45 research outputs found
First record of Pison koreense (Radoszkowski, 1887) from Italy (Hymenoptera: Apoidea, Crabronidae)
No full textFig. 1 – Pison koreense (Radoszkowski, 1887), female from Villanova di Camposampiero (Padua, Italy): lateral habitus.Published as part of Mei, Maurizio & Cappellari, Andree, 2021, First record of Pison koreense (Radoszkowski, 1887) from Italy (Hymenoptera: Apoidea, Crabronidae), pp. 67-68 in Fragmenta entomologica 53 (1) on page 67, DOI: 10.13133/2284-4880/485, http://zenodo.org/record/814800
Pollinator conservation in the Anthropocene
No full textPollinators play a key role in ecosystems, ensuring the reproduction of most cultivated and wild flowering plant species. However, recent studies showed that pollinator communities are rapidly changing due to multiple causes, with potential effects also on the fundamental ecosystem service they provide. Through the chapters of my thesis, I will analyse how the factors shaping the abundance, diversity and distribution of pollinators in landscapes, and thus determine their thriving or decline, affect both managed and wild pollinators.
After a brief introduction (Chapter 1), I investigated the effects of landscape composition and seasonality on the properties of pollen collected by managed honey bees, in particular on pollen diversity (Chapter 2) and pollen contamination by pesticides (Chapter 3). We highlighted how landscape composition strongly affected both pollen features and in particular how a high amount of semi-natural habitats in landscapes helped both to increase the heterogeneity of pollen collected by honey bees and to minimise contamination by pesticides.
In the next chapter, I focused on managed pollinators, which can negatively impact wild pollinator communities when introduced into new ecosystems (Chapter 4). We examined how potential competition between managed honey bees and wild pollinators was influenced by the functional traits of both pollinators and the plants they forage on. We highlighted that plant communities characterised by high functional richness could help mitigate potential competition between managed and wild pollinators by providing alternative resources on which wild pollinators can forage and that pollinators characterised by functional traits similar to those of the honey bee were more prone to potential competition.
I then focused on the effects of climate on pollinators (Chapter 5). Using a space-for-time substitution approach, we explored how increasing temperatures affected wild bee communities in an urban environment. We found that higher temperatures were generally associated with a higher abundance and species richness of wild bees, but they also led to a homogenisation of wild bee community traits, favouring a few traits such as small body size and polylectic diet.
Last, I analysed how two pollinator-friendly measures, i.e., habitat restoration and habitat enhancement for pollinators, affected pollinator diversity and ecosystem multi-functionality (Chapter 6). We sampled wild pollinators and a large number of ecosystem services, using which we calculated two indices of ecosystem multi-functionality, in sites belonging to three habitat types with a gradient of flower coverage. We found that while habitat restoration from intensive to semi-natural habitats benefited both pollinators and multiple ecosystem services, habitat enhancement for pollinators did not affect ecosystem multi-functionality.
In conclusion, the results obtained from my thesis could help develop targeted strategies for the conservation of both wild and managed pollinators. We found that semi-natural areas play a key role in supporting pollinators, that honey bees may pose a threat to specific categories of pollinators, and that rising temperatures will lead to drastic changes in pollinator communities. We also showed how the functional traits of both plants and pollinators have a strong influence on pollinator responses to the factors that threaten their survival. Finally, we pointed out how conservation measures for pollinators may – or may not – also impact other fundamental ecosystem services. It is therefore clear that multiple factors must be considered in order to get a clear picture of how pollinator communities are changing and what we can do to slow, stop or reverse their decline. Species conservation is a complex science, and further studies are needed to investigate the potential effects of interactions between drivers threatening managed and wild pollinators in the Anthropocene
Landscape and habitat effects on pest control and seed predation by carabid beetles
No full textIn both natural and anthropogenic environments, predation by arthropods plays a crucial role in the control of weeds and pests. Carabid beetles (Coleoptera: Carabidae) are key generalist predators feeding on a wide range of prey. The composition and functionality of carabid communities are shaped by multiple factors, both at the local and landscape scale, but these effects can vary depending on the environmental context. Our aim was to explore the effects of landscape composition and local habitat type on carabid community diversity and on insect pest and weed seed predation. We sampled 96 sites belonging to three habitat types (crop field margin, semi-natural and urban green area) selected along a gradient in landscape composition across four regions in northern Italy. Carabid communities were sampled using pitfall traps, insect pest predation was assessed using dummy caterpillars and seed predation was measured using seed cards. Predation rates varied across habitat types, with both pest and seed predation rates decreasing in urban environments compared to crop field margins and semi-natural habitats. Increasing crop areas in the surrounding landscape increased carnivorous carabid diversity and abundance, which in turn increased insect pest predation, while these effects were not observed for seed predation. At the local scale, maintaining semi-natural patches and herbaceous crop field margins, especially in intensive landscapes, represents an effective measure to safeguard carabids and promote the ecosystem services provided by this key arthropod group. However, agricultural expansion at the landscape scale favored carabids and their predation activity indicating that many species are generalist, well-adapted to intensive agricultural landscapes
