Planthoppers: new threats to the sustainability of intensive rice production systems in Asia

Abstract

Rice is the staple food for around half the world’s people and about three-quarters of a billion of the world’s poor depend on rice. Each year, an additional 50 million rice consumers are added to the world population, which means that rice production will need to increase markedly. Lowland rice provides more than 75% of the world’s annual supply. For the world rice supply, these areas are likely to intensify through new high-yielding varieties and improved cultivation practices. But they are also vulnerable to threats from pests. With increases in agricultural labor and inputs, farmers face a dilemma as their income is squeezed. Adding more burden to their livelihoods are unstable yields caused by pest outbreaks. One of the most devastating pests that threatened the Green Revolution in the 1970s and ’80s was the brown planthopper. In 1977, the International Rice Research Institute (IRRI) convened the first brown planthopper conference to outline management strategies that included rice varieties resistant to pests, cultural practices, and integrated pest management (IPM) measures. IRRI’s research in the 1990s clearly demonstrated that brown planthoppers were secondary pests, brought about by insecticide misuse. IRRI therefore developed IPM and communication strategies using a heuristics approach to motivate farmers to reduce their early-season spraying. This campaign reduced farmers’ insecticide use by 53% and lowered vulnerability to outbreaks on thousands of rice farms in Vietnam and Thailand. International agencies, such as FAO, the World Bank, and UNDP, provided IPM training that focused on conserving natural biological control and reducing pesticide use for thousands of farmers. These efforts seemed to keep planthopper pests below damaging levels in most countries. However, the past few years showed signs of a return of this potential threat to rice production. IRRI therefore convened a second conference on rice planthoppers in 2008 to explore new approaches to developing sustainable management strategies. Today, three major species of rice planthoppers (brown planthopper, whitebacked planthopper, and small brown planthopper) have been reported as a menace in Bangladesh, Cambodia, China, India, Indonesia, Japan, Korea, Laos, Malaysia, the Philippines, Thailand, and Vietnam. They transmit five virus diseases and can cause massive damages. Researchers are working to determine why planthoppers are again threatening rice crops. Since the last planthopper conference at IRRI, many scientific articles and books on planthoppers and numerous developments in research on biology, ecology, and biotechnology have become available. This book provides summaries and analyses of the key works and issues and provides details on management approaches.