Impact of low-input meadows on arthropod diversity at habitat and landscape level

In Switzerland, in order to preserve and enhance arthopod diversity in grassland ecosystems (among others), farmers had to convert at least 7 % of their land to ecological compensation areas – ECA. Major ECA are low input grassland, traditional orchards, hedges and wild flower strips. In this paper the difference in species assemblages of 3 arthropod groups, namely spiders, carabid beetles and butterflies between intensively managed and low input meadows is stressed by means of multivariate statistics. On one hand, the consequences of these differences are analysed at the habitat level to promote good practices for the arthropod diversity in grassland ecosystems. On the other hand, the contribution of each meadow type to the regional diversity is investigated to widen the analysis at the landscape level

Spiders (Araneae) of Chernivtsi City (Ukraine)

The spider fauna of buildings and other urban habitats (city parks, green areas of industrial enterprises, and housing estates) of Chernivtsi city was surveyed. In the period 2002-2011, 212 species belonging to 26 families were recorded. Previous studies found a total of 173 species of spiders belonging to 26 families from the territories which are now included in the city limits of Chernivtsi. Currently, the total spider species list for Chernivtsi includes 260 species of 30 families, of which 125 species (21 families) were recorded both by earlier researchers and by ourselves. The most important reasons for changes in urban spider assemblages are as follows: species habitat change, introduction of alien species, and description of new species unknown in the late 19th – early 20th centuries

Assemblages of herb-dwelling spiders (Araneae) of various steppe types in Ukraine and the Central Chernozem region of Russia

A total of 107 spider species from 15 families were recorded in the herbaceous vegetation of the steppe ecosystems of Ukraine and the Central Chernozem region of Russia. Araneidae, Thomisidae, Salticidae and Theridiidae were the most species-rich. The species composition depended on the steppe type; adjacent forest habitats influenced steppe fauna in the forest-steppe and northern part of the steppe natural zone. The number of generalist, forest and wetland dwelling species in the steppe vegetation showed a tendency to decrease towards the south. Dominance of herb-dwelling spiders was specific to each steppe type; no single species was found to predominate in all the steppe habitats

Skalenabhängiger Einfluss der Landschaft auf die Diversität epigäischer Spinnen in Winterrapsfeldern

Agricultural intensification is a major threat to biological diversity worldwide. Land management activities enhancing landscape diversity are therefore regarded as a key strategy to halt species loss in cultural landscapes. Diverse and abundant communities of predatory arthropods, e.g. spiders (Araneae), have a high potential to suppress pest populations (Symondson et al. 2002) and could therefore contribute to allow reductions of pesticide use. Crop fields alone are usually not able to sustain diverse and individual-rich populations of predatory arthropods, because agricultural management results in disturbances and habitat deteriorations (harvest, soil cultivation, pesticide application) that kill or drive away large parts of the populations. Therefore semi-natural and perennial habitats in agricultural landscapes are considered to be of great importance for beneficial arthropods. On the one hand they offer refuge habitats in times when arable fields are hostile, e.g. fields with bare grounds during winter (Schmidt & Tscharntke 2005). On the other hand, viable populations of predatory arthropods in semi-natural habitats can serve as sources for (re-) colonisation of arable fields (Schmidt & Tscharntke 2005). Because of these exchanges between crop and non-crop areas it is important to include the surrounding landscape when investigating field-scale processes. We investigated the relations between spider assemblages in arable fields and the surrounding landscape in 29 fields of winter oilseed rape (OSR) in an agricultural landscape in eastern Austria. The objectives of this study were to estimate (1) how much spider assemblages in oilseed rape fields are influenced by the surrounding landscape, (2) the relative influence of landscape variables compared to field-scale variables and (3) at which spatial scales landscape variables are effective.Die Intensivierung der Landwirtschaft stellt weltweit eine der bedeutendsten Bedrohungen der Biodiversität dar. Maßnahmen, die die Diversität der Landschaft erhöhen werden daher als eine zentrale Möglichkeit gesehen, den Verlust von Arten in Kulturlandschaften zu stoppen und durch die Förderung von Nützlingen einen Betrag zu einer Reduktion des Pestizideinsatzes zu leisten. Wir untersuchten den Einfluss der Landschaft auf epigäische Spinnen (Araneae) in 29 Winterrapsfelder in einer durch landwirtschaftliche Nutzung dominierten Region östlich von Wien (Österreich). Spinnen – generalistische Prädatoren, die ein bedeutsames Potenzial in der natürlichen Schädlingskontrolle aufweisen – wurden während der Feldsaison 2005 mit Barberfallen erfasst. Die umgebenden Landschaften wurden hinsichtlich Zusammensetzung, Diversität und Komplexität charakterisiert (Landschaftsausschnitte mit 250 bis 2000 m Radius). Zusätzlich wurden Feldparameter, vor allem die Bewirtschaftung betreffend, in die Analyse einbezogen. Die Datenanalyse erfolgte mit Generalized Linear Models. Unsere Ergebnisse zeigten, dass die Spinnengemeinschaften hinsichtlich Diversität und Individuenzahlen auf unterschiedliche Landschaftvariablen auf unterschiedlichen Skalenebenen reagieren. Für die Gesamtartenzahl war der Anteil an gehölzdominierten Habitaten in der näheren Umgebung der Felder der wichtigste, fördernde Faktor. Die Anzahl der häufigen Arten und die Gesamtindividuenzahlen hingegen nahmen mit dem Anteil an Brachen bzw. der Lauflänge an Wegrainen in größerem Umkreis der Felder zu. Diese Ergebnisse unterstreichen die Bedeutung von naturnahe Landschaftselementen, v.a. Brachen, für epigäische Spinnen als eine Gruppe von räuberischen Arthropoden in Agrarsystemen

