The arthropod fauna of undersown grass and cereal fields

Undersow spring cereals, with clover for example

A replicated, controlled study of arable fields in West Sussex, England (Vickerman 1978) found that arthropod abundance, density and species richness was higher in undersown spring barley and undersown grass fields compared to mono-cropped fields. Arthropod abundance and diversity was greater in undersown barley fields (767-874 m², 19-23 species), compared to mono-cropped barley (677-714 m², 14-18 species) and grass (281-391 m², 12-15 species). Only the true bugs (Hemiptera) were found in greater numbers in barley than in undersown barley. On average, 70% more arthropods emerged from undersown grass (555-623 m²) than cultivated fields (280-391 m²). Species diversity was also higher in undersown grass (22-28 vs 11-16). Half of the cereal fields in the ley farming area contained over 200 parasitic Hymenoptera/m² compared to just 9% in the ‘modern arable area’ (no grass). Arthropods from the field and ground zone were sampled using a Dietrick vacuum (five sub-samples each 0.09 m²) at regular intervals across one field from each treatment in 1972 and 1973 and in one grass field in 1974. In addition one sample was taken from 150 fields in June 1972-1974. In 1970 and 1971, two adjacent fields, one undersown with grass and one cultivated, were sampled for emergent arthropods using two rows of five emergence traps (area enclosed 2.8 m²). Traps were emptied regularly between March and June.