Ground beetles (Coleoptera: Carabidae) of rice field banks and restored habitats in an agricultural area of the Po Plain (Lombardy, Italy).

An entomological investigation was carried out in an agricultural area, mainly rice fields, of the Po river plain, located in the municipalities of Lacchiarella (MI) and Giussago (PV) (Lombardy, Italy). In 2009 and 2010, ground beetles (Coleoptera: Carabidae) were sampled along rice field banks and in restored habitats, by means of pitfall traps. The area appeared as species-rich, compared to other anthropogenic habitats in the Po river pain. Most of the collected Carabids were species with a wide distribution in the Paleartic region, eurytopic and common in European agroecosystems. The assemblages were dominated by small-medium, macropterous species, with summer larvae. No endemic species were found. Species with southern distribution, rarely found north of the Po river, were also sampled. Amaralittorea is recorded for the first time in Italy.

Introduction

In the last decades, intensification and mechanization of agricultural practices, introduced in order to maximise productivity, led to a decrease in habitat quality and landscape heterogeneity throughout European agroecosystems. Diffusion of monoculture, increased use of chemicals (i.e. pesticides and fertilizers) and removal of non-cropped areas, like small woodlots and hedges, caused a wide-scale loss of biodiversity (Stoate et al. 2001).

Recently, environmentally-friendly agronomic practices and creation of non-cropped habitats have been recognized as a potential solution to this dramatic decline of biodiversity and have become key aims of European Union’s Common Agricultural Policy (CAP) and, as a consequence, of national and regional ones (Stoate et al. 2009). In Lombardy lowland, environmentally-friendly measures includes reforestations, creation of hedges and buffer strips, maintenance of meadows and renaturalization of wetlands (Lombardy Region 2012, http://www.agricoltura.regione.lombardia.it).

Even if agri-environment schemes (AESs) benefit some farmland species (e.g., Peach et al. 2001), gaps in the provision of habitat quality and landscape connectivity for many others still exist (Kleijn et al. 2001, Vickery et al. 2004, Reid et al. 2007). Better understanding on effects of AESs on farmland biodiversity and exhaustive surveys on animal and plant communities in enhanced habitats are required (Kleijn and Sutherland 2003, Stoate et al. 2009).

The aim of this research was to investigate the Carabid assemblages of an intensive agricultural area (mainly rice fields) subjected to environmental improvements since 1996, in particular the creation of buffer strips along paddy fields and the restoration of an area of ​​150 ha.

Materials and methods

Study area

The study was carried out in an 4.5 km2 agricultural area, mainly cultivated with rice, located in north-western Italy, in the middle of the Po plain, approximately 13 km north from the city of Pavia, in the municipalities of Lacchiarella (MI) and Giussago (PV); barycentre 45°17'38.63"N, 09°08'52.08"E (Fig. 1).

Figure 1.

Schematic representation of the study area (anthropic areas include villages, farmsteads, main roads and railways).

The study area included three adjacent rice farms, “La Darsena”, “La Cadenazza” and “Necchi”, and a restored area, “La Cassinazza”. The Carabid fauna was sampled in:

rice field banks (Fig. 2): characterized by herbaceous cover (mainly , , , , and ), sporadically with a row of poplar trees ();

Figure 2.

Rice field with herbaceous banks.

buffer strips (Fig. 3): perimeter land of paddy fields taken out of production and converted into small wetlands and strips of permanent vegetation, planted with autochthonous shrubs and trees (mainly , , , , and ). The first stands were planted in 2003 and, during the study period, strips were fully-developed into arboreal habitats (arboreal buffer strips). The last stands were planted in 2009 and, during the study period, strips were mostly covered by herbaceous vegetation (herbaceous buffer strips, mainly , , , , and );

Figure 3.

Herbaceous buffer strip along a small wetland connected to paddy field.

restored area (~150 ha; Fig. 4): formerly a farmland area undergoing restoration since 1996. The area is composed by a mosaic of different habitats, including wetlands, reforested areas and meadows, connected by a system of hedges. For the descriptive purposes of this paper, Carabid coenosis of meadows, both wet and dry (herbaceous restored habitats, mainly , , , , , and ), was divided from that of the forested areas and hedges (arboreal restored habitats, mainly , , , , , , , , , and ).

Figure 4.