Spatial and temporal structure of the spider community in the clay semi-desert of western Kazakhstan

The spatial and temporal structure of spider communities was studied in the clay semi-desert of the north-western Caspian Lowland, western Kazakhstan (49°23' N, 46°47' E). The soils and vegetation are complex, being composed of a mosaic of desert and steppe plant communities. Besides the native associations, there are plantations of different tree species. The ground-dwelling spider assemblages in the native habitats are the most diverse. The number of species inhabiting forest plantations is three times as small. Gnaphosidae is the leading family in the ground layer. They show high abundance and diversity levels during the whole season. Thomisidae, Lycosidae, Philodromidae, and Salticidae are abundant as well. The species diversity of herbage-dwelling spiders in different open native habitats is very similar. The spectrum of dominant families (Thomisidae, Oxyopidae, Araneidae, and Salticidae) and the seasonal dynamics of their ratio in desert and steppe associations have much in common. Spider assemblages of native and artificial habitats are characterised by change from multispecies polydominant spring-summer communities to impoverished imbalanced autumn ones. Seasonal changes in the species structure of mature spider groupings in native habitats are well pronounced, while the impact of seasonal conditions is even stronger than between-habitat differences. Complexes of typical species with different levels of habitat preference are revealed

Environmental and spatial drivers of spider diversity at contrasting microhabitats

The relative importance of environmental and spatial drivers of animal diversity varies across scales, but identifying these scales can be difficult if a sampling design does not match the scale of the target organisms' interaction with their habitat. In this study, we quantify and compare the effects of environmental variation and spatial proximity on ground-dwelling spider assemblages sampled from three distinct microhabitat types (open grassland, logs, trees) that recur across structurally heterogeneous grassy woodlands. We used model selection and multivariate procedures to compare the effects of different environmental attributes and spatial proximity on spider assemblages at each microhabitat type. We found that species richness and assemblage composition differed among microhabitat types. Bare ground cover had a negative effect on spider richness under trees, but a positive effect on spider richness in open grassland. Turnover in spider assemblages from open grassland was correlated with environmental distance, but not geographic distance. By contrast, turnover in spiders at logs and trees was correlated with geographic distance, but not environmental distance. Our study suggests that spider assemblages from widespread and connected open grassland habitat were more affected by environmental than spatial gradients, whereas spiders at log and tree habitats were more affected by spatial distance among these discrete but recurring microhabitats. Deliberate selection and sampling of small-scale habitat features can provide robust information about the drivers of arthropod diversity and turnover in landscapes. © 2017 Ecological Society of Australi

Carnivorous Pitcher Plants Eat a Diet of Certain Spiders, Regardless of What\u27s on the Menu

The purple pitcher plant, Sarracenia purpurea, is a low-lying carnivorous plant that uses pitcher-shaped leaves to catch arthropod prey for nutrition. Spiders make up a significant portion of these prey. To determine the tendency of specific spider taxa to be captured by the plant, we compared the composition (by taxonomic family) of three spider assemblages: those captured by the plant, those residing on or over the plant, and those found nearby in the local environment. Although there were some broad similarities within the three spider assemblages, significant differences existed when specific families and guilds were considered. While some families (e.g., Linyphiidae and Lycosidae) and guilds (e.g., low sheet/tangle weavers) were heavily represented in all three assemblages, other groups varied, and we found that the taxonomic makeup of victimized and resident spiders did not always reflect their environmental abundances. Moreover, spider assemblages captured by S. purpurea were extremely similar across distant locations regardless of environmental spider assemblage composition, suggesting that S. purpurea is very selective in its spider capture regimen

AGRICULTURAL DRAINAGE DITCHES AS SOURCES OF BENEFICIAL SPIDERS TO ENHANCE CONSERVATION BIOCONTROL IN ADJACENT CROPLANDS

Agricultural drainage ditches are uncropped areas on farms located above high-water tables to assist in the hydrologic control of croplands. Drainage ditches have increasingly become the subject of research as sources of beneficial arthropods for agroecosystems. Spiders, the most common generalist predator in most field crops, are an important component of conservation biocontrol, but little is known of spider assemblages in drainage ditches or the extent they colonize adjacent croplands from these ditches. To better understand the composition and population dynamics of spider assemblages in drainage ditches, my objectives were (1) to assess the structure of spider assemblages inhabiting drainage ditches in Maryland and (2) to determine how spider assemblages in drainage ditches and adjacent soybean fields change throughout the soybean growth cycle. Overall, my work contributes to understanding how valuable drainage ditches are as habitats for natural enemies like spiders and how ditches influence spider assemblages in adjacent croplands

Assembléias de aranhas em manchas de cerrado amplamente separadas no Estado de São Paulo, Brasil

Spider Assemblages in widely-separated patches of cerrado in São Paulo State, BrazilAssembléias de aranhas em manchas de cerrado amplamente separadas no Estado de São Paulo, Brasil