PADI farmers tend to use insecticides liberally to kill grubs and pests such as the leaf folder, a type of caterpillar that eats the leaves of the plant, as they think crop yield would drop otherwise. 

That is not true, says scientist Dr Heong Kong Luen who took the challenge to convince farmers that the damage on those leaves does not affect yield. 

As padi crops can tolerate a substantial amount of damage in the early part of the crop cycle, insecticides aren t really necessary, says Dr Heong Kong Luen, a Malaysian senior entomologist attached to the International Rice Research Institute (IRRI) at Los Banos, in the Philippines. 

In the 1990s, Heong and his partners demonstrated a phenomenon alled plant compensation which is an inherent insect resistance found in modern rice plant varieties.  

Dr. Heong Kong Luen (left) discussing insecticide use with a Thai farmer in Singburi province. Minimising insecticide sprays is Dr. Heong's aim.

Compensation is the capacity of the rice crop to recover from damage wrought by insects.  

Even if 50% of the leaves are removed in the early stages of crop growth, the crop will compensate and will not suffer any yield loss, says 54-year-old Heong. 

He initially found it an uphill task to persuade farmers to stop spraying because of deeply ingrained misconceptions. 

Heong and his collaborators challenged farmers to leave half of their fields for 40 days without any insecticide spraying.  

The first media campaign was carried out in the Mekong Delta province of Long An, Vietnam, in 1995. The exercise prompted farmers in the test area to slash their insecticide use by 53%, from an average of 3.4 to 1.6 sprays per season, with no reduction in yield. 

By 1997, 17 other Vietnamese provincial governments used their own resources to launch similar campaigns. As a result, the two million farmers in the Mekong Delta reduced insecticide spraying by 70%. The Vietnamese Ministry of Agriculture endorsed a no-early-spray rule in 1998 and stopped registering insecticides for controlling leaf folder.  

In 2001, Dr Heong's team carried out a similar campaign in central Thailand and, on June 5, got involved in another media campaign which coincided with World Environment Day 2003, in the northern Vietnamese province of Quang Ninh.  

Heong worked for the Malaysian Agricultural Research and Development Institute (Mardi) in its Rice Research Centre in Bumbong Lima, Penang, in 1973. He conducted similar work in the Muda (Kedah) Irrigation scheme eight years ago. Scientists in Malaysia also discovered that leaf folder attacks do not affect padi yield. Subsequently the Agriculture Department and Mardi advised local padi farmers not to engage in early season spraying for leaf folder control. 

Following the campaigns to stop early spraying, the farmers in turn conveyed the concept to other farmers, using their own languages, says Heong. Farmers in Vietnam explained it through the term phouc hoi, which means complete recovery from an illness, while farmers in the Philippines use the term makabawi, which suggests a complete recovery from an initial setback, such as an initial financial loss.  

Once farmers realised this, they reasoned that it would be better to compensate by applying manure to the crop instead of spraying insecticide. It is like us eating nutritious food when recovering from an illness, he adds. 

In March, Heong became the first Asian to win the prestigious Charles A. Black Award for outstanding contributions to public understanding of food and agricultural sciences. The Council for Agricultural Science and Technology (Cast) based in Washington DC presented the award. 

Contrary to popular perception, Heong pointed out that early sprays would hurt the rice ecosystem because the insecticides kill off the crop's inherent immune system.  

This disruption of the natural balance can cause more problems and the farmers end up spraying more at the later crop stages, says Heong. Insecticides are to be used only when necessary. If there is no early spray, then there is a strong tendency for low pest attacks, even in later stages, he says, and that in most cases, insecticide is not really needed for padi cultivation, except for the odd case of abnormal pest attack, or in locations where pest attacks are bad. 

To understand why farmers do what they do and to find ways to motivate change, Heong studied a number of factors: ecological phenomena, farmers decision-making processes and social psychology frameworks, and anthropological and participatory techniques. 

The ultimate goal is to put a complete stop to insecticide use. In their experimental farm, Heong and his colleagues discovered that insecticide use could be reduced by as much as 95%. Many farmers living nearby here have completely stopped insecticide use and in many villages where we have worked, the insecticide stores had have gone bankrupt, says Heong. 

Response from farmers has been encouraging. In Vietnam, one farmer who was interested in the non-spraying concept discussed the idea with his wife. She was reluctant to participate because they had always sprayed twice in the first 40 days, for the last 20 years. She thought that her husband was trying to get out of doing work, as spraying is usually a man's job in Vietnam. So she told her husband that they would divide their holding (more than one hectare) into two sections. In his plot, he could do whatever he wanted while she would maintain the spraying on hers.  

When the leaf folder attacks started, the farmer's wife urged him to use insecticide.   But since he wanted to participate in the experiment, he did not resort to spraying, although he was concerned.   After 40 days, his wife had used insecticide twice.   Come harvest time, though, they carefully weighed the yield from each plot and found that the yields were the same. His wife was finally convinced.  

This 70-year-old man came up to me and hugged me when I visited the village again and he said: Why didn't you come here 20 years ago? We would have saved so much money. This was most touching and meant a great deal to me and I still cherish such events as my motivation to help these people, says Heong.  

In 1996, the Vietnamese Government honoured Heong with the Medal for Agriculture Development. Last year, he received a medal for Partnering Excellence in Australia for establishing partnerships with scientists from developing countries, Australia and international institutions.  

Upon receiving a Bachelor of Science degree from Universiti Malaya in 1973, Heong began his career as an entomologist at Mardi. He earned a Ph.D in applied entomology and systems analysis from the Imperial College of Science and Technology, University of London, in 1986, and served as president of the Malaysian Plant Protection Society the following year. In 1988, he joined IRRI. 

He has published more than 120 papers in peer-reviewed journals and, in 2000, he became the first IRRI scientist to earn a higher doctorate degree (a D.Sc from Imperial College) based on research conducted at the institute.  

A father of two, Heong currently resides in the Philippines as an expatriate, on a diplomatic visa.