Richness and abundance of Carabidae and Staphylinidae (Coleoptera), in northeastern dairy pastures under intensive grazing

Dairy cattle grazing has become popular to dairy farmers in the Northeast l ooking for management schemes to cut production costs. Carabidae (ground be etles) and Staphylinidae (rove beetles) are indicators of habitat disturban ces, such as drainage of wetlands, or grassland for grazing animals, and th eir monitoring could provide one measure of ecosystem sustainability if int ensive grazing management systems expand or intensify in the future. Our ob jective was to assess the abundance and species richness of these two beetl e families under intensive grazing throughout Pennsylvania, southern New Yo rk and Vermont. We collected 4365 ground beetles (83 species) and 4,027 rov e beetles (79 species) by pitfall traps in three years in Pennsylvania. Nin e ground beetle species, Amara aenea, Poecilus chalcites, Pterostichus mela narius, Bembidion quadrimaculatum oppositum, Amara familiaris, Poecilus luc ublandus, Agonum muelleri, Bembidion obtusum and Bembidion mimus represente d 80% of the Carabidae collected. Five other species were new to Pennsylvania. Four rove beetle species, Phil onthus cognatus, Meronera. venustula, Amischa analis, and Philonthus variou s = (carbonarius), comprised 74% of the total Staphylinidae collected. Year ly distributions of the dominant species did not change significantly in th e three years with A. aenea and P cognatus being most abundant every year. A parasitic rove beetle, Aleochara tristis, was recovered for the first tim e in Pennsylvania and Vermont since its release in the 1960's to control fa ce fly, Musca autumnalis. Similar results were found in New York and Vermont. We collected 1,984 grou nd beetles (68 species). Pterostichus melanarius was most abundant. Pterost ichus vernalis was detected for the first time in the United States (Vermon t). It was previously reported from Montreal, Canada. We collected 843 rove beetles (45 species). Philonthus cognatus was the most abundant rove beetl e. In addition, Tachinus corticinus, previously known only from Canada, was discovered for the first time in the United States in Vermont. Pastures in Pennsylvania were diverse, containing 14 species of forage plan ts and 17 weed species. Botanical composition was similar in New York and V ermont. Sixteen species of grasses and legumes made up 90% of the plant com position and 36 species of weeds made up the remainder. This diverse plant ecosystem may explain the richness of ground and rove beetles in northeaste rn U.S. pastures because the heterogeneity in the plant population provided additional resources which can support a rich assemblage of beetles. Monit oring richness and abundance of Carabidae and Staphylinidae over three year s in Pennsylvania suggests intensive grazing systems are ecologically susta inable.