AGP - What is Integrated Pest Management
 

What is Integrated Pest Management?

 

What is Integrated Pest Management

 

The origin of Integrated Pest Management (IPM) can be dated back to the response of governments, extension systems, and farmers to the emergence of problems associated with the reliance on chemical controls for insect pests that started after the Second World War and intensified during the Green Revolution. The search for solutions to these problems led to the development of a more holistic view of what constituted an agro-ecosystem and how human interventions could either enhance or disrupt a given agro-ecosystem.

 

With the introduction of chemical insecticides following World War II, plant protection specialists were able, almost without restriction, to make use of powerful poisons. The goal of plant protection specialists in the early 1950's was 100% control (eradication). Entomologists such as Ray F. Smith and A. E. Michelbacher sounded warnings against this unrestricted use and proposed an approach that tolerated low levels of pest populations to allow natural enemy populations an opportunity to suppress pest populations. They proposed an approach to crop protection that was based on the analysis of the ecology of a given agro-ecosystem and included biological controls. Their work resulted in the development of what was known as Integrated Pest Control. They proposed that the goal of pest control strategies was to tolerate pest populations that were below specified threshold levels. (J.A. Litsinger, Peter E. Kenmore and G. Aquino, 1982.)

 

Integrated Pest Control eventually became Integrated Pest Management. The stress on decision-making, integration of tactics, and the allowance of tolerable thresholds was seen as a move away from control and towards management. Source: Ten Years of IPM Training in Asia - From Farmer Field School to Community IPM, edited by John Pontius, Russell Dilts, Andrew Bartlett, FAO. 2002.

 

 

Initial ‘Principles of Integrated Pest Control’

 

  1. The use of chemical pesticides, without regard to the complexities of the agro-ecosystems in which they are used has been a major cause of disruption and undesirable side effects. Undesirable side effects include: target pest resistance and/or resurgence, secondary pest outbreaks, residue problems, and environmental pollution.
  2. The agro-ecosystem is a unit composed of the total complex of organisms in the crop area together with the overall conditioning environment. There must be an analysis of the agro-ecosystem to determine population dynamics and mortality factors operating on pest populations.
  3. The kinds of crops, agronomic practises, patterns of land use, weather, total complexity, and self-sufficiency of the agro-ecosystem affect the stability of an agro-ecosystem. As complexity increases, particularly among trophic interactions, there is usually an increase in the stability of the agro-ecosystem. IPC should seek to preserve or improve this complexity.
  4. Levels or limits of tolerable damage are more important than pest population levels. Tolerable levels of damage vary with market conditions, stage of the crop, local conditions or grower economics, and the personal values of the people concerned. These levels will vary widely. The presence of pests is not an indication of a threat of economic damage to the crop.
  5. In more sophisticated programmes, individual fields are surveyed for populations of pests, parasites, predators, and pathogens. On the basis of this information and a consideration of the time of the year, stage of growth of the crop, and weather conditions a prediction can be made of population trends and potential damage. This type of sampling and prediction requires a solid base of fundamental biological and ecological data.
  6. All but the most sterile of man made environments have some biotic agents influencing pest populations. Appropriate consideration must be given to biotic control agents. In some fortunate situations, the biotic agents are all that is necessary to have satisfactory economic control. The failure of natural enemies to keep a given pest under control should not cause us to invoke control practises that disrupt the controlling action of natural enemies of other species in the same agro ecosystem (R.F. Smith and H.T Reynolds, 1966).

 

Approaches to plant protection

 

The increase in pesticide application coincided with the introduction of the new and higher yielding varieties during the Green Revolution, that were assumed to be irresistible to pests; cost of pesticide was seen as an acceptable insurance “premium”. Because farmers were seen as being unable to deal with the complexities of pest control, prophylactic use of insecticides was promoted. This control tactic relied on “calendar based” applications of pesticides. Farmers were told to apply insecticides based on the number of days after transplanting or the stage of plant development. In Indonesia, the calendar based approach in rice cultivation has resulted in farmers applying broad-spectrum systemic insecticides to the nursery bed and at transplanting. Farmers then made additional applications of non-systemic broad-spectrum insecticides around forty days after transplanting and at or around the milky stage of seed development.

