Biodiversity Data Journal :
Research Article
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Corresponding author: Umberto Maritano (umberto.maritano@gmail.com)
Academic editor: Torsten Dikow
Received: 13 May 2020 | Accepted: 16 Jul 2020 | Published: 29 Jul 2020
© 2020 Umberto Maritano
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Maritano U (2020) Hoverfly (Diptera: Syrphidae) assemblage of an oak–hornbeam in the Merlino Wood Natural Reserve and implications for its conservation. Biodiversity Data Journal 8: e54243. https://doi.org/10.3897/BDJ.8.e54243
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Merlino Wood is a typical oak–hornbeam forest in the Po Plain hydrographic region. It is one of the few remaining lowland forests in Northern Italy and is a Regional Natural Reserve and a Site of Community Interest (code IT1160010). This is the first survey on hoverflies in the study area and they act as bioindicators to assess habitat conservation. Sampling was performed with three Malaise traps and an entomological net. A total of 61 species of Syrphidae were recorded between March and October 2019. Three of the species observed are considered to be under threat in Europe, three species have been recorded for the first time in Piedmont and Heringia latitarsis (Egger, 1865) has been recorded for the first time in Northern Italy. The Syrph the Net analysis has been used to assess habitat conservation. It shows good preservation of xylosaprophagous species, while the conservation conditions of other larval trophic categories are poor.
Diptera, Syrphidae, Merlino Wood, hoverfly, Piedmont, Syrph the Net, Spilomyia manicata
The Merlino Wood Natural Reserve (MWNR) is an oak–hornbeam forest located in the Po Plain hydrographic region (Northern Italy). It is a Regional Natural Reserve and a Site of Community Interest (SCI; code IT1160010). The oak–hornbeam woods are considered of high ecological value and, for this reason, are listed as a habitat of European interest according to Directive 92/43 EEC (
The MWNR has been repeatedly investigated for its Coleoptera fauna. Buprestidae assemblage, for instance, reveals a typical fauna of the Po Plain woods with European chorology clearly predominant as opposed to that of Mediterranean origin (
In order to assess ecosystem conservation, it is very important to organise sampling activities to standardise monitoring (
Merlino Wood (Fig.
In order to include all phenological periods of adult Syrphidae species, field research began on 11 March and ended on 30 October 2019, using direct (entomological net) and passive (Malaise traps) collection methods. These two methods are thought to be complementary to collect adult hoverflies (
The use of Syrph the Net (StN) as a tool to assess the natural conservation of ecosystems has been widely tested in Europe (e.g.
The study yielded 61 species sampled in the Merlino Wood Natural Reserve. Table
Checklist of Syrphidae sampled in the Merlino Wood Natural Reserve. Very low density indicates that only a single specimen was seen in the field during the entire season.
Faunistic list | Malaise trap (N of specimens) | Net (N of specimens) | First observation month | Very low density |
Baccha elongata (Fabricius, 1775) | 1 | June | ||
Brachyopa bicolor (Fallen, 1817) | 1 | March | x | |
Brachypalpoides lentus (Meigen, 1822) | 1 | 1 | May | |
Brachypalpus laphriformis (Fallen, 1816) | 1 | March | x | |
Caliprobola speciosa (Rossi, 1790) | 1 | April | x | |
Ceriana conopsoides (Linnaeus, 1758) | 1 | May | ||
Chalcosyrphus nemorum (Fabricius, 1805) | 2 | July | ||
Cheilosia gigantea (Zetterstedt, 1838) | 1 | May | x | |
Cheilosia proxima (Zetterstedt, 1843) | 1 | June | x | |
Chrysotoxum bicinctum (Linnaeus, 1758) | 1 | June | ||
Chrysotoxum cautum (Harris, 1776) | 1 | 2 | March | |
Chrysotoxum festivum (Linnaeus, 1758) | 1 | 1 | May | |
Criorhina floccosa (Meigen, 1822) | 1 | April | ||
Criorhina ranunculi (Panzer, 1804) | 1 | April | ||
Dasysyrphus venustus (Meigen, 1822) | 2 | April | ||
Epistrophe melanostoma (Zetterstedt, 1843) | 1 | April | ||
Epistrophella euchroma (Kowarz, 1885) | 1 | May | ||
Episyrphus balteatus (De Geer, 1776) | 4 | 1 | March | |
Eristalinus aeneus (Scopoli, 1763) | 3 | March | ||
Eristalinus sepulchralis (Linnaeus, 1758) | 1 | June | ||
Eristalinus taeniops (Wiedemann, 1818) | 1 | August | ||
Eristalis arbustorum (Linnaeus, 1758) | 3 | June | ||
Eristalis interrupta (Poda, 1761) | 1 | March | ||
Eristalis tenax (Linnaeus, 1758) | 3 | March | ||
Eumerus ornatus Meigen, 1822 | 7 | June | ||
Eupeodes corollae (Fabricius, 1794) | 1 | 2 | May | |
Eupeodes latifasciatus (Macquart, 1829) | 1 | 1 | March | |
Eupeodes luniger (Meigen, 1822) | 2 | May | ||
Ferdinandea cuprea (Scopoli, 1763) | 4 | May | ||
Ferdinandea ruficornis (Fabricius, 1775) | 1 | May | ||
