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It is well established that the invertebrate community in cropland under conservation-tillage (consT) is often enriched relative to the community under conventional-tillage (CT) systems. The question posed in this research is whether consT contributes to the maintenance of regional biodiversity and to the conservation of prairie-inhabiting species in agriculturally dominated landscapes that contain prairie remnants. During 2002, we sampled the grounddwelling beetle fauna of remnant Palouse prairie and surrounding cropland (under CT and consT) in the Palouse region of northwestern Idaho and southeastern Washington. Biological diversity of the representative taxa-Curculionidae (weevils), Tenebrionidae (darkling beetles) and Scarabaeidae (scarab beetles)-is significantly higher in the prairie than in agricultural fields, while divers ity of these groups in fields under consT is intermediate to that found in the prairie and fields under CT. Faunal similarity (Bray-Curtis Index) is greater between consT and prairie than between CT and prairie. Together, these results indicate that ConsT potentially improves conservation and the preservation of prairie species in agriculturally dominated landscapes.