Search

AbstractFew 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. [ABSTRACT FROM AUTHOR]

Gardens can benefit pollinators living in surrounding farmland landscapes, but the reason for their value is not clear. Gardens are no different from many semi-natural farmland habitats in terms of the quantity of floral resources (pollen and nectar) they produce, but the timing of their resource supply is very different, which may explain their value. We show that gardens provide 15% of overall annual nectar in farmland landscapes in Southwest UK, but between 50% and 95% during early spring and late summer when farmland supplies are low. Gardens can therefore reduce seasonal nectar gaps experienced by farmland bumblebees. Consistent with this pattern, bumblebee activity increased in gardens relative to farmland during early spring and late summer. An agent-based model reinforces this point, showing that timing, not quantity, of garden nectar supply enhances bumblebee colony growth and survival in farmland. We show that over 90% of farmland in Great Britain is within 1 km of a garden and therefore positive actions by gardeners could have widespread spillover benefits for pollinators across the country. Given the widespread distribution of gardens around the world, we highlight their important interplay with surrounding landscapes for pollinator ecology and conservation. [ABSTRACT FROM AUTHOR]

Specialisation enhances the efficiency of plant–pollinator networks through the exchange of conspecific pollen transfer for floral resources. Floral resources form the currency of plant–pollinator interactions, but the understanding of how floral resources affect the structure of plant–pollinator networks remains modest. Previous theory predicts that optimally foraging animal species will specialise to improve resource acquisition under high resource availability. Although floral resource availability depends on both the plant production and animal consumption of the resources, previous work has assumed that production and availability are equivalent. This potentially may have led to erroneous inferences on the effect of resource availability on specialisation. We develop a mutualistic Lotka–Volterra consumer‐resource model to investigate the influence of floral resource availability on plant–pollinator network structure. The model incorporates animal adaptive foraging behaviour, floral resource dynamics, and density‐dependent dynamics. Specialisation, nestedness and modularity of simulated networks generated from the model under a wide range of parameters were explained using the generalised linear model. We found that the distinction between floral resource dynamics and plant density dynamics was necessary for partial specialisation of plant–pollinator networks. This is because floral resource dynamics constrained animal preference due to its depletion by animal species. Floral resource abundance had a positive effect on network specialisation, but animal density had a negative effect on network specialisation. Floral resource dynamics thus play key roles in the structure of plant–pollinator networks, distinctive from plant species density dynamics. [ABSTRACT FROM AUTHOR]

Abstract Pollen and nectar are crucial resources for bees but vary greatly among plant species in their quantity, nutritional quality and timing of availability. This makes it challenging to identify an appropriate range of plants to meet the nutritional needs of bees throughout the year, though this information is important in the design of pollinator conservation schemes. Using DNA metabarcoding of pollen loads, we record the floral resource use of UK farmland bumblebees at different stages of their colony lifecycle, and compare this with null models of ‘expected’ resource use based on landscape‐scale resource availability (pollen and nectar), to identify foraging priorities and preferences. We use this approach to ask three main questions: (i) what is the foraging breadth of individual bumblebees?; (ii) do bumblebees utilise a greater or lesser diversity of plant species than expected if they foraged in proportion to resource availability?; (iii) which plant species do bumblebees preferentially utilise? Individual bumblebees foraged from a highly consistent number of different plant taxa (mean: 10 ± 0.37 SE per bee), regardless of their species, sampling site or time of year. This high consistency in foraging breadth, despite large changes in the quantity, identity and diversity of resource availability, implies a strong behavioural tendency towards a fixed range of foraging resources. This effect was most striking in April when foraging diversity was maintained despite very low landscape‐level resource diversity. Bumblebees used some plant taxa significantly more than predicted from their landscape‐level floral abundance, nectar or pollen supply, implying certain desirable characteristics beyond the mere quantity of resource. These included Allium spp. and Vicia spp. in April; Trifolium repens and Lotus corniculatus in July and Cardueae spp. (thistles) and Taraxacum officinale in September. Practical implication: Our results strongly indicate that resource quantity is not the only factor driving bumblebee foraging patterns and that resource diversity and quality are also important factors. Thus, in addition to providing large quantities of floral resources, we recommend that pollinator conservation schemes also focus on providing a sufficient diversity of preferred floral resources, enabling pollinators to self‐select a diverse and nutritious diet.

