Ecology of the brown planthopper in temperate regions

The population of the brown planthopper Nilaparvata lugens (Stål) in temperate regions is characterized by discrete periods of seasonal appearance, low initial density, steep and steady growth, clumped spatial distribution, and violent fluctuations from year to year. N. lugens, a temporary inhabitant, arrives from long distances barely in the ricegrowing season. Its high potential fecundity, high adaptability to its host in various stages, and high tolerance to crowding cause its uneven, clumped spatial distribution within a field. These characteristics also cause the steep and steady growth in population that enables the insect to increase to destructive levels despite its low initial density. The fluctuations in density of initial migrant populations, which are governed by unstable factors, largely cause the violent year-to-year fluctuations in population. The relevance of these characteristics to the strategy for efficient control of the brown planthopper is discussed.