BumbleKey: an interactive key for the identification of bumblebees of Italy and Corsica (Hymenoptera, Apidae)
No full textBumbleKey is a matrix-based, interactive key to all 45 species of bumblebees of Italy and Corsica. The key allows to identify adult males and females (queens and workers) using morphological characters. The key is published online, open-access, at http://www.interactive-keys.eu/bumblekey/default.aspx
Functional traits of plants and pollinators explain resource overlap between honeybees and wild pollinators
No full textManaged and wild pollinators often cohabit in both managed and natural ecosystems. The western honeybee, Apis mellifera, is the most widespread managed pollinator species. Due to its density and behaviour, it can potentially influence the foraging activity of wild pollinators, but the strength and direction of this effect are often context-dependent. Here, we observed plant–pollinator interactions in 51 grasslands, and we measured functional traits of both plants and pollinators. Using a multi-model inference approach, we explored the effects of honeybee abundance, temperature, plant functional diversity, and trait similarity between wild pollinators and the honeybee on the resource overlap between wild pollinators and the honeybee. Resource overlap decreased with increasing honeybee abundance only in plant communities with high functional diversity, suggesting a potential diet shift of wild pollinators in areas with a high variability of flower morphologies. Moreover, resource overlap increased with increasing trait similarity between wild pollinators and the honeybee. In particular, central-place foragers of family Apidae with proboscis length similar to the honeybee exhibited the highest resource overlap. Our results underline the importance of promoting functional diversity of plant communities to support wild pollinators in areas with a high density of honeybee hives. Moreover, greater attention should be paid to areas where pollinators possess functional traits similar to the honeybee, as they are expected to be more prone to potential competition with this species. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00442-022-05151-6
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
Spatio-temporal dynamics of vectors of Xylella fastidiosa subsp. pauca across heterogeneous landscapes
No full textXylella fastidiosa subsp. pauca is a plant pathogen that causes the Olive Quick Decline Syndrome, the spread of which is linked to insect vectors. Since these vectors can use and move across multiple managed and natural habitats, understanding their occurrence in different habitat types at the landscape scale is particularly challenging. Here, we applied a bipartite network approach to explore the spatio-temporal distribution of confirmed and potential vectors of X. fastidiosa in olive groves. We sampled sharpshooters and spittlebugs in 10 heterogeneous landscapes in southern Italy during spring, summer, and autumn. In each landscape, we sampled insects in the main habitat types, i.e., arable land, grassland, olive grove, vineyard, and woodland. We then built and analyzed the resulting bipartite species–habitat networks. The abundance of vectors in different habitat types throughout the seasons varied from species to species, with Philaenus spumarius, the main vector of X. fastidiosa, being mostly collected in olive groves. However, the analysis of habitat specialization showed that P. spumarius acted as a super-generalist species, occupying all the habitats. Insect vectors in olive grove patches were strongly influenced by other olive grove patches in the landscape and also by grasslands, particularly in spring, therefore highlighting the focal role of non-crop habitats on potential pathogen spread. Landscapes dominated by olive orchards and grasslands seemed to provide the most suitable conditions to support large vector populations. Network analyses helped untangle the complex interactions between vectors of X. fastidiosa and the landscapes and habitats they use
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
Seasonality and landscape composition drive the diversity of pollen collected by managed honey bees
No full textThe western honey bee, Apis mellifera, is the most important and widespread managed pollinator species. Honey bee diet is based on nectar and pollen, and pollen diversity and composition, in particular, affect colony health and fitness. As landscape composition is strongly linked to floral resource heterogeneity, it could influence the resource intake of honey bees. This work aimed to explore how the composition of pollen collected by honey bees was modulated by seasonality and landscape composition heterogeneity in a mountainous cultivated area of Northern Italy. We selected 13 locations, and at each location, we placed two honey bee colonies from which we collected pollen samples every month during the whole flowering season for two consecutive years. We then analyzed pollen samples in the laboratory and determined the Shannon diversity index of each pollen sample and the temporal pollen taxon replacement. We extracted the cover of the main habitat types at three spatial scales and tested the effect of landscape diversity and composition using Principal Component Analysis. Honey bees foraged on a high number of floral resources, however, they mostly collected pollen from a small number of taxa, with pollen type composition changing throughout the flowering season. In early spring and late summer, most pollen grains were collected from a few plant species, while from May to August the number of collected pollen types was significantly higher. Landscape composition affected pollen diversity only at the end of the flowering season. While honey bees were able to collect highly diverse pollen throughout spring and summer regardless of landscape composition, in late summer, when pollen collected is fundamental for the overwintering of the colony and its development in the following season, semi-natural areas became crucial for honey bee foraging activities, with pollen diversity increasing with increasing percentages of semi-natural areas. Our research highlighted the importance for honey bees of certain seasonal resources and of semi-natural habitats at the end of the flowering season, which ensure the subsistence of their colonies throughout the year
