Predatori generalisti in noccioleti piemontesi e sardi

Since information on generalist predators in the hazelnut agroecosystem are extremely scarce, specific investigations were carried out in hazelnut orchards of Piedmont and Sardinia (NW Italy) in the frame of the project CO.RI.BIO. Two sampling methods were used in 2005: i) beating of branches to catch foliage arthropods, ii) corrugated cardboard traps to sample arthropods which seek refuge in the bark roughness during daytime. Results of the investigations on four groups of generalist predators (spiders, bugs, lacewings, and ants) are here given. Overall twenty-five and twenty families of spiders were found in Piedmontese and Sardinian hazelnut orchards, respectively. In particular, nineteen of them (Anyphaenidae, Araneidae, Clubionidae, Corinnidae, Dictynidae, Gnaphosidae, Linyphiidae, Liocranidae, Mimetidae, Miturgidae, Oxyopidae, Philodromidae, Pisauridae, Salticidae, Segestriidae, Tetragnathidae, Theridiidae, Thomisidae, and Uloboridae) were sampled in both regions. Bugs belonging to the families Miridae, Nabidae, Anthocoridae, and Pentatomidae were collected, but the family Miridae was the most abundant and represented by nine species in Piedmont and in Sardinia. Among these species Compsidolon salicellum (Herrich-Schäffer), Deraeocoris lutescens (Schilling), Heterotoma meriopterum (Scopoli), Malacocoris chlorizans (Panzer), Phylus coryli (Linnaeus), and Psallus ambiguus Fallén were sampled, in different quantities, in both regions. Lacewings were more abundant in Piedmont than in Sardinia, both as number of species and number of specimens. Five and three species of green lacewings were found in Piedmontese and Sardinian hazelnut orchards, respectively. Some of them, Chrysoperla pallida Henry, Brooks, Duelli & Johnson, Dichochrysa flavifrons (Brauer), and Dichochrysa prasina (Burmeister), were sampled in both regions. A total of twenty-five ant species were collected in the hazelnut orchards of the two regions. In Sardinia the most abundant species were Crematogaster scutellaris (Olivier) and Lasius niger (Linnaeus), the latter was common also in Piedmont together with Lasius paralienus Seifert. Actually, besides spiders, bugs, lacewings, and ants, many other groups of predators are present in hazelnut orchards, where they play an important role in preserving the biocenotic balance. Therefore the improvement of the knowledge on these organisms, on their behaviour and their ecologic role has to be a crucial aim of research.