Biodiversity Data Journal :
Research Article
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Corresponding author: Davide Giuliano (davide.giuliano@alice.it)
Academic editor: Edward Baker
Received: 02 Feb 2018 | Accepted: 23 Apr 2018 | Published: 02 May 2018
© 2018 Davide Giuliano, Giuseppe Bogliani
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:
Giuliano D, Bogliani G (2018) The orthopterans of the rice agroecosystem in western Lomellina (Lombardy, Italy). Biodiversity Data Journal 6: e24203. https://doi.org/10.3897/BDJ.6.e24203
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Rice fields represent a valuable surrogate habitat for many wetland species, playing an important role for biodiversity conservation in human-managed landscapes. Despite the fact that several taxonomic groups have been thoroughly investigated in this agroecosystem, little is known about the orthopteran fauna which lives in and around rice paddies, especially in Europe. In this paper, we provide a first description of the orthopteran assemblages hosted in the rice agroecosystems of northern Italy, trying to evaluate their conservation value through an analysis of species ecological traits (habitat specificity and dispersal capacity). During field samplings in summer 2016, we detected 25 orthopteran species. The 24% of the community was composed by habitat specialist species and the 56% of the sampled taxa was characterised by high dispersal capacities. Rice fields are an extremely dynamic ecosystem, characterised by the continuous succession of flooding and drying periods and conditioned by many other farming activities. Consequently, the orthopteran fauna in rice crops is mainly composed of species well adapted to sudden environmental changes. On the other hand, rice fields represent a particular biotope, providing a suitable habitat especially for hygrophilous species, which are otherwise restricted to scattered marsh areas. In order to preserve orthopteran diversity in rice agroecosystems, sustainable farming practices should be applied, especially by preserving and restoring marginal semi-natural habitats, by reducing grass management intensity on paddy banks and by discouraging rice cultivation in dry soils.
Orthoptera, check-list, rice fields, dispersal capacity, habitat specificity, farming practices, northern Italy
Orthopterans (Insecta: Orthoptera) are often considered as key components of farmland biodiversity. Indeed, these insects may provide several ecosystem services in arable lands, e.g. limiting weed expansion through seed predation (
In Europe, the highest orthopteran species richness is usually found in open habitats, such as grasslands, heathlands or Mediterranean shrublands (
Rice fields are an agricultural landscape particularly extended in the western portion of the Po Plain (northern Italy). Similarly to other crops, rice cultivation recently underwent a pronounced intensification in this area (
Unlike other taxonomic groups (e.g. birds, amphibians, aquatic insects etc.), little is known about the orthopteran fauna which lives in rice paddies. Indeed, only few studies have been carried out on this subject, mainly in Asian countries (
This paper aims to provide a first description of the orthopteran fauna hosted in the rice agroecosystems of the western Po Plain, providing further important data to assess the value of rice crops for biodiversity conservation.
The study was carried out in three sites within the rice crop district of western Lomellina (Lombardy, northern Italy), located in the municipalities of Robbio (
In order to provide a specific characterisation of the orthopteran fauna in rice crops, the data reported in this paper were collected only in habitat structures typical of this agroecosystem, namely paddies, field banks, irrigation canals and nearby unpaved country roads. Other landscape components, such as wooded patches, hedgerows and tree lines, were not investigated during this study.
This research is part of a biodiversity monitoring programme (“Rice for Life” project) carried out in 2016 in western Lomellina in order to evaluate the effects of different agricultural techniques on a wide range of taxonomic groups in rice agroecosystems. In this framework, orthopterans were used as model organisms to assess the impacts on insect diversity caused by grass management on rice field banks (Giuliano et al., under review).
In accordance with the monitoring project requirements, orthopterans were mainly collected on paddy levees, following a standardised sampling method. Therefore, these insects were sampled monthly, in the period between June and September, by means of a visual census in 50 sampling plots, each one made up by a standard surface of 1x10 m.
However, a consistent amount of the data presented in this paper has also been collected outside the standardised sampling design. Indeed, between May and September 2016, orthopterans were randomly sampled in rice crops, investigating in particular those habitats not considered in the monitoring project previously described (e.g. paddies, irrigation canals and farm roads). These additional samplings were performed in order to ensure the compilation of a species list as complete as possible for the whole rice agroecosystem.