Wet meadow with reforested area on the background.

Sampling method and data analysis

Ground beetles were sampled using plastic pitfall traps (62 mm in diameter and 70 mm deep) buried in the soil and filled with 50 ml of wine vinegar and a drop of detergent (Brandmayr et al. 2005). Pitfalls were covered with a 10 × 10 cm wooden roof to prevent flooding and emptied fortnightly.

Along rice field banks, we placed a total of 60 traps from April to November 2009 and 68 traps from May to November 2010; along buffer strips, we positioned 56 traps from May to November 2009 and 2010; in the restored area, we placed 66 traps from July to November 2009 and from April to November 2010.

Carabids were identified to the species level following the nomenclature of Fauna Europaea (http://www.faunaeur.org, Vigna-Taglianti 2010). Information on chorotype, body size, larval and wing development were reported for each species. Chorotype were obtained from Vigna-Taglianti 2005; larval development were derived from Casale et al. 1982, Drioli 1987 and Brandmayr et al. 2005; data on body size and wing development were mainly obtained from Hůrka 1996, and secondly from Jeannel 1941, Jeannel 1942. As for body size, according to Cole et al. 2002, species were divided as (a) very small (< 5 mm), (b) small (5 - 9 mm), (c) medium (9 - 15 mm) and (d) large (> 15 mm). Data on adult diet were not available for all species and we reported only the existing information, according to Cole et al. 2002, Brandmayr et al. 2005, Purtauf et al. 2005, Melis et al. 2010 and Bettacchioli et al. 2012.

A synthetic description of habitat preference, derived from Hůrka 1996 and personal observations with special reference to the Po plain, were also reported for each species. According to Fournier and Loreau (1999), we classified the species as "rare" when the total capture over the whole area was lower than 0.1% (i.e. < 35 individuals); the other species were classified as "common" and the two most abundant species as "dominant". The total number of captured individuals (n) was reported in brackets.

As for rice field banks and enhanced habitats, ground beetle abundances were expressed both as absolute frequency (i.e. number of collected individuals) and as annual Activity Density (aAD; Brandmayr et al. 2005), that is the number of collected individuals during the entire sampling period (n) divided by sampling effort (US) for each sampling station:

DAa = ntot / US

with US = Σ us and us = trap * (gg/10), where trap is number of traps and gg is the number of days during which the traps were active in each sampling session (Suppl. material 1).

Specimens, dried or preserved in alcohol, are stored in the author’s collections (Nicola Pilon, Milano) and in the collection of the University of Pavia.

Checklists

Checklist

(Olivier, 1795)

Notes

Turanic-European. Open habitats, thermophilous. Macropterous, with winter larvae. Medium size. Spermatophagous.

Uncommon north of the Po river. Rare in the study area (n = 2); recorded in arboreal restored habitats only.

(Dejean, 1829)

Turanic-European-Mediterranean. Open habitats, halophilous. Macropterous, with summer larvae. Very small size. Spermatophagous.

Rare in the study area (n = 1); recorded in herbaceous restored habitats only.

(Sturm, 1825)

European. Paludicolous, ripicolous. Macropterous, with summer larvae. Very small size. Spermatophagous.

Rare in the study area (n = 1); recorded in arboreal restored habitats only.

(Schaum, 1860)

European-Mediterranean. Paludicolous, ripicolous. Macropterous, with summer larvae. Very small size. Spermatophagous.

Rare in the study area (n = 18).

Mulsant

Mediterranean. Paludicolous, halophilous. Macropterous, with summer larvae. Very small size. Spermatophagous.

Rare in the study area (n = 1); recorded in arboreal restored habitats only.

(Gyllenhal, 1827)

European. Paludicolous, ripicolous. Macropterous, with summer larvae. Small size.

Common in the study area (n = 107). Recorded in all habitat categories.

(Herbst, 1784)

Siberic-European (Holoartic). Open habitats, hygrophilous. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 8).

(Linné, 1758)

Siberic-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 1); recorded in rice field banks only.

Sturm, 1824

Siberic-European. Paludicolous, silvi-ripicolous. Macropterous, with summer larvae. Small size.

Rare in the study area (n = 2); recorded in arboreal restored habitats only.

(Panzer, 1796)

Siberic-European. Paludicolous, silvi-ripicolous. Macropterous, with summer larvae. Small size.

