Pest management on high-value crops relies heavily on the use of pesticides, often to the exclusion of other methods. With an increasing restraint on insecticide use due to development of resistance in insect populations and environmental contamination, integration of several management techniques has become essential to reduce reliance on pesticides and prolong the utility of valuable molecules.
In order to overcome the toxic and chronic effects of pesticides, as well as pest resurgence, intensive research efforts are needed to develop a balanced programme for IPM. This would require exploring and refining of various components of IPM, and devising strategies for their suitable integration.
Parasitoids and Predators:
Entomophages, which feed on insects, play an important role in regulating pest populations. However, their potential has largely remained underestimated and under-exploited. It has been estimated that only 15 per cent of entomophages have so far been identified.
Parasitoids belonging to the insect order Hymenoptera have been involved in about 66 per cent of all successful biocontrol programmes. Most of the common predators occur in insect orders Coleoptera, Hemiptera and Neuroptera. In addition, there are several species of mites and spiders feeding on a wide range of insects and mites.
More than 125 species of natural enemies are commercially available at global level for augmentative biological control programmes, including 37 commonly used species such as the moth egg parasitoid, Trichogramma spp.; whitefly parasitoid, Encarsia formosa Gahan, and the spider mite predator, Phytoseiulus petsimilis Athias-Henriot.
The potential of classical biocontrol has been demonstrated in Africa where the cassava mealybug, Phenacoccus manihoti Matile-Ferrero, has been virtually eliminated in 30 countries, by the exotic parasitoid, Epidinocarsis lopezi (De Santis).
Parasitoids and predators can provide long term regulation of pest species provided proper management practices are followed to make the environment conducive to furthering their abundance and efficiency in target agro-ecosystems. Biological control can potentially become a self-perpetuating strategy, providing economic control with the least environmental hazards. However, much work needs to be done to optimize the utilization of parasitoids and predators in integrated pest management.
Some of these are as follows:
i. There is an urgent need to establish a network of large scale multiplication units so that the natural enemies are available to the farmers at reasonable prices. A new industry of mass propagation of natural enemies is born as costs of mass rearing are reduced, making this process commercially competitive. As the technology of mass propagation of natural enemies develops, more arthropod pest species will become amenable to biological control.
ii. Heat-and cold-tolerant strains have to be selected/developed in the case of a number of natural enemies. The environmental implications of releases of these organisms, especially in cases of introductions and genetically engineered organisms should be, investigated.
iii. Since the performance of most biocontrol agents is known to be affected by physical or chemical attributes of the target crops, it is necessary to identify species or strains adapted to major crop systems.
iv. Major improvements in biological control of insect pests can be made through habitat management. Increasing genetic diversity could provide useful means of augmenting natural enemy populations. However, the response varies across crops and cropping systems. Therefore, appropriate cropping systems should be identified for specific predators and parasitoids to increase their efficacy.
v. The allelochemicals produced by the host plant mediated through the pests, affect the biology and efficiency of natural enemies. Hence, a thorough understanding of tritrophic interactions among crop plants, insect pests and their natural enemies is essential to derive strategies for biological control of insect pests.
vi. There is a need to develop entomophage parks, i.e. undisturbed habitats of natural vegetation near agricultural areas to protect and enhance specific natural enemies and provide them with resources such as nectar, pollen, physical refuge, alternative prey, alternative hosts and mating sites. This will improve natural enemy fitness and effectiveness.
Microbial Pesticides:
So far, over 3000 microorganisms have been reported to cause diseases in insects. However, scientists familiar with specific pathogen groups agree that a very large number of insect pathogens remain undiscovered or unidentified. More than 100 bacteria have been identified as arthropod pathogens, among which Bacillus thuringiensis Berliner (Bt) has received the maximum attention as microbial control agent.
Viruses have been isolated from more than 1000 species of insects from 13 different insect orders. World over, about 525 insect species in 52 families and 8 orders are known to be infected by nuclear polyhedrosis virus (NPV) and of this large number of species, 455 belong to Lepidoptera.
