CHAPTER 16A comparative analysis of pest management practices of rice farmers in AsiaK.L. Heong and M.M. Escalada

Abstract

Farmer surveys in 10 Asian countries were used to examine trends in rice pest management practices. Pesticides remain the dominant control tactic of farmers, who use insecticides more frequently than herbicides and fungicides. A large proportion of farmers were still using insecticide compounds classified as extremely or highly hazardous to human health (WHO toxicity classes Ia, Ib)—namely, methyl parathion, monocrotophos, and methamidophos. Herbicides were commonly used in Indonesia, Malaysia, Sri Lanka, China, Vietnam, and the Philippines. Only farmers in China and Vietnam used fungicides regularly. The mean number of insecticide sprays varied from 0.3 in Laos to 3.9 in Vietnam. Most of these sprays were applied during the seedling, tillering, and booting stages of the rice crop. Farmers usually overreacted to leaf-feeding pests, collectively referred to as “worms,” and tended to apply their first insecticide sprays during the first 4 weeks after crop establishment. They strongly believed that leaf-feeding insect pests were damaging and reduced yield. Based on this perception, farmers chose Insecticides (or medicine) to kill pests to protect their yields. To improve farmers’ pest management perceptions and decision making, research needs to address issues such as the influence of communication media on perceptions and attitudes.

Introduction

The Green Revolution in Asia during the 1960s and 1970s had a dramatic impact on the rice economy. Despite limits to land availability, annual growth in rice production in Asia was about 2.7% from 1966 to 1993. Production doubled from 240 million t in 1966 to 482 million t in 1993 (IRRI 1995). The major source of growth had been from yield /ha, which increased from 2.0 to 3.7 t /ha over the same period. In some countries, yields doubled, from 1.8 to 4.4 t /ha in Indonesia, from 1.3 to 2.8 t /ha in the Philippines, from 1.3 to 2.7 t /ha in India, and from 1.8 to 3.5 t /ha in Vietnam. These increases had been attributed to the widespread adoption of modern high-yielding varieties (HYVs) introduced in 1966. In South and Southeast Asia, the adoption rate of HYVs reached 60% by the end of the 1980s (David and Otsuka 1994).

The rapid spread of the modern varieties had been facilitated by national production programs that disseminated the new technology and provided irrigation facilities and credit to farmers. In the Philippines, the Rice Sufficiency Program and the Masagana 99 Program began in 1966 and 1973, respectively (Barker et al 1978). A similar program, BIMAS, began in Indonesia (Adjid 1983). In both countries, the government introduced fertilizer and pesticide credits together with the HYVs. Routine fertilizer and insecticide applications were deemed necessary inputs and, as a result, farmers sprayed insecticides as many as 15 times a season. Although IR8, the first HYV introduced, was susceptible to pests, subsequent varieties incorporated multiple insect and disease resistance (Panda and Khush 1995). But farmers were encouraged to use insecticides at regular intervals, even when growing these varieties, through subsidies and loan schemes (Kenmore et al 1987, Conway and Barbier 1990, Conway and Pretty 1991).

High yields from insecticide-protected fields at experiment stations (Pathak and Khan 1994) and high crop losses attributed to insects (Cramer 1967, IRRI 1990) encouraged the chemical industry to invest in new insecticide development programs and influenced adoption through advertising and marketing strategies. In the Philippines, for instance, most farmers used insecticides despite adopting new HYVs with Philippines, for instance, most farmers used

insecticides despite adopting new HYVs with multiple pest resistance (IRRI 1994). Research, on the other hand, focused on technology generation rather than on solving farmers’ problems. Limited efforts went into understanding farmers’ knowledge, perceptions, attitudes, and practices in pest control.