Rare in the study area (n = 8); recorded in arboreal restored habitats only.

(De Geer, 1774)

Paleartic (Holoartic). Open habitats, eurytopic. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Common in the study area (n = 1180). Recorded in all habitat categories.

(Gyllenhal, 1810)

Central Asiatic-European. Open habitats. Macropterous, with winter larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 2).

(Panzer, 1797)

Asiatic-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 7).

(Duftschmid, 1812)

Siberic-European. Open habitats, eurytopic. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 10).

(Audinet-Serville, 1821)

European. Open habitats, xerophilous. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Rare in the study area (n = 4).

C.G. Thomson, 1857

Asiatic-European. Open habitats, xerophilous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Recorded with certainty for the first time in Italy (Cardarelli and Pilon 2012). Rare in the study area (n = 1); recorded in herbaceous buffer strips only.

(Duftschmid, 1812)

Turanic-European. Open habitats, xerophilous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 31).

Sturm, 1825

Asiatic-European. Open habitats. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 12); recorded in rice field banks only.

(Gyllenhal, 1810)

Asiatic-European. Open habitats, eurytopic. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Common in the study area (n = 203).

(Heer, 1841)

European-Mediterranean. Open habitats, thermophilous. Macropterous, with summer larvae. Very small size.

Uncommon north of the Po river. Rare in the study area (n = 7).

(Pontoppidan, 1763)

Paleartic. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size. Predator.

Common in the study area (n = 234). Recorded in all habitat categories.

(Fabricius, 1787)

Asiatic-European. Open habitats, eurytopic. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 761). Recorded in all habitat categories.

(Panzer, 1796)

Asiatic-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 798). Recorded in all habitat categories.

(Schrank, 1798)

Holoartic. Open habitats. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 11).

(Duftschmid, 1812)

Turanic-European. Paludicolous, silvi-ripicolous. Macropterous, with summer larvae. Very small size. Predator.

Rare in the study area (n = 1); recorded in arboreal buffer strips only.

(Linné, 1761)

Holoartic. Open habitats, hygrophilous. Macropterous, with summer larvae. Very small size. Zoospermatophagous.

Common in the study area (n = 866). Recorded in all habitat categories.

Audinet-Serville, 1821

Central Asiatic-European-Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Very small size.

Rare in the study area (n = 5); recorded in herbaceous buffer strips only.

Chaudoir, 1842

Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size.

Common in the study area (n = 1001). Recorded in all habitat categories.

Duftschmid, 1812

Asiatic-European. Open habitats. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 2).

Latreille

S-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size.

Rare in the study area (n = 14).

Reiche, 1868

Mediterranean. Open habitats, halophilous. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 26).

(Fabricius, 1792)

European-Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size. Predator.

Common in the study area (n = 372).

(Duftschmid, 1812)

Turanic-European. Open habitats, xerophilous. Macropterous, with winter larvae. Very small size. Spermatophagous.

Rare in the study area (n = 2); recorded in herbaceous buffer strips only.

(Goeze, 1777)

European-Mediterranean. Open habitats, xerophilous. Pteridimorphic, with winter larvae. Medium size. Predator.

Rare in the study area (n = 8).

(Linné, 1758)

Paleartic. Open habitats, xerophilous. Pteridimorphic, with winter larvae. Small size. Predator.

Common in the study area (n = 177).

(Herbst, 1784)

Central Asiatic-European. Open habitats, xerophilous. Macropterous, with summer larvae. Large size. Predator.

Common in the study area (n = 115).

Linné, 1758

Asiatic-European (Holoartic). Paludicolous, silvi-ripicolous. Pteridimorphic, with summer larvae. Large size. Predator.

Common in the study area (n = 64).

(Schrank, 1781)

Central Asiatic-European. Paludicolous. Macropterous, with summer larvae. Medium size.

Common in the study area (n = 123). Recorded in all habitat categories.

(Schaller, 1783)

Paleartic. Paludicolous. Macropterous, with summer larvae. Medium size. Predator.

Rare in the study area (n = 4).

(P. Rossi, 1792)

Paleartic. Paludicolous. Macropterous, with summer larvae. Large size. Predator.

Common in the study area (n = 62). Recorded in all habitat categories.

Linné, 1758

Paleartic. Open habitats. Macropterous, with poliennal larvae. Medium size. Predator.