Till now, over 800 species of entomopathogenic fungi have been identified. More than 1000 species of protozoa pathogenic to insects have been described and many more remain to be discovered. The two major groups of entomopathogenic nematodes are Steinernema (55 species) and Heterorhabditis (12 species).
In spite of their great potential, there are several constraints in the use of microbial pesticides, which require a focus in the future. Depending upon the country, registration of a microbial pesticide is a lengthy and expensive procedure. Compared to chemical pesticides, microbial pesticides are expensive, slow acting and field efficacy is inconsistent. Microbial pesticides require special procedures for formulation, packaging, storage and application, and their efficacy is also influenced by environmental conditions.
Narrow host range, necessity to ingest Bt toxins by the target insects, ability of insect larvae to avoid lethal doses of Bt by penetrating into the plant tissue, inactivation by sunlight, and effect of plant surface chemicals on its toxicity limit its widespread use in crop protection. Similarly, narrow range, slow rate of insect mortality, difficulties in mass production, stability under sunlight and farmers’ attitude have limited the use of NPVs as commercial pesticides.
Owing to the early successes and continuing growth of biopesticide market, expectations for the performance of microbial biopesticides are quite high. However, there are many challenges that will need to be overcome so that the self-perpetuating nature of most of the microbial pathogens may prove to be an asset in sustainable agriculture.
Some of the challenges are as follows:
i. In order to increase the utility of microbial pesticides in IPM programmes, systematic surveys are required in different agro-ecological regions to identify naturally occurring pathogens. Detailed studies are necessary on the properties, mode of action and pathogenicity of such organisms.
ii. Ecological studies on the dynamics of diseases in insect populations are necessary because the environmental factors play a significant role in disease outbreaks and ultimate control of the pests.
iii. There is a need to develop and standardize mass production technologies of microbial biopesticides in order to solve potential problems associated with contamination, formulation potency, alternation of pesticidal activity and shelf-life.
iv. Suitable formulations should be developed to increase their residual activity and improve shelf-life. Commercially dry formulations are preferred over liquid formulations. Lyophilization and encapsulation should be explored to produce stable formulations with persistent toxicity. The use of formulations that include stilbene-derived optical brighteners, increase efficiency of NPV formulations.
v. The relatively slow speed with which microbial pathogens kill their host has hampered their effectiveness as well as acceptance by potential users. Genetic improvement with conventional and biotechnological tools would lead to the production of strains with improved pathogenesis and virulence.
Botanical Pesticides:
The use of plants and their crude extracts for the protection of crops and stored products from insect pests has been a part of traditional agriculture for generations. Neem leaves and kernel powder have been traditionally used by farmers against pests of household, agricultural and medical importance.
More than 6000 plant species from at least 235 plant families have been screened for pest control properties. A large number of plant products derived from neem, custard apple, tobacco, pyrethrum, etc. have been used as safer pesticides for pest management. Phytochemicals from Meliaceae family have shown remarkable feeding deterrency, repellency, toxicity, sterilant and growth disruptive activities.
Azadirachtin, the major bioactive principle of Azadiraclita indica A. Juss. and azadirachtin based formulations show wide array of pest control properties and are now globally available. Efforts are needed to identify more molecules of plant origin so that they can be used successfully in pest management in the future.
Several problems have been encountered while commercializing the botanical pesticides, which are related to quantity of raw material, thermal and photostability, as well as quality control and product standardization. Like synthetic pesticides, the repeated and excessive use of botanical pesticides may also lead to pest resistance.
The possibility of insects developing resistance looms large if single botanical pesticide like azadirachtin is allowed to be used too frequently. The phytotoxicity observed with the botanicals is also a matter of concern. Neem oil based formulations are often phytotoxic to tomato, brinjal and ornamental plants at oil levels above 1 per cent. Although plant products are considered to be relatively safe to humans, however, this cannot be assumed for all plant species.
Some of the most toxic substances known to man, e.g., aconitine and ricin are produced by plants. Some of the plant species such as Taxus spp., Aconitum spp. and Ricinus communis Linnaeus have notoriously high toxicity to man. Some of the commonly used plant materials in Africa such as Tephrosia vogelii Hook f. have well-known environmental impacts, particularly against fish.
