Ground-dwelling and foliar arthropods in four cropping systems

Four different corn soybean and wheat cropping systems were established in small replicated plots and simultaneously in larger (4-hectare) unreplicated fields. Each system was subject to distinct tillage practices, fertility programs and methods of pest control based on methods currently in use on farms in the Mid-Atlantic region of the United States. Ground-dwelling arthropods (mostly Carabidae and spiders( were sampled during the fourth and sixth growing season after the establishment of the plots and foliar insects (pest and beneficial) and pest damage were sampled on corn in the sixth growing season. Overall beneficial arthropod populations were lowest and corn pest insect populations (especially Western corn rootworms, Diabrotica virgifera irgifera Le Conte) were highest in the simplest most intensively managed continuous corn system which had annual use of soil insecticides. Generally ground-dwelling species were higher in soybeans than in corn and in no-till than in deep-tilled crops. Growers wishing to enhance populations of beneficial insects should consider predominantly no-till cropping systems with several different crops in the rotation and minimal insectiscide use. For both ground and foliar sampling patterns of abundance among systems and crops in the small replicated plots generally followed those observed in the large yields, but numbers of spiders and carbids collected per pitfall trap were generally much higher in the large fields.