Pollinators benefit from increasing floral resources in agricultural landscapes, which could be an underexplored co‐benefit of mass‐flowering crop cultivation. However, the impacts of mass‐flowering crops on pollinator communities are complex and appear to be context‐dependent, mediated by factors such as crop flowering time and the availability of other flower resources in the landscape. A synthesis of research is needed to develop management recommendations for effective pollinator conservation in agroecosystems.By combining 22 datasets from 13 publications conducted in nine temperate countries (20 European, 2 North American), we investigated if mass‐flowering crop flowering time (early or late season), bloom state (during or after crop flowering) and extent of non‐crop habitat cover in the landscape moderated the effect of mass‐flowering crop cover on wild pollinator abundance and species richness in mass‐flowering crop and non‐crop habitats.During bloom, wild bee abundance and richness are negatively related to mass‐flowering crop cover. Dilution effects were predominant in crop habitats and early in the season, except for bumblebees, which declined with mass‐flowering crop cover irrespective of habitat or season. Late in the season and in non‐crop habitats, several of these negative relationships were either absent or reversed. Late‐season mass‐flowering crop cover is positively related to honeybee abundance in crop habitats and to other bee abundance in non‐crop habitats. These results indicate that crop‐adapted species, like honeybees, move to forage and concentrate on late‐season mass‐flowering crops at a time when flower availability in the landscape is limited, potentially alleviating competition for flower resources in non‐crop habitats. We found no evidence of pollinators moving from mass‐flowering crop to non‐crop habitats after crop bloom.Synthesis and applications: Our results confirm that increasing early‐season mass‐flowering crop cover dilutes wild pollinators in crop habitats during bloom. We find that dilution effects were absent late in the season. While mass‐flowering crop cultivation alone is unlikely to be sufficient for maintaining pollinators, as part of carefully designed diverse crop rotations or mixtures combined with the preservation of permanent non‐crop habitats, it might provide valuable supplementary food resources for pollinators in temperate agroecosystems, particularly later in the season when alternative flower resources are scarce. [ABSTRACT FROM AUTHOR]

Understanding the resources bees use is essential because we depend greatly on their ecosystem services, and this information could help guide conservation efforts. One way to identify the flowers that bees visit is to collect pollen directly from the bee and then identify the pollen with plant taxa. However, the current method for processing such pollen samples, acetolysis, is designed for samples such as those collected across individuals (e.g. pollen trap), bee nests, or, at the very least, from pollen pellets collected from live bees or from the exhaustive removal of pollen from lethally collected individuals. Smaller samples, including those down to just a few pollen grains sampled from live bees, could facilitate additional opportunities for bee-pollen research, if they can be processed effectively. We present a revised acetolysis methodology designed specifically for processing small pollen samples, so that they can then be used for more accurate identification. Using pollen samples from cotton swabs directly applied to live bees in the field, we demonstrate the effectiveness of our methodology for processing small pollen samples, including samples too small to be visually detected. This methodology can permit nonlethal collections in the field from a greater number of bee species. [ABSTRACT FROM AUTHOR]

Korla fragrant pear (Pyrus sinkiangensis Yü) depends on cross‐pollination by honeybees (Apis mellifera) but may suffer from low honeybee visitation.We assessed whether honeybee abundance and visitation frequency are enhanced by using synthetic Nasonov gland pheromone (NGP), which is naturally produced by worker bees to stimulate the aggregation of bees to food resources or nesting sites.The response of honeybees to synthetic NGP was firstly assessed using Y‐tube olfactometer tests in the laboratory, and subsequently in the field, by placing NGP lures on Korla fragrant pear trees in orchards with and without beehives. Honeybee abundance was assessed using coloured pan traps while honeybee visits were assessed by visual observations on pear flowers.Y‐tube olfactometer tests showed a significant preference of honeybees for NGP. In pear orchards with beehives, honeybee abundance was 2.5‐fold higher on trees with NGP lures than on trees without NGP, and 2.2‐fold higher in orchards in which all trees contained NGP lures than in orchards without NGP lures. Such positive effects were not observed in orchards without beehives.Flower visitation by honeybees was significantly higher in trees with NGP lures than without NGP lures, irrespective of the presence (5.7‐fold higher) or absence of beehives (27.6‐fold higher).In mixed pear‐apricot orchards, honeybee abundance was higher in pear trees with NGP lures than without lures.Our results show that NGP lures attract honeybees to flowering pear trees in monoculture pear and mixed pear‐apricot orchards, and that this effect is greatest in orchards with beehives. [ABSTRACT FROM AUTHOR]

Context: Flower-visiting insects depend on floral resource availability from both cultivated and semi-natural habitats in agricultural landscapes. Landscape studies exploring insect abundance mainly focus on land cover maps without considering plant species within. Highlighting the functional role of landscapes through the potential floral resources they provide is an overlooked innovative approach. Objectives: We aimed to identify traits of floral communities that are important, across several spatial scales, for explaining the abundance of flower-visiting insects. Mapping and quantifying potential floral resources according to their attractivity, accessibility and profitability in both crop and non-crop habitats was performed to gain insights into flower-vising insect requirements. Methods: We translated land-cover maps of 39 landscapes of 250 m, 500 m and 1000 m radius into potential floral resource maps, using pre-existing vegetation surveys and floral traits databases. In the centres of the landscapes, the abundance of flower-visiting insect groups (domestic and wild bees, bumblebees and hoverflies) were recorded in organic winter cereal fields. We then fitted Generalized Linear Models (GLMs) to investigate the effects of flower trait variables (pre-selected with conditional random forests) at both field and landscape scales on the abundance of each flower-visiting insect group. Results: Floral resource maps explained the abundances of flower-visiting insect groups. Small wild bees (< 1 cm) responded positively to the relative amount of attractive and accessible floral resources at 250 m. The abundance of domestic bees and bumblebees was positively correlated with the relative amount of high nectar producing plants at 1000 m. The abundance of hoverflies was positively influenced by the relative amount of actinomorphic flowers (i.e., those with radial symmetry), at 1000 m. Conclusion: Resource maps could explain flower-visiting insect abundances, identify which category of floral resources organisms require, and determine in which habitat types these resources prevail. These results open a new research area related to managing the environment by optimising floral resources for flower-visiting insect conservation and pollination maintenance. [ABSTRACT FROM AUTHOR]

