Optimal foraging theory predicts that pollinators will visit dense floral patches over sparse ones. Understanding how the local abundance of floral resources influences pollinator behaviour is crucial for assessing the effect of floral traits on plant reproduction. In this study, we experimentally investigate the role of plant group size and floral display on pollinator foraging behaviour visiting Moricandia arvensis (Brassicaceae). We performed two field experiments: the first manipulated the number of plants per group (group size), and the second manipulated both the total number of flowers per group (group floral display) and group size. We then recorded the foraging behaviour of pollinators using probability of approaching the group, number of plants visited per group, bout length and floral visitation rate. Group floral display was the primary factor influencing pollinator foraging behaviour, except for the probability of approaching the group, where a significant interaction between group floral display and group size was observed. Specifically, the effect of larger floral displays on attracting pollinators increased disproportionately in larger groups. Because the increase in floral visitation rate due to larger displays was less than the increase in the floral display itself, visitation rate per flower was lower in groups with larger displays than in those with smaller displays. Although pollinator foraging behaviour depended largely on local floral resources, the number of plants per group partially shaped the effect of the group floral display on pollinator attraction and visitation rate. This interaction indicates complex effects of neighbouring floral traits on plant-pollinator interactions, which may have important consequences for mating patterns and plant reproductive success.

Due to shared evolutionary history, native pollinator diversity and coexistence is promoted by niche partitioning and behavioural differences between species. Introduced insect species, however, have potential to compete with wild pollinators and negatively affect native insect populations. Honeybee (Apis mellifera) is an introduced pollinator species in northern Europe and may affect native pollinator populations negatively. Diversity in plant communities also promotes variation in the associated pollinator communities. Diversity of a community encompasses not only species diversity but includes within species variation as well. Within species, genetic diversity could promote insect coexistence and affect competitive interactions between pollinator insects. In this study, we measured floral visitation rates in female and hermaphrodite Geranium sylvaticum genotypes in the presence and absence of a beehive (Apis mellifera) in an experimental field located in Central Finland. We show that competition with honeybees reduced visitation rates by bumblebees, but not by other native pollinator groups. Furthermore, bumblebees preferred some plant genotypes in the absence of the honeybees, but not in the presence of honeybees. Overall, bumblebees preferred females over hermaphrodite plants, but honeybees showed no such preference. Our study links the native pollinators and genetically diverse plant populations, and sheds light on the competition between pollinator insects.

Pollinators play a vital role in most terrestrial ecosystems, supporting wild plant communities and enhancing agricultural yields. However, despite their ecological and economic importance, they have been experiencing an alarming decline over the past decades. The Mediterranean region, known for harboring highly diverse communities of plants and pollinators, is particularly vulnerable due to intense anthropogenic pressures. Furthermore, the ecological roles of many floral visitors remain poorly understood, hindering conservation efforts. In response, in recent years, growing attention has been directed toward the contribution that citizens can give in support of pollinator research. An increasing number of projects have adopted a Citizen Science approach to enable large-scale data collection. The LIFE 4 Pollinators project (LIFE18/GIE/IT/000755) “Involving people to protect wild bees and other pollinators in the Mediterranean” aims to promote the conservation of pollinating insects and entomophilous plants across the Mediterranean region by fostering progressive changes in human practices that threaten wild pollinators. In addition to the implementation of several actions to raise awareness, the project launched a web platform to collect photographic records of flower–insect interaction from the public. The platform is expected to remain active for at least ten years, during which we encourage continuing record submissions by interested bodies. With this data paper we are making the current dataset freely accessible to anyone, committing to periodic online updates.

In northern India and surrounding countries of the Lower Himalaya, apple is an important cash crop that contributes significantly to state economies and farmer livelihoods. Apple cultivation is shifting to higher elevations to counter declining fruit yields associated with climate change. Pollinator scarcity is another factor linked to declines in fruit yield and quality. To advance understanding of bee diversity and pollination ecology in apples for this region, we compiled a taxonomically updated list of bee taxa associated with apple orchards using records from existing literature and a new field study. Our list includes 25 bee genera, 75 named species, and numerous morphospecies. Common genera also feature prominently in apple studies elsewhere in the world. Apis cerana and A. mellifera were the most frequently reported visitors to apple flowers; Bombus, Ceratina, Lasioglossum, and Syrphidae flies were the most common non-Apis floral visitors. Bee species richness was inversely correlated with elevation and pollination deficit whereas bee abundance was not. Therefore, apples grown at higher elevations may experience more favourable growing conditions but also incur greater pollination deficits that are linked to reduced bee richness. This underscores the importance of conserving bee diversity to safeguard pollination services and farmer livelihoods in the region. Our literature review further highlights the need for more tools to identify the regional bee fauna, more thoroughly documented and standardised study methods to build capacity within the research community and aid comparative studies, and more expansive cataloguing and monitoring of pollinator communities to better understand the diversity, roles, and status of bees throughout this under-studied region.

The sugar concentration of floral nectar is a key metric for describing nectar composition and a major factor influencing pollinator visitation to flowers. Across pollination biology research there are multiple approaches in use for describing nectar sugar concentration. With these different approaches there are several potential sources of confusion which, if not accounted for, can lead to errors. Further potential for error arises if researchers wish to make comparisons between the energetic content of nectars containing different ratios of sucrose, fructose and glucose. Regardless of whether concentration is measured per mole or per unit mass, the energetic content differs between the hexose sugars (glucose and fructose) and sucrose. Appropriate conversion is needed for direct comparison. Here we address these two issues with the following aims. We consolidate the literature on this topic with examples of the different methods for reporting nectar sugar concentrations, provide insight into potential sources of error, and derive equations for converting between the different ways of expressing sugar concentration for the three primary nectar sugars: sucrose, glucose and fructose. Second, we discuss the relative energetic content of sucrose, glucose, and fructose, and rationalise adjustment of ‘energetic value’ rather than reporting concentration directly. In this way, we hope to harmonise ongoing work in pollination ecology.

