Ecological engineering: a new approach for managing rice pests

G.M. Gurr | EH Graham Centre for Agricultural Innovation 

Although ‘green revolution’ technologies including modern insecticides have led to increases in average rice yields, the last decade has witnessed a fight-back by insect pests, especially planthoppers (Hemiptera: Delphacidae).  Crop losses have resulted as pest populations develop resistance to widely used insecticides and rice variety resistance breaks down.  It is estimated that the world’s largest rice producer, China, loses about a million tons of rice paddy from planthopper outbreaks annually.  Over recent years, pest damage has been amongst the most important factors leading to crop losses and price rises.  Countries such as Vietnam, Brazil, India and Cambodia suspended exports in 2008 to prevent possible domestic shortages.  Outbreaks of delphacid pests have occurred each year since that time resulting in crop failures over large areas.   

In response to this problem, the International Rice Research Institute organised an international conference in June 2008 to discuss new approaches and the ‘Ricehoppers’ project was born.  A central aim of this large, collaborative project was to evaluate the potential of ecological engineering, an approach in which a farm system is manipulated to enhance biological control of pests.

In rice this has involved strategies such as planting the earth banks that surround each rice field with flowers to provide nectar and shelter for beneficial insects.  Asian farmers have welcomed this approach because those plants can be a supplementary crop like sesame, soy beans or vegetables.  The predatory and parasitic insects that flourish in ecologically engineered rice crops have proven so effective that pest numbers have declined at the same time as insecticide sprays have been reduced.  Yield of rice has been maintained and, reflecting reduced input costs, initial economic analyses suggest that growing rice under ecological engineering is approximately 10% less expensive than conventional practice.  An additional benefit of this new system is the value of the secondary crop grown around the rice fields.  Sesame has proven particularly suitable in China.  Finally, there appear to be benefits to wildlife from the reduced chemical inputs associated with ecological engineering; frogs have become significantly more common.

So successful has this research been that the Asian Development Bank has granted additional funding plus the governments of China, Vietnam and Thailand have committed tens of thousands of dollars to extend the work over more rice growing districts.  Part of this up-scaling is a comprehensive communicating strategy involving field demonstration sites, print and web based resources and even a TV series airing in Vietnam. The work has also won friends in high places with HRH Princess Maha Chakri Sirindhorn of Thailand recently visiting one of the ecological engineering sites and ceremonially planting insect-attracting flowers.

The research team is currently integrating data from three years and multiple experimental sites in China, Thailand and Vietnam and a series of formal publications will be released over the coming 12 months.

Now researchers are looking at developing ecological engineering approaches in other crop systems in developed and developing countries.

Additional Information

More details are available at http://ricehoppers.net/ or from Prof Geoff Gurr, [email protected]. EH Graham Centre for Agricultural Innovation (Industry and Innovation NSW and Charles Sturt University), PO Box 883 Orange, NSW 2800, Australia.