Recent analyses of farmers’ pest management in the Philippines and Vietnam (Heong et al 1994, 1995a, b) showed that a large proportion of insecticide sprays that farmers used did not produce economic returns. Instead, they could be detrimental to the ecological balance and cause secondary pest problems, such as the brown planthopper (Cohen et al 1994, Schoenly et al 1994, Way and Heong 1994). In addition, pesticides pose threats to farmers’ health (Rola and Pingali 1993). Between 1991 and 1996, farmer surveys to document farmers’ pest management knowledge, attitudes, and practices were carried out in 10 Asian countries. In this paper, we have extracted a few indicator variables of these practices from the surveys and made a comparative analysis.

Each farmer survey was conceptualized and conducted independently by the respective researchers; in some cases, the generic survey questionnaire developed by the Rice IPM Network for an earlier survey in Leyte, Philippines (Heong et al 1995a), served as a guide. Except for the survey in Thailand, which focused on women’s perceptions and practices, nearly all of the farmer surveys in the analysis—Cambodia, China, India, Indonesia, Laos, Malaysia, Philippines, and Sri Lanka—addressed farmers’ pest management knowledge, attitudes, and practices. The surveys were conducted in predominantly lowland rice areas, except in Cambodia and Laos, and covered sample sizes ranging from 120 to 1,145 (Table 1). The average farm sizes of respondents in the 10 countries were between 0.25 ha (China) and 4.6 ha (Thailand). Most of the farmers interviewed were between 30 and 45 years old.

Results

Types of pesticides used

Pesticide application was the main pest management tactic used. A majority of the rice farmers interviewed reported using insecticides. Table 2 shows their widespread use in seven countries, with the highest proportions of users coming from Vietnam (99.4%), the Philippines (94.8%), Indonesia (74.6%), Sri Lanka (68.4%), and Thailand (57.6%). Likewise, there was a high use of herbicides, particularly in Indonesia and Malaysia. Of the farmers using rodenticides, 79.3% were from Malaysia and 63.5% from Indonesia. Fungicide use was generally low. In Vietnam, where disease problems were commonly reported, 75.6% of the farmers used fungicides.

Chemical groupsInsecticides. The main products used by farmers in nine countries were organophosphates, organochlorines, pyrethroids, and carbamates (Table 3). Methyl parathion, monocrotophos, and methamidophos were the most commonly used organophosphates.

Methyl parathion was used by farmers in Laos (37.4%), the Philippines (27.9%), Thailand (21 %), and Vietnam (12.1 %). For methamidophos, most users were farmers in China (39.8%) and Vietnam (28.9%), whereas monocrotophos was applied by more farmers in Indonesia (61.8%), the Philippines (53.2%), and Cambodia (10.4%). Among the organochlorines, endosulfan was the most popular, with the highest use recorded for farmers in the Philippines (49.5%), followed by Thailand (8.8%), Malaysia (7.8%). Vietnam (4%), Indonesia (2.8%), and Sri Lanka (2.5%). Cypermethrin and deltamethrin were the most common pyrethroids used. The majority of cypermethrin users were farmers in the Philippines (52.7%), followed by those in Malaysia (13.1%) and a few in Indonesia (2%) and Vietnam (2%). Deltamethrin was used mainly in Indonesia (18.8%) and the Philippines (14.7%).

Compared with other carbamates, carbofuran appeared to be popular among farmers in Indonesia (38.1 %), Thailand (21.9%), Malaysia (12.7%), and Sri Lanka (11.8%), followed by fenobucarb (BPMC), used mainly in Indonesia (42%) and Vietnam (16.5%). MTMC and MIPC were used mostly by farmers in China.

Fungicides. The surveys revealed that only farmers interviewed in China and Vietnam were heavy fungicide users. In China, 100% of the farmers reported using Jinggang-mycin, a local fungicide. Vietnamese farmers indicated that they used a variety of fungicides, such as hexaconazole (37.9%), validamycin (23.1 %), benomyl (15.6%), carbendazim (4.9%), and propiconazole (4.6%) (Vo Mai et al, this volume, Chapter 15). In India, farmers were reported using edifenphos, but the exact percentages of farmers using pesticides were not specified.

