荒漠草原豆荚螟对柠条林生境破碎化的反应

aragana are major sand-fixation plant in arid and semi-arid regions. Etiella zinckenella is one of seed pests of Caragana. We experimentally investigated the effects of habitat area, habitat fragmentation, and matrix composition on the distribution of Etiella zinckenella in desert steppe of Ningxia Lingwu Beijitan National Nature Reserve. Total 13 patches of four landscapes were investigated. We calculated the landscape fragmentation index and statistic the population quantity and parasitic ratio of Etiella zinckenella to Caragana for each patch. We compared population densities and parasitic ratio among plots that were made to vary in the area and fragmentation of Caragana habitat. The result showed that the landscape matrix, landscape fragmentation had some positive effect on Etiella zinckenella population densities and parasitic ratio. Patch area were not significantly associated with population densities（F=1.0977, R=0.3012）. The landscape patch fragmentation index (R=0.91129) and the patch density index（R=0.89864） showed a positive correlation with parasitic ratio. The fragmentation shape index (R=-0.89675) and the habitat within the area of landscape fragmentation index (R=-0.77646) show some negative correlation. Differences in the conditions of the landscape matrix and Caragana species are the main factors affecting Etiella zinckenella parasitize in Caragana.