Bee-plant Interactions Research Articles

Melissopalynological study of Melipona (Eomelipona) torrida Friese, 1916: a native stingless bee from southern Brazil

Few data are on bee–plant interactions for the Melipona torrida bee in southern Brazil. This is a native bee vulnerable to extinction that pollinates native plants and produces honey that is especially appreciated by local populations. Aiming to evaluate the floral sources visited by Melipona torrida bee in southern Brazil a palynology investigation on honeys of this bee were carried out. Honeys were extracted each month from March 2020 to November 2021 of hives from two locations of Rio Grande do Sul (Cachoeirinha and Canoas). The 34 samples were analysed with a light microscope. In the honey samples of the Melipona torrida bee were identified 39 pollen types, principally tree plants. Melipona torrida bee visited frequently the plants of Myrcia type, Eucalyptus sp., Schinus terebenthifolia, Mimosa bimucronata, Parapiptadenia rigida, Morus nigra and Solanum sisymbrifolium. The pollen diagram show differences in pollen percentages throughout the year and CONISS grouped the samples in five groups (MT-1–MT-5). Richness of pollen types of samples was low in the months of winter and March and high in the honeys of months of Spring and Summer. The honeys were monofloral and heterofloral, and native plants were more visited than exotic species. The 33 pollen types from honey of Melipona torrida bee from southern Brazil can help in the knowledge of the bee–plant interaction of this native bee and propose appropriate plant management around the hives.

Experimental elevated temperature affects bumblebee foraging and flight speed.

Global warming threatens wild bees and their interaction with plants. While earlier studies have highlighted the negative effects of elevated temperatures on bee-plant interactions, we still lack knowledge about how they impact the foraging behaviours that are central to bee pollination activities. To address this knowledge gap, we investigated how ambient temperature affected the foraging behaviours of the bumblebee Bombus terrestris. We allowed the bumblebees to forage freely on artificial flowers in two climate-controlled rooms set at 24°C and 32°C. The colonies were alternated between the two temperatures every week. We recorded the flower visitation rate, flight speed, total foraging time and number of foraging trips. In addition, we measured flight metabolic rate across a range of temperatures to assess its potential as an underlying mechanism. In comparison to 24°C, at 32°C, flower visitation time decreased while flower visitation rate and flight speed increased. This is consistent with the reduction in flight metabolic rate recorded between these temperatures. At 32°C, the number of trips made by each worker decreased, suggesting that, despite the reduced energetic cost, flight in elevated temperatures may be stressful. Our results suggest that elevated temperatures affect bumblebee foraging behaviour and that this would likely disrupt plant-insect interactions.

Bee–plant interactions identified by pollen analysis of honey from the stingless bee Tetragonisca fiebrigi (Schwarz, 1938) in southern Brazil

ABSTRACT Pollen analysis of honey reveals information about bee–plant interactions and networks that, in some cases, are lost through mere observation of bees on flowers. This information on bee–plant interactions is valuable for the protection of bees and vegetal speciesand pollination of crop plants. To provideinsights into bee–plant interactions, palynological evidence was developedfromthe collection of honey. The objective of this study is to determine the plants that the bees (Tetragonisca fiebrigi) visit for honey production in southern Brazil (Rio Grande do Sul). For this, 24 honey samples were collectedfrom five regions of northeastern Rio Grande do Sul, southern Brazil. A total of 64 pollen types were found in the honey samples fromT.fiebrigi in southern Brazil, mainly from trees. The most common pollen types in the samples were from Schinus terebinthifolia, Schizolobium parahyba, Handroanthus sp., Morus nigra, and Rosa cf. grandiflora. The pollen grains show a high diversity of plants, including those with important ecological functions.

Bees and their interactions with flowering plants in disturbed and semi-natural settings

A knowledge of bee populations is scarce, particularly in sub-Saharan Africa, where human-induced changes appear to have a considerable negative effect on wild bees. The goal of the study was to assess the abundance, diversity, and richness of bees and their interactions (or visitation) with flowering plants in disturbed and semi-natural habitats in Tanzania. Bees were sampled using sweep nets and pan traps whereas bee-plant interaction and floral abundance were visually assessed. We show that semi-natural habitats are crucial places for bees to forage and nest, as their richness, diversity, and species composition were higher than disturbed habitats. The study areas in semi-natural habitats also had a higher number of bee visits compared to the disturbed habitats. The lower number of bees found in disturbed habitats implies that human-caused alterations have a negative impact on foraging resources and bee communities. Furthermore, we recorded more than 400 bee-plant interactions and high floral abundance in semi-natural habitats compared to disturbed habitats. However, in both disturbed and semi-natural habitats, there was a positive relationship between floral abundance and bee abundance. This reveals that floral resources have a significant impact on bee abundance and their visitation. Our findings demonstrate further that, if natural environments are disturbed and floral resources are depleted, bee populations may decline. Therefore, habitat management, whether disturbed or semi-natural, is critical for the survival of bees.