Herbicides. Based on the data available, farmers in Malaysia and Indonesia were high users of herbicides (Table 4). Although farmers in Cambodia and Sri Lanka reported using them, the specific compounds used were not indicated. For herbicides, Indonesian farmers preferred metsulfuron-methyl (75.1%) and 2,4-D (38.1 %), whereas farmers in Malaysia preferred 2,4-D (46.4%) and molinate + 2,4-D (20.4%). In thePhilippines, pretilachlor and piperophos + 2,4-D were the most common herbicides.

Rodenticides. In the 10 countries, more farmers in Indonesia, Malaysia, and Cambodia used rodenticides. Zinc phosphide was most commonly used by farmers in Cambodia and Malaysia, whereas brodifacoum was mainly used in Malaysia. To control rats in irrigated and tidal swamp areas, 87.3% of the farmers in Indonesia used the insecticide aldicarb.

Farmers used some pesticides that were extremely or highly hazardous to human health. Table 5 shows the proportions of farmers interviewed who used pesticides in the various WHO classifications. In Laos, the Philippines, and Thailand, many farmers were still using methyl parathion, classified as WHO Ia (extremely hazardous). Highly hazardous WHO Ib compounds were reportedly used by more fanners in Malaysia, the Philippines, China. Vietnam, Thailand and Sri Lanka. These pesticides were mainly methamidophos, monocrotophos, and carbofuran. About 60% of the farmers in Malaysia reported using zinc phosphide, a WHO Ib compound, in rat baits.

Pests reported to be most important by farmers

Insect pests dominated the list of pests reported by rice farmers in the 10 countries surveyed, followed by weeds, rats, and diseases. Table 6 lists the pests mentioned as important by farmers. In 9 out of the 10 countries—Cambodia, China, India, Laos, Malaysia, Philippines, Sri Lanka, Thailand, and Vietnam—rice farmers reported lepidopteran leaf feeders to be the most important pests, followed by the stem borer, brown planthopper, weeds, rice bug, rats, and birds.

Farmers’ pesticide spray targets

Farmers’ pesticide applications in Asia mainly targeted insect pests and weeds (Table 7). Among the insects, lepidopteran leaf feeders, stem borers, brown planthopper, and rice bugs appeared to be commonly sprayed. Rice farmers in China, Indonesia, Malaysia, Sri Lanka, Thailand, and Vietnam also commonly used herbicides. For disease problems, fungicides were often used only in China and Vietnam. Their main targets were sheath blight, blast, and yellow leaf disease.

Frequency and timing of insecticide applications

Insecticides were applied as many as 11 times a season in some countries (e.g., Vietnam), whereas in Cambodia and Laos, many farmers (63% and 77%, respectively) did not apply any. According to the frequency distributions of applications in some countries (Table 8), Vietnamese farmers applied an average of 4 sprays per season, whereas in Laos the average was only 0.3. We used both the mean and the mode to describe the central tendency of the farmers’ number of insecticide sprays. There was a high variation among farmers in most countries, with the Philippines and Vietnam having the highest. In Laos, where variance was low, most farmers did not apply any insecticides. In Malaysia, 47% applied two sprays and in Thailand 35% applied one.

Most pesticide applications were made in the early stages of the crop (Table 9). Except for Cambodia and Laos, some of these were herbicides. At the tillering stage, most farmers who sprayed their crops were in Vietnam (83.4%), Indonesia (75.98), and Malaysia (57.3%). At the booting stage, most farmers who applied pesticides were from Vietnam (86.2%). In most of these cases, the main pesticides used were insecticides.

