Saproxylic beetles of the Po plain woodlands, Italy

Abstract. Forest ecosystems play an important role for the conservation of biodiversity, and for the protection of ecological processes. The Po plain woodlands which once covered the whole Plain, today are reduced in isolated highly threatened remnants by modern intensive agriculture. These close to natural floodplain forests are one of the most scarce and endangered ecosystems in Europe. Saproxylic species represent a major part of biodiversity of woodlands. The saproxylic insects are considered one of the most reliable bio-indicators of high-quality mature woodlands and have a very important role in regard to the protection and monitoring of forest biodiversity due to their highly specific living environments. As a result of the dramatic reduction of mature forests and the decreased availability of deadwood most of the saproxylic communities are greatly diminishing. The study was conducted in the Ticino Valley Regional Park and the aim is to contribute to the expansion of knowledge on the saproxylic beetles of Lombardy. We investigated 6 sampling sites belonging to alluvial and riparian mixed forests. For each forest we selected 12 trees. For beetles’ collection we used two different traps: Eclector Traps and Trunk Window Traps (total of 72 traps and 864 samples collected). We determined 4.387 beetles from 87 saproxylic species belonging to 21 families. Of these species 51 were not included in the previous checklist of the Park. By comparing the two different techniques used for catching saproxylic beetles, we found a significantly high difference in species richness between Window Traps (WT) and Eclector Traps (ET) with a higher number of species captured in the Window Traps. However, the combined use of two different types of traps significantly expanded the spectrum of insects captured Among the species reported as Least Concern in the IUCN Red List, we found interesting species such as the Elateridae Calambus bipustulats, the Eucnemidae Melasis buprestoides and the following species never previously found in the Park: Cerambycidae Xylotrechus rusticus, the Cetoniidae Valgus hemipterus, the Elateridae Lacon punctatus, the Mycetophagidae Mycetophagus piceus, Litargus connexus. Although we didn’t find species listed in the Annexes of the EU Habitat Directive, some of the species found are locally threatened because of their rarity, local distribution, and strong linkage to old forests. Among these species there are the Bothrideridae Bothrideres bipunctatus, the Cerambycidae Prionus coriarius and Xylotrechus rusticus, the Dryophthoridae Dryophthorus corticalis, the Eucnemidae Nematodes filum (with only 1 individual captured in Alnus unmanged forest), the Histeridae Aeletes atomarius and Paromalus flavicornis, the Laemophloeidae Cryptolestes duplicatus, the Latridiidae Enicmus rugosus and Latridius hirtus, the Mycetophagidae Mycetophagus piceus, and the Zopheridae Colydium elongatum and Pycnomerus terebrans.