Analysis of vertical stratification of Syrphidae (Diptera) in an oak‐hornbeam forest in northern Italy

Abstract

There is growing interest in the vertical stratification of forest biodiversity, but little is known about this aspect for Syrphidae living in forests. For this study, seven Malaise traps were suspended in the canopy and seven were placed on the ground, in a lowland forest in northern Italy. Altogether, 868 specimens of Syrphidae were collected; 229 from the canopy and 639 from the ground, comprising a total of 53 species. Three species [(Ceriana conopsoides (Linnaeus), Eupeodes corollae (Fabricius), Psilota atra Fallén)] were associated significantly with the canopy layer, and seven species [(Brachypalpoides lentus (Meigen), Chalcosyrphus nemorum (Fabricius), Chrysotoxum cautum (Harris), Eumerus flavitarsis Zetterstedt, Helophilus pendulus (Linnaeus), Myathropa florea (Linnaeus) and Xylota segnis (Linnaeus)] with the ground level. The sex‐ratio of the Syrphidae differed significantly between the two layers, as females were caught mainly at ground level, while males were caught preferentially in the canopy. Species with saprophagous and saproxylic larvae were caught more commonly at ground level. Species richness declined from April to November but vertical stratification was constant for most of the season. Multivariate analyses showed that two factors were correlated significantly with the community composition of Syrphidae: height of Malaise trap and estimated age of dominant trees.

Vertical stratification of selected Hymenoptera in a remnant forest of the Po Plain (Italy, Lombardy) (Hymenoptera: Ampulicidae, Crabronidae, Sphecidae)

“…As already observed in other insect groups (Birtele & Hardersen 2012;Stireman et al 2012;Hardersen et al 2014;Di Giovanni et al 2015), the canopy community of Spheciformes at "Bosco della Fontana" is markedly different from that of the understory. Previous studies performed in temperate forests also showed a vertical stratification in the community composition of hymenopterans (Vance et al 2007;Pucci 2008;Sobek et al 2009;Ulyshen et al 2010Ulyshen et al , 2011.…”

“…In both tropical and temperate forests, canopies can provide resources which are seasonally unavailable in the understory (Ulyshen et al 2010) and can offer nesting sites for specialized saproxylic organisms (Sobek et al 2009;Ulyshen et al 2011b). In certain conditions, the canopy layer may also work as aggregation point for several flying insects during mating swarming (Birtele & Hardersen 2012;Stireman et al 2012). …”

“…Yet, only few studies have focused on highly mobile (and highly diverse) insects as dipterans or hymenopterans of the canopy of temperate forests (Preisser et al 1998;Sperber et al 2004;Thunes et al 2004;Vance et al 2007;Pucci 2008;Stireman 2008;Sobek et al 2009;Ulyshen et al 2010Ulyshen et al , 2011aUlyshen et al , 2011bBirtele & Hardersen 2012;Stireman et al 2012;Di Giovanni et al 2015). In this study, we analyzed the community composition of solitary wasps belonging to Ampulicidae, Crabronidae and Sphecidae (the three families of Apoidea Spheciformes present in Italy) of understory and canopy of the Natural Reserve of "Bosco della Fontana", a temperate plain forest in North Italy.…”

“…Adults feed on nectar or sugary secretions, more rarely on fluids of the prey hunted as food for their larvae (Pagliano & Negrisolo 2005). So far, several surveys have been carried out in this area to provide a comprehensive framework of the arthropod fauna of this remnant forest (Mason et al 2002;Cerretti et al 2004;Birtele & Hardersen 2012;Hardersen et al 2012;Stireman et al 2012;eISSN: 2284-4880 (online version) pISSN: 0429-288X (print version) Di Giovanni et al 2015). Thanks to an intensive sampling with Malaise traps, we tested for differences in community composition of Spheciformes between canopy and understory.…”

Patterns in diurnal co-occurrence in an assemblage of hoverflies (Diptera: Syrphidae)

“…Goulson & Wright, 1998;Branquart & Hemptinne, 2000;Jauker et al, 2009;Birtele & Hardersen, 2012), one aspect that has received relatively little attention is the interspecific structure of syrphid assemblages. The structure of plant and animal communities is a product of many interacting processes.…”