692 research outputs found
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Spatial synchrony in Drosophila suzukii population dynamics along elevational gradients
No full text1. Spotted wing drosophila (SWD; Drosophila suzukii Matsumura, 1931) is a polyphagous invasive crop pest native of Southeast Asia able to attack a wide array of host plant species in both cultivated and natural habitats. SWD is now widespread in several mountain regions, but it is still unclear how the species moves to different elevations across the seasons, and how this depends on environmental conditions and food resources. 2. The temporal dynamics of several SWD populations were studied along elevational gradients in the Alps using a synchrony analysis. Twelve transects were selected, covering an overall elevational gradient of 2100 m. SWD abundance was monitored every 2 weeks during the growing season (from June to November 2015) when cultivated and wild hosts are potentially susceptible (i.e. fruits are ripe). 3. Spotted wing drosophila were widely distributed along all the tested elevations, revealing synchrony in population dynamics across ranges in elevation and geographic distance. Synchronised populations were observed at distances of up to 100 km at sites with similar temperatures. The high dispersal potential of the pest together with the seasonal variation in temperature are likely to be the dominant mechanisms causing the observed spatial synchrony. A factor that seemed to reduce synchrony is the large concentration of host plants (i.e. crop) in lowland agricultural landscapes. 4. The spatial synchrony in pest abundance at large spatial scale indicates that the risk of SWD outbreaks is highly dependent on drivers beyond the control of traditional field-scale management. These findings could help in developing monitoring and predictive models of SWD population dynamics
Contrasting effects of exotic plant invasions and managed honeybees on plant–flower visitor interactions
No full textAim To explore how a highly invasive plant species (Buddleja davidii Franch.), managed honeybees and flower diversity affected plant–flower visitor interactions over the whole elevational range distribution of the exotic plant. Location Italian Alps. Methods We selected nine pairs of sites (one invaded and one non‐invaded by B. davidii ) across gradients in honeybee abundance and diversity of flower resources. We observed plant–flower visitor interactions every three weeks, for a total of five surveys covering the full flowering season of B. davidii (June–August). We tested how B. davidii , honeybee abundance and flowering plant diversity affected network robustness, overlap in flower resource use of wild flower visitors with honeybees and flower visitor specialization. We also tested for an interaction between B. davidii presence and honeybee abundance, and tested whether the effects of the two variables changed among insect orders. Results Buddleja davidii and honeybees had contrasting effects on network robustness and on several species‐level metrics. Network robustness increased with increasing honeybee abundance and flower diversity. Increasing honeybee abundance generally increased specialization of lepidopterans and dipterans that tended to switch to less visited plant species, possibly in order to avoid competition. Specialization of flower visitors declined in sites invaded by B. davidii , indicating that the invasive plant attracted pollinators, which in turn also visited co‐occurring species in the neighbourhood. Main conclusions Although increasing honeybee abundance was associated with higher network stability, it also modified plant–flower visitor interactions by forcing species to shift their diet irrespective of floral diversity. The effect was particularly strong for non‐bee flower visitors. The consequences of these changes in plant–flower visitor interactions for the reproductive success of flowering plants are still largely unknown
Elevational homogenization of mountain parasitoids across six decades
No full textElevational gradients are characterized by strong environmental changes within small geographical distances, providing important insights on the response of biological communities to climate change. Mountain biodiversity is particularly sensitive to climate change, given the limited capacity to colonize new areas and the competition from upshifting lowland species. Knowledge on the impact of climate change on mountain insect communities is patchy, but elevation is known to influence parasitic interactions which control insect communities and functions within ecosystems. We analyzed a European dataset of bristle flies, a parasitoid group which regulates insect herbivory in both managed and natural ecosystems. Our dataset spans six decades and multiple elevational bands, and we found marked elevational homogenization in the host specialization of bristle fly species through time. The proportion of specialized parasitoids has increased by ca. 70% at low elevations, from 17 to 29%, and has decreased by ca. 20% at high elevations, from 48 to 37%. As a result, the strong elevational gradient in bristle fly specialization observed in the 1960s has become much flatter over time. As climate warming is predicted to accelerate, the disappearance of specialized parasitoids from high elevations might become even faster. This parasitoid homogenization can reshape the ecological function of mountain insect communities, increasing the risk of herbivory outbreak at high elevations. Our results add to the mounting evidence that symbiotic species might be especially at risk from climate change: Monitoring the effects of these changes is urgently needed to define effective conservation strategies for mountain biodiversity
Impact of urbanization on predator and parasitoid insects at multiple spatial scales
