Ground-dwelling Arthropods Research Articles

Effects of post-mining forest restoration and alternative land uses on ground-dwelling arthropods in Ghana

In an Afrotropical region experiencing massive deforestation, restoration approaches should provide sustainable solutions for recovering biodiversity. Arthropods are a sensitive taxonomic group for habitat alteration by deforestation and can be good indicators for restoration studies. Ground-dwelling arthropods provide important ecosystem functions, such as predation or organic matter decomposition, thereby contributing to ecosystem functionality. The consequences of post-mining management on arthropods in the Afrotropical region remain understudied. We carried out a comprehensive sampling of ground-dwelling arthropods in the dry and wet seasons across four land-use types in the semi-deciduous forest zone of Ghana. We then analysed whether the specific tree communities, vegetation structure and seasonal differences affected arthropod communities in the restored post-mining forest compared to the dominant alternative land-use type (agroforestry plantation), a natural reference (natural forest) or an unmanaged former mining area (gravel mine). In total, 43,364 arthropods were sampled and assigned to 78 taxonomic groups representing 14 order/sub-order, 28 beetle families, 25 spider families, 5 hunting guilds of spiders and 6 trophic groups of beetles. Overall, Araneae, Coleoptera, Hymenoptera and Orthoptera all had higher activity densities in the wet season. The vegetation structure of the three land-use types with trees supported a greater overall activity density of arthropods and a more diverse functional composition compared to the unmanaged gravel site. Pronounced variation between the dry and wet seasons further influenced the taxonomic and functional composition. The active forest restoration of this post-mining area is a promising approach to drive arthropod communities towards a comparable state observed in the natural forest.

Net effects of pasture-raised poultry on arthropod communities driven by top-down and bottom-up forces in a mixed-cover crop system

As consumer demand and grower interest for pasture-raised poultry grow, more research is needed to understand the ecological consequences of the integration of pasture-raised poultry on agroecosystems. Poultry could have profound and complex net effects on arthropod communities given their high density per area, broad omnivory, and high manure deposition. Further, some studies suggest poultry may aid in the suppression of agricultural pests in integrated systems. Yet, unlike wild birds, pasture-raised poultry have received little attention in the field of agroecological net effects. Across 2 years, we examined how an absence (control- cover crop only), low- [9.51 m2 (102.4 ft.2) of pasture per broiler] and high-densities [4.76 m2 (51.2 ft.2) of pasture per broiler] of broilers impacted cover crop biomass, ground-dwelling arthropods, and plant-dwelling arthropods in a rotationally grazed mixed-cover crop system. High- and low-density poultry treatments had 7.8-fold and 3.5-fold less cover crop biomass compared to the control treatment after 1–3 days of access, respectively. Despite the depletion of cover crops, there were substantial positive effects on ground-dwelling arthropods. Most striking was the impact on house fly larvae where high-density poultry treatments had ~1,432-fold more house fly larvae relative to the control treatments. Dung beetle, spider, and rove beetle mean relative abundances increased 47-, 2.4-, and 3.5-fold, respectively, from the control treatment to the high-density poultry treatment. In contrast, the mean relative abundances of plant-dwelling arthropod orders Coleoptera, Hemiptera, and Hymenoptera were 4-, 5-, and 3.6-fold higher, respectively, in the control treatment relative to the high-density poultry treatment. Overall, these results suggest that pasture-raised poultry may promote the abundance of ground-dwelling arthropods through bottom-up mechanisms by depositing fecal material. However, poultry decreased the abundance of plant-dwelling arthropods, likely by destroying their habitat and food resources (via consumption and trampling of cover crop) and direct consumption of arthropods. While the integration of poultry into crop rotations is thought to benefit crop yield through nutrient deposition in the form of manure, this study suggests it may also stimulate the soil and ground-foraging arthropod food webs. This study is the first to evaluate the impacts of pastured poultry to arthropod communities in a mixed-cover crop system.

