Hundreds of millions of farmers in the developing world continue to overuse pesticides despite the emergence > in recent years of exciting alternative strategies for pest control.  

Not only do misapplied pesticides pollute the environment and threaten the health of farmers and their families, they set the stage for secondary pest infestations that can cause devastating crop losses.

The huge scale of the problem was highlighted this week in London at the presentation of the Green Apple environmental awards. One of the award winners was an innovative research project that has encouraged millions of Vietnamese rice farmers to reduce their pesticide use. In addition to environmental and health benefits, the project, funded by the Swiss Agency for Development Cooperation, has helped many farmers reduce input costs by US$30-50 per season -- equal to a month's income in Vietnam.

"This project has exposed only the tip of the iceberg regarding the inappropriate use of agricultural pesticides in the developing world," said K.L. Heong, the leader of the award-winning project. "We convinced farmers to reduce their pesticide use, but no sooner did the project end than the continued marketing of such products cause  pesticide use levels to climb again."

Dr. Heong, a senior entomologist at the Philippines-based International Rice Research Institute (IRRI), said that the major multinational pesticide corporations act responsibly by organizing educational and awareness programs for farmers and other pesticide users. However, he added, the same cannot be said for local dealers in many countries. "It is the local dealers who actively persuade poor farmers to use pesticides inappropriately," he stated. "And many of them are very creative in their marketing and promotion."

First launched in 1994 in the Mekong Delta - long one of the great rice bowls of Asia -- the IRRI-led partnership's research and subsequent campaign marked a milestone in rice production for two reasons. First, it clearly identified the damage caused by misapplied insecticides, which kill off insect predators and so encourage the pests they would otherwise help control. Second, it developed innovative and effective ways to communicate important scientific information to farmers.

After testing their campaign in the Mekong Delta, where almost 2 million rice growers were persuaded to cut back on harmful and unnecessary applications of farm chemicals, the research partners launched, on World Environment Day 2001, a similar campaign in central Thailand's Sing Buri Province. On World Environment Day 2003, the partners expanded the project to the Red River Delta of northern Vietnam.

The key members of the collaborative team are, in addition to Dr. Heong, Monina Escalada, a communications professor at the Philippines' Leyte State University, now seconded to IRRI; Nguyen Huu Huan, the vice director general of Vietnam's Plant Protection Department; and Vo Mai, Dr. Huan's predecessor.

Research has found that many Asian rice farmers apply insecticides at the wrong time and against the wrong targets. Farmers in Vietnam and elsewhere spray in the early crop stages because of leaf damage caused by caterpillars, beetles and grasshoppers -- damage that is highly visible but has little or no effect on yield. Some farmers spray routinely even though many modern rice varieties are bred for pest resistance and generally do not require further protection. By killing predators, these sprays disrupt natural biological control of pests and thereby create an environment favorable to outbreaks later in the cropping cycle, prompting farmers to spray even more.

Many of the chemicals used, such as methyl parathion, monocrotophos and metamidophos, are highly hazardous to human health and so are banned in the developed world. Not only do farmers personally risk pesticide poisoning, but sprays also hinder potentially profitable fish- and prawn-culture sidelines and cause broad damage to the environment.

The project team realized that overuse and misuse of insecticides was largely due to years of aggressive pesticide marketing that plays to farmers' often misplaced fears.

"What appeared to motivate farmers to spray insecticides during the early stages were misconceptions, lack of knowledge and biased estimations of losses due to pests," Dr. Heong explained. "We found that the amount of rice farmers expected to lose if they didn't use insecticides was about 13 times higher than their actual losses. So we set out to find ways to change their attitudes, to motivate them to stop spraying -- or at least spray less."

Because farmers depend on local radio broadcasts as their primary source of information, the researchers placed the farmers' ever-present radios at the heart of a media campaign. "We got a group of actors to play out a series of brief comedies, relating solid scientific facts through rustic situations to make the audience laugh," Dr. Heong explained. "We found these simple, humorous messages fixed themselves in the minds of thousands of farmers."

The radio dramas, supported by leaflets and posters, aired first in Long An Province in 1994. Farmers learned from the broadcasts that research had shown that spraying in the first 40 days after sowing was a waste of time and money.

They were encouraged to test this for themselves with a simple experiment, spraying only part of their crop and comparing the yield from the sprayed and unsprayed portions. The benefits were soon obvious, and by 1997 the radio-and-poster campaign had been picked up by 11 other provincial governments and was reaching about 92 percent of the Mekong Delta's 2.3 million farm households.

The results became clear with the analysis in 1999 of intensive surveys. Insecticide use had halved from an average of 3.4 applications per farmer per season to 1.7 applications. The number of farmers who believed that insecticides would bring higher yields had fallen from 83 percent to 13 percent. The number who realized that insecticides killed the natural enemies of rice pests had risen from 29 percent to 79 percent.

At the same time, the gross paddy output of the Mekong Delta increased from 11 million to 14 million tons per year. Dr. Heong believes that insecticide use can be halved again without affecting rice production -- but he and his partners fear that insecticide use will creep up again if the campaign is allowed to lapse.

"The only information most farmers get is advice from local suppliers to use more sprays," Dr. Heong says. "They think that every dollar they spend on insecticide is going to mean about $13 in their pockets at harvest time. In fact, that far exceeds reality. Even in a worst-case scenario, a seriously damaging pest infestation, they might benefit by only $4 from each dollar spent. And the worst-case scenario is a rare event.

"We should be training extension workers to communicate more effectively," Dr. Heong concluded, "to deliver correct information to the farmers and to motivate them to evaluate it objectively. We can't afford to leave pesticide education to those who profit by spreading misinformation about these chemicals."

The International Rice Research Institute (IRRI) is the world's leading rice research and training center. Based in the Philippines and with offices in 10 other Asian countries, it is an autonomous, nonprofit institution focused on improving the well-being of present and future generations of rice farmers and consumers, particularly those with low incomes, while preserving natural resources. IRRI is one of 16 centers funded through the Consultative Group on International Agricultural Research (CGIAR), an association of public and private donor agencies. Please visit the Web sites of the CGIAR (www.cgiar.org) or Future Harvest Foundation (www.futureharvest.org), a nonprofit organization that builds awareness and supports food and environmental research.