No full textLandscapes are becoming increasingly urbanized, causing loss and fragmentation of natural habitats, with potentially negative effects on biodiversity. Insects are among the organisms with the largest diversity in urbanized environments. Here, we sampled predator (Ampulicidae, Sphecidae and Crabronidae) and parasitoid (Tachinidae) flower-visiting insects in 36 sites in the city of Rome (Italy). Although the diversity of herbivorous insects in urban areas mostly depends on the availability of flowering plants and nesting sites, predators and parasitoids generally require a larger number of resources during their life cycle, and are expected to be particularly influenced by urbanization. As flower-visitors can easily move between habitat patches, the effect of urbanization was tested at multiple spatial scales (local, landscape and sub-regional). We found that urbanization influenced predator and parasitoid flower-visitors at all three spatial scales. At the local scale, streets and buildings negatively influenced evenness of predators and species richness and abundance of parasitoids probably acting as dispersal barrier. At the landscape scale, higher percentage of urban decreased predator abundance, while increasing their evenness, suggesting an increase in generalist and highly mobile species. Area and compactness (i.e. Contiguity index) of urban green interactively influenced predator communities, whereas evenness of parasitoids increased with increasing Contiguity index. At the sub-regional scale, species richness and abundance of predators increased with increasing distance from the city center. Compared to previous studies testing the effect of urbanization, we found little variation in species richness, abundance and evenness along our urbanization gradient. The current insect fauna has been probably selected for its tolerance to habitat loss and fragmentation, being the result of the intensive anthropogenic alteration occurred in the area in the last centuries. Conservation strategies aimed at predator and parasitoid flying insects have to take in account variables at multiple spatial-scales, as well as the complementarity of resources across the landscape
Contrasting response of native and non‐native plants to disturbance and herbivory in mountain environments
No full textAim: Climate warming and increasing human disturbance are expected to promote non-native plant invasions in mountain ecosystems. Although biological invasions are also expected to be modulated by biotic interactions, it is still not clear how invertebrate herbivores can affect plant invasion dynamics. Using a large manipulative experiment, we aimed at testing: 1) the effect of soil disturbance and elevation on native and non-native plant communities, and 2) the effect of plant-herbivore interactions, nitrogen deposition, and elevation in driving plant establishment after soil disturbance.
Location: European Alps, NE Italy
Taxon: Vascular plants
Methods: We selected remote, uninvaded dry semi-natural grasslands along the core elevational range of non-native plants in the European Alps (0-1330 m) and manipulated soil disturbance, nitrogen deposition, and invertebrate herbivory. Then, we followed the natural establishment under real field conditions of both native and non-native plants over one growing season. We used generalized mixed-effects models to test the effects of the experimental treatments.
Results: Native and non-native species showed contrasting responses to soil disturbance and elevation. Low elevations and disturbance promoted non-native success, while affecting native species diversity negatively. Two-thirds of the experimental sites acquired novel non-natives after disturbance. Most of the observed non-natives were not present in the surrounding vegetation as mature plants, indicating that propagules were able to reach even remote natural areas. While current N deposition levels did not affect plant establishment, we found that after disturbance invertebrate herbivory might play an important role in facilitating non-native invasions by reducing native cover.
Main conclusions: Our findings show that highly resistant ecosystems such as continuous grasslands can be easily invaded once the resident vegetation has been removed, and that natural herbivory pressure from invertebrates might amplify the negative effects of disturbance on resident native species irrespective of elevation. Together, these results indicate increasing risks of future plant invasions on mountains under global change
Effects of natural pyrethrum and synthetic pyrethroids on the tiger mosquito, Aedes albopictus (skuse) and non-target flower-visiting insects in urban green areas of Padua, Italy
No full textThe tiger mosquito is a key vector of several human diseases and is considered a public health concern worldwide. The implementation of strategies aimed at maximizing mosquito control without affecting non-target insect groups is of major importance. In a field trial, we tested the efficiency of a natural pyrethrum-based vs. a synthetic pyrethroid-based insecticide in reducing tiger mosquito population and how they affect the diversity of non-target flower-visiting insects in green urban areas. Only the pyrethroid insecticide was effective in reducing mosquito abundance, although its effects disappeared nine days after application. The two adulticides did not significantly affect the diversity of flower-visiting insects, probably because of their large body size and the difference in flying and foraging activity. To effectively control mosquito populations while preventing intoxication of non-target flower-visiting insects, adulticide applications should be applied early in the morning and only on bushes and trees. Results from our small-scale applications cannot be extrapolate when larger areas are treated
Temperature and not landscape composition shapes wild bee communities in an urban environment
No full textMore than half of the world's population lives in urban areas, a proportion that is expected to increase. Even if urbanisation is widely regarded as a major threat to global biodiversity, recent research highlighted the potential ecological importance of cities for pollinators. Key determinants of cities' ability to sustain pollinators are the presence of green areas and the connectivity between them. However, also temperature is expected to be of primary importance for pollinator activities.