To ensure there is a future for pesticidal plants, there are many issues that need to be addressed by the scientific community, policy makers and institutions involved in knowledge dissemination.
Some of these are as follows:
i. Scientists need to provide better information that explains how pesticidal plants work, which arthropod species are affected, how the bioactive chemicals may vary according to season, locality or variety and how best plants should be harvested and processed to conserve and deliver bioactivity.
ii. Furthermore, scientists need to engage with policy makers to tackle issues such as conservation of wild habitats and survey of unexplored plant biodiversity for pesticidal plants.
iii. There is a need of special set of guidelines for registration of plant products, which should be less stringent than other chemical pesticides.
iv. Quality control in botanical pesticides is a major problem. The active ingredient levels are often affected by the agro-ecological factors in different regions of plant growth. There is an urgent need to define quality standards for botanical pesticides in order to obtain consistent results.
v The threshold of active ingredients such as azadirachtin in neem, pyrethrins in chrysanthemum, their biomass etc. may be raised through natural selection, exotic introductions, tissue culture and other biotechnological manipulations.
vi. The photo- and heat-liability of botanical pesticides is another area which requires serious attention. Because of these undesirable traits, repeated outdoor applications of products are necessitated. Appropriate methodologies need to be developed to improve both residual and shelf life. Suitable stabilizers, UV-screens and antioxidants need to be identified for incorporation in the formulations.
Semiochemicals:
Semiochemicals or behaviour modifying chemicals have gained prominence since quite recently in pest management programmes. There was a rapid growth in the identification of insect pheromones during 19705, and by the end of 1980s, pheromones and pheromone mimics were known for about 1000 species of insects.
Today, more than 1500 moth sex pheromones and hundreds of other pheromones have been identified, including sex and aggregation pheromones from beetles and other groups. The first field trials that involved assaying pheromones for pest control were carried out in mid 1980s.
Since then, hundreds of other pheromones have been identified and there are more than 50 (in over 300 different formulations) that can be used in pest management programmes. Over 30 target species have been controlled successfully by mating disruption. It has been estimated that at least 20 million pheromone lures are produced for monitoring or mass trapping every year.
The world mean sale of semiochemical products is about US$ 70-80 million or 1 per cent of the agrochemical market. The fact that producers rely on the deployment of air permeation and attract- and kill- techniques for pest control over 1 million ha would justify continued efforts to develop and implement management programmes based on the use of these semiochemicals.
Development of semiochemical-based techniques for pest management needs stimulus from the scientific community, industry and the policy makers.
i. Basic studies on understanding of the mechanisms underlying communication systems in insects, coupled with a good working knowledge of biology, behaviour and mating systems to target insects, should be undertaken. The effect of various meteorological and physiochemical factors on chemical language of insects and plants should be understood to achieve success with semiochemicals.
ii. Many of the semiochemicals are photodegradable and, therefore, rapidly loose their efficacy following their applications on the crop. Therefore, suitable protected and controlled release formulations should be developed, which retain their effectiveness for a considerable length of time.
iii. Insects are believed to be less prone to development of resistance to semiochemicals because of their novel mode of action. However, several cases of semiochemical resistance have been documented and therefore, timely and effective measures should be undertaken so that we may not loose the useful attributes of these safe compounds.
iv. The best successes with semiochemicals have been achieved where large, contiguous areas have been treated with these compounds. Therefore, an area-wide approach will have to be followed to control the target pests in a defined area. For this, cooperation of the farmers is essential and there is a need for more efficient technology transfer for those who will benefit by application of control methods based on semiochemicals.
v. Commercialization of semiochemical-based products is strongly affected by the size of the potential market, cost of registration and the product’s price competitiveness. The lack of commercial interest by major agrochemical firms has clearly hampered the development of semiochemical-based products. Therefore, the industry should be given proper incentives and the commercial successes achieved with semiochemicals should energize the level of commitment by industry in developing new products.