Context: From landscape variables to weather, multiple environmental factors affect honey bees and other pollinators. Detailed honey bee colony assessments in a variety of landscape and weather conditions offer the opportunity to develop a mechanistic understanding of how landscape composition, configuration, and weather are associated with colony nutrition, demography, and productivity. Objectives: Our objective was to test if weather and landscape characteristics (e.g., agricultural versus forested land use) are associated with different honey bee colony outcomes (foraged nectar mass, foraged pollen mass, pupal population size, and adult population size change). Methods: We collected detailed colony measurements on over 450 honey bee colonies over four years across an agricultural-to-forested land use gradient in Michigan, USA. Results: We found that higher than normal precipitation in the preceding spring and fall was negatively correlated with colony size change and with foraged nectar mass, respectively. Sites surrounded by less agricultural land and more forested land also had fewer pupae by the end of summer. Conclusions: These inter-dependent colony metrics offer insights into environmental-plant-pollinator dynamics. Our finding that extreme weather events, associated with climate change, are negatively correlated with colony performance point to likely lagged effects of weather on pollinator floral resources. Landscapes managed with climate-resilient, temporally continuous floral resources are likely to support pollinators. Capturing extreme weather phenomena in field studies is a valuable way to investigate the associations between land use, climate change and biological systems. However, caution should be taken in overinterpreting observational studies, so further research is needed. [ABSTRACT FROM AUTHOR]

Nectar is an important floral resource, often representing the only source of water for pollinators in arid environments. We investigated whether successive nectar removal would affect the nectar production dynamics of four Melocactus species growing in the Caatinga domain. Nectar was serially extracted from flowers four times per day at regular 60‐min intervals after anthesis. The cactus species showed a consistent pattern of secretion linked to ornithophily, with no significant responses to successive nectar removal and no reabsorption. Nectar secretion covered the entire period of anthesis, starting at 2:30 p.m. and continuing to 5:30 p.m., with the production of 11–38 μl per flower, with sugar concentrations of 10%–32% (3–16 mg of sugar). Individual flowers produced average amounts of 16.9–3.43 mg of sugar per day, corresponding to energy values of 0.06–0.28 kJ. Sympatric populations produced an average of 150–200 flowers per day. The nectar produced by Melocactus can therefore meet the daily energy needs of hummingbirds, which is of special importance during the dry season, when resources are scarce in the Caatinga. [ABSTRACT FROM AUTHOR]

Predaceous ladybeetles are highly polyphagous predators that ingest supplementary food from flowering plants. Flowering plants widely grown in agroecosystems can sustain multiple natural enemies of agricultural pests, and the pollen and nectar resources from flowering plants may have a positive role in natural enemies. Cnidium monnieri (L.) Cusson, an annual herb with many flowers, blooms from May to July. C. monnieri can support several predatory natural enemies, and the addition of C. monnieri strips increases the density of Harmonia axyridis (Pallas) and improves the biological control of apple aphids in an apple orchard. H. axyridis is also the most important natural enemy in wheat aphid biocontrol and is attracted to healthy and aphid-infested C. monnieri plants. In addition, adult Propylaea japonica Thunberg survives significantly longer on C. monnieri flowers than on a water-only diet. In this study, a laboratory experiment was conducted to assess (i) the effect of nutritional supplements derived from C. monnieri flowers on the development and reproduction of H. axyridis under a wheat aphids-only diet; (ii) the effect of C. monnieri flowers on H. axyridis adult reproduction performance. We compared the larval durations, survival, weight, adult longevity, and reproduction of H. axyridis reared on wheat aphids-only and aphids plus C. monnieri flower diets. The results showed that H. axyridis larvae reared on aphids plus flowers had significantly greater weights and survival rates, shorter larval durations, and produced 1.62 times more eggs than those reared on wheat aphids-only diets. H. axyridis adults ingesting a C. monnieri flowers plus an aphid diet increased egg production 1.44 times compared to the aphids-only diet. Our study demonstrates that C. monnieri flowers as a supplementary food positively affect the survival, development, and reproduction performance of H. axyridis. [ABSTRACT FROM AUTHOR]