Data were then disaggregated to examine the distribution of farmers’ first insecticide applications. Among the four countries where data were available (Table 10), many farmers applied their first sprays during the first 4 weeks after crop establishment, especially in the Philippines (97.8%) and Vietnam (84.1%). Most of these early crop insecticide sprays were for leaf-feeding insects. When examining farmers’ perceptions of leaf-feeding insects, we found an interesting association between perceptions and behavior. Table 11 shows that a large proportion of farmers in Sri Lanka (72%), Vietnam (66.7%), Laos (66%), and the Philippines (60%) believe that leaf-feeding insects cause severe damage to the rice crop. Similarly, a majority of the farmers in six countries—China (93.6%) , Laos (72.5%), Vietnam (69.7%), Sri Lanka (65.2%), the Philippines (52.3%), and Thailand (51.4%)—believe that leaf-feeding insects cause yield losses and that it is necessary to control them early in the cropping season.

Discussion

From a total of 4,055 farmers surveyed and the hundreds that we interviewed personally, several trends in Asian rice farmers’ pest management are evident. Pesticides remain the dominant control tactic that farmers rely on. This might be attributed partly to their association of pesticides with medicine. Indeed, pesticides are referred to as medicine in all the countries we surveyed (Appendix I). The surveys showed that rice farmers’ pest management practices have changed little since 1984 from the description of Lim and Heong (1984). In some cases, such as Malaysia, the proportion of farmers using insecticides rose from 46% in 1975 to 62% in 1984 (Heong et al 1985) and 95% in 1995 (Nonniyah and Chang, this volume, Chapter 8). The chemicals changed, from less use of endosulfan to increased use of cypermethrin. In other cases, however, such as the Philippines, farmers were still using chemicals they had used 15 years ago (Litsinger et al 1980).

Pesticides used by farmers

Farmers used insecticides more frequently than any other pesticides, followed by herbicides and fungicides. This distribution of pesticide use is reflected in the rice pesticide market outside Japan for the period 1990-95 (Fig. 1) (McKenzie 1996). The total market value was US$1.6 billion. Insecticides accounted for 47%, herbicides 31%, and fungicides 22%. Large proportions of farmers surveyed in the Philippines, China, Thailand, and Vietnam were still using pesticides classified by WHO as extremely hazardous (WHO Ia) or highly hazardous (WHO Ib) to human health, banned, or under restricted use in many countries.

Many farmers were still using insecticide compounds banned or restricted because of their potential hazards to human health. Methyl parathion (WHO Ia), monocrotophos (WHO Ib), and methamidophos (WHO Ib) were commonly used in Cambodia, China, India, Indonesia, Laos, the Philippines, Thailand, and Vietnam. Although banned by governments, these products remain readily available to farmers in Indonesia, the Philippines, and Vietnam, whereas governments of the other countries had not categorically banned them. In Malaysia, rice farmers hardly used any of these products, perhaps because of strong government commitments to implement the Pesticides Act.

Pyrethroids, particularly cypermethrin and deltamethrin, were commonly applied to Asian rice fields. These chemicals mainly targeted leaf-feeding insects, such as rice leaffolders. Though frequently sprayed, however, these pests cause negligible yield losses (Heong 1993). Damage by these pests can be highly visible, especially during the early crop stages, which stimulates farmers to respond by spraying. These early insecticide applications may, however, favor the development of secondary pests, such as the brown planthopper (BPH), Nilaparvata lugens. Evidence that BPH is a secondary pest of rice is well documented (Kenmore et al 1984, Heinrichs and Mochida 1984, Schoenly et al 1994, Rombach and Gallagher 1994, Way and Heong 1994) and pyrethroid insecticides have been shown to disorganize ecological food web relationships that favor planthoppers (Cohen et al 1994).

