Anthropogenic islands in the arid West: comparing the richness and diversity of insect communities in cultivated fields and neighboring wildlands.

The interface between cultivated fields and wildlands has become a central focus for conservation biology, particularly as previously uncultivated lands worldwide are converted to agriculture at an escalating pace. Although research in some parts of the world has highlighted the potential value of agricultural lands for managing and preserving native animals, we know comparatively little about native animals spanning the cultivated/wildlands interface in North America. The study reported here investigated insect communities at three sets of paired sites (cultivated alfalfa fields and native, sagebrush areas) on the western edge of the Great Basin. Two hundred ninety-nine morphospecies were sorted from a collection of >9,000 insects: 221 morphospecies were found in cultivated fields, and 143 were found in the native areas. Insect communities in alfalfa fields were higher in species richness and abundance than communities in adjacent, native fields. However, communities in the cultivated habitat were relatively more homogenous: species composition was more similar among cultivated fields than among native fields. Considering the number of individual insects and morphospecies found in the cultivated habitat, and the relatively small number of species that overlap the two habitat types, the potential ecological consequences of the widespread, anthropogenic habitat are discussed.