|Synopsis on Integrated Pest Management in Developing Countries (NRI, 1991, 20 p.)|
9. The potential economic and social benefits of IPM are high even where the principal outcome is limited to a reduction in pesticide use through improved and timely application. For developing countries the gains to be derived in foreign exchange and reduction in operator hazard through eliminating unnecessary or inappropriate use of agrochemicals are very considerable.
10. Furthermore, the dynamics of tropical agro-ecosystems differ quite markedly from those of their temperate counterparts. More production is invested in standing biomass; this makes them more susceptible to perturbation and degradation. Biological processes feature more prominently in maintaining stability where climatic factors are not primary determinants of temporal cropping profiles. An illustration makes the point. Chemical control contains the brown plant hopper even under intensive rice cultivation in temperate Japan and Korea. Intensification of rice in tropical SE Asia established this species as a pest because applying the temperate solution led to insecticide-induced resurgence and the creation of a 'super-pest'. A gross oversimplification, but in essence the loss of natural enemies in temperate rice had marginal impact and the balance was in favour of the pesticide; in tropical rice this factor was of overwhelming importance.
11. Against this background it is clear why many attempts have been made to implement IPM in developing countries. Few have had more than limited success and it is difficult to draw general conclusions as to why this is the case from experience to date, not least because failures are rarely subjected to critical appraisal. The Working Group Consultancy addressed this problem by devising a questionnaire which was issued to scientists with extensive experience of pest management in Developing Countries. A detailed analysis of these data is presented in Annex III of the Consultant's Report (see Iles, 1990); it has yielded some valuable insights and some of the general lessons and principles are reviewed here.
12. The FAO IPC programme for SE Asia under Peter Kenmore has broken new ground and provides perhaps the best example of a tropical crop of developing countries, irrigated rice, in which recent developments have closely followed the IPM concept. The programme has adopted a holistic approach
Rice is arguably the world's most important crop since it is the staple food of half the world's population. It is grown on 148 million hectares of land globally of which Asia claims the largest proportion (126 million ha) followed by South America (6.8 million ha) and Africa (5 million ha). The balance is made up by North and Central America, Europe and Oceania. Asian countries therefore contribute nearly 90% of the global total while supporting 60% of the world's population (IRRI, 1985). to addressing crop protection issues. Recognizing the importance of policy-makers, researchers, extension workers and farmers within any system, it has successfully involved each group in the development and implementation of integrated technologies for crop protection. As a result, many farmers have been trained, appropriate technologies have been adopted, pesticide subsidies removed (in Indonesia) and pest management policies are being influenced within the SE Asia region. Although still constrained by limited availability of appropriate technology and over-emphasis on entomology, it is significant that these achievements have been possible only through the evolution of an appropriate policy environment. The case is analysed in detail by Paul Teng (see Appendix C) and has provided much needed reinforcement of the conviction that farmers are able to appreciate 'ecological principles' and both recognize and husband natural enemies in their fields.
13. It is clear that pesticide use, particularly against insects, overshadows all other control technologies as a means of crop protection in the Developing World. This is true even for crops such as rice, where significant progress has been made in the breeding and adoption by farmers of resistant varieties.
Host Plant Resistance (HPR) has been the basis of plant protection for centuries. It is also the main means of technology transfer, via improved seeds, to rice farmers all over the world. IRRI genotypes are probably the most widely grown of any crop. Although much rice HPR is of the successful single gene type, frequent insect and disease outbreaks reveal its weakness when used as the sole method of plant protection.
14. Widespread adoption of the IPM concept was stimulated and necessitated by the negative effects of injudicious pesticide use. The following classification of the status of pest management situations based on the level of pesticide intervention and resultant stress, helps to explain how this comes about.
- non-use: typically rainfed subsistence agriculture in which indigenous cultural controls are presumed to feature; pest damage may or may not warrant intervention but pesticides are unavailable for cultural, political or socio-economic reasons.
- balanced use: need-based application of pesticides in conjunction with other control technologies (a loose definition of IPM); alternatively, pesticide use constrained by external factors which if modified would lead to a shift into the next category.
- excessive use: the beginnings of the familiar 'pesticide treadmill' characterized by increasing pesticide use to maintain yield stability in the face of developing pesticide resistance and resurgence problems.
- pesticide crisis: here resistance to pesticide is well established and yet dependence on chemical intervention is complete, with no natural buffering of pest populations other than climatic variability; minor inefficiencies in pesticide application and management lead to severe crop damage. Problems may become so extreme that cultivation must be abandoned.
The stages are recognizable as an evolutionary series that often accompanies the intensification of agriculture.
15. Malcolm Iles (see Appendix C) deals with detailed points identified by questionnaire respondents. They are presented by crop. This in itself reflects our failure to take sufficiently systems-based approach to the problems of pest management, but there is much valuable information synthesized and specific weaknesses in both available technology and its application are highlighted. It is noteworthy that one of the appendices in Annex III of the Consultants' Report diverges from the commodity approach and is concerned with the parasitic weed Striga as a problem across commodities and thus farming systems. The importance and current neglect of weed management as an integral part of IPM is brought sharply into focus here and elsewhere.
The identification and utilization of crop varieties having at
least reduced susceptibility to attack, is not complete immunity, has been the
goal of many research programmes since the 1940s. Unforitunately, despite
substantial research effort, Striga species continue to cause problems. However
a success story has been the discovery of a high-level of resistance in cowpea
to S. gesneriodes. Lines in which resistance is based on a single dominant gene
are now being utilized at IITA and other national research institutions. A major
challenge still remains the discovery of true resistance to Striga in maize.
IITA has been successful in identifying potentially valuable sources of
tolerance to S. hermonthica although for pearl millet there has been little
Adapted from Parker, C, 1991. Protection of Crops against Parasitic Weeds.
16. The major themes that pervade the responses are presented here. The reader is referred to the Consultants' Report (Annex III) for specific crop and pest information. The views expressed by respondents to the Consultants' survey do not entirely support the claim that sufficient research has been done and what now remains is to apply it. Both basic and adaptive research still merit high priority, particularly in crop resistance strategies and pest monitoring, and the farming context in which technologies are to be used. Each situation is different; a country or cropping system must be examined independently in order to identify the right balance of resource allocation between research and implant.
17. There is universal agreement that more research does not simply mean more of the same; research must shift its focus to broaden the discipline base and to accommodate the needs of farmers. The failure of researchers to adequately comprehend farmers' resource constraints and decision processes were widely cited as a major cause of poor adoption of IPM research recommendations.
Conventional agricultural research tends to be scientist-led with the aim of producing technology that farmers can use. However, low adoption by farmers of IPM research output has led to drastic rethinking by scientists and socio-economists over the past decade. It is now considered extremely important that the farmer be involved in the research process in some way. Scientists must also recognize the socio-economic situation in which individual farmers operate. The most successful examples of farmers adopting research output are those which have maintained a high degree of farmer participation in all stages of the research process.
18. Considerable emphasis was given to the communication gap between farmer and researcher; the need to strengthen the role of intermediaries such as extension services and NGOs through better information management and flow, and through upgrading problem-solving skills is clear.
19. Almost all respondents felt that if the pace of IPM implementation is to be increased, more resources must be committed over a longer time-frame; there must be much improved co-ordination accompanied by functional specialization amongst both donors and research institutions.