Many flowering plants rely on pollination for their reproductive success, but the introduction of non-native plants can impact these essential plant-pollinator relationships. Chloropyron maritimum ssp. maritimum is a rare salt marsh plant that has been known to benefit from insect pollination, and its habitat is being encroached on by the non-native Limonium duriusculum. We use plant-pollinator observation, network analysis, and small-scale experimental removal of L. duriusculum to understand which insects are visiting C. maritimum maritimum, and the impact, if any, of L. durisiculum on C. maritimum maritimum pollination and the plant-pollinator network. We documented infrequent visitation to C. maritimum maritimum at the Carpinteria Salt Marsh, California, USA, with native bees being the only observed C. maritimum maritimum visitors. We found that the pollinator composition of C. maritimum maritimum and L. duriusculum were significantly different. The vast majority (96%) of L. duriusculum visitors were two non-native insect species (Hymenoptera: Apis mellifera and Diptera: Eristalinus aeneus), neither of which entered C. maritimum maritimum flowers. The experimental removal of L. duriusculum had no effect on C. maritimum maritimum visitation. However, the plant-pollinator network was more nested, more connected and had higher specialization when L. duriusculum was removed. Future studies should implement larger-scale removal to further investigate these findings. Additionally, subsequent work should investigate if there is adequate nesting habitat for C. maritimum maritimum pollinators in surrounding areas, to ensure the survival of the few plant-pollinator interactions this rare plant currently maintains.

The development of large databases of plant-pollinator relationships poses both great opportunities and a particular problem for scientists and practitioners interested in these interactions. A major issue is that it is rare for measures of data quality to be included, in the sense of stating the evidence by which animal X has been determined to be a pollinator of plant Y. Adding such information to databases is vital if we are to fully understand the plant-pollinator relationships that they describe and address information gaps. We present some examples of data quality schemas that have been used in the past and then adopted by the Pollinators of Apocynaceae Database and the Database of Pollinator Interactions (DoPI), and how the forthcoming USDA-NRCS PLANTS database has tackled this question. In addition, we discuss the use of controlled vocabularies developed by the Brazilian Network of Plant-Pollinator Interactions (REBIPP), allied to a vocabulary based on the Darwin Core standard. It is our hope that the pollination ecology community will see the importance of these or other evaluations of data quality and adopt them accordingly.

The predicted effects of climate change on pollination processes are multiple, including earlier blooming times and decoupling from pollinators. Yet, little research has been conducted, especially in urban areas where the heat island effect is known to speed up warming. Our aim is to investigate which bee species visit two native, vernal-blooming tree species with continuous distributions from urban to exurban sites. In 2019 and 2020, we collected bees on the native, mass-flowering Cercis canadensis and Cornus florida in the St. Louis metropolitan and exurban areas in Missouri, USA. A total of 434 bees carrying pollen were collected identifying 54 species representing five families. An additional 123 specimens which did not carry any pollen at all were captured representing 37 species within five families. We observed a greater species diversity among pollen carrying bees at exurban sites while the numbers of male bees collected were proportionately higher in urban versus exurban sites. Although flowering periods of the two tree species overlapped, the pollen of both tree species was identified on only 34 bees.

Caffeine is a widely occurring plant defence chemical that occurs in the nectar of some plants, e.g. Coffea or Citrus spp., where it may influence pollinator behaviour to enhance pollination. Previous laboratory work found inexperienced bumblebees (Bombus terrestris) located new food sources emitting a learned floral odour more consistently if they had been fed caffeine in association with the odour and a food reward. Inexperienced bees primed with caffeine also made more initial visits to target robotic flowers emitting the target odour, compared to control bees or those primed with odour alone. We tested whether these behaviours could be replicated under semi-field conditions in strawberry crops, to improve crop pollination and hence marketable yield. In three trials in mini-polytunnels, odour/caffeine-primed and control bumblebee colonies were allowed to forage on strawberry crops with nectar-rich distractor flowers present. Some small effects of caffeine priming were observed (a slight increase in the proportion of visits to the target flowers in one trial), but after controlling for polytunnel identity, the priming treatment did not influence crop yield and quality. While caffeine priming of commercial bumblebee colonies may have potential to improve pollination in crops, further research is needed to optimise the system for in-field use.

Most orchid species face significant challenges in urban environments. Particularly, pollination services and reproductive success can be altered due to habitat fragmentation related to human activities. Despite this, several terrestrial orchid species thrive in these environments. This study investigates the pollination ecology of Altensteinia fimbriata, a terrestrial orchid prevalent in disturbed habitats from the neotropics. This research aims to identify the pollination mechanism and to list the pollinators and floral visitors associated to A. fimbriata. During 30 hours of observation in a patch with 60 inflorescences of A. fimbriata within an anthropic area of the city of Quito, Ecuador, we recorded 121 visits from ten moth species, identifying four moth species as effective pollinators. Three of the pollinator species were noctuid moths. Moth activity peaked in the evening, coinciding with the emission of distinctive floral scents, suggesting that both scent and nectar attract visitors. We found that the four pollinators of A. fimbriata transfer pollinariums using their legs. This pollination mechanism is found in other terrestrial orchid species from different subtribes where noctuid moths are also the main pollinators. Our findings highlight the adaptability of A. fimbriata in urbanized areas and emphasize the need to understand its pollination dynamics in the context of global change.