In both cases, orthopterans were collected manually and most of the individuals were identified directly in the field, while those not readily identifiable were suppressed in a 70% ethanol solution and recognised later in laboratory. Species identification was carried out mainly by analysing the morphological traits, following the keys of
Moreover, during field surveys, several individuals were also identified by listening to their acoustic signals, comparing them with the recordings provided by
In order to assess the conservation value of the orthopteran assemblages observed in the rice agroecosystem, we collected information about the ecological traits of all the sampled species, focusing in particular on their dispersal capacity and habitat specificity. These features are considered important factors in determining species sensitivity to habitat loss and human disturbance, with sedentary and habitat specialist taxa often more susceptible to local extinction events (
Dispersal capacity was measured using the Mobility Index developed by
Concerning habitat specificity, each species was assessed according to its moisture preferences, following the procedure reported by
The species not treated by
During the study period, we collected 348 individuals, belonging to 25 species (10 Ensifera and 15 Caelifera) (Table
List of the orthopteran species collected in the rice agroecosystem of western Lomellina. For each species, information is reported about the period of observation (Phe; months in roman numerals), the mobility class (Mob), the habitat specificity class (HS) and habitat of occurrence. Mobility classes are: 1 = Sedentary; 2 = Intermediate dispersers; 3 = Mobile species. Habitat specificity classes are: 1 = Generalists; 2 = Medium specialised species; 3 = Specialists (* indicates hygrophilous species). Nomenclature follows
Species |
Phe |
Mob |
HS |
Habitats |
|||
Paddies |
Banks |
Canals |
Farm roads |
||||
Phaneroptera nana Fieber, 1853 |
VII |
3 |
2 |
+ |
|||
Conocephalus (Anisoptera) fuscus (Fabricius, 1793) |
VI-IX |
2 |
3* |
+ |
+ |
||
Ruspolia nitidula (Scopoli, 1786) |
VII-IX |
3 |
3* |
+ |
+ |
||
Tettigonia viridissima (Linnaeus, 1758) |
VI-VIII |
3 |
1 |
+ |
|||
Decticus albifrons (Fabricius, 1775) |
VIII-IX |
2 |
2 |
+ |
|||
Roeseliana azami (Finot, 1892) |
VI-VIII |
1 |
2 |
+ |
|||
Pteronemobius (Pteronemobius) heydenii (Fischer, 1853) |
V-IX |
1 |
3* |
+ |
+ |
||
Gryllus (Gryllus) campestris Linnaeus, 1758 |
V |
1 |
2 |
+ |
|||
Eumodicogryllus bordigalensis (Latreille, 1804) |
V-IX |
1 |
2 |
+ |
+ |
+ |
|
Gryllotalpa sp. |
V-IX |
2 |
2 |
+ |
+ |
||
Paratettix meridionalis (Rambur, 1838) |
VII-IX |
3 |
3* |
+ |
+ |
+ |
|
Tetrix ceperoi (Bolivar, 1887) |
VII |
3 |
3* |
+ |
+ |
+ |
|
Calliptamus italicus (Linnaeus, 1758) |
VII-VIII |
2 |
2 |
+ |
|||
Locusta migratoria Fabricius, 1781 |
VI-IX |
3 |
2 |
+ |
+ |
+ |
|
Oedipoda caerulescens (Linnaeus, 1758) |
VIII |
3 |
2 |
+ |
|||
Oedipoda germanica (Latreille, 1804) |
VIII |
1 |
2 |
+ |
|||
Acrotylus patruelis (Herrich-Schaeffer, 1838) |
VIII |
3 |
2 |
+ |
|||
Aiolopus strepens (Latreille, 1804) |
IX |
3 |
2 |
+ |
|||
Mecostethus parapleurus (Hagenbach, 1822) |
VI-VIII |
2 |
2 |
+ |
+ |
||
Paracinema tricolor (Thunberg, 1815) |
VII-IX |
3 |
3* |
+ |
+ |
||
Omocestus (Omocestus) rufipes (Zetterstedt, 1821) |
VI-IX |
2 |
2 |
+ |
|||
Chorthippus (Chorthippus) dorsatus (Zetterstedt, 1821) |
VII-IX |
3 |
1 |
+ |
|||
Chorthippus (Glyptobothrus) brunneus (Thunberg, 1815) |
VI-IX |
3 |
2 |
+ |
+ |
||
Pseudochorthippus parallelus (Zetterstedt, 1821) |
VI-VIII |
3 |
1 |
+ |
+ |
||
Euchortippus declivus (Brisout de Barneville, 1848) |
VII-IX |
3 |
2 |
+ |
Rice field banks hosted the higher species richness between the investigated habitats (17), while in farm roads (10), irrigation canals (8) and rice paddies (6), the observed number of species was lower. Nevertheless, these results should be interpreted carefully, since our sampling effort has been higher on paddy levees and not standardised between habitats.
