In this article we will discuss about:- 1. Introduction to Integrated Pest Management (IPM) 2. Origin of Integrated Pest Management (IPM) 3. Integration of Pest Management Tactics 4. Constraints in Implementation 5. Framework of IPM Programme 6. Advantages.
Introduction to Integrated Pest Management (IPM):
Integrated pest management (IPM) is based on ecological principles and involves the integration and synthesis of different components/control tactics into a pest management system. Many components of IPM were developed in late 19th and 20th century.
By early 1920s, a highly complex and sophisticated system involving the use of multiple component suppression techniques, viz., resistant varieties, sanitation practices and chemical treatments with calcium arsenate at fixed population levels, was clearly developed for the control of boll weevil on cotton in USA. However, during the period from 1920s to 1940s, the emphasis in crop protection shifted from cultural and biological control techniques to inorganic chemical pesticides.
The discovery of insecticidal properties of DDT rapidly followed by the manufacture of other broad spectrum synthetic organic pesticides during 1940s and 1950s virtually eclipsed all other techniques. These insecticides were easy to apply and produced an almost immediate kill. Therefore, they became our first and only line of defence or attack against all insects.
However, even at that time, many scientists had warned regarding the consequences of exclusive reliance on chemical insecticides ignoring ecological principles. Unfortunately, their sane voices were drowned in the euphoria generated by the initial success of synthetic insecticides.
The use of toxic chemicals for the control of pests increased tremendously during the green revolution era. At that time, their use was considered a necessity for increasing agricultural production at a reasonable cost. It was later realized that many of these chemicals were not biologically degradable and they not only persisted in the environment but also became concentrated through food chains.
This realization came only when the recurrence of pests with even a greater severity was evidenced as a result of the death of natural enemies along with the pests. With the consciousness of using the chemicals judiciously to minimize the pollution hazards, the scientists recommended that pests should be controlled by integrating the use of biological agents with the use of pesticides.
Origin of Integrated Pest Management (IPM):
The use of toxic chemicals for the control of pests increased tremendously during the last few decades. It was realized later that many of these chemicals were not biologically degradable and they not only persisted in the environment but also became concentrated through the food chains.
With the consciousness of using the chemicals judiciously to minimize the pollution hazards, the scientists recommended that pests should be controlled by integrating the use of biological agents with the use of insecticides. Based on this concept, Bartlett (1956) coined the term ‘Integrated Pest Control’ which was defined as the blending of biological control agents with chemical control measures.
Later on in 1961, Geier and Clark advocated the integrated use of all available techniques for the control of insects and not confining only to the biological and chemical methods of control. They suggested that the methods which are considered promising should first be evaluated and, if found effective, be consolidated into a unified programme to manage pest populations. Subsequently, the term ‘pest management’ was advocated by Geier (1970).
Thus, pest management may be considered, an intelligent selection and use of pest control actions that will ensure optimal economic, ecological and sociological benefits. Pest ‘management includes all approaches ranging from single component control method to the most sophisticated and complex control method. A number of definitions have been proposed for the twin terms of integrated pest control (IPC) and integrated pest management (IPM).
According to the expert panel of the Food and Agriculture Organization, integrated pest control may be defined as a system that in the context of the associated environment and the population dynamics of pest species, utilizes all suitable techniques and methods in as compatible a manner as possible and maintains the pest populations at level below those causing economic injury.
According to the National Academy of Sciences, IPM refers to an ecological approach in pest management in which all available necessary techniques are consolidated in a unified programme, so that population can be managed in such a manner that economic damage is avoided and adverse side effects are minimized.
Smith (1975) defined IPM as a multidisciplinary ecological approach to the management of pest populations, which utilizes a variety of control tactics compatibly in a single co-ordinated pest management system. Dr Ray F. Smith and Dr Perry Adkisson have been awarded the 1997 World Food Prize for their pioneering work on development and implementation of IPM concept.
Pedigo (1991) expanded the FAO definition to lay stress on the importance of socio-economics, and defined IPM as a pest management strategy that, in the socio-economic context of farming systems, the associated environment and the population dynamics of the pest species, utilizes all suitable techniques and methods in as compatible a manner as possible, and maintains the pest population levels below those causing economic injury.
Dhaliwal and Arora (2015) defined IPM as a dynamic and constantly evolving approach to crop protection in which all the suitable management tactics and available surveillance and forecasting information are utilized to develop a holistic management programme as part of a sustainable crop production technology. It is a systems approach to pest management based on an understanding of pest ecology and begins with steps to accurately diagnose the nature and source of pest problems, and then relies on a range of preventive and curative measures.
