BENEFICIAL INSECTS IN FIELDS SURROUNDED BY HEDGEROWS IN NORTH EASTERNITALY

Wheat and alfalfa fields, encircled by hedgerows, on a biological farm in the low plains of North East Italy, were investigated to detect th e distribution of invertebrates. During 1990, hedgerows, margins and t he centre of the field were sampled using sweep nets. The number of pr edator-parasitoid specimens and species found in the hedgerows was hig her than found in the centre of the field. The wheat-field margins had higher catches of predator-parasitoids than the field centre but lowe r 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.