Rare in the study area (n = 1); recorded in rice field banks only.

(Herbst, 1784)

Turanic-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size.

Rare in the study area (n = 1); recorded in rice field banks only.

(Linné, 1758)

Asiatic-European (Holoartic). Open habitats, hygrophilous. Pteridimophic, with summer larvae. Small size. Predator.

Rare in the study area (n = 28). Recorded in all habitat categories.

(Linné, 1758)

Turanic-European-Mediterranean. Open habitats. Macropterous, with summer larvae. Small size.

Common in the study area (n = 161).

(L. Dufour, 1820)

European-Mediterranean. Open habitats, xerophilous. Macropterous, with summer larvae. Medium size.

Uncommon north of the Po river. Rare in the study area (n = 3).

(Schaller, 1783)

Asiatic-European. Open habitats. Macropterous, with winter larvae. Large size.

Rare in the study area (n = 5); recorded in herbaceous buffer strips only.

(P. Rossi, 1790)

Afrotropical and Paleartic. Paludicolous. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 1); recorded in arboreal buffer strips only.

(Schrank, 1781)

Asiatic-European (Holoartic). Open habitats. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 372).

Reitter, 1900

S-European. Open habitats. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 3); recorded in rice field banks only.

(Duftschmid, 1812)

Paleartic. Open habitats. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Common in the study area (n = 331). Recorded in all habitat categories.

Dejean, 1829

S-European. Open habitats, thermophilous. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Uncommon north of the Po river. Rare in the study area (n = 12).

(P. Rossi, 1790)

European. Open habitats, xerophilous. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Rare in the study area (n = 15).

(Duftschmid, 1812)

Paleartic. Open habitats. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 1396). Recorded in all habitat categories.

(Duftschmid, 1812)

European. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Common in the study area (n = 80). Recorded in all habitat categories.

Dejean, 1829

Turanic-European-Mediterranean. Open habitats, xerophilous. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Uncommon north of the Po river. Common in the study area (n = 61).

Sturm, 1818

Paleartic. Open habitats, xerophilous. Pteridimorphic, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 2); recorded in rice field banks only.

Dejean, 1829

S-European. Open habitats. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Common in the study area (n = 51).

(Duftschmid, 1812)

Asiatic-European. Open habitats. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 180). Recorded in all habitat categories.

(Quensel in Schönherr, 1806)

Paleartic. Open habitats, xerophilous. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 177).

(Panzer, 1797)

Asiatic-European. Open habitats, eurytopic. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Common in the study area (n = 97).

(Paykull, 1790)

Siberic-European. Paludicolous, silvi-ripicolous. Macropterous, with summer larvae. Medium size. Predator.

Common in the study area (n = 263); recorded in arboreal restored habitats only.

(Sperk, 1835)

Siberic-European. Paludicolous, silvi-ripicolous. Macropterous, with summer larvae. Medium size.

Common in the study area (n = 50); recorded in arboreal restored habitats only.

(Herbst, 1784)

Paleartic (Holoartic). Open habitats, eurytopic. Pteridimorphic, with summer larvae. Very small size. Predator.

Common in the study area (n = 49).

(Stephens, 1828)

Siberic-European. Open habitats, eurytopic. Pteridimorphic, with summer larvae. Very small size.

Common in the study area (n = 225). Recorded in all habitat categories.

(L. Dufour, 1820)

Turanic-Mediterranean. Open habitats. Macropterous, with summer larvae. Very small size.

Rare in the study area (n = 2).

(Goeze, 1777)

Holoartic. Open habitats, eurytopic. Pteridimorphic, with summer larvae. Very small size.

Common in the study area (n = 111).

(Fabricius, 1792)

Turanic-European. Open habitats, hygrophilous. Macropterous, with winter larvae. Medium size. Predator.

Rare in the study area (n = 1); recorded in arboreal restored habitats only.

(Fabricius, 1792)

Siberic-European. Paludicolous. Macropterous, with summer larvae. Small size. Predator.

Rare in the study area (n = 15).

(Fabricius, 1775)

Central Asiatic-European-Mediterranean. Open habitats, xerophilous. Pteridimorphic, with winter larvae. Small size. Spermatophagous.

Rare in the study area (n = 1); recorded in herbaceous buffer strips only.