Flowering plants and pollinators are in a mutualistic association, where pollinators collect floral resources and plants receive pollination services. Bees and other pollinators are declining in many parts of the world, and their loss affects the functional composition of fauna, flora, and habitats. Different strategies are being deployed to improve pollinator services, including the management of bees. Sustainable management of a bee species strongly depends on floral resource availability. Therefore, beekeepers need to have adequate knowledge about the surrounding vegetation (especially nectar and pollen sources for the bee species). Diverse methodologies are used around the world to determine floral resources for bees. Field surveys and pollen analysis of honey, corbicular/scopal pollen loads, residual pollens in brood cells, forager's body surface pollen content, and internal organs (gut, intestine, crop, etc.) were used by the researchers. For pollen identification, most researchers carried out microscopy-based methods. However, pollen DNA-based methods were also used by researchers in recent years. Regarding the morphology-based identification, most researchers processed pollen samples according to Erdtman's acetolysis method to increase the visibility of diagnostic characteristics of the pollen grains. The method specified by the International Commission for Bee Botany was used to conduct qualitative and quantitative pollen analysis on honey samples. For quantitative pollen load analysis, researchers used numerous techniques that may have been the most effective. Our discussion about the different techniques utilized to determine floral resources of a bee species will be helpful for researchers in selecting a suitable protocol and may assist in developing superior methodologies. [ABSTRACT FROM AUTHOR]

Predaceous ladybeetles are highly polyphagous predators that ingest supplementary food from flowering plants. Flowering plants widely grown in agroecosystems can sustain multiple natural enemies of agricultural pests, and the pollen and nectar resources from flowering plants may have a positive role in natural enemies. Cnidium monnieri (L.) Cusson, an annual herb with many flowers, blooms from May to July. C. monnieri can support several predatory natural enemies, and the addition of C. monnieri strips increases the density of Harmonia axyridis (Pallas) and improves the biological control of apple aphids in an apple orchard. H. axyridis is also the most important natural enemy in wheat aphid biocontrol and is attracted to healthy and aphid-infested C. monnieri plants. In addition, adult Propylaea japonica Thunberg survives significantly longer on C. monnieri flowers than on a water-only diet. In this study, a laboratory experiment was conducted to assess (i) the effect of nutritional supplements derived from C. monnieri flowers on the development and reproduction of H. axyridis under a wheat aphids-only diet; (ii) the effect of C. monnieri flowers on H. axyridis adult reproduction performance. We compared the larval durations, survival, weight, adult longevity, and reproduction of H. axyridis reared on wheat aphids-only and aphids plus C. monnieri flower diets. The results showed that H. axyridis larvae reared on aphids plus flowers had significantly greater weights and survival rates, shorter larval durations, and produced 1.62 times more eggs than those reared on wheat aphids-only diets. H. axyridis adults ingesting a C. monnieri flowers plus an aphid diet increased egg production 1.44 times compared to the aphids-only diet. Our study demonstrates that C. monnieri flowers as a supplementary food positively affect the survival, development, and reproduction performance of H. axyridis.

Various strategies incorporate floral resources into agricultural landscapes to support beneficial insects. Specialty cut flower production offers a rarely explored approach to offer floral resources while yielding a marketable product for growers. We characterized insect visitation to six species of specialty cut flowers. Due to Wyoming's growing conditions, the flowers were grown in high tunnels, thus offering insight into insect abundance in this unique semi-controlled environment. The flower species tested were Calendula officinalis, Celosia argentea, Daucus carota, Helichrysum bracteatum, Matthiola incana, and a Zinnia elegans-Zinnia hybrida mixture. At least four species were in bloom from early June through late September. The flowers attracted diverse pollinator groups including Diptera, Hymenoptera, Coleoptera, and Lepidoptera. Bees most often visited Ca. officinalis, H. bracteatum, and Celosia spicata whereas flies most often visited D. carota. Bombus were the most oft-collected bees from the flowers and were found on all six cut flower species. Wasp abundance varied little across the cut flowers, but wasp community composition was distinct. The highest diversity of wasp families was collected from the Zinnia mixture (seven families) in contrast to less diverse collections from Ce. spicata (two families). The most abundant wasp families collected were Crabronidae and Sphecidae. Our experiment documented that ornamental cut flower species attract pollinator insects into high tunnel environments. All cut flower species tested were visited by multiple types of beneficial insects. Planting a mixture of specialty cut flowers can support insect diversity while also diversifying on-farm agricultural products through sale of cut flower stems. [ABSTRACT FROM AUTHOR]

Over the past century, habitat loss from agricultural intensification has contributed to pollinator decline. One way to mitigate the harmful effects of agricultural intensification is through the re-introduction of native flowering plants as border strips that provide supplemental floral and nesting resources to pollinators. However, border crop species vary in bloom period and flower densities, and are thus likely to attract different suites of pollinator species. Resulting differences in pollinator community composition are likely to affect their ability to provide pollination services to adjacent crop habitat. To address these issues, we implemented a two-year study on the impact of different flowering border crops on pollinator abundance, richness, and community composition. We also examined which crop features (bloom duration, number of flowers, floral area) were most likely to affect pollinator densities. We found that native flowering plant border crops of diverse prairie mix and monocultures of silflower (Silphium integrifolium Michx.) and cup plant (Silphium perfoliatum L.) attracted the highest abundance and species richness of bees and pollinator groups combined, while alfalfa (Medicago sativa L.) attracted the highest lepidopteran abundance and species richness. We also found a significant, positive relationship between pollinator abundance and floral resource amount and bloom duration. These findings offer valuable insight into the impacts of different land management strategies on different pollinator groups, and thus provide landowners with management options for attracting specific pollinator groups and species. [ABSTRACT FROM AUTHOR]