Trade-offs between passive and trophic rewilding for biodiversity and ecosystem functioning

Trophic rewilding that reintroduces large animals into landscapes to re-establish food web interactions and restore biodiverse ecosystems has gained widespread attention. Despite this attention, few empirical studies have assessed the effectiveness of trophic rewilding for promoting biodiversity and its wider ecological benefits. Here we tested if trophic rewilding that introduced functional analogues for extinct large herbivores into former farmland of lowland England delivered additional benefits to biodiversity and ecosystems functioning. We predicted that these benefits would exceed those achieved through passive rewilding, that is, unassisted habitat succession after the cessation of agricultural activity. Using a 9-year exclosure experiment, we found trophic rewilding reduced woody plant diversity and total carbon storage by 73% and 23%, respectively, compared to passive rewilding plots that excluded mammalian herbivores. However, trophic rewilding likely increased plant diversity and carbon storage compared to if land was left under continued agricultural production, e.g. artificial pastures associated with intensive livestock production. The vegetation changes accompanying trophic rewilding were further linked to a greater diversity and biomass of ground-dwelling arthropods by 21% and 167%, respectively, relative to passive rewilding, partly by creating more structurally complex vegetation. Given the trade-offs in biodiversity and ecosystem functions between trophic and passive rewilding, our study highlights that trophic rewilding will need to be applied alongside other interventions to tackle biodiversity loss while combatting climate change. Ultimately, the utility of trophic rewilding as a restoration tool will depend on the conservation outcomes valued by society.

Diversity of ground-dwelling arthropods on overburden dumps after coal mining

Technogenic landscapes formed by coal mining are unique model sites for studying primary succession. We studied the formation of arthropod communities on rock dumps at coal mine dump sites of different ages and in natural environments. Using the pitfall traps, 5 classes of arthropods were found, with the domination of Insecta and Arachnida. The species composition for most of the studied groups of invertebrates was determined, the Berger-Parker dominance and Shannon species diversity indices were calculated. It has been established that the colonization of dumps depends not only on the age of recultivated lands, but also on habitat conditions (soil characteristics, vegetation parameters). At the beginning of the succession, dumps are massively populated by small-sized species that are tolerant of extreme conditions and have high dispersal abilities. Further development of vegetation entailed a change in the general structure of the ground-dwelling of arthropods communities. Discriminant analysis showed that the macrofauna of the compared sites differs statistically significantly in the space of discriminant functions. The areas at the foot of the dump and the natural biotope are characterized by the maximum differences; the greatest similarity was found between the young and old dumps. A significant contribution to the overall discrimination is made by the beetles of the families Geotrupidae, Staphylinidae, Elateridae, as well as centipedes (Chilopoda), and terrestrial bugs (Hemiptera). This study showed that communities of ground invertebrates are good indicators for monitoring the restoration of technogenically disturbed lands.

Does habitat type in no‐tillage agroecosystems influence ground‐dwelling macroarthropod community structure? A case study in KwaZulu‐Natal, South Africa

AbstractLoss of biodiversity in agroecosystems has negative implications for crop production and the functioning of the ecosystem. As such, agroecologists advocate minimum tillage practices in order to conserve biological diversity. To establish the influence of agricultural practices on biodiversity, we compared the species richness, abundance and composition of beetles, ants, spiders and small groups of ground dwelling arthropods in a veld and three agroecosystems (maize, sugarcane and multispecies pasture) under minimum tillage. Sampling was by pitfall trapping during the summer rainfall season in December 2019. Although ants were the most abundant (47%), followed by beetles (31%); beetles were the most speciose making up 40% of the morphospecies followed by spiders (31%). The veld had significantly greater relative proportion of species richness of spiders (54%) than the three agroecosystems, while significantly low relative proportion of species richness of ants was in the pasture (6%) compared to the veld (63%). Species richness and abundance of beetles were similar across habitat types. The four habitats supported different assemblages of ants, beetles and spiders. The differences in species composition among the habitats support the notion that agricultural practices with minimum soil disturbance enhance conservation of biological diversity, particularly, specialist species.

Intercropping shifts the balance between generalist arthropod predators and oilseed pests towards natural pest control

