Abstract: To explore the approaches and methods of insect pest management in organic farming paddy fields, a two-year investigation was conducted on the quanti
tative dynamics of spiders and rice planthoppers in organic farming middle-late rice-duck field in East China across rice growth season, with the conventional paddy fields (Ⅰand Ⅱ, according to the pesticide application rate) as the control. A total of 9-10 families of spiders were recorded for different farming systems. The spider’s species diversity as measured by Shannon index was in the order of conventional paddy field Ⅱ> conventional paddy field Ⅰ > organic farming rice-duck field, while the dominance index was the highest in organic farming rice-duck field. The spider’s abundance in early growth season was lower in organic farming rice-duck field than in conventional paddy fields Ⅰand Ⅱ, while that in middle and late growth seasons was in reverse. Rice planthopper’s abundance in organic farming rice-duck field had a greater seasonal fluctuation, compared with that in conventional paddy fields. The abundance of rice planthoppers was greater in organic farming rice-duck field than in conventional paddy fields, but the abundance of spiders had less difference, resulting in a lower spider/rice planthopper ratio in organic farming rice-duck field than in conventional paddy fields across rice growth season. The results suggest that the pest control in organic farming rice-duck field confronts serious challenge, and it is necessary to explore practical and feasible ecology-based management methods.

Key words: Windbreak, Shrub, Numerical simulation, Relative velocity