Here, we aimed at disentangling the effects of temperature, open habitat cover, and distance from the city centre on wild bee communities in the city of Rome (Italy). We selected 36 sites along two statistically independent gradients of temperature and open habitat cover, and we sampled wild bee communities using pan-traps for 4 months. Then, we measured functional traits of wild bee species, that is, body size, social behaviour, nesting strategy, and diet breadth.
Temperature emerged as the main driver of wild bee communities, with communities richer in species and individuals at warmer temperatures. We found little species replacement between cold and warm sites. In addition, with increasing temperatures, bee communities were dominated by polylectic and small-bodied species.
Here, we showed that in a highly urbanised environment, temperature shapes pollinator communities irrespective of other landscape metrics. Even if warming seemed beneficial for urban pollinator abundance and richness, it might strongly homogenise bee communities by selecting for those traits that make species more easily adaptable
Predator and parasitoid insects along elevational gradients. Role of temperature and habitat diversity
No full textElevational gradients are characterized by strong abiotic variation within small geographical distances and provide a powerful tool to evaluate community response to variation in climatic and other environmental factors. We explored how temperature and habitat diversity shape the diversity of holometabolous predator and parasitoid insects along temperate elevational gradients in the European Alps. We surveyed insect communities along 12 elevational transects that were selected to separate effects of temperature from those of habitat diversity. Pitfall traps and pan traps were placed every 100 m of elevation increment along the transects ranging from 120 to 2200 m a.s.l. Sampling took place once a month from June to September 2015. Four groups characterized by having at least one life stage behaving as predator or parasitoid were examined: tachinids (Diptera), hoverflies (Diptera), sphecids (Hymenoptera) and ground beetles (Coleoptera). Species richness and evenness changed with elevation, but the shape and direction of the elevation–diversity patterns varied between groups. The effect of temperature on species richness was positive for all groups except for hoverflies. Habitat diversity did not affect species richness, while it modulated the evenness of most groups. Often, elevational patterns of species richness and evenness were contrasting. Our study indicates that natural enemies characterized by diverse ecological requirements can be differentially affected by temperature and habitat diversity across the same elevational gradients. As climate warming is predicted to increase mean annual temperatures and exacerbate weather variability, it is also expected to strongly influence natural enemies and their ability to regulate herbivore populations
Boccaccio (comico) nel teatro (comico) di Machiavelli
No full textMolti critici hanno posto in parallelo Boccaccio e Machiavelli: cronologicamente, il primo testo trovato è una lettera di Girolamo Muzio del 1535. Oltre alla presenza del Decameron nella Mandragola, la cui influenza viene ulteriormente sottolineata, lo studio è orientato in funzione della Clizia, in cui lo stesso Machiavelli sembra allontanarsi e sfuggire dalle situazioni ironicamente boccaccesche che egli stesso aveva poco tempo prima creato per rifugiarsi in un linguaggio estremamente più piano e posato, quello che stava diventando predominante, dell'imitazione plautina e terenziana. A proposito viene anche riportato un significativo passo della traduzione dell'Andria. Vengono poi esaminati alcuni temi chiave: le donne, i vecchi e i giovani, la paura della maldicenza, le abilità sessuali dei personaggi, i giochi linguistici di attesa che implicano una teatralità dirompente, tutti letti nella ripresa più o meno letterale (ma sempre indicata) dai testi di Boccaccio. La conclusione è che Machiavelli, nel riprendere il Boccaccio comico, si diverte nel compiere un gioco equivoco con i termini usati: l'equivoco può sembrare della stessa natura, ma in un autore può addirittura diventare parodia del significato di quello che è nell'altro.Many critics have placed Boccaccio and Machiavelli side by side. Chronologically, the first text we find is a letter written by Girolamo Muzio in 1535. Besides the presence of the Decameron in Mandragola, the influence is further underlined as we allow Clizia to guide the study. In this work Machiavelli seems to distance himself and flee from ironically Boccaccio-esque situations that he himself had created just slightly earlier in order to take refuge in extremely flat and composed language. This sober language which imitated Plautus and Terrence was becoming dominant at the time. In this line of investigation a significant passage from the translation of Andria is analyzed. Then some key themes are examined: women, old age and youth, fear of curses, the sexual skill of the characters, the linguistic waiting games involving unsettling theatrics, all of which are taken more or less literally (but always clearly) from the texts of Boccaccio. The conclusion is that in taking from Boccaccio's comedies, Machiavelli enjoys playing a game of ambiguity with the terms used. This ambiguity may seem to be of the same nature, but in it one author can even parody the meaning of the other author
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