Pest management in intensive crop production currently underutilizes natural biological control, and frequently results in pesticide application. Intercropping modifies physical and ecological conditions in the field and alters the predator-prey dynamics to potentially benefit generalist arthropod predators. We investigated the assemblages of ground-dwelling arthropod predators and crop pests of spring turnip rape (Brassica rapa L. ssp. oleifera) and faba bean (Vicia faba L.) in a replicated two-year field experiment. Pitfall traps and pan traps were used to sample arthropod predators and pests. Arthropod assemblages were compared between intercropping and monocropping systems to illustrate the changes. Intercropping was associated with lower abundance of turnip rape pests compared with monoculture. The total abundance of ground-dwelling predators did not differ between cropping systems. Carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) were the dominant generalist predator taxa. Faba bean monoculture supported the highest abundance of harvestmen (Opiliones) and the lowest abundance of ants (Hymenoptera: Formicidae). The turnip rape monoculture had the highest abundance of spiders in the first year but not in the second. The abundance and species assemblage of carabids indicated a response to season progress but not to cropping system. The abundance of turnip rape pests reflected host crop proportions in each cropping system. Because the cropping method had no significant impact on predator abundance, intercropping potentially facilitated natural biological control resulting from a higher ratio of ground-dwelling predators to pests. Differential within-season dynamics among abundant predator taxa also implied a temporal shift in predation characteristics, and hence, vulnerability of crop production to pest injuries. To utilize natural biological control more effectively at the field scale, intercropping with no shared pests between crops, minimal chemical pest control, and heterogeneous agricultural landscapes are needed.

Composition, abundance and biodiversity of terrestrial arthropods in pastures and their relationship with landscaping plants

We investigated the association of landscaping plants with the communities of ground-dwelling arthropods within pastures and tested the hypothesis that arthropod biodiversity increases with vegetation heterogeneity. The community characterization and biodiversity of arthropods in a pasture were compared with those within communities with landscaping plants, including forest remnants, Forsythia koreana and Prunus serotina. The total abundance of mites was greater within the forest remnants than within the pasture; however, the abundance of insects and spiders did not differ. Nonmetric multidimensional scaling and the multiresponse permutation procedure revealed that the community composition of insects and spiders differed according to vegetation type. The abundance of Teleogryllus emma was highest within the forest remnant community, which suggested the species’ dependency on vegetation type. Species richness and the Shannon index of insects increased within F. koreana but not within P. serotina compared with the pasture. This suggested that belts of shrubs might have a greater promoting effect on insect biodiversity than belts of trees. Species richness of spiders did not differ by vegetation type. The total number of insect and spider species within the study area increased by 2.8 and 3.5 times, respectively, by establishing three types of vegetation. These results suggested that increasing vegetation heterogeneity by establishing landscaping plants is a good option for conserving insect and spider biodiversity in pastures.

Response of foliage- and ground-dwelling arthropods to insecticide application: Early step for cotton IPM in the Brazilian semiarid

Foliage- and ground-dwelling arthropods provide ecosystem services, including decomposition and biological control of agricultural pests. Despite this, there is little information on the ground-dwelling arthropod community associated with cotton crops and about their role under pest control practices. Identifying these communities and their preservation would assist smallholder cotton growers in considering an Integrated Pest Management (IPM) approach to pest control. In this context, the strategy of using selective- or broad-spectrum insecticides (both applied only once the pests reached an economic threshold) was assessed using field plots set up within non-Bt cotton structured refuge of a grower field measuring the response of both foliage- and ground-dwelling arthropods and yield. The abundance, species richness, dominance indices, and foliage-dwelling predators and pest species and ground-dwelling predators and decomposers were compared between untreated and insecticide treatments, as was the crop yield. In response to pest monitoring, insecticides were applied 5 and 3 times during the 2018 and 2020 growing seasons, respectively. In 2018 and 2020, 16 and 12 foliage-dwelling predator arthropods and 43 and 47 ground-dwelling predator and decomposer arthropods were collected, respectively. During the 2018 season, broad-spectrum insecticide applications reduced the abundance of foliage-dwelling predators, but had no significant impact on the ground-dwelling community. Principal response curves (PRC) indicated a negative impact of broad-spectrum insecticides only on the foliage-dwelling community, particularly among the Formicidae and Araneae species. Insecticide applications in the 2020 season were only required at the end of the crop season and did not significantly influence the foliage- or ground-dwelling communities. The selective insecticide regime yielded as well as the broad-spectrum insecticide regimes higher yielded than untreated plots. These results demonstrated to the small landholders engaging conservation biological control for the first time, the advantages of an IPM approach to pest management.