Endosulfan was the main organochlorine often used by Asian farmers. Although endosulfan was banned in the Philippines, about 50% of the farmers surveyed said they were still using it. Endosulfan was used to control the golden apple snail, besides controlling insect pests. Farmers in China, Indonesia, Malaysia, the Philippines, and Vietnam frequently used carbamates. The most common chemicals were BPMC and MIPC, used mainly to control planthoppers and leafhoppers. Another insecticide used, mainly in Indonesia, for hopper control was buprofezin. In Indonesia, Thailand, Sri Lanka, and Malaysia, farmers used carbofuran granules for stem borer control. Another carbamate, aldicarb, categorized as an extremely hazardous pesticide (WHO Ia), was a common ingredient in rat poisons in Indonesia. Farmers commonly used herbicides in Cambodia, Indonesia, Malaysia, Sri Lanka, China, Vietnam, and the Philippines. According to results from Indonesia, Malaysia, and the Philippines (Moody et al, this volume, Chapter 10), farmers mainly used the herbicides 2,4-D, pretilachlor, metsulfuron-methyl, piperophos + 2,4-D, and MCPA.

In the Philippines, most farmers made one or two applications, mainly during the seedling stage, to control Echinochloa species and other weeds. Of the 10 countries surveyed, only farmers in China and Vietnam used fungicides regularly. In China, a locally manufactured antibiotic,

Jinggang-mycin, was commonly applied to rice fields, mainly to control sheath blight. Similarly, many farmers in Vietnam used validamycin to manage sheath blight. Two other fungicides frequently used in Vietnam were hexaconazole and benomyl to control sheath blight and yellow leaf disease (Vo Mai et al, this volume, Chapter 15). Although the causal agent of yellow leaf disease had not been determined, farmers were responding to the symptoms by spraying fungicides. Because about 98% of the farmers interviewed in Long An had applied fungicides to control this disease, this is an opportunity for research to help farmers avoid pesticide misuse.

The mean number of insecticide sprays varied from 0.3 in Laos to 3.9 in Vietnam. In Cambodia and Laos, more than 60% of the farmers did not use any insecticides and in Sri Lanka 36% did not apply any. In the other countries, farmers usually applied 2 or 3 sprays. Most of these sprays were applied during the seedling, tillering, and booting stages of the rice crop. At these stages, the main pests that are highly visible are leaf-feeding insects, such as rice leaffolders Chaphalocrocis medinalis, Marasmia spp, the rice caseworm Nymphula depunctalis, thrips Stenchaetothrips biformis, whorl maggots Hydrellia philippina, and armyworms Mythimna separata. Under extreme conditions, each of these species can destroy a rice crop, but such conditions in nature are extremely rare. The whorl maggot usually attacks rice in the first 2 weeks after transplanting. Although as much as 100% of the hills can be damaged, causing the crop to look devastated, no yield loss could be detected (Viajante and Heinrichs 1986). Similarly, for leaffolders, normal larval densities are under 5 /hill; it was shown that densities need to reach 15 before any yield loss can be detected (Fabellar et al 1994).

Farmers’ perceptions of pests

In the 10 countries surveyed, farmers’ overreactions to pests—collectively referred to as “worms”—were rather similar to those of an earlier analysis of farmers’ pest management practices in the Mekong Delta of Vietnam and Leyte Province in the Philippines (Heong et al 1994). In countries where data were available, we found that farmers tended to apply their first insecticides, usually to control leaf-feeding insects, during the first 4 weeks after crop establishment. Farmers also strongly believed that leaf-feeding insects would cause yield losses. Perhaps Asian rice farmers in general have similar attitudes and behavior toward pest management. They strongly believe that leaf-feeding pests are damaging and yield-reducing. Based on this perception, they choose insecticides (or medicine) to kill pests to protect their yields. Farmers seem to emphasize “killing” pests rather than preventing losses. Over the years, farmers have learned to use insecticides that are less expensive and highly toxic to “worms,” which might account for the high use of methyl parathion and monocrotophos.