Chemical Control:
Pesticides have played a pivotal role in bringing about green revolution in many countries. The potential of high yielding varieties was realized under the pesticide umbrella. Pesticides are the most powerful tool in pest management. Pesticides are highly effective, economical, rapid in action, adaptable to most situations and flexible enough to meet the changing agronomic situations.
Pesticides are the most reliable means of reducing crop damage when the pest populations exceed economic threshold levels (ETLs). When used properly based on ETLs, pesticides provide a dependable tool to protect the crops from the ravages of insect pests. Despite their effectiveness, much pesticide use has been unsound, leading to problems of development of resistance, pest resurgence, pesticide residues in the food commodities, non-target effects in the environment, and direct hazards to human beings.
More than 577 species of insects and mites have developed resistance to different groups of pesticides. Resurgence of insect pests not only leads to increased use of pesticides, but also increases the cost of cultivation, greater exposure of the operators to toxic chemicals, and failure of the crop in the event of poor control of target pests.
Many scientific studies have proved bio-magnification of pesticide residues in human tissues, and products of animal origin. Over 100,000 cases of accidental exposure to pesticides are reported every year, of which a large number prove fatal. Hence, there is a need to look for new molecules, which are effective against insect pests but cause minimum environmental hazards.
Many industrialized countries have enforced stringent pesticide regulations and developed alternative pest management approaches as a result of which pesticide use in these countries has shown a declining trend. Consequently, the magnitude of contamination of food materials has also slowed down.
However, many developing countries continue to use persistent pesticides in agriculture and public health programmes, and the contamination of different components of the environment continues to be excessive and pervasive. In addition, pesticide subsidies coupled with improper pesticide application and use has further accentuated the problems. Therefore, there is an urgent need to rationalise the use of pesticides in the context of IPM.
i. Development of resistance to pesticides has often resulted in widespread failure of chemical control. Pesticide resistance management strategies have aimed either at preventing the development of resistance or to contain it. All rely on a strict temporal restriction in the use of certain pesticides and their alteration with other pesticide groups to minimize selection for resistance. Because of economic advantages and safety to non-target organisms, all efforts should be directed towards developing management strategies aimed at prolonging the life of useful molecules.
ii. Resurgence of insect pests in several species on various crops has posed a serious problem. This phenomenon not only leads to increased use of pesticides, but also increases the cost of cultivation, greater exposure of the operators to toxic chemicals, and failure of the crop in the event of poor control of the target pests. Therefore, mechanisms underlying resurgence must be taken to avoid/or delay insect resurgence.
iii. There is an urgent need for improvements in pesticide application methods, timing and placement. The refinement of spray technology will result in improved efficacy with reduced pesticide residues in raw agricultural commodities. Some of the application equipment does not give the desired performance for specific crop-pest, climatic, and topographic conditions.
There is a need to devise suitable application equipment to meet the farmers’ needs in rain-fed agriculture. Moreover, dry areas need different types of pesticide formulations, which require a minimum amount of water. Hence, research efforts should be concentrated on developing the right type of plant protection equipment vis-a-vis pesticide formulations.
iv. Efforts should continue to search and identify newer compounds that can be successfully used in pest management programmes. The pesticide industry must emphasize the development of new products with greater selectivity for natural enemies and minimal environmental hazards.
v. In view of the environmental hazards of the pesticides, there is an urgent need to rationalize the use of pesticides in pest management. This would require vigilant efforts on the part of policy planners, government implementing agencies, scientists, farmers and the consumers, to reduce the pesticide load in the environment. Pesticides would remain an indispensable part of modern agriculture and must be used in combination with other approaches in integrated pest management.
Host Plant Resistance:
Inspite of the significance of host plant resistance as an important component of IPM, breeding for plant resistance to insects has not been as rapidly accepted as breeding of disease-resistant cultivars. This is partially due to the relative ease with which insect control is achieved with the use of insecticides and slow progress in developing insect resistant cultivars because of the difficulties involved in ensuring adequate insect infestation for resistance screening.
High levels of plant resistance are available against a few insect species only. In fact, very high levels of resistance are not a pre-requisite for use in IPM. Varieties with low to moderate levels of resistance or those that can avoid pest damage can be deployed for pest management in combination with other components of IPM. Deployment of pest-resistant cultivars should be aimed at conservation of natural enemies and minimizing the number of pesticide applications.