Increased arthropod biomass, abundance and species richness in an agricultural landscape after 32 years

Recent studies reporting widespread declines in arthropod biomass, abundance and species diversity raised wide concerns in research and conservation. However, repeated arthropod surveys over long periods are rare, even though they are key for assessing the causes of the decline and for developing measures to halt the losses. We repeatedly sampled arthropod fauna in a representative Swiss agricultural landscape over 32 years (1987, 1997, 2019). Sampling included eight study sites in four different semi-natural and agricultural habitat types and different trap types (pitfall, window, yellow bucket) over an annual period of 10 weeks to capture flying and ground dwelling arthropod taxa. In total, we analyzed 58,448 individuals from 1343 different species. Mean arthropod biomass, abundance and species richness per trap was significantly higher in 2019 than in the prior years. Also, species diversity of the study area was highest in 2019. Three main factors likely have contributed to the observed positive or at least stable development. First, the implementation of agri-environmental schemes has improved habitat quality since 1993, 6 years after the first sampling. Second, landscape composition remained stable, and pesticide and fertilizer was constant over the study period. Third, climate warming might have favored the immigration and increase of warm adapted species. Our results support the idea that changes in arthropod communities over time is highly context-dependent and complex.Implications for insect conservationWe conclude that the integration and long-term management of ecological compensation patches into a heterogenous agricultural landscape supports insect conservation and can contribute to stable or even increased arthropod abundance, biomass and diversity. Future studies are needed to clarify interdepending effects between agricultural management and climate change on insect communities.

Can rare arable plants benefit biological pest control potential of cereal aphids in croplands?

In agricultural landscapes, arable plants are negatively affected by management intensification. These species can fulfill various ecosystem functions, such as biological pest control, by supporting predators. The ecosystem functions of common plant species are widely known. By contrast, the contribution of rare arable plants (RAPs) to biocontrol in cereal fields remains poorly understood. This study investigated the effect of RAPs on biocontrol potential. We compared cropped plots with and without sowing of rare and threatened arable plant species and investigated the effects on cereal aphids and their antagonistic predators, active hunting, and web-building spiders, as well as carnivorous/omnivorous carabids. We counted the total number of aphids on cereal shoots and trapped ground-dwelling arthropods on an experimental field and on 10 agricultural farms in the vicinity of Munich, Germany, in 2018 and 2019. The effects of the presence of RAPs were analyzed using linear mixed-effect models, whereas cover of RAPs was analyzed using structural equation models. Linear models revealed that the presence of RAPs did not significantly affect the aphid density and the activity densities of spiders and carabids. Structural equation models revealed direct negative effects of RAP cover on aphid density. However, no indirect effects via the predators of aphids were detected. Direct negative effects of active hunting spiders on aphids were determined, but not of the other potential predators. Our results suggest that RAPs may impact aphid infestation, however, the activity density of spiders and carabids were unsuitable indicators for such interactions.

Trophic interactions of an invasive gecko in an endemic-rich oceanic island: Insights using DNA metabarcoding

Understanding the trophic interactions of introduced predators is key for evidence-based management of biological invasions. This is particularly important in oceanic islands, where predator-prey networks often include numerous endemic and range-restricted species. Geckos are successful island colonizers and in recent years numerous species have established populations in a wide array of oceanic islands. One such species is the Moorish gecko (Tarentola mauritanica), which has colonized multiple islands across the Mediterranean basin, Caribbean and Macaronesia. The species was first reported in Madeira Island in 1993 and over the last 30 years has colonized most of the islands' southern coast and expanded to the nearby island of Porto Santo. Here, we used DNA metabarcoding to provide the first insights into the diet of this successful colonizer in its introduced range. The species' diet was mainly composed of ground-dwelling arthropods belonging to the families Porcellionidae (Isopoda), Julidae (Diplopoda) and Formicidae (Hymenoptera). The diet richness and composition were not affected by neither sex nor size of adult geckos, instead they both change across populations. However, trophic niche-width differed among size classes, with smaller geckos feeding on a wider range of prey. We identified over 160 different Operational Taxonomic Units in the diet of T. mauritanica, with 21.6% of them belonging to introduced invertebrates and 13.6% to native species. Native prey taxa included the endemic Madeira wall lizard (Teira dugesii), the sole native reptile to Madeira. We also detected several agricultural pests and disease vectors in the diet of this exotic predator, and 19 taxa identified as prey had not yet been recorded to Madeira. Of these, several are serious agricultural pests, highlighting how this introduced gecko can be used as a natural sampler, in particular for the early detection of invasive arthropod pests. This study emphasizes the importance of trophic studies for monitoring the impacts of introduced predators in fragile insular systems.