Pollinators are an essential component of terrestrial food webs and agricultural systems but are threatened by insufficient access to floral resources. Managed honey bees, as generalist foragers that hoard nectar as honey, can act as bioindicators of floral resources available to pollinators in a given landscape through their accumulation of honey. Honey yields across the United States have decreased appreciably since the 1990s, concurrent with shifts in climate, land-use, and large-scale pesticide application. While many factors can affect honey accumulation, this suggests that anthropogenic stressors may be having large-scale impacts on the floral resources that pollinators depend on for their nutrition. We used hierarchical partitioning on five decades of state-level data to parse the most important environmental factors and likely mechanisms associated with spatial and temporal variation in honey yields across the US. Climatic conditions and soil productivity were among the most important variables for estimating honey yields, with states in warm or cool regions with productive soils having the highest honey yields per colony. These findings suggest that foundational factors constrain pollinator habitat suitability and define ecoregions of low or high honey production. The most important temporally varying factors were change in herbicide use, land use (i.e. increase in intensive agriculture and reduction in land conservation programs that support pollinators) and annual weather anomalies. This study provides insights into the interplay between broad abiotic conditions and fine temporal variation on habitat suitability for honey bees and other pollinators. Our results also provide a baseline for investigating how these factors influence floral resource availability, which is essential to developing strategies for resilient plant–pollinator communities in the face of global change.

In temperate ecosystems, elevated temperatures, and drought occur especially during spring and summer, which are crucial periods for flowering, pollination, and reproduction of a majority of temperate plants. While many mechanisms may underlie pollinator decline in the wake of climate change, the interactive effects of temperature and water stress on the quantity and quality of floral nectar and pollen resources remain poorly studied. We investigated the impact of temperature rise (+3 and +6°C) and water stress (soil humidity lower than 15%) on the floral resources produced by the bee-pollinated species Borago officinalis. Nectar volume decreased with both temperature rise and water stress (6.1 ± 0.5 μl per flower under control conditions, 0.8 ± 0.1 μl per flower under high temperature and water stress conditions), resulting in a 60% decrease in the total quantity of nectar sugars (mg) produced per flower. Temperature rise but not water stress also induced a 50% decrease in pollen weight per flower but a 65% increase in pollen polypeptide concentration. Both temperature rise and water stress increased the total amino acid concentration and the essential amino acid percentage in nectar but not in pollen. In both pollen and nectar, the relative percentage of the different amino acids were modified under stresses. We discuss these modifications in floral resources in regards to plant–pollinator interactions and consequences on plant pollination success and on insect nutritional needs. [ABSTRACT FROM AUTHOR]

[Display omitted] • We assessed bee–pollinators population and their interactions with flowering plants. • Bee species diversity and richness were higher in semi-natural habitats than disturbed habitats. • Plant-bee interactions and floral abundance were high in semi-natural habitats. • Thus, habitat management is vital for the survival of bee-pollinators. 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. [ABSTRACT FROM AUTHOR]

Despite the wide interest in flower colours, only after the end of the nineteenth-century studies started to comprise floral UV reflection, which is invisible to humans but visible to the major groups of pollinators. Many flowers and inflorescences display colour patterns, an important signal for pollinators, promoted by the presence of at least two different colours within flowers or inflorescences, including colours in the UV waveband. For Neotropical savanna plant species, we characterised floral UV features using UV-photography and reflectance measurements. We tested (i) whether floral UV features were constrained by their shared ancestry, (ii) whether floral UV features were associated with pollinators, and (iii) whether floral UV features were associated with floral traits mediating these interactions, including floral resource, type of attraction unit and presence/absence of non-UV colour patterns. Of 80 plant species, ca. 70% were UV-patternless, most of them UV-absorbing. Approximately 30% presented one of three types of UV-patterns: bullseye, contrasting corolla markings oriented toward floral resources or contrasting reproductive structures, which were all considered as floral guides. Floral UV features were phylogenetically constrained and were associated with pollinators, floral resources and attraction unit, but not with non-UV colour patterns. UV-patternless flowers were associated with most of the pollination systems, while UV-patterned flowers were mainly associated with bee-pollination. UV-absorbing flowers comprised the only category with hawkmoth- and butterfly-pollinated flowers, and a high percentage of hummingbird-pollinated species. Nocturnal pollinated species were also commonly UV-absorbing, except for one UV-reflecting bat-pollinated species and one beetle-pollinated species with UV-reflecting stigmas. All types of floral UV features were associated with nectar; however, flowers with contrasting reproductive structures were mainly associated with pollen. There was an association between UV-absorbing species and the presence of inflorescences and intermediate attraction units. Our results evince that phylogenetic relatedness can constraint floral UV features’ diversification, but combinations of evolutionary and ecological processes may be expected in this scenario.

