The Structure And Niche Of The Predatory Arthropod Communities In Different Risistant Variety Rice Field

The structure of the predatory arthropod community was investigated in the paddy field of various resistant rice varieties in Nanning in 2003. The result shown that there were 2 class, 5 orders, 24 families, 67 species predatory arthropods, it included predatory insects which have 4 orders 11 families 20 species and spiders which have 1 order 13 families 47 species. The abundance of predatory arthropod community in early rice field was higher than that of late rice field. The abundance of spiders was far higher than that of predatory insects. The abundance of medial resistant variety rice was higher than that of resistant or susceptible varieties. Ulmmeliata insecticeps play a key role controlling rice planthopper in rice field, the relative abundance ofLycosidae was highest in late rice field, but the dominant species was still Ulmmeliata insecticeps.In early community the fluctuation tendency of predatory natural enemies were different in different resistant rice samples, the peak phase of the medial variety rice was longest among three samples. The mean densities of natural enemies were not significantly different between the susceptible and medial resistant varieties, but it were significantly different between the sensitive and resistant varieties. The diversity of the sub-community of spiders was higher than that of predatory insect sub-community, and the diversity of predatory arthropod was decreased when the resistance of variety was increased. The concentration was increased when the resistance of variety was increased. In the medial resistant variety rice field not only natural enemies could keep higher level but also their peak phase was longest. And the diversity of predatory arthropod was higher than that of resistant variety rice. The result shown that there could be a co-relation between the resistance and the predatory of natural enemies to insects on medial resistant variety rice.In late rice community, resistant variety rice gave significant effects on thestructure of predatory communities. Mean density of natural enemies was significantly different between two kings of resistant variety rice and susceptible variety rice. Not only was the diversity of late rice significantly higher than that of early rice, but also it's fluctuation was less than that of early rice. It has shown that the community of late rice has higher stability. However, the diversity was little different among different varieties rice. The concentration of medial variety rice was the highest.The study on niche of rice planthopper and its main predatory natural enemies among three samples has show that the space niche breadth of Dyschiriognatha dentate was the highest in two kinds of resistant varieties rice fields, and Paederus fuscipes was the highest in the susceptible variety rice. The space niche of the same predatory natural enemy in three samples was different. In early rice community time-space niche breadth of Coleosoma octomaculatum, Ulmmeliata insecticeps were the largest at all samples, and time-space niche overlap of Ulmmeliata insecticeps to rice planthopper was the highest in every samples, and time-space niche overlap of all natural enemies to rice planthopper were all higher in the medial variety rice than that of resistant variety rice except Lycosidae. The result indicated that medial variety rice could more effectively control the amount of rice planthopper.In late rice community, the time-space niche breadth of Tetragnathidae was the highest. Generally, not only predators each other but also predators to rice planthoppers' time-space niche overlap were higher in the late rice field than that of early rice field. It has shown that the competition between these predators and competed with predators each other for preys were intense in late rice community. The time niche overlap of predators to rice planthopper was higher in the medial variety rice than that of resistant or susceptible varieties rice. There were three predators to rice planthoppers time-space niche overlap in medial resistant variety...