Restore ecology to prevent rice pest outbreaks in Thailand

Bangkok, Thailand – Devastating outbreaks of brown planthoppers (BPH) in Thailand’s rice crop can be prevented if an eco-friendly approach to pest management is adopted, according to the International Rice Research Institute (IRRI).
The brown planthopper (BPH) is one of the most destructive pests of rice and, this season, they are in plague proportions in Thailand – the world’s biggest exporter of rice.
Khun Manit Luecha, director of Chainat Rice Seed Center, says, “This is the worst outbreak of BPH I have seen in my career since 1977. Most of the paddy fields – probably more than 1 million hectares – will suffer rice yield losses of more than 30%.”
Damage has spread from the north, especially in Khampaeng Phet and Phichit, to Suphan Buri, Chainat and Ang Thong in the Central Plains – the rice bowl of Thailand. Damages are serious already and new outbreaks are being reported every day. BPH also transmits two viral diseases that can severely stunt and discolor the plant and prevent grain formation.
“BPH becomes a pest when natural control mechanisms fail,” says Dr. K.L. Heong, an insect ecologist at IRRI.
“To prevent outbreaks we must restore the natural environment and biodiversity to keep BPH numbers below economically damaging levels," he added. "To achieve this, farmers will have to use pesticides more strategically and adopt ecological engineering principles."

To manage BPH, IRRI recommends that farmers:

• Adopt integrated pest management (IPM) practices.
• Grow beneficial plants in the “bunds” between rice paddies to attract BPH predators such as spiders, crickets, and parasitoids.
• Synchronize rice plantings so that there are times when no rice is growing to prevent immigrant BPH from establishing new populations.
• Plant a BPH-resistant rice variety, such as RD29, RD31, RD41, Pisanulok2, Supanburi2, Supanburi3, and Supanburi90.
• Do not apply fertilizer in excess as overfertilized crops tend to promote BPH growth.
• Limit pesticide use to control leaf-eating insects as these products kill the BPH’s natural predators as well.
• If a pesticide must be used to control BPH, use BPH-specific chemicals, such as buprofezin, as it has fewer effects on BPH’s natural enemies.

IRRI has been monitoring the BPH and virus situation across Asia with increasing concern over the past several years.
“Last year, high rice prices motivated Thai farmers to grow rice continuously, fertilize their rice more in an effort to boost yields, and attempt to protect their investment by spraying more pesticides to keep leaf-eating insects at bay,” said Dr. Heong. “This combination of practices helped cause the current BPH outbreak in Thailand."
Dr. Heong coordinates the Rice Planthopper Project, a collaborative research network with national scientists in Asia co-funded by IRRI and the Asian Development Bank that aims to share knowledge and develop sustainable ways to manage BPH problems.
If farmers or their advisors want to find ways to manage existing BPH problems and to prevent future outbreaks they can go to the Ricehoppers Blog.
IRRI helps farmers manage pests in a sustainable way by developing pest-resistant rice varieties, IPM strategies, and ecological engineering approaches.