The western honeybee, Apis mellifera, is the most widespread pollinator species. As honeybee hives can host more than 50,000 bees, their abundance in natural and managed habitats can be extremely high. The presence of such large numbers of honeybees can influence the foraging activity of wild pollinators and potentially lead to competition for floral resources. Our study aims to understand which pollinator groups may be more prone to potential competition for floral resources with managed honeybees, and how this competition could change in areas with flowering plant communities with very or little different morphology, focusing on functional traits of both plants and pollinators. By observing plant-pollinator interactions in 51 grasslands, and measuring the functional traits of plants and pollinators, we found that:
•    The functional composition of the flower community in which pollinators forage has a strong effect on the potential competition;
•    Where honeybee abundances were high, the overlap of floral resources between managed honeybees and wild pollinators was lower in areas where the flower community was characterised by high functional diversity than in areas where functional diversity was low, suggesting a potential diet shift of wild pollinators in areas with a high variability of flower morphologies;
•    Wild pollinators with functional traits similar to the honeybee visited the same plant species as the honeybee and were, therefore, more prone to potential competition. In particular, the study observed a high overlap of floral resources between honeybees and large-sized bees belonging to the Apidae family with proboscis length similar to the honeybee.

Link to the study: https://doi.org/10.1007/s00442-022-05151-6 

Pollinating animals are essential for the reproduction of many cultivated plants, including fruits, vegetables, and nuts. However, despite a large amount of research on pollinators’ contribution to agricultural production and the consequences of their decline on human welfare, many aspects are still unclear or under-researched, and results are sometimes conflicting. Against this background, our study aimed to provide a global quantitative review of the effects of animal pollination on several aspects of food quality, including organoleptic characteristics and nutritional value. The main results reveal that:
•    food crops pollinated by animals had on average 23% better quality than those not pollinated by animals, indicating that almost one-fourth of the total quality of the fruit depends solely on the pollination services provided naturally by animals;
•    pollinators critically improve the shape, size and shelf-life of fruits and vegetables, but contribute also to increasing their nutrients.

The production of commercially suboptimal fruits and vegetables derived from inadequate animal pollination has important consequences:
1.    it affects farmers’ decision to harvest and consequently their access to fresh produce markets or alternative processing;
2.    growing fruit that is short-lived and looks imperfect is likely to increase food waste, impacting on a larger scale the whole food production chain, the global consumption of healthy food, and the management of agricultural land;
3.    it is necessary to maintain effective and efficient animal pollination of food crops throughout agricultural production landscapes.

Link to the study: https://doi.org/10.1038/s41467-023-40231-y 

Globally, numerous initiatives addressing the decline of pollinators have been implemented. However, these interventions aimed at safeguarding pollinators can have ripple effects on multiple ecosystem services equally important for human well-being. In our study, we aimed to 1) understand how wild pollinator diversity and ecosystem multi-functionality varied among different habitat types, and 2) test whether improving local conditions for pollinators would also boost ecosystem multi-functionality. To do that, we selected 96 sites in Northeastern Italy belonging to three habitat types with different roles in supporting pollinators, i.e., crop field margins, semi-natural patches, and urban green areas. We sampled wild pollinators and seven ecosystem services, which included provisioning, cultural, and regulatory services, using which we calculated two ecosystem multi-functionality metrics. In summary, we found that:
•    Interventions supporting pollinators can affect multiple ecosystem services;
•    Semi-natural patches and field margins enhanced pollinators and multi-functionality;
•    Increasing flower cover benefitted pollinators, but not multi-functionality;
•    Promoting pollinators does not always produce environmental co-benefits.
Future investigations are needed to understand how pollinator interventions could affect ecosystem services and ecosystem multi-functionality in different habitat types, and how landscape composition and structure could modulate these relationships.

Link to the study: https://doi.org/10.1016/j.agee.2023.108615 

In times of disturbing global changes affecting pollinators worldwide, more knowledge of species distribution at the national and continental levels is needed to implement effective conservation actions. However, this knowledge, especially concerning European bee and hoverfly species, is limited and difficult to access. To address this need, we incorporated published and unpublished data, and knowledge from a large set of taxonomists and ecologists in both groups. We updated the list of European bee and hoverfly species (around 3000), and centralised the current state of the knowledge of pollinator distributions at the European, country and sub-national levels for both bees and hoverflies. The list reflects the species’ current distributional status in the form of present, absent, regionally extinct, possibly extinct or non-native. With 2138 bee species and 913 hoverfly species in total being recorded, results show that the European country with the highest number of recorded bee species was Greece (1187 species), followed by Spain (1171 species) and Italy (1050 species). Regarding hoverflies, France was the most species-rich (566 species), followed by Italy (513 species), Switzerland (492 species) and Germany (467 species).  For bees, the most species-rich countries were present in the Mediterranean basin, while for hoverflies, countries with Alpine habitats hosted the highest number of species. In total, 807 species of bees and 199 species of hoverflies were recorded in only one or two countries, mostly the countries richest in species. This result is important for assigning conservation priorities across Europe.

Link to the study: https://doi.org/10.1111/icad.12680

Green areas and the connectivity between them are key determinants of cities' ability to sustain pollinators. However, little is known about how wild bees in urban environments will be affected by rising temperatures, which are expected to be of primal importance for pollinator activities. In our study, we aimed to disentangle the effects of temperature, open habitat cover, and distance from the city centre on wild bee communities in 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. We then measured the functional traits of wild bee species (body size, social behaviour, nesting strategy, and diet breadth). We found that:
•    In a highly urbanised environment, temperature is a fundamental driver of pollinator communities;
•    More bee individuals and species were present in the warm areas of Rome compared to the cold ones;
•    Warming might homogenise bee communities by selecting those traits that make species more easily adaptable to high temperatures, such as small body size and a very flexible diet. 

This leads to the prediction that while heat-tolerant wild bee species will benefit from increasing temperatures, these heat-tolerant communities will be dominated by small-bodied bees with a flexible diet, rather than by bees specialised in few flowers and larger bees such as bumblebees. Therefore, urban greening is key to adapting to the impacts of the urban heat island effect and mitigating it. High-quality and connected green spaces could offer climate change refugia for pollinators in urban environments, as well as flower and nesting resources.
Link to the study: https://doi.org/10.1111/icad.12602 

Pollinating insects are drastically decreasing, one reason being their reduced floral food resource availability. The spread of invasive species is one of the five most important causes of biodiversity loss. Invasive plant species dominate the landscape, reduce diversity and make habitats more homogeneous. In many cases, they also reduce the range of available flowers, thus helping some compatible pollinator species while displacing the food resources of others. In general, the impacts of invasive plant species on native vegetation and pollinator insects are often varied and dependent on their specific traits. Our study aimed to reveal the trait-based patterns of plant invasions on floral resources and pollinators using 10 case study examples of invasive plant species. Our main results show that:
•    Invaded areas are similar to crop fields such as rapeseed or sunflowers: during their blooming period, they provide significant amounts of food for the pollinating insects, while beyond their flowering period, these areas are extremely poor in resources of pollinators.
•    The invasive plants dominate the area with their green vegetation mass for most of the year, while only blooming for a short period of time. In contrast, natural habitats have more diverse resources throughout the year.
•    Two invasive species with deep flowers maintain more long-tongued and also larger-bodied bees, while a species with shallow flowers had more smaller-bodied bees.
Link to the study: https://doi.org/10.1111/icad.12640