Despite the wide interest in flower colours, only after the end of the nineteenth-century studies started to comprise floral UV reflection, which is invisible to humans but visible to the major groups of pollinators. Many flowers and inflorescences display colour patterns, an important signal for pollinators, promoted by the presence of at least two different colours within flowers or inflorescences, including colours in the UV waveband. For Neotropical savanna plant species, we characterised floral UV features using UV-photography and reflectance measurements. We tested (i) whether floral UV features were constrained by their shared ancestry, (ii) whether floral UV features were associated with pollinators, and (iii) whether floral UV features were associated with floral traits mediating these interactions, including floral resource, type of attraction unit and presence/absence of non-UV colour patterns. Of 80 plant species, ca. 70% were UV-patternless, most of them UV-absorbing. Approximately 30% presented one of three types of UV-patterns: bullseye, contrasting corolla markings oriented toward floral resources or contrasting reproductive structures, which were all considered as floral guides. Floral UV features were phylogenetically constrained and were associated with pollinators, floral resources and attraction unit, but not with non-UV colour patterns. UV-patternless flowers were associated with most of the pollination systems, while UV-patterned flowers were mainly associated with bee-pollination. UV-absorbing flowers comprised the only category with hawkmoth- and butterfly-pollinated flowers, and a high percentage of hummingbird-pollinated species. Nocturnal pollinated species were also commonly UV-absorbing, except for one UV-reflecting bat-pollinated species and one beetle-pollinated species with UV-reflecting stigmas. All types of floral UV features were associated with nectar; however, flowers with contrasting reproductive structures were mainly associated with pollen. There was an association between UV-absorbing species and the presence of inflorescences and intermediate attraction units. Our results evince that phylogenetic relatedness can constraint floral UV features' diversification, but combinations of evolutionary and ecological processes may be expected in this scenario. [ABSTRACT FROM AUTHOR]

Although urban gardens are often celebrated for supporting bee abundance and diversity within cities, little is known about how garden management and urbanization levels influence bee foraging behavior and ability to utilize resources within these landscapes. Specifically, the preferences and diet breadth of bees may depend critically on local and landscape conditions in human-managed, urban environments. To understand how foraging patterns and pollen preferences are influenced by urban landscape composition, we first examined if bees visit plants grown within urban gardens and second assessed the relationships between local floral resources, urban land cover, and pollen collection patterns, focusing on 20 community gardens across 125 km of the California central coast. We targeted a well-studied, essential native pollinator in this ecoregion, Bombus vosnesenskii, and analyzed pollen on the bodies of individuals collected in our study gardens to compare their contents to local and landscape garden composition factors. We found that greater landscape-level urban cover and greater plant species richness in the garden both drove higher within-garden pollen collection. We also found that B. vosnesenskii preferred ornamental plant species over highly available crop species in the gardens. Our study indicates that landscapes that support plant diversity, including both ornamental plants and sustenance-oriented food crops, promote greater within-garden pollen collection patterns, with likely benefits for urban garden food production. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work was to evaluate the variations in the stored food resources and in the number of immature bees in Apis mellifera hives used for apple (Malus domestica) pollination. The study was conducted in the municipality of Vacaria, in the state of Rio Grande do Sul, Brazil, with 40 hives, over two consecutive harvests. The evaluations were done in the hive brood frames before, during, and 45 days after a pollination period, by interpreting photographic field records. Before being transported to the orchards, the bees foraged primarily in areas with native forest or canola (Brassica napus) crop, in 2014/2015, and with native forest or eucalyptus (Eucalyptus sp.) reforestation, in 2015/2016. In both harvests, the percentage of food resources (honey and pollen) stored in the hives reduced significantly between the pre- and post-pollination periods, but there was no significant difference between the pollination and post-pollination periods. The greatest reduction in the storage of these resources was observed in the hives from the canola crop, which had a large supply of floral resources compared with the apple orchards. The hives most susceptible to population variations within the apple orchards are those from the canola crop, whereas those from areas with a lower food supply (forest and eucalyptus) show population gains in the apple orchards.

Some wild bees can persist in human‐altered habitats in the face of global wild bee decline. To date, however, little is known about why those bees can tolerate human disturbances. Here we hypothesized that wild bees living in human‐altered habitats could achieve their nesting resources and floral resources. Moreover, persistent provision of those resources could enhance their populations.The foraging areas of solitary, cavity‐nesting bees Anthophora waltoni were determined in two agricultural ecosystems with rich bee populations. The influences of seminatural habitats, nesting resources and farmlands on A. waltoni visit density were assessed by modelling bee density against landscape factors in 17 agricultural ecosystems. Moreover, temporal availabilities of those resources were measured across the last three decades.A. waltoni used vetch fields and field margins, instead of seminatural habitats, as foraging areas. The area of brick walls and the area of farmlands, as well as their temporal increases, synergistically positively influenced A. waltoni visit density on vetch flowers. The percentage of buildings and farmlands increased across the last three decades in spite of a slowdown in 5‐year growth of brick walls.The results demonstrated the synergistically positive effects of nesting resources and floral resources, as well as persistent provisions of those resources, on A. waltoni populations in agricultural ecosystems. A. waltoni could live in the human‐altered habitats because they persistently achieved their nesting resources and floral resources. [ABSTRACT FROM AUTHOR]