Based on an analysis of 64 definitions spanning the past 35 years, Kogan (1998) defined IPM as a decision support system for the selection and use of pest control tactics, singly or harmoniously co-ordinated into a management strategy, based on cost/benefit analyses that take into account the interests of and impacts on producers, society and the environment.
A special committee of the National Research Council’s Board of Agriculture (NRC, 1996) proposed ‘ecologically based pest management’ (EBPM), also called ‘ecologically based integrated pest management’ (EBIPM), emphasizing on some key issues:
i. In EBIPM, programmes should emphasize on an understanding of the ecological relationships between the host plant and the management practices like cultural control, biological control and host plant resistance.
ii. Integration of management practices involves biological (e.g., parasitoids, predators and microbials), chemical (e.g., selective pesticides and pheromones) and cultural (e.g., crop rotation, planting date and aeration).
iii. Sustainability implies durability over time.
iv. EBIPM programmes should minimize economic, environmental and health risks.
The idea behind EBIPM is to shift the IPM paradigm from focusing on pest management strategies relying on pesticide management to a systems approach relying primarily on biological knowledge of pests and their interaction with the crops. Hence EBIPM programmes should represent a sustainable approach to manage pests combining biological, chemical, physical and cultural tools to ensure favourable economic, ecological and sociological consequences.
Huffaker and Croft (1976) have described the following series of phases in the evolution of an IPM programme:
(i) Single Tactic Phase:
Emphasis is generally placed on a single pest utilizing a single tactic. This phase does not represent IPM, but the limitations in this approach may lead to its development.
(ii) Multiple Tactic Phase:
This phase embraces a variety of tactics (cultural, mechanical, physical, chemical, biological, host resistance, regulatory, etc.) in manipulating pest populations.
(iii) Biological Monitoring Phase:
This phase introduces monitoring of pest, natural enemies and host plant (phenology) populations as the basis for timing the application of various control tactics.
(iv) Modeling Phase:
This involves the conceptualization of the processes involved in pest management systems through mental, pictorial, flowchart and mathematical models. As the volume and complexity of data increase, more sophisticated modeling techniques become necessary.
(v) Management or Optimization Phase:
This process involves the construction of a functional IPM system utilizing compatible subsystems in optimizing the integration of this IPM system with the overall crop production system.
(vi) Systems Implementation Phase:
This is the ultimate phase through which the optimal systems are unified for delivery to and utilization by the farmer.
The ultimate aim of scientific pest management is to maintain a low level of pest population which would not only maintain the damage lower than the economic injury level but will also support the growth and survival of its natural enemies.
The concept is to suppress the pest but not to annihilate it. For that very reason, the broad spectrum insecticides should not be used because they often have the effect of eliminating the pest as well as its natural enemies, thus upsetting the balancing of natural system of insect-parasitoid relationship.
For application in the field it is essential in the first instance to understand the concept of pest management and then to disseminate the knowledge among the practising farmers, translated in terms of their own local conditions and specific farm operations.
In other words, the philosophy of pest management is to maintain the population of a potential pest at a sub-threshold level than to eradicate it. This philosophy is based on the observation that every plant can withstand a level of population without showing loss in yield or vigour.
However, sometimes an insect may be a vector of a serious plant disease and in that case even extremely low levels of population can be instrumental in complete loss of yield. To understand these concepts more clearly, quantitative measurements are sometimes undertaken which define clearly the degree of damage and allowable damage.
Integration of Pest Management Tactics:
The pest management tactics are either preventive or therapeutic. Preventive practice utilizes tactics to lower environmental carrying capacity (reduce the general equilibrium position) or increase tolerance of the host to pest injury. Prevention relies on an intimate understanding of the pest life cycle, behaviour and ecology. The preventive tactics involve natural enemies, host resistance and cultural practices.
In addition, quarantines are also an important component of preventive tactics. Therapeutic tactics are applied as a correction to the system when necessary. The objective of therapy is to dampen pest population below EIL. The only widely used therapeutic tactic is the use of conventional insecticides but other approaches like microbial agents, augmentation of natural enemies, use of insect growth regulators, etc., also plays a vital role.
Actual integration involves proper choice of compatible tactics and blending them so that each component potentiates or complements the other. Probably, the earliest example of integration of techniques was the use of a combination of resistant varieties and sanitation practices as prophylactic measures combined with application of calcium arsenate at high population level in case of boll weevil on cotton in USA in early 1920s.