Resistant cultivars can be used as a principal method of pest control, an adjunct to other management tactics, and a check against the release of susceptible cultivars. Resistant crop varieties developed in recent years represent some of the greatest achievements of modern agriculture in increasing and stabilizing world food and fibre supplies.
Considerable progress has been made in identification and utilization of plant resistance to insects. The current global economic value of plant resistance is several hundred million dollars per year. The ecological value of plant resistance has greatly decreased world pesticide usage, contributing to healthier environment for humans, livestock and wildlife.
Agricultural producers have benefited from crops with arthropod resistance through decreased production costs. Consumer benefits derived from insect-resistant crops include safer and more economically produced food. Plant resistance to insects should form the backbone of pest management programmes in integrated pest management.
i. Multilocational testing of the identified sources and breeding material need to be strengthened to identify stable and diverse sources of resistance or establish the presence of new insect biotypes. Resistance to insects should be given as much emphasis as yield to identify new varieties and hybrids.
ii. New and improved insect infestation techniques and devices that safely and efficiently place test insects onto the crop plants will also be essential to future progress. The development and refinement of standardized rating scales to determine insect damage to more crops will greatly facilitate the development of insect-resistant cultivars to several additional crop plant species.
iii. More information is needed on mechanisms of resistance, genetic regulation of resistance traits, and biochemical pathways and their physiological effects. Our knowledge of how plants recognize insect-feeding attacks and the elicitors they produce in response to insect feeding is increasing rapidly. The evolving model of the differences in plant defense- response elicitors must be researched, challenged and modified to better understand induced resistance function and how plant metabolism can possibly be modified to use induced crop-plant resistance in insect pest management programmes.
iv. The complexicity of tritrophic interactions plays a vital role in host plant resistance. Elucidation of these interactions can help further understanding, and provide greater potential for manipulation of these systems to specific crop species and varieties. The possibility of using compounds from plants to reduce herbivore damage and increase the effectiveness of biological control agents is quite attractive. Ideally, plant resistance should strive to reduce substances attractive to herbivores, while increasing the substances attractive to natural enemies.
v. Occurrence of new biotypes of the target pest may limit the use of certain insect resistant varieties in time and space. In such situations, we should go for polygenic resistance or continuously search for new genes and transfer them into high yielding varieties.
Transgenic Crops:
The introduction of transgenic technology has added a new dimension to pest management. The global area under transgenic crops has increased from 1.7 million ha in 1996 to 175.2 million ha in 2013. Of the 27 countries growing transgenic crops, 19 were developing and the remaining 8 were developed countries.
A total of 18 million farmers grew transgenic crops in 2013; about 90 per cent were small resource-poor farmers from developing countries. India celebrated a decade of successful cultivation of Bt cotton in 2011, when Bt cotton occupied 88 per cent of the total 12.1 million ha of cotton crop.
The increase from 50,000 ha of Bt cotton in 2002 to 10.6 million ha in 2011 represents an unprecedented 212-fold increase in 10 years. The area under Bt cotton further increased to 11 million ha in 2013. India enhanced farm income from Bt cotton by US$ 12.6 billion in the period 2002 to 2011 and US$ 3.2 billion in 2011 alone.
Thus, Bt cotton has transformed cotton production in India by increasing yield substantially, decreasing insecticide applications by about 50 per cent, and through welfare benefits,’ contributed to the alleviation of poverty of 7.3 million small resource-poor farmers and their families in 2013 alone.
In addition to higher yield, the benefits to farmers of transgenic crops include the lower input costs in terms of pesticide use, and ease of crop management. The reduction in pesticide usage would lead to reduced exposure of farm labour to pesticides, reduction in harmful effects of pesticides on non-target organisms, and reduced amounts of pesticide residues in food and food products.
The additional benefits to farmers would be to control insect pests which have become resistant to commonly used-pesticides, and reduction in crop protection costs. These factors are likely to have substantial impact on the livelihood of farmers in both developed and developing countries.
