Analysis and comparison of the ground Coleoptera communities in organic and conventional orchards within the Etna Regional Park (Catania, Sicily)

Abstract

In recent years, more and more emphasis has been placed on the value of biodiversity as a biological heritage that concerns not only the conservation of nature, but also of the gene pool of cultivated autochthonous plants and animals that have been bred. In this perspective, agriculture, which in the past, has had a significantly negative impact on biodiversity, today takes a major role in the maintenance of environmental diversity. Over the past few decades, the agricultural landscape has undergone considerable simplification, with the destruction of many natural and semi-natural elements that have interfered with the cultivated areas. Today it is possible to speak of agriculture with a totally different outlook, inserting it in an "organic" balance, in which the agro-ecosystem can be conceived as an area large enough to include those uncultivated areas that effect the crops through exchanges between communities of organisms, substances and energy. From studies conducted by several authors on the role of small wooded areas, hedges, borders and margins in relation to wildlife, both vertebrate and invertebrate, it was found that, in most cases, the elements of diversification of the landscape have a positive influence on biodiversity of fauna, especially on the so-called "useful fauna" to agro-ecosystems: pollinators, predators and parasitoids of insect pests that are harmful to adjacent crops. These effects arise mainly from the fact that the natural vegetation provides food sources and alternative shelter, which are used in the periods in which the cultivated areas are not hospitable. The biocenosis, in an agro-ecosystem, can remain extremely complex, if not altered, because the pests many predatory species and parasites are bound or restricted. Recent studies show that a high level of biodiversity in agro-ecosystems corresponds more to a neighboring landscape mosaic than to a reduction of conventional agronomical practices. The area of this research has been carried out in what is called Contrada Cassone , which can be found in the B zone of the southeastern side of the Etna Park. The territory that we are analyzing, shows a situation characterized by extensive woods, interposed by lava streams that date back to different periods and which sometimes surround some uncultivated areas (real isle of natural vegetation) and by some orchards. All this determines a mosaic of natural environments, half-natural and half agrarian, fragmented and isolated, inserted in a context characterized, however, by a high level of natural landscape. This research has involved the study of ground Coleoptera communities (beetles) of three different ecosystems: a biological orchard (BIO), a conventional orchard (CON) and chestnut wooded remnants (BOS), investigated with the purpose of emphasizing the structure and the differences and similarities of these communities from a qualitative and quantitative point of view. Therefore, the study focused on the Coleoptera Families, for which the examination with particular reference to species of the Carabidae, Tenebrionidae and Staphylinidae (excluding Aleocharinae and Scydmaeninae), has been developed.