Pollen is the source of protein for most bee species, yet the quality and quantity of pollen is variable across landscapes and growing seasons. Understanding the role of landscapes in providing nutritious forage to bees is important for pollinator health, particularly in areas undergoing significant land-use change such as in the Northern Great Plains (NGP) region of the United States where grasslands are being converted to row crops. We investigated how the quality and quantity of pollen collected by honey bees (Apis mellifera L. [Hymenoptera: Apidae]) changed with land use and across the growing season by sampling bee-collected pollen from apiaries in North Dakota, South Dakota, and Minnesota, USA, throughout the flowering season in 2015–2016. We quantified protein content and quantity of pollen to investigate how they varied temporally and across a land-use gradient of grasslands to row crops. Neither pollen weight nor crude protein content varied linearly across the land-use gradient; however, there were significant interactions between land use and sampling date across the season, particularly in grasslands. Generally, pollen protein peaked mid-July while pollen weight had two maxima in late-June and late-August. Results suggest that while land use itself may not correlate with the quality or quantity of pollen resources collected by honey bees among our study apiaries, the nutritional landscape of the NGP is seasonally dynamic, especially in certain land covers, and may impose seasonal resource limitations for both managed and native bee species. Furthermore, results indicate periods of qualitative and quantitative pollen dearth may not coincide. [ABSTRACT FROM AUTHOR]

As garden plants in urbanized environments provide considerable diverse floral resources to pollinators, the availability of floral resources has changed as a consequence of increasing urbanization. Although pollinators often forage at different sites in response to spatiotemporal variations in floral resources, little is known about the differences in pollinator foraging between urban and nearby natural environments. We monitored the foraging patterns of bumblebees in open and forest habitats in two areas with and without urban gardens with respect to flowering phenology and the availability of floral resources in each habitat. Floral richness in the forest habitat decreased as the season progressed, with a peak in late spring to early summer, whereas floral resources in the open habitat increased late in the season. Thus, floral resources in the open habitat could compensate for seasonal declines in forest floral resources. In the urban area, which contained green gardens, floral richness in the open habitat was much greater than that in the forest habitat. This resulted in a relatively high density of bumblebees in the open habitat in the urban area compared with those in the natural area, which lacked green gardens. Visitation frequency of bumblebees to forest flowers decreased as the floral richness of the open habitat increased. These results suggest that although urban gardens are important foraging sites for pollinators, the high attractiveness of garden flowers reduces pollinator visits to wildflowers in nearby forests. This may result in reduced pollination of native flowers. [ABSTRACT FROM AUTHOR]

Foraging honey bees (Apis mellifera) seem to use the presence of conspecific foragers as cues for flower quality. However, there is disagreement regarding how a conspecific cue is perceived by other foragers (enhancement or inhibition). Most studies manipulate the total number of bees foraging in an arena or the presence or absence of a bee on a flower and then observe the behavior of one forager in response to a single conspecific, which does not reflect natural foraging. We tested how a range of conspecifics on flowers affected on which flowers foraging honey bees landed. We trained students from a biology class for non-STEM majors to collect data and tested whether the number of conspecifics on flowers influences on which flower foragers land. We found that foragers land more frequently on flowers occupied by more conspecifics, which supports the hypothesis that conspecifics are cues for local enhancement. Our results increase our understanding of how honey bees forage once at a flower patch. [ABSTRACT FROM AUTHOR]

Supporting managed honey bees by pasturing in natural landscapes has come under review due to concerns that honey bees could negatively impact the survival of wild bees through competition for floral resources. Critique and assessment of the existing body of published literature against our criteria focussing on studies that can support best management resulted in 19 experimental papers. Indirect measures of competition examining foraging patterns and behavior yielded equivocal results. Direct measures of reproduction and growth were investigated in only seven studies, with six indicating negative impacts to wild bees from the presence of managed honey bees. Three of these studies examined fitness impacts to Bombus Latreille and all three indicated reduced growth or reduced reproductive output. Because there is a severe lack of literature, yet potential that honey bee presence could negatively impact wild bees, exemplified with bumble bee studies, we advocate for further research into the fitness impacts of competition between managed and wild pollinators. Conservative approaches should be taken with respect to pasturing honey bees on natural lands with sensitive bumble bee populations. Correspondingly, forage opportunities for honey bees in managed, agricultural landscapes, should be increased in an effort to reduce potential pressure and infringement on wild bee populations in natural areas. [ABSTRACT FROM AUTHOR]