Xicotli Data: a project to retrieve plant-bee interactions from citizen science.

Xicotli data is the short name given to the dataset generated within the project framework "Integration of Biodiversity Data for the Management and Conservation of Wild Bee-Plant Interactions in Mexico (2021-2023)", as xicotli is the generic word for a bee in Nahuatl. The team comprised eco-informaticians, ecologists and taxonomists of both native bees and flora. The generated dataset contains so far 4,532 curated records of the plants, which are potential hosts of species of three focal families of bees native to Mexico: Apidae, Halictidae and Megachilidae and morphological and ecological data of the plant-bee interactions. This dataset was integrated and mobilised from citizen observations available at naturalista.mx (iNat), which were compiled through the iNaturalist project. The new information obtained with the Xicotli data project was: Taxonomic information about bee species curated by taxonomists based on the information contained in iNaturalist;Taxonomic identification of the host plants by a botanist from the photos compiled by the Xicotli Data project;Data on the ecomorphological traits of bees and plants based on expert knowledge and literature. All the data were integrated into the Xicotli Data Project via the creation of new "observation fields". The visibility of the information originally contained in iNaturalist was maximized and can be consulted directly on the iNaturalist platform.

Honey bees (Apis mellifera) modify plant-pollinator network structure, but do not alter wild species' interactions.

Honey bees (Apis mellifera) are widely used for honey production and crop pollination, raising concern for wild pollinators, as honey bees may compete with wild pollinators for floral resources. The first sign of competition, before changes appear in wild pollinator abundance or diversity, may be changes to wild pollinator interactions with plants. Such changes for a community can be measured by looking at changes to metrics of resource use overlap in plant-pollinator interaction networks. Studies of honey bee effects on plant-pollinator networks have usually not distinguished whether honey bees alter wild pollinator interactions, or if they merely alter total network structure by adding their own interactions. To test this question, we experimentally introduced honey bees to a Canadian grassland and measured plant-pollinator interactions at varying distances from the introduced hives. We found that honey bees increased the network metrics of pollinator and plant functional complementarity and decreased interaction evenness. However, in networks constructed from just wild pollinator interactions, honey bee abundance did not affect any of the metrics calculated. Thus, all network structural changes to the full network (including honey bee interactions) were due only to honey bee-plant interactions, and not to honey bees causing changes in wild pollinator-plant interactions. Given widespread and increasing use of honey bees, it is important to establish whether they affect wild pollinator communities. Our results suggest that honey bees did not alter wild pollinator foraging patterns in this system, even in a year that was drier than the 20-year average.

Disparate continental scale patterns in floral host breadth of Australian colletid bees (Colletidae: Hymenoptera)

Plant-bee networks are rarely, if ever, studied quantitatively at continental scales, yet these have the potential to inform how biota and ecosystems are assembled beyond narrower regional biomes. The short-tongued bee family Colletidae comprises the major component of bee diversity in Australia, with three key subfamilies: the Neopasiphaeinae, Hylaeinae, and Euryglossinae. We use museum data (> 27,000 records) to record binary interactions between these bees (from each of these subfamilies, resolved to subgenera) and plants (resolved to genera). The resulting networks were analysed using bipartite graphs and associated indices of network structure. The three bee subfamilies showed markedly different network structures with their floral hosts. Euryglossinae had strong interactions with Myrtaceae and an otherwise relatively narrow host breadth, Neopasiphaeinae had little signal of host specialisation above genera and a very broad host breadth, and Hylaeinae appeared intermediate in network structure. Furthermore, Euryglossinae is more speciose within Australia (404 species, or ~ 25% of described Australian bee fauna) than Hylaeinae and Neopasiphaeinae, but these differences do not correspond to the stem ages of the three subfamilies, suggesting that time-since-origin does not explain bee species diversity or floral host breadth. Patterns of host breadth persist after rarefaction analyses that correct for differing numbers of observation records. We suggest that visitation networks could be influenced by evolutionary constraints to expansion of floral host breadth, but it is also possible that many bee-plant interactions are shaped by bees exploiting floral traits that are driven by non-bee fauna operating at large biogeographical scales.

