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Urban areas can be both detrimental for pollinators or function as suitable habitats, depending on the land-use type, the urban context and the pollinator group in focus. Urban green spaces, including gardens, parks or cemeteries can provide essential resources for a wide range of pollinator groups, like wild bees, hoverflies and beetles. Urban community gardens can be particularly structurally complex and harbour a diverse range of nesting and food resources for pollinators. However, we know little about how garden features may vary with the urban context of gardens and which specific garden features can increase the abundance of pollinators in general and of different pollinator groups. Over two summer seasons, we recorded garden features and pollinators using flower observations in 33 urban community gardens in Munich and Berlin, Germany. We examined how garden features differ amongst urban community gardens from three urbanisation categories, and analysed the effects of garden features such as floral and nesting resources and landscape imperviousness (as indicator of urbanisation) on pollinator abundance, richness and diversity. In more urbanised gardens, flower richness and bare substrate were less prevalent. Flower richness was positively correlated with overall pollinator abundance, richness and diversity as well as with the abundances of all pollinator taxa excluding beetles. Landscape imperviousness was negatively correlated with hoverfly and beetle abundances. Hoverflies also decreased with increasing bare substrate and wasp abundance decreased with increasing deadwood availability. Our findings highlight the important role of flower richness for insect conservation in urban management and show that pollinator taxa react differently to garden features and urbanisation. To support pollinating insects, gardeners can increase flower richness, especially in highly urbanised areas. [Display omitted] [ABSTRACT FROM AUTHOR]

• The field cultivation of oil tree peony experienced a "medium" pollination deficit. • Excluding pollinator pollination reduced the yield of oil tree peony by 44.24%, and oil tree peony showed a high dependence on bumblebee pollination. • Supplemental bumblebee pollination increased the seed yield of oil tree peony by 82.87% and the oil yield by 10.21%, which reduced the degree of pollination defects to a lower level. • Pollination by bumblebees ensures the stability of yield and quality of oil tree peony over time. Oil tree peony is a unique woody oil crop found exclusively in China. Its seed oil is a highly nutritious edible vegetable oil. However, its seed production varies greatly and is often low. Oil tree peony is a plant that relies on insects for pollination, but inadequate pollination is a common occurrence. In this study, we focused on the Paeonia ostii 'Fengdan' species and conducted a five-year study (from 2017 to 2022) in Luoyang, China. Our objective was to assess the extent of pollination deficiency and dependence, as well as quantify the contribution of supplemented bumblebees (Bombus terrestris) to the yield of oil tree peony. We also examined the effect of supplemented bumblebees on the temporal variation in yield through various pollinator survey designs, including supplemented bumblebees (BP), open pollination (OP), pollinator exclusion (EP), self-pollination treatments (SP), and artificial cross-pollination (CP). The results revealed a medium pollination deficit (D = 0.50) at the study sites for three consecutive years from 2020 to 2022, indicating limited pollination for oil tree peony under natural conditions. Importantly, BP significantly compensated for this deficiency (D = 0.22). Over the course of five years, BP increased the yield of oil tree peony by 82.87% on average compared to EP. Furthermore, the yield variation coefficient of EP (CVt=0.20) increased by 100% compared to BP (CVt=0.10). And we also observed significant variability in other yield parameters. Additionally, oil tree peony production was reduced by 44.24% in the absence of flower visitors, and the dependence on BP reached a "high" level. The fatty acid content in the seed oil did not show significant differences across treatments, indicating its stability. Overall, our pollination practices demonstrate that supplementing bee pollination can provide sufficient and stable pollination services, resulting in a higher and more stable yield of oil tree peony seeds. [ABSTRACT FROM AUTHOR]

• Specialised plant pollination systems can suffer reduced fertility if they receive insufficient pollinator service. • The Cape endemic Cyanella alba possess specialised floral adaptations – mirror-image flowers and dimorphic anthers – usually associated with buzz pollination by bees. • Experimental pollinations demonstrated that plants possess ovarian self-incompatibility and depend on pollinators for cross-pollination. • Chronic pollen limitation of seed set owing to the near absence of visitation by buzz pollinating bees was evident in several natural populations. • Land use and climate change may explain the paucity of buzz pollination with implications for ecology and evolution of plant populations. Plants with specialised pollination systems may be susceptible to reduced fertility if they are incapable of autonomous self-pollination and are visited infrequently by pollinators capable of promoting effective cross-pollination. Here, we investigate this question by examining the reproductive ecology of the Cape endemic Cyanella alba subsp. flavescens (Tecophilaeaceae), which has mirror-image flowers (enantiostyly) and dimorphic anthers (heteranthery). These traits are usually associated with buzz pollination mediated by bees that extract pollen from the poricidal anthers of flowers through vibration. We quantified insect visitation to flowers in three populations over two years in the vicinity of the Biedouw Valley, Western Cape, South Africa to determine whether plants were visited by buzz-pollinating bees. We also recorded visits by pollinators to other co-flowering species at each site and constructed a network on insect visitation. We conducted controlled hand pollinations and bagging experiments to determine whether plants were self-compatible and capable of autonomous self-pollination, and compared natural levels of fruit and seed set with those obtained from hand cross-pollination to evaluate evidence for pollen limitation of seed fertility. Despite 74 h of field observations, only two actively buzz-pollinating bees were recorded visiting flowers, although they were observed visiting other species in the community. The most frequent visitors to C. alba were opportunistic pollen-consuming beetles although we obtained no direct evidence that they were effective in promoting cross-pollination. Plants in each population exhibited chronic pollen limitation of seed set. Controlled pollinations demonstrated that plants were moderately self-sterile and incapable of autonomous self-pollination. Although fruit set was high following self-pollination, few seeds were evident within developing fruit. Observations of pollen-tube growth following controlled hand self- and cross-pollination revealed abundant pollen tubes at the base of styles in both treatments. Thus, self-sterility in C. alba probably results from late-acting ovarian self-incompatibility, and possibly also the abortion of developing seed due to inbreeding depression. We discuss the possible causes of scarce buzz pollination in C. alba and consider its ecological and evolutionary consequences. [ABSTRACT FROM AUTHOR]

