The arthropod fauna of undersown grass and cereal fields.

Abstract

The practice of undersowing spring-sown cereals with mixtures of grasses and legumes to establish leys has declined in the last 25 years, but the effects of this change on the arthropod fauna of farmland have been little studied.

In 1972, 1973, and 1974 comparisons were made between the ground zone and field layer faunas of grass fields which had been established by undersowing, undersown spring barley fields, and spring barley fields. In general, both the diversity and the density of the arthropod fauna were greater in undersown cereal fields than in cereal fields or grass. The only group which was consistently more abundant in spring barley than in undersown spring barley crops was the Hemiptera: in both 1972 and 1973 approximately 60% more Aphididae were found in barley than in undersown barley fields, and it was considered that this difference could be attributable to increased predation pressure in the latter situation.

In the spring, both the density and the diversity of the arthropod fauna emerging from first-year undersown grass fields were greater than that emerging from cultivated fields. Difference were greatest in the Hymenoptera, Hemiptera, Coleoptera and Araneae. It was considered possible that the spatial distribution and abundance of some arthropod taxa on farmland could be related to the presence of such undersown fields in the rotation.