Short-term response of ground-dwelling arthropods to storm-related disturbances is mediated by topography and dispersal

Wind disturbances and consequent salvage logging lead to drastic changes in forest soil conditions, vegetation and microclimate, potentially affecting arthropod communities. In mountain regions, topography is expected to be particularly important to modulate the effect of canopy removal and soil disturbance potentially amplifying the ecological contrast between forest and disturbed areas. Here, we studied the short-term response of ground beetles (Carabidae), spiders (Araneae), and harvestmen (Opiliones) in wind-damaged spruce forests along statistically orthogonal gradients in elevation, slope, and aspect. We addressed three main ecological questions: (i) Does the effect of wind disturbance on diversity depend on topography? (ii) Are there specific taxon-related responses to disturbances?, and (iii) What is the role of dispersal in shaping species assembly dynamics? We generally observed that increasing slope and elevation amplified the differences between undisturbed forest and windfall areas. On the one hand, the diversity of ground beetles and harvestmen seemed to be negatively affected by wind disturbance, causing a loss of specialized forest species with a low rate of colonization of species typical of open habitats. On the other hand, several novel spider species were able to rapidly colonize windfalls and community composition strongly shifted from forest to disturbed areas. Species with long-range dispersal strategies (e.g. flying and ballooning) were those more likely to colonize windfalls. Our findings suggest that disturbance effects on ground-dwelling organisms were modulated by underlying environmental gradients and that short-term response of different taxa was dependent on their dispersal ability.

Habitat change and interspecific associations mediate the response of riparian ground-dwelling arthropod assemblages to flooding in the Three Gorges Reservoir

Seasonal water level fluctuation is a typical characteristic of reservoirs created by dams on rivers. Due to their important roles in connecting ecological processes between riparian zones and adjacent uplands or waterbodies, ground-dwelling arthropods are essential components for maintaining riparian ecosystem health. However, the dynamic characteristics and response mechanisms of ground-dwelling arthropod assemblages to seasonal water level fluctuations have not been clearly established. We investigated ground-dwelling arthropods before and after summer floods (along with the influence of planned winter impoundment) in the drawdown zone of the Three Gorges Reservoir. Redundancy analysis and examination of interspecific associations were conducted to explore driving mechanisms for variations in these arthropod assemblages. Our results demonstrated that: i. floods are dominant mediating factors for variations in ground-dwelling arthropod assemblages in riparian zones; ii. species composition and abundances of ground-dwelling arthropod assemblages were in a state of dynamic change under the influence of floods; iii. Interplay of habitat modifications and interspecific associations influenced the composition as well as the distribution of ground-dwelling arthropods. We suggest that ground-dwelling arthropods are sensitive indicators for riparian ecosystem health and are valuable for evaluating work on the conservation and management of riparian zones.

Fire Severity Causes Temporal Changes in Ground-Dwelling Arthropod Assemblages of Patagonian Araucaria–Nothofagus Forests

Fire is one of the main drivers of anthropogenic disturbances in temperate forest ecosystems worldwide, with multiple effects spread across ecological networks. Nevertheless, the biodiversity effects of fire are poorly known for species-diverse groups such as arthropods. In this research, we used a burn gradient generated two and three years after a large fire event to assess how different levels of fire severity affect arthropod diversity in the forest with the main forest forming long-living tree species Araucaria araucana, in southern Chile. The species richness and abundance of arthropods among trophic guilds was estimated annually in four fire-severity levels. We found that arthropods responded differently to fire severity levels, depending on their trophic guilds and years after fire (two and three years after fire). During the second year after fire, zoophages, phytophages, and parasitoids were more diverse in areas with high fire severity within the second year after fire, as compared to those in areas with low severity or unburned stands. In the third year after fire, a change in this trend was observed, where the abundance of all groups dropped significantly, with positive changes in the diversity in zoophages, phytophages, polyphages and saprophages, which is more noticeable in sites with high severity. These results indicate that annual variation in environmental conditions triggers bottom-up cascading effects for arthropods. Forests stands severely impacted by fires support highly fluctuating and possibly unstable arthropod assemblages. Hence, restoration efforts should be focused on recovering microhabitat conditions in these stands to allow the persistence of arthropods.