Helophilus pendulus (Linnaeus, 1758) | 17 | 1 | March | |
Helophilus trivittatus (Fabricius, 1805) | 2 | May | ||
Heringia heringi (Zetterstedt, 1843) | 2 | April | ||
Heringia latitarsis (Egger, 1865) | 2 | May | ||
Mallota fuciformis (Fabricius, 1794) | 1 | March | ||
Melanostoma mellinum (Linnaeus, 1758) | 6 | April | ||
Melanostoma scalare (Fabricius, 1794) | 1 | 3 | March | |
Merodon avidus (Rossi, 1790) | 3 | May | ||
Milesia crabroniformis (Fabricius, 1775) | 1 | July | ||
Myathropa florea (Linnaeus, 1758) | 2 | April | ||
Myolepta vara (Panzer, 1798) | 1 | April | x | |
Paragus haemorrhous Meigen, 1822 | 4 | April | ||
Paragus pecchiolii Rondani, 1857 | 5 | April | ||
Pipizella viduata (Linnaeus, 1758) | 12 | March | ||
Psilota anthracina Meigen, 1822 | 1 | May | x | |
Scaeva dignota (Rondani, 1857) | 1 | May | ||
Scaeva pyrastri (Linnaeus, 1758) | 1 | April | ||
Sphaerophoria rueppelli (Wiedemann, 1830) | 2 | July | ||
Sphaerophoria scripta (Linnaeus, 1758) | 1 | May | ||
Spilomyia manicata (Rondani, 1865) | 1 | June | ||
Syritta pipiens (Linnaeus, 1758) | 2 | March | ||
Syrphus ribesii (Linnaeus, 1758) | 4 | 3 | June | |
Syrphus torvus Osten-Sacken, 1875 | 1 | March | ||
Syrphus vitripennis Meigen, 1822 | 19 | 3 | March | |
Volucella inanis (Linnaeus, 1758) | 1 | July | ||
Volucella inflata (Fabricius, 1794) | 1 | May | ||
Volucella pellucens (Linnaeus, 1758) | 1 | June | ||
Volucella zonaria (Poda, 1761) | 1 | June | ||
Xanthandrus comtus (Harris, 1780) | 20 | March | ||
Xanthogramma stackelbergi Violovitsh, 1975 | 1 | 2 | May | |
Xylota segnis (Linnaeus, 1758) | 1 | May | x |
By applying Syrph the Net (including migratory species and using the Piedmont checklist as reference), the BDMF value in over-mature mesophilic Quercus/Carpinus habitat is 37.5% (Table
Derivation of BDMF (Biodiversity Maintenance Function) percentage value for macrohabitat, based on Syrph the Net (StN).
Macrohabitat | CORINE Code | StN Code | Expected species (N) | Observed species (N) | BDMF (%) | Unpredicted species observed not migrant (N) |
Mesophilic Quercus/Carpinus over-mature | 41.2 | 11221 | 112 | 42 | 37.5 | 9 |
Microhabitats associated with old trees seem to be in very good conservation conditions (Table
BDMF percentage value for trophic larval categories, based on Syrph the Net (StN). Exp.: Number of Expected species, Obs.: Number of Observed species
Macrohabitat | Xilosaprophagous | Phytophagous | Predators | Detritivores | ||||||||
Exp. | Obs. | % | Exp. | Obs. | % | Exp. | Obs. | % | Exp. | Obs. | % | |
Mesophilic Quercus/Carpinus over-mature | 28 | 15 | 53.6 | 23 | 4 | 17.4 | 49 | 20 | 40.8 | 12 | 3 | 25 |
BDMF percentage values for voltinism and larval microsites, based on Syrph the Net (StN).
Expected species (N) | BDMF (%) | ||
Number of generations/year | < 1 | 5 | 60.0 |
1 | 71 | 28.2 | |
2 | 46 | 41.3 | |
> 2 | 10 | 70.0 | |
Larval microsite | Foliage | 25 | 48.0 |
Stem bases | 11 | 18.2 | |
Grass-root zone | 14 | 50.0 | |
Bulbs/tubers | 10 | 30.0 | |
Mature trees | 33 | 48.5 | |
Timber stumps | 9 | 55.6 | |
Timber fallen | 4 | 75.0 | |
Timber standing | 5 | 60.0 | |
Trunk cavities | 17 | 58.8 | |
Sap runs/lesions | 18 | 44.4 | |
Nests of social insects | 5 | 60.0 | |
Submerged sediment/debris | 8 | 37.5 |
Hoverflies are the main pollinators after Apoidea (
Conservation actions on saproxylic insects play a key role in the management of forest ecosystems (
From the conservation strategy viewpoint, it would be advisable to avoid planting intensive crops close to the forest. There should be a buffer zone of at least 50 m around the full whole perimeter of the wood, in addition to internal clearings, assuming harvesting at times that do not compromise the blooming of the grasses. This could also favour phytophagous species. Forest management should allow the possibility of indefinite growth of the oldest oaks, in order to support the greatest possible number of microhabitats. The average age of the oldest Quercus robur is just 110–120 years, which is too young to reach adequate senescence. By contrast, in Quercus woods in Slavonia (Croatia), the minimum shearing turn is 150–160 years and, in the French forest of Tronçais, it is 250 years (
Merlino Wood is subject to enormous human pressure, but still represents an isolated source of saproxylic organisms. Strict habitat conservation measures are required to preserve its flora and fauna.
I am grateful to Simon Piers Aiken for improvements to the English. Many thanks to Luca Cristiano and Daniele Sommaggio for precious comments and suggestions which they made on the manuscript. I would like to thank Monviso Park for giving me permission to sample in the study area. I sincerely thank the reviewers whose comments helped in improving the preliminary draft of the manuscript.