Similar programmes were being developed for other pests also but the advent of synthetic organic insecticides intervened and these techniques were relegated to the background. The misuses and abuses of insecticides have again focused our attention on integrated control measures.
Rhodes grass scale, Antonina graminis (Maskell) is a cosmopolitan insect feeding on over 100 hosts including 38 species of range grasses in Texas. A parasite introduced from India, Neodusmetia sangwani (Subba Rao), was successfully established against the pest in Texas. However, during the June population peak of the pest, natural enemy population was lower due to general host unsuitability during May.
The resistant Rhodes grass variety ‘Bell’ was found to tolerate pest attack without appreciable damage. This variety, thus, provided relief until the parasite effectively reduced scale populations. The predation rate was highest on resistant cultivars and this was attributed to the greater movement of hoppers in search of suitable feeding sites.
It has been found that the rate of parasitism by Bracon mellitor Say, the most important native parasite of boll weevil, Anthonomus grandis Boheman was higher on frego bract (resistant) than on normal bract (susceptible cotton).
The mortality of Nephotettix virescens (Distant) has been found to be highest and population lowest when resistant varieties IR 26 and IR 56 were combined with predators, myrid bug, Cyrtorhinus lividipennis Reuter and spider, Lycosa pseudoannulata (Bosenberg & Strand).
The feeding of Helicoverpa zea (Boddie) on ED73-371, a soybean genotype resistant to the Mexican bean beetle, Epilachna varivestis Mulsant increased its susceptibility to Bacillus thuringiensis Berliner. Thus, Bt which is normally ineffective against f H.zea might be effective on resistant soybean.
Natural control by parasitoids and predators can be greatly strengthened by use of a large number of cultural practices like intercropping, trap cropping, strip harvesting, etc. Modification of the crop environment by manipulation of irrigation, fertilizer, row spacing, seed rate and tillage operations, etc., may also lead to substantial improvement in benefits of biological control.
A combination of moderate resistance to carrot fly, Psila rosae (Fabricius), with specific sowing and harvesting dates, has enabled satisfactory yield of marketable carrots in heavily infested fields. The effect of plant resistance, planting dates and tillage practices was complementary in reducing greenbug, Schizaphis graminum (Rondani) population on sorghum; the resistant hybrids coupled with late planting dates and no tillage have been Consistently effective for controlling the pest.
Combining plant resistance with well-timed lower dosages of insecticides can sometimes achieve adequate pest suppression while reducing otherwise high insecticide inputs.
Sweet corn hybrids resistant to corn earworm require less insecticide than susceptible hybrids to obtain an equivalent reduction in pest incidence. The insecticide rates on an insect-resistant groundnut cultivar (NC 6) can be reduced by 75-80 per cent against Diabrotica undecimpunctata howardi Barber and 60 per cent against Frankliniella fusca (Hinds).
Insect pest management in cotton in Texas is a good example of integration of different tactics. The foundation of the programme begins with preventive tactics aimed at boll weevils. The basic tactic in prevention is a return to early planting of short season cotton cultivars, moderate fertilizer use and well-timed irrigation. Plant thinning is delayed or not implemented, which suppresses vegetative growth and stimulates early fruiting.
These practices shorten the production season and period of vulnerability to insects. Early harvesting, stalk destruction and use of defoliants late in the season prevent further weevil production and weaken or starve weevils going into hibernation. Pest surveillance and therapeutic treatments with organophosphates against boll weevil and flea hopper, Psallus seriatus (Reuter) are used at ETLs. Pyrethroids are applied in case of Heliothis outbreaks.
The Indian Institute of Horticultural Research has developed IPM in cabbage and tomato by employing trap cropping and biopesticides. Growing of Indian mustard in paired rows at the beginning and after every 25 rows of cabbage attracted more than 80 per cent of diamondback moth infestation besides almost entire population of leaf Webber, stem borer, bugs and aphids.
To control the remaining attack of diamondback moth, a 4 per cent neem seed kernel extract (NSKE) is applied at primordial or head initiation stage of the crop. Similarly, trap cropping of marigold after every 8 rows of tomato attracts most of the ovipositing moths of Helicoverpa armigera (Hubner) to the former crop.
The use of conventional insecticides on the trap crop reduces their attractiveness to the pest. Therefore, the pest on the trap crop has to be removed mechanically. The residual pest population on both the crops is controlled by sprays of H. armigera NPV @ 500 larval equivalent per ha.