Bee–plant interaction and community response along an urbanization gradient

Abstract Elucidating bee response to urbanization is essential to promoting pollinator diversity in cities especially considering such landscapes are projected to expand to support future global populations. To determine how bee community composition and plant–pollinator interactions respond to urbanization, 29 sites representing three urban categories (high, medium and low urbanization) were monitored biweekly from May through early October in Toronto, Canada. Bees were collected passively using pan and blue vane traps as well as actively using aerial nets and vacuums to compare community structure and plant–pollinator networks among urban categories. Functional traits such as dietary breadth, behaviour, nesting substrate and native or non-native status were also examined to determine how landscape influences bee community assemblages. In total, 5477 bees, comprising 26 genera and 164 species, were represented in this study. The urban landscape was largely supportive of species within the family Apidae and Halictidae as well as ground nesting, native and generalist species. Overall, community composition was affected by urban landscape characteristics such as percent tree cover and impervious (i.e. paved and built) surface surrounding sites; however, bee richness and abundance were significantly influenced by plant richness and not by landscape variables. A total of 3267 interactions were observed throughout the study region with characteristics of plant–pollinator networks remaining consistent along the urban gradient with a few floral host plants such as Solidago dominating interactions in certain urban contexts. These results provide important land use and floral host information for targeting pollinator conservation and habitat restoration.

Favourite plants of wild bees

Flower strips are a commonly used tool for improving agricultural landscapes for pollinators. The plant composition of the seed mixtures employed is based on logistic decisions, e.g. costs or seed availability, the literature and expert opinion, and only rarely on direct information about bee-plant interactions. We combined two datasets on bee-plant interactions involving 460 bee species. The first consisted of 23,864 bee-plant interactions, recorded in twenty locations in Germany from 2018 and 2019, whereas the second consisted of 86,509 bee-plant interactions sampled across multiple sites in southwest Germany over more than 30 years. We explored three objectives. (1) Which plant species attract the greatest number of wild bee species and individuals across plant communities within and across seasons of bee activity? (2) Do the most attractive plant species also support threatened and specialized wild bees? (3) Do seed mixtures contain attractive plant species? High attractiveness was defined as a consistently high interaction frequency and number of visiting bee species to a plant species across the sampled communities. Our results identified 34 herbaceous key plant species that were highly attractive for wild bees independently of plant abundance and across locations. Further, we identified a large number of plant species for which the attractiveness for wild bees depended on the sampled community. The identified key plant species attracted between 2% and 32% of oligolectic or red-listed bees present in our datasets. Although some of these plant species, such as Centaurea cyanus or C. jacea, are commonly found in seed mixtures, others, such as Stachys recta or Carduus nutans, are not. These large-scale and robust interaction data highlight key plant species that provide an attractive core for herbaceous floral strips aimed at supporting high numbers of wild bee species.

Increasing flower species richness in agricultural landscapes alters insect pollinator networks: Implications for bee health and competition.

Ecological restoration programs are established to reverse land degradation, mitigate biodiversity loss, and reinstate ecosystem services. Following recent agricultural intensification that led to a decrease in flower diversity and density in rural areas and subsequently to the decline of many insects, conservation measures targeted at pollinators have been established, including sown wildflower strips (WFS) along field margins. Historically successful in establishing a high density of generalist bees and increasing pollinator diversity, the impact of enhanced flower provision on wider ecological interactions and the structure of pollinator networks has been rarely investigated. Here, we tested the effects of increasing flower species richness and flower density in agricultural landscapes on bee‐plant interaction networks. We measured plant species richness and flower density and surveyed honeybee and bumblebee visits on flowers across a range of field margins on 10 UK farms that applied different pollinator conservation measures. We found that both flower species richness and flower density significantly increased bee abundance, in early and late summer, respectively. At the network level, we found that higher flower species richness did not significantly alter bee species' generality indices, but significantly reduced network connectance and marginally reduced niche overlap across honeybees and bumblebee species, a proxy for insect competition. While higher connectance and niche overlap is believed to strengthen network robustness and often is the aim for the restoration of pollinator networks, we argue that carefully designed WFS may benefit bees by partitioning their foraging niche, limiting competition for resources and the potential for disease transmission via shared floral use. We also discuss the need to extend WFS and their positive effects into spring when wild bee populations are established.

Heat of the moment: extreme heat poses a risk to bee-plant interactions and crop yields.

