The spread of arable land in semi-desert regions may change biodiversity in nearby uncultivated natural areas by increasing habitat loss and fragmentation and negatively affecting habitat specialists. Crop fields can harbor large populations of agrobionts, which may spill over into nearby semi-desert. We tested the influence of percentage area of agricultural fields on spider assemblages in semi-desert habitat of agroecosystems in the northwestern Negev desert, Israel. We found that species richness, diversity and composition of the spider assemblages were not affected by the percentage of crop in the surrounding landscape. However, spider communities changed along a geographic rainfall gradient. We suggest that due to strong environmental differences between the crop fields and the semi-desert, the spider assemblages in semi-desert may be resistant to immigrants from crop fields