Abstract: Floral resources from native plants that are adapted to the local environment could be more advantageous than the use of nonnative plants. In Australia, there is a dearth of information on the benefits of native plants to natural enemies and their selectivity against pests. Accordingly, we examined the longevity of the parasitoids Diaeretiella rapae (McIntosh) and Cotesia glomerata (L.) (both Hymenoptera: Braconidae), and Diadegma semiclausum (Hellen) (Hymenoptera: Ichneumonidae) exposed to flowering shoots from Australian native plants which was compared with the nonnative buckwheat (Fagopyrum esculentum), often used in conservation biological control. Longevity of parasitoids was significantly enhanced by the Australian natives Westringia fruticosa, Mentha satureioides, Callistemon citrinus, Leptospermum cv. ‘Rudolph’, Grevillea cv. ‘Bronze Rambler’, Myoporum parvifolium, Lotus australis, and nonnative F. esculentum. The highest mean survival by native plant species was 3.4× higher for D. rapae with Leptospermum sp. and 4.3× higher for D. semiclausum with M. parvifolium. For C. glomerata, Grevillea sp. increased longevity by 6.9× compared with water only. Longevity of Plutella xylostella (L.) (Lepidoptera: Plutellidae), a major crop pest, was enhanced by all plants against which it was screened except Acacia baileyana, a species that had no effect on parasitoid longevity. Several Australian native plant species that benefit parasitoids were identified. None of the plant species provided a selective benefit to the parasitoid D. semiclausum compared with its host P. xylostella; however, the benefit of M. parvifolium and Grevillea sp. on the longevity of D. semiclausum was relatively higher compared with the pest. These results suggest the need for field studies to determine whether native Australian plants increase P. xylostella impact in nearby brassica crops. [ABSTRACT FROM AUTHOR]

This study aimed to assess the pollen availability and foraging behavior of visiting bees to identify the effective pollinators of Solanum lycocarpum at a forest fragment. Five flowers of each of two floral morphs were used to determine pollen viability using optical microscopy. Bees were collected during the first 15 minutes of every hour of collection and classified into large, medium and small. Behavioral observations were performed during the remaining 45 minutes. Both floral morphs presented high percentage of viable pollen, without much difference between them. A total of 322 bees from 12 species were collected. Visits were more frequent when the anthers were maintained. Epi charis flava, Centris scopipes and Oxaea flavescens, along with Centris analis had large body size and, due to the behavior presented, were considered effective pollinators of S. lycocarpum. The intense intraspecific and interspecific competition observed among visiting bees may be advantageous for S. lycocarpum reproduction. [ABSTRACT FROM AUTHOR]

Crane flies and microlepidoptera have been recorded as pollinators in unrelated orchid groups, but these insects have never been recorded in Epidendroideae, the most species-rich orchid subfamily, which includes one of the most diverse genera among Orchidaceae, Epidendrum. Based on data on phenology, floral morpho-anatomy, pollinators, pollination mechanisms and breeding system, the reproductive biology of E. avicula was studied in south-eastern Brazil. Epidendrum avicula possess osmophores that produce a citric fragrance at night. The flowers attract Tipulidae flies and several families of microlepidoptera that drink the nectar produced in a tube formed by the adnation of the labellum and column. As is common in Epidendrum, after removing the pollinarium, both crane flies and micro-moths get trapped by the proboscis, which frightens the insects and inhibits any possible intent to immediately visit another flower. The behavior of the pollinators on flowers, plus the retention of the anther cap by the pollinarium, results in a reduction in the occurrence of geitonogamy. Because E. avicula is self-incompatible, the consequence of pollinator behavior and the floral mechanisms tend to reduce the pollen loss. As far as we know, this is the first study to report the reproductive biology of a species of Epidendroideae pollinated by crane flies and microlepidoptera. Based on more recent concepts of plant-pollinator interactions, although E. avicula is pollinated by several species belonging to two distinct orders, suggesting an unspecialized pollination system is involved, nectar-seeking microlepidoptera and Tipulidae flies can be recognized as a single functional group. [ABSTRACT FROM AUTHOR]

Encyclia is a neotropical orchid genus distributed from Florida to South Brazil and comprises ~120 taxa, including Encyclia mapuerae (Huber) Brade & Pabst. Besides its diversity and wide distribution, conclusive data on pollinators and reproductive biology of this orchid genus is scarce. Furthermore, nothing is known about the production of floral reward in Encyclia but the pollinators of their species are assumed to be attracted through food deception. Based on data on phenology, floral morpho-anatomy, histochemistry, pollinators, pollination mechanisms, and breeding system, the reproductive biology of E. mapuerae was studied in a nature reserve at Central Amazonia, Brazil. The flowers of E. mapuerae show longitudinal lines on the labellum that act as a nectar guide. The secretory epidermis has papillae whose cells are covered by an ornamented cuticle. The subtended tissue is composed of a tree-layered collenchyma. The flowers attract several species of Hymenoptera. However, a single species of Centris was recorded as pollinator. The bees collect the nectar produced inside the cuniculus. When the bees leave the flower the pollinarium is attached to their heads. Encyclia mapuerae is self-compatible and pollinator-dependent. The reproductive success in natural conditions is low because of deficient pollen transference due to the scarcity of pollinators. As far we know this is the first study that reports and production of floral reward in Encyclia. This discovery provides new insights on the function of the cuniculus in Laeliinae, and sheds light on the evolution of floral rewards and pollination mechanisms within this diverse group of Neotropical orchids. [ABSTRACT FROM AUTHOR]