Abstract: Taking the desert landscape in mid-eastern Ningxia of Northeast China as the background, eighteen patches of Caragana shrub lands (natural or manned) with the habitat types of manually-fixed sandy land, mobile sandy land, and silty-loam downland were selected as study sites to investigate the responses of three Caragana seed pest species (Kytorhinus immixtus, Etiella zinckenella, and Bruchophagus neocaraganae) to the host plant patch quality, patch area, and patch spatial pattern. The damaged rate of host plant by the pests had close relations to the patch quality, patch pattern, and the transferring capability of the pests. The responses of the pests to patch quality were affected by patch scale, and among the three habitat types, manually-fixed sandy land had the highest damaged rate, followed by mobile sandy land, and silty-loam downland, with significant differences among them (P<0.05). In small scale patch pattern, there existed definite correlations between the pest number and the patch area and its fragmentation degree. The decrease of patch area and the increase of the fragmentation degree reduced the damage rate of high transferring capability Etiella zinckenella (r=0.365), but had less effects on low transferring capability K. immixtus (r=0.160) and B. neocaraganae (r=0.193). The strength of patch edge effect and the mutual complement of the resources around patches had positive effects on the population density of the pests.

Key words: desert landscape, habitat fragmentation, patch quality, patch pattern, seed pests, Caragana, stable isotope, local meteoric water line, below-cloud evaporation effect, Northwest China, temporal and spatial distribution