In many developing countries, small-scale farmers suffer pest-related yield losses because of technical and economic constraints. Pest-resistant genetically modified crops can contribute to increased yields and agricultural growth in such situations.
Available impact studies of insect-resistant and herbicide-tolerant crops show that these technologies are beneficial to farmers and consumers, producing large aggregate welfare gains as well as positive effects for the environment and human health. The advantages of future applications could be even much bigger. Transgenic crops can contribute significantly to global food security and poverty alleviation.
Despite numerous future promises, there are number of ecological and economic issues that need to be addressed when considering the development and deployment of transgenic crops for pest management. There is a multitude of concerns about the real or conjectural effects of transgenic plants on non-target organisms, including human beings, and evolution of resistant strains of insects.
As a result, caution has given rise to doubt because of lack of adequate information. One of the risks of growing transgenic plants for pest management is the potential spread of the transgene beyond the target area. There is a feeling that the genes introduced from outside the range of sexual compatibility might present new risks to the environment and humans, and will lead to development of resistance to herbicides in weeds, and to antibiotics.
The biosafety issues related to the development of transgenic plants include risks for animal and human health, such as allergies, toxicity, and food quality and safety. While some of these concerns may be real, others seem to be conjectural and highly exaggerated.
Future research on development and deployment of transgenic crops should focus on the following issues:
i. Effects of transgenic plants on the activity and abundance of non-target herbivore arthropods, natural enemies, and fauna and flora in the rhizosphere and aquatic systems should be thoroughly investigated. Development of transgenic crops with wide spectrum of activity against insect pests feeding on a crop, but harmless to natural enemies and other non-target organisms should be given top priority.
ii. There is a need for having a detailed understanding of resistance mechanisms, insect biology, and plant molecular biology to tailor gene expression in transgenic plants for efficient pest management. Future researches should focus on pyramiding of novel genes with different modes of action with conventional host plant resistance, and multiple resistances to insect pests and diseases.
iii. The potential of RNAi, a technique to study the function of particular gene by silencing that gene in an organism, has been established in insects. The research efforts must be intensified to identify the potential insect genes which are important for biological functions of the target insects. The identified potential genes should be used for development of transgenic plants against that particular insect.
iv. One of the risks of growing transgenic crops is the potential spread of the transgene beyond the target area. There is a feeling that genes introduced from outside the range of sexual compatibility might present new risks to the environment. Therefore, studies should be undertaken to determine the extent and implications of gene transfer. Appropriate measures should be devised to contain gene flow where its likely consequences may be deleterious to the environment.
v. The need for identification and detection of transgenic crops and food products derived from them has increased with the rapid expansion in cultivation of transgenic crops over the past decade. Labeling and traceability of transgenic material is important to address the concerns of the consumer. Establishment of reliable and economical methods for detection, identification and quantification of genetically modified food continues to be a great challenge at the international level.
Integrated Pest Management:
Integrated pest management (IPM) programmes were initially evolved as a result of the pest problems caused by repeated and excessive use of pesticides and increasing cases of pest resistance to these chemicals. It is only during the past two decades that economic and social aspects of IPM have also received increasing attention.
If the environmental and social costs of pesticide use are taken into account, IPM appears to be more attractive alternative with lower economic costs. Production, storage, transport, distribution and application of pesticides involves greater health hazards than the safer inputs used in IPM. The IPM programmes do not endanger non-target organisms nor do they pollute soil, water and air.
IPM builds upon indigenous farming knowledge, treating traditional cultivation practices as components of location-specific 1PM practices. The incorporation of IPM into traditional practices helps the farmers to modernize while maintaining their cultural roots. The inputs used in IPM are usually based on local resources and outside dependence is minimized.
This helps in maintaining social and political stability. It is now being increasingly realized that modern agriculture cannot sustain the present productivity levels with the exclusive use of pesticides. Increasing pest problems and disruption in agro-ecosystems can only be corrected by use of holistic pest management programmes.
Pest management practices may not be sustainable for a variety of reasons:
(i) The control tactic may no longer be effective over time due to selection against pests that are susceptible to the tactic.
