Abstract: Three treatments including chemical fertilization, rice-duck  farming, and no chemical pesticides/fertilizer application (control) were installed to study the spatial distribution patterns and ecological niches of Nilaparvata lugens and its main predatory natural enemies. In the plots of chemical fertilization, rice-duck  farming, and the control, Theridiidae, Clubionidae and Salticidae shared the highest niche width, respectively, with a value of over 0.80. The spatial niche breadth of N. lugens in the plots of rice-duck  farming was 0.83, being 5.0% and 5.9% lower than that in the control and chemical fertilization plots, respectively. Rice-duck  farming made the common spatial domain of N. lugens and its main natural enemies Tetragnathidae, Coccinellidae, Salticidae, and Staphylinid increased, affording more probability of their encounter and enhancing the control potentialities of these natural enemies on N. lugens  to a certain extent. However, the niche overlapped between N. lugens and natural enemies Lycosidae, Linyphiidae, and Clubionidae decreased, which weakened the control potentialities of these natural enemies. Rice-duck  farming also had definite effects on the occurrence position and spatial domain of main predatory natural enemies on rice plant. In sum, rice-duck  farming could have positive effects on the outbreak and trade-off of N. lugens via altering the spatial distribution patterns and ecological niche characteristics of N. lugens and its main predatory natural enemies.

Key words: Rice, Isogenic lines, Plant morphology, Competition, Allelopathy