A study of the more important predators (Insecta Heteroptera, Neuroptera et Coleoptera) in three Po-valley pear orchards

The study comprised cenotic seasonal variations and interrelation between insecticides, prey and predators. The taxa amounted to less than 25, of which there were large populations of only three species: Anthocoris nemoralis (Fabricius), Orius majusculus (Reuter) e Stethorus punctillum (Weise). The cenotic composition in spring and autumn differed considerably from that of summer, when An. nemoralis was effectively the only abundant species. Decreasing insecticidal treatments had no important effect on the number of species, whereas the populations already present increased. The numbers of predators also depended directly upon population densities of the respective prey. For the moment, predator migration between orchards and surrounding crops was confirmed in the case of aphidiphagous Coccinellidae.