 

Tactical IPM first arrived in tropical rice production systems with the introduction of economic threshold levels (ETL’s). This tactic seemed to be a rational way to reduce the amount of insecticides that were being applied under the calendar based system. ETL’s failed to take into account the role of natural enemies in suppressing pest populations. General ETL’s were developed for insecticide use throughout a given country. Farmers were told to count the number of a pest, for example BPH, and spray when there was a certain amount of BPH per hill of rice. National forecasting systems were another approach taken to control pests. These systems took the responsibility for decision making off of the farmer and allowed professionals to take charge. Forecasting systems based their control tactics on ETL’s. The greater the fear of a particular pest the lower the ETL and the more pressure put on farmers to apply insecticides. Surveillance systems sometimes made "recommendations” to farmers regarding insecticide applications. The systems also included pest eradication brigades to handle “outbreaks”.

 

Prophylactic spraying, the use of ETL’s, and forecasting systems, all placed limitations on the management role of rice farmers. Crop protection experts assumed that “professionals” could take better decisions than could farmers. It was not until 1990, when the Indonesian government instituted a farmer IPM education programme, that a truly farmer based IPM “system” was promoted. The process of getting to this point required several discoveries on the part of researchers and the realisation on the part of both scientists and government that it was appropriate for farmers to be the ultimate decision makers in an IPM crop protection system.

 

 

Ecological principles of IPM

 

Scientists began working out some of the basics of rice field ecology in the late 1970’s and early 1980’s. Their attention was generally focused on the brown planthopper (BPH), which at the time was ravaging rice fields across Southeast Asia. They discovered that BPH outbreaks were insecticide induced (P.E. Kenmore, 1980) and that breeding rice varieties resistant to BPH under continued pressure of insecticide use was futile (K.D. Gallagher, 1984). Researchers soon worked out an ecologically based means to BPH control (P.A.C. Ooi, 1988). Yet it was to take some time before the broader ecological approach became part of mainstream extension.

Whereas the specific conditions critical for management decisions regarding inputs vary over a small spatial scale, agro ecosystems do have a general structure and dynamics that is reasonably consistent for the entire system. In essence, it is possible for us to think in terms of a general theory for the structure and dynamics of specific agricultural ecosystems. IPM is not a “theory” in a strict scientific sense; rather, it is merely a set of practical guidelines for how to best manage a specific crop.

The existence of diverse populations of natural enemies, supported by abundant alternative food species, assures that populations of pests are consistently maintained at low levels. In effect, the structured biodiversity of arthropods in tropical irrigated rice functions to consistently suppress pest populations by denying pests refuge in time or space. All the key variables can be found in any rice ecosystem—only when the process is disrupted do pest populations explode, causing serious damage. Given this set of implications for rice, IPM practice can be determined. The use of insecticides disrupts and destabilises natural enemy populations. The use of insecticides is by far the most common cause of pest outbreaks, especially for pests such as the rice brown planthopper. These kinds of pest outbreaks are generally referred to as “pesticide-induced resurgence”. Several factors combine to enable resurgence to occur:

 

·            Eggs of many pests, such as BPH, are not susceptible to chemical sprays.

·            Insecticides create a refuge for the development of pest populations by reducing the abundance of natural enemies.

·            Migratory abilities of pests are generally better and their generation many times faster than those of natural enemies.

 

Certain landscape designs can cause delays in the arrival of natural enemies after long dry fallow periods. In many tropical areas, the potential exists for year-round cultivation of rice. However, some areas—both by natural constraints or government design, are planted synchronously over thousands of hectares, and have long (3-4 month) dry fallow periods. These are the areas in which natural enemy populations are weakest and where pest outbreaks are most frequent (see Settle et al. 1996).

After such a long dry spell, when the next season of rice is planted, it takes up to half a season to build up predator populations that would otherwise have been there from the beginning. Again, as pests are better recolonizers than natural enemies, the potential for outbreak is much higher in these synchronous, large-scale areas. Much attention has been given to the ideas of “synchronous planting” and “breaking the pest cycle with long dry fallow periods” to the point that these ideas have become ingrained almost as “fundamental principles” of IPM. However, a close look at the empirical data and experiments that purport to demonstrate these principles will show that the support is very weak. Soils, high in organic matter, are the foundation for a “healthy ecosystem”. Soil organic matter is not emphasized as much for irrigated rice as for dry-land cropping systems because of the lesser need for good soil texture. However, as we have seen, soil organic matter is the foundation for energy cycles that ultimately support high populations of natural enemies.