(Dejean, 1829)

Turanic-European. Open habitats, xerophilous. Macropterous, with winter larvae. Small size. Spermatophagous.

Rare in the study area (n = 2); recorded in rice field banks only.

(Dejean, 1829)

European. Open habitats. Macropterous, with winter larvae. Medium size. Spermatophagous.

Rare in the study area (n = 1); recorded in herbaceous restored habitats only.

(Dejean, 1829)

European. Open habitats. Macropterous, with winter larvae. Small size. Spermatophagous.

Rare in the study area (n = 3); recorded in arboreal restored habitats only.

(Linné, 1758)

Siberic-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size.

Rare in the study area (n = 1); recorded in herbaceous buffer strips only.

(Fabricius, 1796)

European-Mediterranean (Holoartic). Ripicolous. Macropterous, with summer larvae. Small size.

Rare in the study area (n = 1); recorded in arboreal restored habitats only.

(Dejean, 1829)

Turanic-Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size.

Common in the study area (n = 190). Recorded in all habitat categories.

(Duftschmid, 1812)

S-European. Open habitats, thermophilous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Common in the study area (n = 65).

(P. Rossi, 1790)

S-European. Open habitats, thermophilous. Macropterous, with summer larvae. Small size.

Uncommon north of the Po river. Rare in the study area (n = 18).

(Dejean, 1829)

E-Mediterranean. Open habitats, thermophilous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Uncommon north of the Po river. Rare in the study area (n = 11).

(Stroem, 1768)

Siberic-European. Silvi-ripicolous. Ptedirimorphic, with winter larvae. Small size. Predator.

Common in the study area (n = 314).

(Geffroy in Fourcroy, 1785)

European-Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Very small size. Predator.

Rare in the study area (n = 28). Recorded in all habitat categories.

(Linné, 1758)

Asiatic-European. Open habitats, eurytopic. Macropterous, with summer larvae. Medium size. Zoospermatophagous.

Dominant in the study area (n = 6127). Recorded in all habitat categories.

(Sturm, 1824)

Asiatic-European. Open habitats, hygrophilous. Macropterous, with summer larvae. Medium size. Predator.

Common in the study area (n = 1025). Recorded in all habitat categories.

(Panzer, 1796)

Paleartic. Open habitats, eurytopic. Macropterous, with winter larvae. Medium size.

Common in the study area (n = 286). Recorded in all habitat categories.

(De Geer, 1774)

Paleartic (Holoartic). Open habitats, eurytopic. Macropterous, with winter larvae. Medium size. Zoospermatophagous.

Dominant in the study area (n = 12 626). Recorded in all habitat categories.

(Herbst, 1784)

W-Paleartic. Paludicolous, silvi-ripicolous. Macropterous, with summer larvae. Medium size.

Rare in the study area (n = 25). Recorded in all habitat categories.

(Marsham, 1802)

Asiatic-European. Open habitats, xerophilous. Macropterous, with summer larvae. Medium size. Predator.

Uncommon north of the Po river. Rare in the study area (n = 1); recorded in rice field banks only.

(Illiger, 1798)

Holoartic. Eurytopic. Pteridimorphic, with winter larvae. Large size. Predator.

Common in the study area (n = 869). Recorded in all habitat categories.

(Schaller, 1783)

Asiatic-European. Silvicolous, hygrophilous. Pteridimorphic, with winter larvae. Large size. Predator.

Common in the study area (n = 1292). Recorded in all habitat categories.

(Paykull, 1790)

Paleartic. Eurytopic, hygrophilus. Pteridimorphic, with summer larvae. Medium size. Predator.

Rare in the study area (n = 34).

(Panzer, 1797)

Asiatic-European. Silvi-ripicolous. Pteridimorphic, with summer larvae. Small size. Predator.

Common in the study area (n = 263). Recorded in all habitat categories.

(Panzer, 1796)

Paleartic. Eurytopic, hygrophilous. Macropterous, with summer larvae. Small size. Predator.

Common in the study area (n = 160). Recorded in all habitat categories.

(Ponza, 1805)

Afrotropical-Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Very small size.

Rare in the study area (n = 4).

(Herbst, 1784)

Paleartic. Paludicolous. Macropterous, with summer larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 5).

(Schrank, 1781)

Turanic-European-Mediterranean. Open habitats, hygrophilous. Macropterous, with summer larvae. Small size.