Asian rice farmers seem to be trapped in a vicious circle of making wrong decisions about pest problems and insecticide use and have become victims of insecticide abuse (Bentley 1989). It is evident that, to improve farmers’ pest management decisions, we need to identify processes that can help change farmers’ perceptions of pests and their management. From season to season, farmers are likely to face similar pest problems. Decisions made in the previous season (period t) can influence the current season’s decisions (period t+l) (Mumford and Norton 1984). Because pest problems, control options, and objectives often remain much the same year after year, farmers’ perceptions and actions rarely change. This could account for the persistence in farmers’ insecticide misuse. Since the outcome of period t can influence perceptions in the next period, introducing an action that can result in a different outcome can be used to change farmers’ perceptions. Farmers can also be persuaded to use other objectives, such as yields and profits, rather than insect deaths, when comparing outcomes. This approach was applied to change farmers’ perceptions and practices in rice leaffolder control in the Philippines (Heong and Escalada 1997) and Vietnam (Heong et al 1995b).

Participating farmers reduced their insecticide use by 50% after conducting an experiment to evaluate whether the heuristic (or simple rule)—spraying insecticides in the first 30 days after transplanting (or 40 days after sowing direct seeded rice)—would make a difference in yields. According to Festinger’s (1957) cognitive dissonance theory, an information in direct conflict with current beliefs can create a state of psychological dissonance and can motivate information recipients to seek resolution through re-evaluation. The potential rewards when the question is resolved can serve as important incentives. Because the use of conflicting information on changing perceptions works well when information can be evaluated objectively (de Bono 1970), communicating new information along with a simple farmer’s experiment for evaluation seems to be effective.

Training through the farmer field school (FFS) approach can also change perceptions and pest management practices. In Indonesia, FFS-trained farmers reduced insecticide spraying from an average of 2.8 sprays /farmer to 0.9 and the proportion of farmers not spraying increased from 26% to 50% (Matteson et al 1994, van de Fliert et al 1995). In 15 weeks of training, farmers often went through exercises in identifying components of the ecosystem, discussing their functions (ecosystem analysis), and doing a series of simple experiments to evaluate ideas. To evaluate whether leaf-feeding insects would cause yield losses, farmers observed an experiment in which leaves were removed by cutting and measured differences in yields.

An important role of research is to transform farmers’ needs into researchable problems and communicate the results back to farmers (Pray and Echeverria 1990). To facilitate this, we need to adopt a radical change in the research approach by emphasizing understanding farmers’ pest management knowledge and practices and the root causes of farmers’ problems. This has been discussed by Norton and Mumford (1993), Bentley and Andrews (1996), and Heong (1996). We also need to emphasize the participatory process, which begins with a problem definition from farmers’ perspectives before setting research priorities and activities (Fig. 2). Even when research is well targeted, the results may not get through to be adopted by farmers—a problem of delivery (Norton and Mumford 1993). Disseminating, receiving, understanding, internalizing, and using research information in decision making would probably require improvements in communication. Because farmers live in an environment that contains numerous competing sources of information, we need research to address how communication media shape perceptions and attitudes of rice farmers. In pest management, where risk aversion among farmers seems to be more pervasive, understanding the impact of information provided by various sources on decision making would help identify intervention opportunities.

References

Adjid DA. 1983. Vertical transfer of agrotechnology in Indonesia: the case of the BIMAS Programme. In: Cagauan BG et al (editors). Agrotechnology transfer in Indonesia and the Philippines. BSP Technical Report 9. IITAHR Research Series 027. Manoa, Hawaii, USA: University of Hawaii. P. 3-10.

Barker R, Bennager E, Hayami Y. 1978. New rice technology and policy alternatives for food self-sufficiency. In: Economic consequences of the new rice technology. Los Baños, Philippines: International Rice Research Institute. p. 337-356.

Bentley J, Andrews K. 1996. Through the road blocks: IPM and Central American smallholders. Gatekeeper Series No. 56. London (UK): International Institute for Environment and Development.

Bentley JW. 1989. What farmers don’t know can’t help them: the strengths and weaknesses of indigenous technical knowledge in Honduras. Agriculture and Human Values 6:25-31.