Concerning ecological traits, the orthopteran assemblage was dominated by highly mobile species (14), while intermediate dispersers (6) and sedentary species (5) were little represented in the rice agroecosystem (Fig.
According to the IUCN European Red List of Orthopterans (
To date, the most detailed information about the orthopteran fauna in the western Po Plain were reported by
Rice fields represent a particular biotope, typically characterised by a temporary aquatic ecosystem (
This is the case of Paracinema tricolor, which is strongly related to wetland habitats and included in the Near Threatened category by
Although rice crops have been proved to be a suitable habitat for hygrophilous orthopterans, during our research we also noticed the occurrence of several thermophilous species. Landscape structures, such as bare banks, mown levees and unpaved country roads, often provide unexpected xerothermic micro-habitats in rice fields, improving the suitability of this agroecosystem also for species adapted to dry and warm conditions. This result highlights the value of habitat heterogeneity in maintaining a high orthopteran diversity in rice crops, especially allowing the coexistence in the same ecosystem of species with different ecological requirements.
Despite the described environmental value of rice agroecosystems for orthopteran diversity, a large proportion of the species sampled in our study area is characterised by high dispersal capacities (56.0%), a typical feature of arthropods adapted to temporary and highly disturbed habitats (
In this context, intensive agriculture is likely to further restrict the occurrence of species with low mobility, therefore emerging as an important factor in conditioning orthopteran diversity in rice crops. In particular, the widespread reduction of semi-natural habitats may prevent the availability of stable ecosystems, often essential for the conservation of many sedentary and sensitive species. Moreover, the intensification of grass management on rice field banks can also strongly affect orthopteran diversity (Giuliano et al., under review), especially by limiting the occurrence of species specifically adapted to live in habitats characterised by a well-developed vegetation structure, as already demonstrated for ground beetles in this agroecosystem (
Lastly, hygrophilous orthopterans are today seriously threatened in rice crops by the introduction of new rice cultivation methods, which often involve limited water inputs. Indeed, the spread of dry cultivated rice fields may reduce the suitability of this agroecosystem for species with high moisture requirements, thus contributing to further aggravate their conservation status in Europe.
Rice crops proved to be an important ecosystem for orthopteran diversity in western Lomellina, especially providing a suitable habitat for several hygrophilous species. This result confirms the value of rice fields for biodiversity conservation, already recognised for many other taxonomic groups (
Besides, conservation efforts should be applied in rice agroecosystems to limit the impacts of intensive agriculture on orthopteran assemblages, especially through the introduction of sustainable farming strategies. First of all, farmers should be provided with incentives for preserving and restoring marginal semi-natural habitats (e.g. uncultivated grasslands, wetlands etc.), in order to improve landscape heterogeneity and to ensure the occurrence of permanent biotopes. These features are often essential for biodiversity conservation in farmlands (
Secondly, grass management intensity on paddy banks should be reduced by rice growers. This goal could be easily achieved by leaving uncut levee portions, proved to be an effective solution to control the detrimental impact of mowing on orthopterans (
Although the integrated application of these management strategies may increase the suitability of intensive rice crops for orthopterans, further detrimental agronomic practices, like rice cultivation in dry soils, should be discouraged in future, in order to preserve the environmental value of rice agroecosystems for these insects.
We wish to thank Buffa P.A. and Braggio R., owners of the rice farms where the study took place, who kindly made their fields available for our research. Moreover, we also acknowledge Sindaco R. and Savoldelli P. for their help in the identification of some of the collected specimens; and Cardarelli E. and Stanganello R.P. for their support during this research.
This work was part of the “Rice for Life” project, promoted by Lipu BirdLife Italia, Parboriz S.p.A. and Unilever.