By K.L. Heong
International Rice Research Institute
China loses about a million tons of paddy caused by planthopper outbreaks annually. This is despite the huge amounts of pesticides being used by farmers. On average, Chinese rice farmers spray at least 3 times more than farmers in the Philippines. In 2005, planthopper outbreaks were very extensive in 5 provinces and some estimates show that China lost 2.8 million tons of paddy. Some researchers attributed these extraordinary outbreaks to elevated summer temperatures. Is this an expected effect of climate change? Why does China experience such high intensive outbreaks of planthoppers, which most entomologists classify as “secondary outbreaks? In the 1970s, Californian entomologists, led by Robert van den Bosch, described how agriculturalists create an insecticidal treadmill because of the new pesticides that were used extensively. Three phenomena were observed: 1) target pest resurgence, 2) secondary pest outbreaks and 3) pesticide resistance. All these are related to the increasing “pesticide addiction”. Today we see the same three phenomena occurring in highly intensive rice production systems of China, Vietnam and India.
About 35 years ago, rice intensification programs in Asia, particularly Indonesia and the Philippines, had similar experiences with rice planthoppers. Through the introduction of IPM, insecticide reduction campaigns, farmer training and policy changes to reduce pesticide use, the planthopper problem had become insignificant. Subsequently, entomological research and planthoppers in particular, began to receive lesser attention In 2005, the planthopper problem was not only serious in China, but in Japan, Vietnam, Korea and Malaysia as well and it is a wake-up call. We seem to have neglected the basic ecological principles of IPM. The key question we now need to address is “Will planthoppers become a threat to the sustainability of intensive rice systems?”. This question was addressed in a paper “Are planthopper problems due to breakdown in ecosystem services?”
The International Rice Research Institute (IRRI) initiated an international scientific discussion by organizing an International Conference, which brought together 88 scientists, agricultural directors and pesticide company representatives from Australia, Bangladesh, Cambodia, China, FAO, India, Indonesia, Japan, Korea, Laos, Malaysia, Philippines, Singapore, Taiwan, Thailand, USA and Vietnam to develop new approaches, new techniques and management tools. Report of the Conference is available.
The ecological engineering or eco-engineering approach is a new direction in sustainable pest management introduced by Professor Geoff Gurr in the Conference. The principles and examples are discussed in his book “Ecological Engineering for Pest Management” published by CABI publishing. The eco engineering approach provides a framework to strengthen essential pest management ecosystem services that will improve crop health, thus preventing secondary pest outbreaks, like planthoppers. The utilization of these principles are now being explored in Guilin, China by the Ministry of Agriculture and in Jin Hua by the Zhejiang Academy of Agricultural Sciences (ZAAS).