Common in the study area (n = 605). Recorded in all habitat categories.

(Duftschmid, 1812)

European-Mediterranean. Eurytopic. Macropterous, with summer larvae. Very small size. Predator.

Common in the study area (n = 190).

(Linné, 1761)

Siberic-European. Silvicolous. Pteridimorphic, with summer larvae. Very small size. Predator.

Rare in the study area (n = 8).

(Illiger, 1798)

Asiatic-European. Silvicolous, hygrophilous. Pteridimorphic, with winter larvae. Small size. Zoospermatophagous.

Rare in the study area (n = 1); recorded in arboreal restored habitats only.

(Schrank, 1781)

Turanic-European-Mediterranean. Eurytopic. Pteridimorphic, with winter larvae. Very small size. Predator.

Rare in the study area (n = 7).

Analysis

Overall, we collected 34,108 individuals belonging to 98 carabid species. We recorded 65 species in rice field banks, 73 species in buffer strips and 78 in restored habitats. Eight species were found only in rice field banks (, , , , , , , ), 6 species only in herbaceous buffer strips (, , , , , ), 2 species only in arboreal buffer strips (, ), 2 species only in herbaceous restored habitats (, ) and 11 species only in arboreal restored habitats (, , , , , , , , , , ). and consituted about 55% of the capture with 18 753 individuals.

The collected species belonged to 17 chorotypes (Fig. 5), grouped into 4 complexes (Subcosmopolitan, Holoartic, European and Mediterranean). About 80% of the species captured in the area were Holoartic, 13.3% European, 4.1% Mediterranean and 2% Subcosmopolitan (Table 1). Most of the species were small (very small species: 18.4%, small species: 46.9%) and medium (28.6%); only 6.1% of the captured carabids had size larger than 15 mm (, , , , and ). About 80% of the collected species had larvae that develop during summer, without dormancy (i.e. were spring breeders) and 18.4% were species with winter larvae, that grow slowly with compulsory dormancy (i.e. were autumn breeders). (one individual recorded along rice field banks) was the only species with poliennal larvae. Macropterous and pteridimorphic species were 82.7% and 17.3% respectively; we didn’t find any strictly brachypterous species.

Figure 5.

Chorotypes of ground beetles collected in the study area during 2009 and 2010 (AFM = Afrotropical-Mediterranean, AFP = Afrotropical and Paleartic, ASE = Asiatic-European, CAE = Central Asiatic-European, CEM = Central Asiatic-European-Mediterranean, EME = E-Mediterranean, EUM = European-Mediterranean, EUR = European, MED = Mediterranean, HOL = Holoartic, PAL = Paleartic, SCO = Subcosmopolitan, SEU = S-European, SIE = Siberic-European, TEM = Turanic-European-Mediterranean, TUE = Turanic-European, TUM = Turanic-Mediterranean, WPA = W-Paleartic) (plotted after data in Table 1).

Table 1.

Number and percentage of carabid species for each ecological categories (chorological complexes, body size, larval and wing development) in rice field banks, buffer strips and restored habitats.

	Rice field banks		Buffer strips				Restored habitats				Total
			herbaceous		arboreal		herbaceous		arboreal
	N	%	N	%	N	%	N	%	N	%	N	%
Chorotype
Subcosmopolitan	0	0	1	1.5	1	2.6	0	0	1	1.4	2	2
Holoartic	54	83.1	53	80.3	33	86.8	49	81.7	58	84.1	79	80.6
European	8	12.3	9	13.7	3	7.9	10	16.7	8	11.6	13	13.3
Mediterranean	3	4.6	3	4.5	1	2.7	1	1.6	2	2.9	4	4.1
Size
Very small	6	9.2	12	18.2	5	13.2	10	16.7	13	18.8	18	18.4
Small	36	55.4	30	45.5	18	47.4	25	41.7	28	40.6	46	46.9
Medium	20	30.8	18	27.2	12	31.5	20	33.3	23	33.3	28	46.9
Large	3	4.6	6	9.1	3	7.9	5	8.3	5	7.3	6	6.1
Larvae
summer	55	84.6	56	84.8	31	81.6	53	88.3	57	82.6	79	80.6
winter	9	13.8	10	15.2	7	18.4	7	11.7	12	17.4	18	18.4
poliennal	1	1.5	0	0.0	0	0.0	0	0.0	0	0.0	1	1.0
Wing
macropterous	54	83.1	54	81.8	29	76.3	49	81.7	54	78.3	81	82.7
pteridimorphic	11	16.9	12	18.2	9	23.7	11	18.3	15	21.7	17	17.3

Also rice field banks, buffer strips and restored habitats, analyzed separately, were dominated by Holoartic, medium-small, winged species, with summer larvae (Table 1); species number and percentages for chorotype, body size, larval and wing development were similar in the different habitat categories (Figs 6, 7, 8, 9).