(ii) The control tactic leads to disruption in the ecosystem that may result in further outbreak of the target pest or outbreaks of new pests.
(iii) The cost of the practice may be too expensive to maintain indefinitely.
(iv) The practice may degrade the quality of human health, environment or agronomic resources over time.
(v) New pest problems may arise due to introduction of pests or natural enemies that attack existing biological control agents and thereby increase pest populations.
(vi) As the types and the abundance of pests change due to crop intensification, the previous management tactics may not adequately control pest population.
Therefore, pest management decisions will have to be taken, keeping in view the dynamics of pest population, sustainability of the management tactics, compatibility of the tactics and stability of the agro-ecosystem. As control measures are generally disruptive to the ecosystems, preventing the pest problem from arising in the first place is preferable to control and promote sustainability.
If pesticides are part of the IPM system, a pesticide resistance management strategy is essential, so that the target pest’s susceptibility to pesticide does not decline over time. Other management tactics like pest-resistant cultivars, biological control agents and cultural practices are not necessarily sustainable over time, which may require periodical monitoring. Farmers’ own management practices need to be incorporated in IPM systems to make them more acceptable and sustainable.
Many of the IPM strategies can be implemented effectively only on an area-wide basis. This is possible through increased farmers’ awareness and enactment of suitable legislative measures. IPM also needs to be integrated with other components of crop production and rural development.
Ultimately, IPM is to be used at the farmers’ level and, therefore, it needs to be converted from a scientist-oriented to a farmer-oriented concept. The recent advances in information and communication technology have provided us a unique opportunity to achieve these objectives.
Computer-based interaction systems installed at the village level can help the farmers in pest identification, forecasting of pest populations, range of options available for pest management with advantages and limitations of each of these options. This will help the farmers in identifying the best option based on their requirements and resources.
IPM programmes gained momentum during 1980s and since then many major food and fibre crops were covered under IPM technology in many countries. However, many crops of extreme importance to subsistence and resource-poor farmers around the world have not received due attention.
These crops, often referred to as ‘orphan crops’ because of relative lack of research and development applied to them, include root and tuber crops such as cassava, sweet potato and yam; millets such as pearl millet, finger millet and foxtail millet; and several legumes and tree crops.
Moreover, the package of practices in many developing countries still lay emphasis on pesticide based pest management programmes. Therefore, the future IPM programmes need to be ecologically based in order to achieve sustainable crop protection.
i. IPM programmes have been developed and validated for almost all the major crops in different parts of the world. However, their widespread acceptance by the farmers in many developing countries is far from satisfactory. Therefore, farmers must be involved in devising and refining IPM schedules so that they are convinced of the benefits of the IPM technology. Viewing farmers as an equal partner in technology development and testing will foster ownership of IPM technologies and increase adoption.
ii. Different tactics of IPM may not always be complementary to each other. There have been situations where host plant resistance and chemical control, host plant resistance and biological control, chemical control and biological control, and transgenic crops and biological control have been incompatible. Therefore, the interactions among various tactics of IPM should be thoroughly investigated before applying them to IPM programmes.
iii. Generally IPM programmes have been devised taking into consideration the major target pest. Efforts should be made to follow a holistic approach by taking into consideration the entire insect pest and disease complex of the agro-ecosystem.
iv. A field-to-field approach is followed by individual farmer to manage pests on their farms. There are always chances of movement of insects from the adjoining untreated fields to colonise the treated crop after a few days of the control operation. Therefore, area-wide pest management approach should be followed where the farmers practice the IPM schedule in contiguous blocks.
v. Pesticides have been dominating the scene of pest management even after the concept of IPM became popular and widely accepted. There is a need to shift the IPM paradigm from focusing on pest management strategies relying on pest management to a system approach relying primarily on biological knowledge of pests and their ecological interactions with the crops. Digital technology and high-speed telecommunications can enable access to recent information in the Internet.
The use of GPS will compliment web networks by providing researchers and extension workers with tools that will enable them to define regions where production constraints are most acute, develop targeted technologies for those regions and monitor their use. Modeling and computer programmes can aid in understating the dynamics of pest populations and devising sustainable pest management strategies.