Many rice farmers work under the mistaken impression that regular insecticide applications are necessary to attain high yields. However, decades of research by scientists around the world has shown that healthy and productive rice crops can be produced with little or no insecticide applications in most years. Nonetheless, farmers continue to apply dangerous chemicals in the mistaken belief that they are providing a kind of "insurance" for their crop.
Insecticides are often applied many times during each rice crop. In the vast rice-growing region of the Mekong Delta in southern Vietnam, insecticide use in rice crops effectively dumps tons of chemicals into the environment.
Sadly, this insecticide use often puts farmers at risk because they do not wear protective clothing and are not educated in how to use the chemicals safely. In addition, despite the insecticides being used to control pest outbreaks some actually increase the incidence and severity of the very outbreaks they are trying to avoid. This happens because the complex relationships among the many creatures that inhabit rice fields are destroyed.
Aside from killing the target pest, insecticides can also kill "beneficial" creatures that predate or harm the pests, keeping their numbers below the levels that cause damage to the crop. Studies show that outbreaks of the notorious brown planthopper, which is widely considered the worst rice pest, are ten times more likely to occur when insecticides used are highly toxic to the beneficial creatures such as spiders and parasitoids. General insecticide spraying also fails to kill planthopper eggs, meaning the hoppers hatch in a rice field devoid of natural enemies that allows their numbers to explode.
The pest outbreaks that result can cause massive damage to rice production. In 2009 outbreaks of brown planthoppers occurred across northern Vietnam, and viruses spread by the hoppers were detected in central Vietnam. Back in 2007 Vietnam suspended rice exports because of losses caused by planthoppers. This contributed to the major run-up in rice prices later that year and into 2008.
Other factors also contribute to pest outbreaks such as excessive fertilizers which create luxuriant crops for the hoppers to feed on and continuous rice cropping that does not allow for a break in the pests' food supply. Hoppers in large numbers can eventually overcome rice varieties resistant to them and lead to insecticide resistance in the pest.
But there is hope. We simply need to create a "greener game plan" to build healthier rice crops free of pest outbreaks across Vietnam and the rest of Asia.
Best practice in pest management in rice is not well understood by farmers nor widely implemented, and insecticide abuse is rampant. Farmers often simply follow the instructions of local pesticide retailers, who may be ill-informed about choosing suitable insecticides for rice and their effective and safe use. We see "pesticide supermarkets" across most major rice-growing countries in Asia where insecticides are sold as consumer goods much like shampoo and toothpaste. Rather, they should be sold as regulated materials, which would better reflect what they actually are poisons that should be sold under a regulatory framework. Dealers in insecticides should be trained and licensed, much like pharmacists are today, with price incentives in place to reward sales people on the appropriateness of the products sold, rather than simply volume.
It is heartening that Vietnam and other neighboring countries including Thailand are now stepping forward as leaders in trying to reduce this insecticide abuse and are planning and implementing the roll-out of better practices.
Earlier this year, with International Rice Research Institute (IRRI)'s support, Thailand banned the use of two rice insecticides abamectin and cypermethrin because they are known to be major causes of planthopper outbreaks. In August the Vietnamese province of An Giang started adopting ecological engineering practices like growing flowers near paddies to nurture planthopper predators.
Vietnam has seen dramatic changes in its rice production since the 1980s when it adopted Doi Moi. Willingness to embrace change was the reason behind the success of two campaigns by IRRI and Vietnam's Ministry of Agriculture and Rural Development to better manage rice crops and rice pests, namely "Three Gains, Three Reductions" in 1994 and "No Early Spray" in 2003.
Vietnam continues this approach to this day and is joining us and other global partners to combat brown planthoppers through our new "Action plan to reduce planthopper damage to rice crops in Asia."
The plan recommends two major principles first to enhance biodiversity and second to regulate the marketing and use of insecticides, including the banning of certain outbreak-causing insecticides in rice.
We also believe that training of extension agents and insecticide retailers is critical as is the promotion of other best practices like synchronized planting and fallow periods, and the strategic use of pest-resistant rice varieties.
With Vietnam's support, the plan is on the right path to cutting insecticide abuse and improving pest management in rice and securing the country's role as a leading global rice exporter.
By Dr. Robert Zeigler
Dr. Robert Zeigler is the director general of the Philippines-based International Rice Research Institute and an internationally renowned plant pathologist.