Introduction

Rice is the staple food crop in China, which is the biggest rice producer and consumer in the world. In 1990, 33 million hectares of rice produced approximately 180 million tonnes of grain, representing 45% of the country's total grain output and 37% of world rice output. However, preharvest losses caused by insect pests are estimated at several million tonnes each year and a substantial proportion of these losses is attributable to the Brown Planthopper Nilaparvata lugens.

N. lugens has become an increasingly serious problem since the 1970s. Outbreaks have increased in frequency and the area regularly infested has extended into the Jianghuai region (between the Yangtze and Huaihe Rivers) and north of the Huaihe River. On average, some 13.3 million hectares of the crop are likely to be affected, with an annual loss of some half a million tonnes of grain (Table 17.1). In 1991, the worst year on record, severe damage extended over the whole rice-growing region and 17.3 million hectares of paddy fields were infested by N. lugens. In spite of great efforts at prevention and control, which were estimated to have saved approximately 9.8 million tonnes of grain, more than 2 million tonnes were still lost to these infestations. These efforts represented a substantial investment of manpower and material resources and the total loss sustained in that year was estimated at 2000 million Yuan (about US$ 400 million).