• Tritoniopsis parviflora has three different floral rewards to attract pollinators. • The protandrous flowers secreted oil and nectar temporally segregated. • None of the oil bees predicted were observed on flowers along geographical distribution. • The potential bi-modal pollination system did not ensure high reproductive rates. Pollination in the South African species Tritoniopsis parviflora is of particular interest as it is the only oil-producing member of Iridaceae outside the Americas and the only species in the family known to secrete both floral oil and nectar. We evaluated oil and nectar secretion dynamics of T. parviflora, identified floral visitors and characterized their foraging behavior, and quantified reproductive success. Chemical and anatomical analyses suggest temporal segregation in rewards offered in male and female phases of the protandrous flowers. The diacetin amount was vestigial and none of the bees observed on flowers were specialist oil-collecting bees. Fruit set in the four studied populations was very low (c. 16 % of flowers). These results suggest that the T. parviflora pollination may be ensured by different functional bee groups and the visits by nectar-feeding and pollen-collecting bees may have been supplementary for seed production in the study period in conditions of low abundance of oil bees. The diversity of rewards in T. parviflora may serve as a form of bet-hedging that allows for pollination by generalist bees in the face of unreliable pollination service by specialist oil-collecting bees. [ABSTRACT FROM AUTHOR]

• Xylocopid bees were the only pollinators of four commercially important Cyclopia species (C. maculata, C. subternata, C. intermedia and C. genistoides). • Honey bees were ineffective pollinators of Cyclopia owing to their inability to trip Cyclopia flowers and gain access to the floral reproductive parts. • Nectar measurements revealed low volume of nectar production with varied sugar concentration across species of Cyclopia. • The value of native non- Apis insects for crop pollination in a changing world is highlighted in Cyclopia. Pollination is an important ecosystem service. Animal-mediated pollination (mostly insects) increases the production of 35% of global crops. Honey bees (Apis mellifera) are considered important crop pollinators globally, but are under pressure and therefore the value of wild pollinators for crop production is receiving more attention. The importance of pollinators (including non- Apis) has been extensively studied in the agricultural sector of South Africa, however little research is available on the pollination of indigenous crops. With the considerable value of the indigenous honeybush (Cyclopia Vent.) in the tea industry, it is important to determine the pollinators since Cyclopia is widespread across the fynbos biome and the pollinators are largely unknown. Here we ask whether carpenter bees (xylocopid bees) are the only pollinators of commercially important Cyclopia species, or if honey bees contribute to pollination. Floral observations and camera trapping confirmed that six species of xylocopid bees were the only pollinators of four commercially important Cyclopia species. Honey bees were observed to be ineffective pollinators of Cyclopia owing to their inability to trip Cyclopia flowers and gain access to the floral reproductive parts. Similarly, an additional seven species including Diptera, Apidae and Lema sp. were unable to gain access to Cyclopia flowers, although were observed visiting. Nectar measurements revealed the highest nectar volume in C. genistoides, while C. intermedia had the highest nectar sugar concentration (above 35% for all species). The value of native non- Apis insects for crop pollination in a changing world is highlighted in Cyclopia, an indigenous legume gaining traction in the global tea market and therefore in cultivation. [ABSTRACT FROM AUTHOR]