Extreme heat events threaten the development, functioning, and success of bee pollinators and crops that rely on pollinators for high yields. While direct effects of extreme heat and climate warming have gained more attention, the indirect effects on bees and crops remain largely unexplored. Extreme heat can directly alter the nutritional value of floral rewards, which indirectly contributes to lower bee survival, development, and reproduction with implications for pollination. Phenological mismatches between bee activity and crop flowering are also expected. Heat-stressed crop plants with reduced floral rewards may reduce bee foraging and nesting, limiting pollination services. Understanding how extreme heat affects bee-crop interactions will be essential for resilient production of pollinator-dependent crops in this era of climate change.

Effects of short‐term managed honey bee deployment in a native ecosystem on wild bee foraging and plant–pollinator networks

Abstract Honey bees (Apis mellifera L.) are important agricultural pollinators, and there is increasing demand for forage habitat for managed colonies. However, there is also evidence that pasturing honey bee colonies within natural landscapes may negatively affect wild bees through resource competition. To assess resource competition between managed honey bees and wild bees, we conducted repeated, short‐term deployments of honey bee colonies within Florida forests coinciding with seasonal wildflower bloom, and compared wild bee foraging with and without honey bee colonies present over multiple seasons. We recorded over 2000 bee visits including 196 pairwise bee–plant interactions. Deploying honey bee colonies was associated with a reduction in wild bee foraging rates, and honey bee and wild bee foraging rates were significantly, negatively correlated. Honey bees disproportionately visited resources with high floral density. Honey bee foraging preferences differed significantly from genera with small‐bodied (Lasioglossum, Perdita, Augochlorella), and/or specialist species (Perdita, Andrena), as well as with Megachile, but overlapped with genera including larger‐bodied (Bombus, Habropoda, Osmia, Xylocopa) and/or generalist species (Bombus, Xylocopa, Agapostemon). Deploying honey bee colonies did not significantly affect plant–pollinator network metrics. These results illustrate that short‐term honey bee colony deployment can negatively affect wild bee foraging and that competition may be greater for certain genera, particularly larger‐bodied bees or those with generalist diets though less for smaller‐bodied and/or specialist bees. Our short‐term, low‐density deployment treatments may have precluded significant effects on network metrics and likely underestimate the effects of typical higher density and longer‐term honey bee deployment.

The role of seasonality and disturbance in bee–plant interactions in semi‐arid communities of the southern Chihuahuan desert

The maintenance of interactions between plants and their floral visitors depends on factors such as resource variability, seasonality, and population dynamics. Changes in water availability along with different types and levels of anthropogenic disturbance may influence how plants and pollinators interact, especially in arid environments. In a semi-arid area of the southernmost Chihuahuan Desert (Mexico), we surveyed bee–plant interactions in the dry and rainy season at sites that differed in disturbance type. We used a mutualistic network approach to analyse our data. We collected 946 bee individuals belonging to 32 bee species, almost a third of the total richness previously reported for Querétaro state. We detected a strong impact of seasonality on the structure of ecological interactions, with more complex and robust interactions among bee and plant species in the rainy season. We did not find statistical support for a relationship among disturbance, nestedness, or niche overlap. We did find disturbance negatively affected plant robustness to secondary extinctions. Four plants: Echinocactus platyacanthus, Opuntia stenopetala, Senna wislizeni var. painteri and Cylindropuntia imbricata comprised the core species that were primarily responsible for the resilience of the bee communities. The following bees conformed the generalist core of species: Diadasia rinconis, Lasioglossum (Dialictus) sp. 1, Apis mellifera, and Augochlorella pomoniella. Overall, network nestedness and robustness differed significantly between seasons but not among sites with different levels of disturbance.

Documenting pollinators, floral hosts, and plant-pollinator interactions in U.S. Pacific Northwest agroecosystems.

The abundance and diversity of pollinator populations are in global decline. Managed pollinator species, like honey bees, and wild species are key ecosystem service providers in both natural and managed agroecosystems. However, relatively few studies have exhaustively characterized pollinator populations in diverse agroecosystems over multiple years, while also thoroughly documenting plant-pollinator interactions. Yet, such studies are needed to fulfill the national pollinator protection plans that have been released by the United States and other nations. Our research is among the first studies to respond to these directives by systematically documenting bee and plant biodiversity, bee-plant interactions, and bee-mediated pollen movement in farming systems of the Pacific Northwest, USA. Our data provides insight into the processes mediating pollinator and plant community assembly, persistence, and resilience across landscapes with variable crop and landscape diversity and agroecosystem management practices. These data will also contribute to the development of a United States pollinator database, supporting the United States' plan to promote pollinators. With few publicly available data sets that systematically take account of agroecosystem practices, plant populations, and pollinators, our research will provide future users the means to conduct synesthetic studies of pollinators and ecosystem function in a period of rapid and global pollinator declines. There are no copyright or proprietary restrictions for research or teaching purposes. Usage of the data set must be cited.