Cohen JE, Schoenly K, Heong KL, Justo H, Arida G, Bamon AT, Litsinger JA. 1994. A food web approach to evaluating the effect of insecticide spraying on insect pest population dynamics in a Philippine irrigated rice ecosystem. Journal of Applied Ecology 31:747-763.

Conway GR, Barbier ED. 1990. After the Green Revolution: sustainable agriculture for development. London, UK: Earthscan Publications.

Conway GR, Pretty JN. 1991. Unwelcome harvest: agriculture and pollution. London UK: Earthscan Publications.

Cramer HH. 1967. Plant protection and world crop production. Pflanzen Schutz-NachrichtenBayer 20:1-254.

David CC, Otsuka K, editors. 1994. Modern rice technology and income distribution in Asia. Boulder, Colorado, USA: Lynne Rienner Publishers, Inc.

De Bono E. 1970. Lateral thinking. Hermondsworth, Middesex, England: Penguin Books.

Fabella LT, Fabellar N, Heong KL. 1994. Simulating rice leaffolder feeding effects on yield using MACROS. International Rice Research Newsletter 19(2):7-8.

Festinger L. 1957. A theory of cognitive dissonance. Stanford, California, USA: Stanford University Press.

Heinrichs EA, Mochida O. 1984. From secondary to major pest status: the case of insecticide induced rice brown planthopper Nilaparvata lugens resurgence. Protection Ecology 7:201-218.

Heong KL. 1993. Rice leaffolders: are they serious pests? In: Research on rice leaffolder management in China. Proceedings of the International Workshop on Economic Threshold for Rice Leaffolders in China, 4-6 March 1992, Beijing, China. Hangzhou (P.R. China): National Rice Research Institute. p. 8-11.

Heong KL, Escalada MM. 1997. Perception change in rice pest management: a case study of farmers’ evaluation of conflict information. Journal of Applied Communications 81(2):3-17.

Heong KL, Escalada MM, Lazaro AA. 1995a. Misuse of pesticides among rice farmers in Leyte, Philippines. In: Pingali, PL, Roger PA (editors). Impact of pesticides on farmers’ health and the rice environment. Norwell, Massachusetts, USA: Kluwer Academic Publishers. p. 97-108.

Heong KL, Ho NK, Jegatheesan S. 1985. The perception and management of pests among rice farmers in the Muda Irrigation Scheme, Malaysia. MARDI Report No. 105. Kuala Lumpur (Malaysia): Malaysian Agricultural Research and Development Institute. 11 p.

Heong KL, Teng PS, Moody K. 1995b. Managing rice pests with less chemicals. Geojournal 35:337-349.

Heong KL, Escalada MM, Vo Mai. 1994. An analysis of insecticide use in rice: case studies in the Philippines and Vietnam. International Journal of Pest Management 40:173-178.

Heong KL. 1996. Pest management in tropical rice ecosystems: new paradigms for research. In: Hokyo N, Norton G (editors). Proceedings of the International Workshop on Pest Management Strategies in Asian Monsoon Agroecosystems. Japan: Kyushu National Agricultural Experiment Station, Ministry of Agriculture, Forestry and Fisheries. p. 139-154.

IRRI (International Rice Research Institute). 1990. Crop loss assessment in rice. Los Baños(Philippines): IRRI.

IRRI (International Rice Research Institute). 1994. Integrated pest management: the IRRI perspective.

IRRI (International Rice Research Institute). 1995. World rice statistics 1993-94. Information Series No. 3. IRRI, Los Baños, Philippines.

Kenmore PE, Cariño FO, Perez CA, Dyck VA, Gutierrez AP. 1984. Population regulation of the rice brown planthopper Nilaparvata lugens (Stål.) within rice fields in the Philippines. Journal of Plant Protection in the Tropics 1:19-38.

