Biodiversità dell'entomofauna in ambienti forestali dell'alto Lazio: il caso dei Ditteri Sirfidi
Author(s)
Prestininzi, Marco
Date Issued
February 10, 2009
Type
Doctoral Thesis
Abstract
Surveys carried out in this doctoral thesis aimed at contributing to the knowledge of insect biodiversity of some forestry environments of Northern Lazio – Central Italy. To this purpose, in 2006, samples of insects were weekly gathered from April to August, by means of Malaise traps which were placed both on the ground and close to the canopy layer. The sampling sites were located inside two Region Natural Reserve areas, named “Monte Rufeno” and “Selva del Lamone”, mainly characterized by semi-natural stands of oak trees (Quercus cerris L.). For the whole period, at Lamone site a total amount of 73,022 insect specimens were collected from traps placed on the ground, whereas 21,659 insect specimens were collected from the canopy layer traps, which was equal to 77% and 23% respectively. At Rufeno site, the amount of gathered insect specimens was 53,599 from the ground traps and 12,348 from the canopy traps, that is 81% and 19% respectively. Specimens captured at Lamone area belonged to the following major Orders: Diptera (62%), Hymenoptera (18.5%), Lepidoptera (7.5%), Coleoptera (5.9%), Homoptera (3.5%), Collembola (0.8%), Heteroptera (0.5%) and Psocoptera (0.3%). All the remaining observed taxa such as Diplura, Ephemeroptera, Isoptera, Orthoptera, Phasmatodea, Dermaptera, Plecoptera, Thysanoptera, Raphidioptera, Planipennia, Mecoptera and Siphonaptera, did not exceed 1% altogether. Similarly, insect specimens collected at Rufeno area mainly belonged to the following taxa:Diptera (67.6%), Hymenoptera (16.7%), Lepidoptera (5%), Coleoptera (4%), Homoptera (4%), Collembola (1.3%), Psocoptera (0.5) and Heteroptera (0.3%). Blattaria, Orthoptera, Plecoptera, Thysanoptera, Raphidioptera, Planipennia, Mecoptera and Trichoptera summed up 0.6% altogether. Within Diptera Brachycera, specimens belonging to the following Families were sorted and counted: Tabanidae (8151 at Lamone and 563 at Rufeno), Stratiomyidae (93 at Lamone and 26 at Rufeno) Syrphidae (322 at Lamone and 192 at Rufeno) e Tachinidae (717 at Lamone and 248 at Rufeno). Their spatial (ground and canopy) and temporal (flight period) distribution was also studied. Particular attention was given to Syrphidae (hoverflies), as the insects belonging to this Family play an important role in different aspects of a forestry ecosystem. Firstly, with the assistance of a taxonomist, a catalogue of Syrphid species was compiled resulting in 45 species found at Lamone and 38 species found at Rufeno. Secondly, for both hoverfly communities, several indexes related with biodiversity measures were calculated, such as Margalef & Menchinick, Shannon, Simpson, Hill.
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Thirdly, it has been applied Syrph-the-Net (StN), a software which uses syrphid species as bioindicators, through a specific function (FMB) which describes the level of biodiversity conservation of an ecosystem. The most relevant observations pointed out from the above mentioned surveys on syrphid flies can be summarized as follows:
it was captured Sphiximorpha garibaldi Rondani, 1860, a species known only as type and not seen anymore in Italy since its description.
it was captured Criorhina pachymera Egger, 1858, species not reported in the Italian Fauna checklist (2003)
both sites present similar species richness, although biodiversity and evenness at Rufeno site seems to be slightly higher
according to StN, the FMBs obtained for the observation areas were 61% at Lamone and 67% at Rufeno. It implies that both the investigated ecosystems are well preserved and can support a high degree of biodiversity.
Additional information
Dottorato di ricerca in Ecologia forestale
Subjects
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