Acta Arachnologica
Online ISSN : 1880-7852
Print ISSN : 0001-5202
53 巻 , 2 号
  • Kouhei Murata, Koichi Tanaka
    2004 年 53 巻 2 号 p. 75-86
    発行日: 2004年
    公開日: 2006/03/03
    ジャーナル フリー
    We surveyed the populations of spiders and their prey insects in a paddy field under sustainable cultivation in Aso, Kumamoto Prefecture in 2001 and 2003. Dominant species of spiders were Pardosa pseudoannulata, Tetragnatha sp. (certainly T. maxillosa) and Clubiona kurilensis and dominant prey insects included a non-pest, i.e. chironomids, and rice pests, i.e. Sogatella furcifera and Nephotettix cincticeps. We investigated the spatial distribution of the dominant species involving the vertical distribution on rice plants and the horizontal distribution within a paddy field. Sogatella furcifera and C. kurilensis were mostly located at lower parts of rice plants, 0-10 cm high, and sometimes at the upper parts. Pardosa pseudoannulata inhabited significantly lower parts, 0 and 0-5 cm, than the two species. On the other hand, N. cincticeps was observed from lower to upper parts. We surveyed the number of spiders and prey insects in 26 quadrats of 1 × 1 m and analyzed the degree of spatial overlapping between them using the Iwao's (1977) ω index. High values of ω were obtained between all spiders and chironomids and between C. kurilensis and S. furcifera. These results suggest that chironomids are important prey for spiders and C. kurilensis is an effective predator of rice planthoppers though this spider has not been regarded as an important predator.