FURTHER RANGE EXPANSION OF THE SCULPTURED RESIN BEE (MEGACHILE SCULPTURALIS) IN SERBIA AND BOSNIA & HERZEGOVINA

Megachile sculpturalis is the first non-native bee species established in Europe, originating from E-Asia. Since early detections in SW-Europe (2008–2010) its spreading resulted in a range currently spanning nearly 2,800 km x 1,100 km across the southern and central Europe. In SE-Europe establishment was confirmed since 2015 in NE-Hungary, followed by detection in N-Serbia (2017), and wider spreading across the eastern Pannonian Plain (2018–2019); eventually it was detected in NW-Bosnia & Herzegovina (2020). Accordingly, the repeated calls for monitoring of M. sculpturalis spread were voiced, aiming to address its potential invasiveness, but mostly lacking a more specific assessment protocol. A 'working concept' for a comprehensive monitoring of M. sculpturalis was proposed within the survey conducted in Belgrade (Serbia) during 2017–2019, based on quantitative assessment of bee population trends in relation to focal plant resources. There was a need to improve and broaden this initial framework, e.g., to allow for different spatio-temporal scales and various potential usage requirements. Therefore, in 2020 we considerably extended the research scope, defined at two spatial scales: LOCAL, for the Belgrade area – the continuation of protocol development, through a high-intensity assessment of M. sculpturalis abundance, bionomics, and distribution, in parallel with assessment of extended set of relevant plants (and potential bee-plant interactions); REGIONAL, a survey covering the bee spreading across Serbia and Bosnia & Herzegovina, aiming to provide a reference time-section in expanding SE-European front, while also extending the knowledge of its environmental affinities. The study included the launching of a pioneering citizen science project, which enabled a remarkable geographic coverage despite modest return of positive reports. The Belgrade-scale survey yielded a modest increase in recorded locations, relative to 2019, but the recording efficiency was decreased, despite a much intensified surveying efforts and extended coverage. This corroborated the importance of inter-seasonal variation of key food resources, which affects both the population dynamics and detectability of this bee, through alternating concentration and dilution effects. We confirmed the strong association of detection success with availability and variability of blooming Styphnolobium, at both scales, indicating the highest relevance of inclusion of this plant into monitoring assessment protocols. The established phenological extent of M. sculpturalis activity (>70 days) also closely corresponded with the phenology of Styphnolobium blooming; yet it does not represent the entire phenological span for the region. Almost no record came from surveying other plants. The regional expansion of M. sculpturalis during 2017–2020 is documented from 19 wider locations (16 added in 2020). It is particularly well established in the Pannonian, and to a lesser extent in peri-Pannonian area of Serbia and B&H, while the approximated range extent was likely doubled during 2019–2020. Further south records were scarce, indicating the slower expansion across the hilly-mountainous part of the Balkans. Records largely came from urban or other settlements, only about a third from semi-natural or agricultural environments.

Survey of bee friendly flowering plants and bee-plant interaction in an urban green space in Bengaluru, India

Aim: To study bee friendly plant species, nutritional sources, flowering season, and the dynamic relationship between urban flora and native bee species in a centrally located urban green space in Bengaluru, India. Methodology: Flowers of different plant species visited by bees were observed and recorded from September 2018 to August 2019. Based on the foraging pattern of visiting bees, the plants were classified into nectar or pollen or both nectar and pollen species. The monthly abundance of nutritional resources was estimated based on the floral phenology. Results: A total of 51 plant species, from 25 families, were visited by bees for foraging. Polylectic social bees namely Apis florea and Tetragonula iridipennis, visited 45 and 39 plant species, and two species of solitary bees, namely Amigella cingulate and Xylocopa violacea, visited 26 and 23 plant species, respectively. The urban green landscape was dominated by a variety of ornamental plants (49%) and also included vegetables (17.6%), fruit trees (13.7%), and weeds (19.6%). Plants that served as a source of both nectar and pollen (60.8%) were predominant over those that supplied either nectar alone (24.5%) or pollen alone (13.7%). Moreover, 72% of the species bloomed all the year round, which meant that floral resources were available to bees throughout the year. Interpretation: The study underscores the role of bee friendly floral diversity in the urban green spaces in protection and conservation of bee diversity. Efficient management of urban green spaces can provide dynamic habitat for bee conservation and can prevent the loss of biodiversity.

