occur because growers using IPM monitor fields more frequently and therefore, may spray more than growers using a timed spray regime. Also, the increase in pesticide cost could result from the use of newer, more expensive pesticides that have a lesser impact on the environment but come at a higher cost for producers. Reliance on an affordable broad-spectrum pesticide such as a pyrethroid insecticide can sometimes be cheaper than implementing an IPM program. One of the main limitations of IPM is that the ability to implement multiple strategies and the effectiveness of those strategies varies between geographic regions and crops produced. Although there is variation, IPM can be implemented to some extent in all cases. Individual growers have to assess their needs and make management decisions based on the evaluation of IPM tactics used. This process can ultimately cost producers time and money, which can be a limitation for producers in under-researched areas and cropping systems in particular. General IPM principles can be applied in under-researched areas by applying basic strategies from similar pests or crops which promote natural enemies and minimize the use of broad-spectrum pesticides.

The effectiveness of IPM is dependent on continued research on the ever-changing population of pests across all types of production systems, but more importantly, the dissemination of that research to producers who use it. Promotion of IPM will improve the rate of adoption across communities and, over time, increase the benefits to producers and decrease the environmental impact of the management of pests in crop production, landscapes, and urban settings.

References Cited

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