Abstract
We investigated the effects of tillage practices on the densities of wolf spiders and planthoppers and leafhoppers in rice paddy fields. Paddies were subjected to one of two different treatments (no tillage and conventional tillage), and seasonal changes in the densities of wolf spiders and hoppers were investigated over two growing seasons (1999 and 2000). In both years, the density of wolf spiders was significantly higher and the density of hoppers tended to be lower in no-tilled paddies than in conventionally tilled paddies, although the latter difference was not statistically significant. The Iwao's omega values, which represent the degree of correlation between the spatial distributions of wolf spiders and hoppers, were higher in no-tilled than in tilled paddies during August when the hopper density decreased in no-tilled paddies.