Evaluating competition for forage plants between honey bees and wild bees in Denmark.

A recurrent concern in nature conservation is the potential competition for forage plants between wild bees and managed honey bees. Specifically, that the highly sophisticated system of recruitment and large perennial colonies of honey bees quickly exhaust forage resources leading to the local extirpation of wild bees. However, different species of bees show different preferences for forage plants. We here summarize known forage plants for honey bees and wild bee species at national scale in Denmark. Our focus is on floral resources shared by honey bees and wild bees, with an emphasis on both threatened wild bee species and foraging specialist species. Across all 292 known bee species from Denmark, a total of 410 plant genera were recorded as forage plants. These included 294 plant genera visited by honey bees and 292 plant genera visited by different species of wild bees. Honey bees and wild bees share 176 plant genera in Denmark. Comparing the pairwise niche overlap for individual bee species, no significant relationship was found between their overlap and forage specialization or conservation status. Network analysis of the bee-plant interactions placed honey bees aside from most other bee species, specifically the module containing the honey bee had fewer links to any other modules, while the remaining modules were more highly inter-connected. Despite the lack of predictive relationship from the pairwise niche overlap, data for individual species could be summarized. Consequently, we have identified a set of operational parameters that, based on a high foraging overlap (>70%) and unfavorable conservation status (Vulnerable+Endangered+Critically Endangered), can guide both conservation actions and land management decisions in proximity to known or suspected populations of these species.

Pairwise learning for predicting pollination interactions based on traits and phylogeny

Mutualistic bee–plant interaction networks are a vital part of terrestrial ecosystems. They frequently arise through co-evolutionary processes, which match the traits of both partners, facilitating their interaction. Insights in these interaction mechanisms are vital to be able to manage changing ecosystems. This entails the need for models to predict species interaction networks in general and pollination networks in particular.We show how kernel-based pairwise learning can predict bee–plant interactions based on the traits and the phylogeny of the plant and bee species. The traits and the phylogeny of the plant and bee species proved to be highly predictive. Although the traits were slightly more informative compared to the phylogeny, the best results were obtained by combining both the traits and the phylogeny in the model Notably, the model performance varied greatly depending on whether the goal was to pinpoint missing interactions in the network or to predict interactions for new bee species, new plant species, or both. This issue highlights the importance of proper stratification when fitting biological network prediction models. Our model, however, showed the capacity to generalize beyond the original dataset provided by FlorAbeilles. The model was validated by predicting potentially interacting plant species for the invasive bee species Megachile sculpturalis. Four out of the five plant species identified by the model could be validated based on literature.Our results indicate that pairwise learning has potential as a general method for supervised species interaction prediction. Caution should be taken to validate such models correctly.

Extreme host range in an insular bee supports the super-generalist hypothesis with implications for both weed invasion and crop pollination

Super-generalism is a pollinator trait where species obtain floral resources from a very wide range of plant species. Theoretical and empirical studies suggest that on islands with low pollinator diversity, such pollinators should evolve to exploit a very wide range of floral morphologies. Super-generalism has implications not only for securing pollination network stability, but also for the invasibility of potential weeds that require specialist pollinators in their original ranges. Here we expand earlier studies on bees in Fiji to include a wider range of bee-plant interactions for bees that have been recently introduced into Fiji as well as the endemic Fijian halictine bee, Homalictus fijiensis. Our data show that the endemic Fijian bee has a much wider range of floral hosts than introduced bees, and this extends to pollen larceny of solanoid plant species that are usually buzz pollinated. Importantly, solanoid plants were not visited by introduced bee species, including the honeybee Apis mellifera, which is usually regarded as a super-generalist. Our findings are important because they add critical support to the hypothesis that super-generalism evolves in insular ecosystems with low pollinator diversity and that this may make such ecosystems vulnerable to invasion by exotic weeds. However, insular super-generalists may also have potential to stabilize plant-pollinator networks and may also be effective pollinators for exotic crop species, and this needs to be further explored in agricultural settings.

Bee-Plant Interactions in Coffee Agroecosystems: Management and Matrix Effects on Mutualistic and Antagonistic Relationships

Bee-Plant Interactions in Coffee Agroecosystems: Management and Matrix Effects on Mutualistic and Antagonistic Relationships