Beneficial Insects in Fields Surrounded by Hedgerows in North Eastern Italy

Wheat and alfalfa fields, encircled by hedgerows, on a biological farm in the low plains of North East Italy, were investigated to detect the distribution of invertebrates. During 1990, hedgerows, margins and the centre of the field were sampled using sweep nets. The number of predator-parasitoid specimens and species found in the hedgerows was higher than found in the centre of the field. The wheat-field margins had higher catches of predator-parasitoids than the field centre but lower than the hedgerows. In the alfalfa, the field margins and the field centre had similar catches of predator-parasitoids. It is likely that the perennial alfalfa allows the development of a more stable predator-parasitoid community in the field centre.