Constraints in IPM Implementation:
The Consultant Group of the IPM Task Force has conducted an in-depth study of the constraints on the implementation of IPM in developing countries, which can be categorized into the following five main groups:
1. Institutional Constraints:
IPM requires an interdisciplinary, multi-functional approach to solving pest problems. Fragmentation between disciplines, between research, extension and implementation, and between institutes, all lead to a lack of institutional integration. Secondly, both the national programmes of developing countries and the donor agencies have lacked a policy commitment to IPM in the context of national economic planning and agricultural development. This has resulted in a low priority for IPM from national programmes and donors alike.
Thirdly, the traditional top-down research in many cases does not address the real needs of farmers, who eventually are the end-users, and who select to adopt or reject the technology based on its appropriateness. Institutional barriers to research scientists in national programmes conducting on-farm research in developing countries are real, and need to be addressed.
2. Informational Constraints:
The lack of IPM information which could be used by the farmer and by extension workers is a major constraint in implementation. In a study regarding implementation of IPM in Haryana, India, it was found that more than three-fourth of the farmers were not even aware of the concept of IPM. Even those aware of the concept reported that they lacked the skills necessary to practise IPM.
While the individual control techniques are well known, little knowledge is available on using these in an integrated fashion under farm conditions. The lack of training materials, curricula and experienced teachers on the principles and practice of IPM is another major constraint. In many cases, the field level extension workers are not sufficiently trained in IPM to instill confidence in the farmers.
3. Sociological Constraints:
The conditioning of most farmers and farm level extension workers by the pesticide industry has created a situation where chemicals are presented as highly effective and simple to apply. This acts as a major constraint in IPM implementation. There appears to be a direct conflict between industry’s objective of more sales, and the IPM message of rational pesticide use, in the eyes of farmers.
There is a need for private industry and public sector extension agencies to work in a more complementary manner. A majority of the farmers in a study in Haryana, India, expressed their lack of faith in IPM. They considered IPM practices to be risky as compared to the use of chemical pesticides.
4. Economic Constraints:
A major constraint, even if IPM is adopted in principle, is the funding for research, extension and farmer training needed for an accelerated programme. IPM must be viewed as an investment, and as with other forms of investment, requires an outlay.
In the long run, IPM programmes may become self-generating due to saving on resource inputs for production. A majority of the farmers purchase pesticides on credit and depend on shopkeepers and pesticide dealers for information about the pest control methods.
5. Political Constraints:
The relatively low status of plant protection workers in the administrative hierarchy is a constraint to general improvement in plant protection. Associated with the above are the morale and financial standing of these workers.
The continuance of pesticide subsidy by the government for political reasons and its tie up with the government-provided credit for crop production, acts as a major constraint to farmers’ acceptance of IPM. Various vested interests associated with the pesticide trade also act as a political constraint on the implementation of IPM.
Framework of IPM Programme:
There has been a widespread tendency to work within specialized subject areas of IPM and this movement towards specialization among researchers has now reached its peak of ascendancy. The need now is to place this specialist knowledge, abilities and skills within a broader scientific framework. There ought to be better coordination and exploitation of this valuable resource.
This means that work of specialist groups dealing with different aspects of a common problem of insect pest control needs to be coordinated and placed in the context of the framework of an integrated pest management programme. This integration needs to be started at the top, in funding policy and reach up to the lowest level, in implementation.
The funding authorities need to develop a coherent policy and ensure that all individual research groups working on similar cropping systems coordinate their approaches. There is a need to allocate funds for development of complete pest management programmes.
Secondly, there is an urgent need to develop conceptual and theoretical framework for IPM. The present situation is that IPM is made up of a great many isolated parts, each of which can be developed internally but which is not clearly connected to anything else, e.g., farming systems, host plant resistance, natural enemies and decision-making behaviour.
These pieces ought to be combined in an integrated programme. This requires a theoretical framework that will provide guidelines for pest managers. The framework will incorporate pest outbreak theory, a classification of pest types, their hosts and farming systems, and to identify options most appropriate for management strategies.
Thirdly, integrative level of research in the form of field trials to test combination of control options for their compatibility and effectiveness is essential. This integrative research will require the combined input of all relevant disciplines to design, carry out and analyze the data from suitable factorial or multifactorial experiments.
These experimental designs will be necessary to assess the interaction between the various treatments under test and arrive at a combination of options that produce higher yields.