Figure 6.

Percentage of carabid species for each chorological complexes (Subcosmopolitan, Holoartic, European, Mediterranean) in rice field banks, buffer strips and restored habitats (plotted after data in Table 1).

Figure 7.

Percentage of carabid species for each body size (very small: < 5 mm, small: 5 – 9 mm, medium: 9 – 15 mm, large: > 15 mm) in rice field banks, buffer strips and restored habitats (plotted after data in Table 1).

Figure 8.

Percentage of carabid species for each larval development (summer, winter, poliennal) in rice field banks, buffer strips and restored habitats (plotted after data in Table 1).

Figure 9.

Percentage of carabid species for each wing development (macropterous and pteridimorphic) in rice field banks, buffer strips and restored habitats (plotted after data in Table 1).

Discussion

On the whole, 98 carabid species were collected in rice field banks, buffer strips adjacent to paddy fields, and restored habitats (herbaceous and arboreal). Species number could be slightly underestimated because of the sampling method which is not very well suited for some taxa as and . Nevertheless, the area resulted species-rich, especially when you consider that it is not placed inside a riverine corridor and when you compare the species number with that recorded in other anthropogenic habitats of the Po plain: 60-70 species in rye, oat and fallow fields (Pescarolo 1990, Pescarolo 1993); 48 species in a complex of habitats composed by one poplar grove, one artificial wetland, banks of irrigation canals and cropped areas (Casale et al. 1993); 55 species in poplar groves of different ages (Casale et al. 1993); 60 species in meadows of different ages (Gobbi et al. 2005); 60 species in meadows, crops and reforested areas of two urban parks in Milan (Pilon et al. 2010).

Most of the collected carabids, both in the whole area and in each habitat categories, were species with a wide distribution in the Paleartic region, eurytopic and common in European agroecosystems. The assemblages were dominated by small-medium, macropterous species, with summer larvae; we didn’t find any endemism.

No brachypterous and strictly forest-dwelling species were sampled, despite the presence of some recent woodlots (i.e about 10 years old). In fact, species unable to disperse by flight were prevented to colonize these stands (including Ganglbauer 1891, very common in woods of the Lombardy plain), because of the absence of ecological corridors connecting woodlots with forest remnants (Macarthur and Wilson 1967). As a consequence, the Carabid fauna was mainly composed by species of open habitats. Most of the species were also hygrophilous, due to a dense network of artificial irrigation canals and a superficial water-table.

The most interesting aspect of this Carabid coenosis is the presence of several species with southern distribution, quite common in clay soil on the right bank of the Po river, and known only in few stations north of the Po river. Among these species, we list , , , , , , , . Although a comparison with the past coenosis is not possible for the lack of similar surveys in the area, it could be hypothesized that these species are recent colonizers (7-10 years). They are not reported in the historical catalogue of Magistretti (1965), and are also not listed in several recent faunistic investigations carried out in the Lombardy lowland, particularly along the Ticino river (Pasquetto 1992, Bogliani et al. 2003), Adda river (Conti 1991), Po river (Pilon et al. 1991, Rancati and Sciaky 1994) and in Milan (Pilon et al. 2010), where potentially suitable habitats were sampled. Even in an intensive survey along the Po river included in Piedmont region, only some of these species have been collected (Allegro and Sciaky 2001). If so, we could assume a tendency to a northward shift in the distribution of these species, according to what has been observed for other zoological groups well studied and that have great mobility, such as birds (Chen et al. 2011) and dragonflies (Ott 2010).

We underline also the presence of , an uncommon halophilous species. Moreover , an Asiatic-European distribution species, has been recorded with certainty for the first time in Italy (Cardarelli and Pilon 2012).