Kenmore PE, Litsinger JA, Bandong JP, Santiago AC, Salac MM. 1987. Philippines rice farmers and insecticides: thirty years of growing dependency and new options for change. In: Tait J, Napompeth B (editors). Management of pests and pesticides—farmers’ perceptions and practices. Boulder, Colorado, USA): Westview Press. p. 98-108.

Lim GS, Heong KL. 1984. The role of insecticides in rice integrated pest management. In: Judicious and efficient use of insecticides on rice. Los Baños, Philippines: International Rice Research Institute.

Litsinger JA, Price EC, Herrera RT. 1980. Small farmer pest control practices for rainfed rice, corn and grain legumes in three Philippine provinces. Philippine Entomologist 4:65-80.

McKenzie W. 1996. World rice pesticide market. London: Wood McKenzie Consultants, Ltd.

Matteson PC, Gallagher KD, Kenmore PE. 1994. Extension of integrated pest management for planthoppers in Asian irrigated rice: empowering the user. In: Planthoppers: their ecology and management. London: Chapman & Hall. p. 656-685.

Mumford JD, Norton GA. 1984. Economics of decision making in pest management. Annual Review of Entomology 29:157-174.

Norton GA, Mumford JD, editors. 1993. Decision tools for pest management. Oxford, UK:CAB International.

Panda N, Khush GS. 1995. Host plant resistance to insects. Wallingford, UK: CAB International.

Pathak MD, Khan ZR. 1994. Insect Pests of Rice. Los Baños, Philippines: International Rice Research Institute.

Pray C, Echeverria R. 1990. Private sector agricultural research and technology transfer links in developing countries. In: Kaimowitz D (editor). Making the link: agricultural research and technology transfer in developing countries. Boulder, Colorado, USA: Westview Press. p. 197-216.

Rola AC, Pingali PL. 1993. Pesticides, rice productivity and farmers’ health: an economic assessment. Los Baños Philippines: International Rice Research Institute.

Rombach MC, Gallagher KD. 1994. The brown planthopper: promises, problems and prospects. In: Heinrichs EA (editor). Biology and management of rice insects. New Delhi, India: Wiley Eastern. p. 693-709.

Schoenly KG, Cohen JE, Heong KL, Arida GS, Barrion AT, Litsinger JA. 1994. Quantifying the impact of insecticides on food web structure of rice arthropod populations in a Philippine

farmer’s irrigated field: a case study: In: Polis GA, Wisemiller K, editors. Food webs: integration of patterns and dynamics. London: Chapman and Hall. p. 343-351.

van de Fliert E, Pontius J, Roling N. 1995. Searching for strategies to replicate a successful extension approach: training of IPM trainers in Indonesia. European Journal of Agricultural Education and Extension 1141-63.

Viajante V, Heinrichs EA. 1986. Rice growth and yield as affected by the whorl maggot, Hydrellia philippina Ferino (Diptera: Ephydridae). Crop Protection 5:176-181.

Way MJ, Heong KL. 1994. The role of biodiversity in the dynamics and management of insect pests of tropical irrigated rice—a review. Bulletin of Entomological Research 84:567-587.

NotesAuthors’ addresses: M.M. Escalada, Department of Development Communication, Visayas State College of Agriculture, Baybay, Leyte, Philippines; K.L. Heong, Entomology and Plant Pathology Division, International Rice Research Institute, Los Baños, Laguna, Philippines.

Acknowledgments: The authors would like to thank the Swiss Agency for Development and Cooperation, through the Rice IPM Network based at the International Rice Research Institute, for funding most of the farmer surveys reported, and all the authors who provided us with the data, which served as the basis for this synthesis paper.

Citation: Heong KL, MM Escalada. 1997. A comparative analysis of pest management practices of rice farmers in Asia. p. 227-245. In: Heong KL, Escalada MM (editors). 1997. Pest management of rice farmers in Asia. Manila, Philippines: International Rice Research Institute, 245 p.