抛秧稻田节肢动物及杂草群落结构研究

抛秧稻田节肢动物在水稻生育前期以剌吸类物种为主，相对多度为67．96％-75．79％，其中以稻蓟马优势度指数最高，幅度为0．6004～0．7333；至拔节以后，以食叶类和刺吸类为主，相对多度分别为6．93％～41．87％和3．25％-33．20％；水稻各生长期，钻蛀类物种相对多度为0．35％-3．66％，相对多度很低。天敌主要为隐翅虫类和蜘蛛类捕食性类群。整个生长季节，禾本科杂草和阔叶类杂草为主要类群，禾本科杂草相对多度为24．49％-62．04％，阔叶类杂草相对多度为27．74％-69．39％，稗草和慈菇为其中的优势种群，优势度指数分别为0．1873—0．6156和0．0825—0．1715。

STUDY ON THE COMMUNITY STRUCTURE OF ARTHROPOD ANIMALS AND WEEDS IN BROAD CASTING SEEDLING FIELDS OF RICE

In the earlier growth periods of rice plants,the dominant pests in broad casting seedling fields were found to be sucking insects,their relative abundance varying between 67.96% and 75.79%.The index of richness of rice thripid(Thrips oryxae) was the highest((0.600 4)~0.733 3) in the sucking group.After the jointing stage of the plants,the dominant pests were leaf-eating and sucking groups,their relative abundance being 6.93%~41.87% and 3.25%~33.20%,respectively.Throughout the whole growth period of rice,the relative abundance of the borer group was low,varying from 0.35% to 3.66%.The main natural enemies of the pests were such predators as damselfly,Staphylinidae and spiders.Broad-leaf plants and grasses were the main weeds throughout the growing season,their relative abundance being 27.74%~69.39% and 27.74%~69.39%,respectively.Barnyard grass(Echinochloa crusgalli Beauv.) and Sagittifolia L.were the dominant weed species,their richness index being 0.187 3~0.615 6 and 0.082 5~0.163 3,respectively.