Importance of grassy and forest non-crop habitat islands for overwintering of ground-dwelling arthropods in agricultural landscapes: A multi-taxa approach

Non-crop habitats are supposed to provide valuable resources to beneficial arthropods inhabiting agricultural landscapes during both the growing and winter seasons. Unfortunately, studies focused on the performance of non-crop habitats during the winter period are much less abundant, despite their importance for efficient biodiversity conservation measures. In this study, we assessed the distribution of ground-dwelling arthropods overwintering on arable land as well as the boundaries and interiors of neighbouring grassy and forest non-crop habitat islands. Myriapods, spiders, carabid and rove beetles were collected using a combination of quadrat sampling (soil sampling) and pitfall trapping. Our results revealed the importance of both non-crop habitat islands for overwintering arthropods, though slightly higher abundance and species richness were recorded in forest compared to grassy islands. Abundance and species richness of overwintering arthropods were lower on arable land for all the investigated taxa. Carabid and rove beetles overwintered more on non-crop boundaries than interiors, whereas spiders and myriapods used both boundaries and interiors. Landscape composition had stronger effects on carabids and myriapods collected with pitfall traps, which were benefitted in landscapes with high non-crop habitat cover. Grassy and forest non-crop habitat islands hosted different assemblages of myriapods, carabids and rove beetles, highlighting the complementarity of both non-crop habitat types for ground-dwelling arthropods. We recommend to preserve all existing non-crop habitat patches and to create new permanent non-crop habitat patches in intensively managed agricultural landscapes, as even relatively small non-crop habitat islands within the cultivated land can play a relevant role for overwintering arthropods.

How are arthropod communities structured in a modified wetland under different productive activities?

Wetlands are among the most threatened ecosystems around the world due to changes in land use. Particularly, in the Lower Parana River Delta the main productive activities with economic impact in the region are planted forest and silvopastoral systems. To carry out these productive activities, natural hydrology of this wetland has been deeply modified and different management practices are implemented. Ground-dwelling arthropods are among the most sensitive taxa to environmental changes, so they are good bioindicators of the effect of these changes on biodiversity. In this context, we compare the structure and composition of ground-dwelling arthropod communities and their seasonal variations in the planted forest and silvopastoral systems of the Lower Parana River Delta, to characterize these land use associated with different management practices. We recorded a total of 73 families using pitfall traps (N = 1728). We observed that communities in intensive-managed planted forests were less rich and more evenness, while communities in less-managed planted forests were richer and less evenness. Also, we observed that warm seasons presented more arthropod family richness than cold seasons. The intensity of management practices, the presence of cattle and seasonality are factors that significantly decrease ground-dwelling arthropod richness. So, Silvopastoral systems negatively affect ground-dwelling arthropod communities compared to planted forest. A decrease in the intensity of management practices favors the understory growth, offering more resources for the arthropod families already established and facilitating the establishment of new ones. This increase in arthropod diversity promotes the presence of benefic species and the conservation of biodiversity in this modified wetland ecosystem.

Transgenic Maize Has Insignificant Effects on the Diversity of Arthropods: A 3-Year Study.

In order to provide more evidence for the evaluation of the ecological risks of transgenic maize, arthropod population dynamics and biodiversity in fields planted with two kinds of transgenic maize (DBN9868, expressing the PAT and EPSPS genes, and DBN9936, expressing the Cry1Ab and EPSPS gene) were investigated by direct observation and trapping for three years. The recorded arthropod species belonged to 19 orders and 87 families, including Aphidoidea, Chrysomelidae, Coccinellidae, Chrysopidae and Araneae. The species richness, Shannon–Wiener diversity index, Pielou evenness index, dominance index and community similarity index of arthropod communities in maize fields were statistically analyzed, and the results showed that (1) the biodiversity difference of arthropod communities between transgenic maize and non-transgenic maize was smaller than that between different conventional cultivars; (2) the differences between ground-dwelling arthropod communities were less obvious than those between plant-inhabiting arthropod communities; and (3) Lepidoptera, the target pests of Bt maize, were not the dominant population in maize fields, and the dominant arthropod population in maize fields varied greatly between years and months. Combining those results, we concluded that the transgenic maize DBN9868 and DBN9936 had no significant effect on the arthropod communities in the field.