Fourthly, integration is required at the level of organizational behaviour. It is important that appropriate organizational structures are developed because they are fundamental to good management. Without them, integration of research will be less likely to occur and at a different level it may be found to affect motivation, innovation, morale and decision making, and exacerbate conflict and poor coordination.
Ideally, IPM should involve integration of control options for the management of all types of pests and not just insects. Insect pest management will then just be a subsystem of integrated pest management (IPM). This will require multidisciplinary research encompassing insects, pathogens, weeds and other pests.
The importance of integrating the control of insects and pathogens is illustrated by an early story involving control of grape phylloxera on grapes in Europe. This example is often cited to illustrate the importance of plant resistance.
The other part of the story is not so well known. Ironically, plants introduced from North America carried the pathogen of Plasmopara viticola, the causal agent of downy mildew to which European grapes were highly susceptible.
The American root stock saved French vineyards from grape phylloxera but exposed them to an even more dangerous risk. The devastating epidemic of downy mildew that followed threatened wine production throughout Europe.
Ultimately, the development of Bordeaux mixture, an early fungicide against the pathogen, saved European vineyards. This example underlines the need to consider the whole pest complex and the implications of any management strategy.
vi. Lastly, the development of an implementation strategy should not be left to the final phases of a research programme. It should initially be considered during problem formulation and then continually readdressed throughout the research phase of the programme because it is often at the point of implementation that many pest management programmes fail.
Advantages of IPM:
Initially, IPM programmes evolved as a result of the pest problems caused by repeated and intensive use of pesticides and increasing cases of past resistance to these chemicals. It is only during the past few years that economic and social aspects of IPM have also received increasing attention.
Some of the important advantages offered by IPM over the pesticide-based plant protection programmes are listed below:
1. Sustainability:
It is now being increasingly recognized that modern agriculture cannot sustain programmes that present productivity levels with the exclusive use of pesticides. Increasing pest problems and disruptions in agro-ecosystems can only be corrected by use of holistic pest management programmes.
2. Economics:
If the environmental and social costs of pesticide use are taken into account, IPM appears to be a more attractive alternative with lower economic costs.
3. Health:
Production, storage, transport, distribution, and application of pesticides involves greater health hazards than the safer inputs used in IPM. In developing countries, it is almost impossible to implement residue limits or waiting periods for pesticides on food products and other commodities. This endangers the safely of the entire population of these countries.
4. Environmental Quality:
The IPM programmes do not endanger non-target organisms, nor do they pollute the soil, water and air. The clean air, water and soil are now being recognized as nonrenewable resources which once polluted are almost impossible to purify.
5. Social and Political Stability:
The pesticides used by the farmers are obtained from the corporate houses and even from other countries. The inputs used in IPM are usually based on local resources and outside dependence is minimized. This helps in maintaining social and political stability.
6. Local Knowledge:
IPM builds upon indigenous farming knowledge, training traditional cultivation practices as components of location specific IPM practices. This is especially important for the farmers in developing countries where traditional agricultural systems are based on indigenous farming practices. The incorporation of IPM into these practices helps the farmers to modernise while maintaining their cultural roots.
7. Export of Agricultural Commodities:
The presence of pesticide residues is affecting our exports of agricultural and horticultural commodities. There is a growing demand for organically cultivated, fresh and processed fruits and vegetables. The current consumption of organically produced fruits and vegetables at the global level is valued at US$ 27 billion. The pesticides in beverages like tea and coffee have affected our exports of these commodities during the last few years.
There is also a considerable export market for cotton fabrics and garments devoid of pesticide residues in Japan and Western countries. Residue-free basmati rice is also highly prized in the international market. Thus, implementation of IPM in these crops will give boost to export of fresh and processed agricultural commodities from India and other Asian countries.
The strategy of exclusive reliance on pesticides for all pest problems created a number of ecological and environmental problems. We now know that insects possess a remarkable ability to survive in the face of selection pressure exerted by insecticides and other forms of pest control.
To overcome these problems, integrated pest management based on ecological principles was developed as a viable and attractive alternative. Though the concept of IPM has been universally accepted, there are as yet few IPM programmes functioning at the farmers’ level. A major limitation is the lack of a theoretical framework into which various components of IPM can be fitted to develop a viable IPM system.
There is an urgent need to develop IPM systems for different crops, which are environmentally benign, conserve our plant and animal genetic resources and are economically viable. This requires intensified research efforts in formulation, research and implementation phases of the IPM programmes.