Syrphids as landscape bioindicators in Italian agroecosystems

The aim of the work was to study the syrphid fauna in rural landscapes and to evaluate the quality of environment by means of the faunistic data collected. Sampling was carried out by Malaise traps and yellow sticky traps, baited with different kinds of glue. Malaise traps proved to be the most efficient monitoring system. Despite the greater efficiency, the Malaise trap failed to collect some species and in a few cases the number of species collected only by yellow trap was high. Among the three categories of landscape complexity, classified by measuring the linear development of hedgerows around the sites, the highest number of species was recorded in sites belonging to ‘‘high’’ complexity. In spite of this general trend, the landscape-complexity criterion showed some contradictory results, because ‘‘low’’ complexity habitats had higher numbers of species than ‘‘intermediate’’ ones. Among vegetation types, ‘‘hedgerow and abundant grass and flower strips’’ collected the most species. A standard method for Syrphidae, that calculates a ‘‘biodiversity maintenance function’’, Syrph the Net, was used to evaluate sites.