Impact of mowing frequency on arthropod abundance and diversity in urban habitats: A meta-analysis

Urbanization is an important driver of global insect decline. Yet, recent studies have demonstrated the potential of greenspaces in cities to promote biodiversity conservation. One of many factors negatively affecting arthropods in urban areas are unsuitable habitats, as non-woody greenspaces predominantly consist of manicured lawns. Maintenance practices such as high mowing frequencies, can have direct and indirect negative impacts on the local flora and fauna. The present study examines the effects of different mowing regimes on arthropod abundance and diversity by conducting meta-analyses of studies assessing the effect of mowing on arthropod abundance (46 datasets) and taxa richness (23 datasets) in urban environments. Due to a geographical bias in the literature, only data from the temperate, northern hemisphere are analyzed. While our meta-analysis on arthropod abundance showed a medium positive effect (effect size: g = 0.54) of reduced mowing, the cumulative positive effect of reduced mowing on arthropod taxa richness was large (g = 1.25). Grouping the studies not only resulted in lower heterogeneity, but also showed that manicured lawns disproportionately favor the abundance of “pest” species as well as ground-dwelling arthropods. There was also a significantly higher abundance of winged insects on sites with reduced mowing as compared to arthropods without wings. Overall, the findings of the present meta-analysis strongly support the notion that a reduction in mowing frequencies in urban greenspaces benefits insect biodiversity.

Small mammals in a mountain ecosystem: the effect of topographic, micrometeorological, and biological correlates on their community structure

An increasing number of studies have investigated spatial and temporal patterns in species richness and assemblage composition in mountain ecosystems along altitudinal gradients. Small mammals have been successfully used as indicators of environmental health and as proxies of biodiversity. However, information about the composition and distribution of species assemblages in the mosaic of habitat and rocky landform types at a high altitude is still lacking for most of the mountain regions. Through the use of live traps and camera trapping, we described the small mammal community living above the treeline of the Western Dolomites (Italian Alps), investigating the species richness, abundance of individuals and community composition in relation to topographic, micrometeorological, mesohabitat, and biological correlates. A total of five species and 50 individuals were sampled, analysed, and released. At the extremes of the analysed altitudinal range (i.e. 1900 vs 2900 m a.s.l.), community composition was completely different and species richness was related to elevation, steepness, and vegetation cover. At the same time, the taxonomic distinctness of ground-dwelling arthropods (namely carabid beetles and spiders), a proxy of habitat complexity, showed higher values in areas with a greater small mammal species richness. We found a positive effect of steepness and rocky landform type “carsism” on the number of captured individuals, showing the importance of the availability of shelters and underground burrows for the sampled species. As a confirmation of the altitudinal shift for these species in relation to the ongoing climate change, we detected a negative impact of sub-surface ground temperature on small mammal abundance during the monitoring period. In conclusion, small mammals represent an excellent model for understanding the evolutionary processes of ecosystems, population dynamics under changing environmental conditions, and habitat vulnerabilities.

Six groups of ground-dwelling arthropods show different diversity responses along elevational gradients in the Swiss Alps.

Elevational gradients along mountain slopes offer opportunities to study key factors shaping species diversity patterns. Several environmental factors change over short distances along the elevational gradient in predictable ways. However, different taxa respond to these factors differently resulting in various proposed models for biodiversity patterns along elevational transects. Using a multi-taxa approach, we investigated the effects of elevation, area, habitat and soil characteristics on species richness, individual abundance and species composition of six groups of ground-dwelling arthropods along four transect lines in the Swiss National Park and its surroundings (Eastern Alps). Spiders, millipedes, centipedes, ants, ground beetles and rove beetles were sampled using standardized methods (pitfall traps, cardboard traps, visual search) in 65 sites spanning an elevational range from 1800 to 2750 m a.s.l.. A total of 14,782 individuals comprising 248 species were collected (86 spider, 74 rove beetle, 34 ground beetle, 21 millipede, 19 centipede and 14 ant species). Linear mixed model-analysis revealed that rarefied species richness in five out of the six arthropod groups was affected by elevation (the quadratic term of elevation provided the best fit in most cases). We found three different patterns (linear decrease in centipedes, low elevation plateau followed by a decrease in ants and rove beetles, and midpoint peak in spiders and millipedes). These patterns were only partially mirrored when considering individual abundance. Elevation influenced species composition in all groups examined. Overall, elevation was the most important factor explaining the diversity patterns, while most local habitat and soil characteristics have little influence on these patterns. Our study supports the importance of using multi-taxa approaches when examining effects of elevational gradients. Considering only a single group may result in misleading findings for overall biodiversity.