How farms and the surrounding landscape are managed locally substantially affects biodiversity, with consequent impacts on the supply of certain ecosystem services, such as pollination. Wild bees provide pollination services for small-scale horticultural farming, and are key to determining and improving farm production, as well as maintaining ecosystem-level diversity. Here, we investigated how landscape composition and agroecological practices affect wild bee community in small-scale horticultural farms. The study was conducted at 16 horticultural farms in the northern part of Madrid. The pan-trapping method was used to collect wild bees during the flowering period of horticultural plants. We interviewed farmers to identify which agroecological practices were primarily adopted to attain a resilient ecosystem. The most common practices adopted were weed control methods, natural fertilizer usage, pest control, and crop diversification. In total, 109 wild bee species were identified, and included individuals from all six bee families present on the Iberian Peninsula. One genus (Lasioglossum) was highly abundant, accounting for 68% of individuals, and is a known ground nester. Areas of sparse vegetation and bare soil and forested areas primarily enhanced the richness of bee species. On the other hand, abundance of wild bees is enhanced by pasture and forest areas. The presence of these habitats in areas surrounding farms might represent the potential nesting sites with important resources for wild bees. Small-scale horticulture production promotes landscape diversity, which strongly promotes the potential of different ecosystem services, including pollination and wild bees. Thus, implementing agroecological practices could transcend farms, and individual fields, to the landscape level, providing long-term sustainability of ecosystems. [ABSTRACT FROM AUTHOR]

• Habitats in urban areas with low levels of urbanization are particularly valuable for bee diversity. • Conservation of traditional meadow habitats, such as sheep fescue dry meadows and meadows on bedrock also support bee diversity. • Strategies for enhancing diversity of bees should focus on oligolectic and cavity-nesting species, as well as kleptoparasites. • To support populations of pollinating insects in urban regions requires management of semi-natural grasslands against overgrowth and encroachment. Bees constitute a key taxon of grassland ecosystems and are the main providers of the essential Ecosystem Service of pollination. We studied bee assemblages of 17 grassland sites in Helsinki, Finland. Bees were sampled using coloured pan traps. The total catch comprised 353 individuals of 35 species. The most abundant species were Lasioglossum leucopus, Lasioglossum lucidulum and Bombus lucorum complex. We used NMDS ordination to depict habitat associations, and GLMM to model the responses of species and trophic groups to habitat type and level of urbanization. Polylectic ground-nesting species were the most abundant trait group. There were only few records of oligolectic species, which showed a significant preference for areas with the lowest level of urbanization. We recommend the provision and maintenance of a diverse range of grassland habitats, with particular attention to the conservation of late successional meadow habitats. [ABSTRACT FROM AUTHOR]

The key role of wild bees in providing pollination services is well recognized. Most wild bees nest in the ground and need suitable nesting habitat to thrive. Despite covering 14 million km2 of the world's surface, the potential of arable land as a nesting habitat has been largely neglected, although studies indicate that ground-nesting bees nest in arable soils. Therefore, it is important to understand the impact of tillage on bees' nesting and reproductive success. Here, we synthesize the existing knowledge of potential consequences and mechanisms underlying tillage effects on ground-nesting bees, identify knowledge gaps, and propose directions and approaches for future research. Our literature review has identified ten studies that directly or indirectly assessed impacts of tillage on ground-nesting wild bees in arable cropping systems, showing either no effect or a negative effect of tilled compared to no-till systems. Potential tillage effects include direct impacts related to physical injury of bees, offspring, and brood cells, destruction of nest burrow architecture, displacement of brood cells, and alteration of soil environmental conditions surrounding brood cells, as well as indirect effects related to soil cover, soil properties, and soil conditions. Our review highlights that we poorly understand how tillage influences bee nesting incidence, survival, emergence timing, offspring sex ratio, and, in the longer term, community composition. In particular, it remains unclear whether tilled arable soils are suitable nesting habitat or ecological traps for ground-nesting bees. To address these research gaps, we propose methods to directly quantify nesting and emergence of bees, and (semi-)field and laboratory experiments that allow to disentangle mechanisms driving tillage effects. Improved understanding of tillage effects and underlying mechanisms will help to develop more effective strategies to promote ground-nesting wild bees and the crop-pollinating and soil ecosystem services they provide through their foraging and nesting activities. • Various ground-nesting wild bee species nest in arable soils. • Review of effects of tillage and underlying mechanisms on ground-nesting bees. • Several direct and indirect tillage impacts on bee nesting and survival highlighted. • Novel methodological approaches are proposed to better understand tillage effects. • Understanding tillage impacts is needed to improve agricultural policy. [ABSTRACT FROM AUTHOR]

Insect pollinators provide important crop pollination services but are declining in response to lack of diverse flower resources and exposure to pesticides. Despite increasing evidence that the benefits of insect pollination for crop production depend on other ecosystem services and crop management practices, investigations have mostly been limited to how pollination benefits are affected by insect pest control and soil fertility levels. Here we used a factorial cage experiment in the field to test how pollination by bumble bees, manual weed removal and fungicide application interactively shape faba bean (Vicia faba) yield components, and how weed removal and fungicide application affect bumble bee foraging behaviour. We found that insect pollination and weed removal increased faba bean yield components mostly additively, with insect pollination being the most important factor to maximise yield. The fungicide treatment did not affect crop yield, probably due to the low fungal pathogen incidence in the experiment, but instead affected bumble bee visitation behaviour. Bumble bees visited flowers of fungicide-sprayed plants more often than fungicide-free plants. This has potential consequences on bee health that should be further assessed. Guidelines on pesticide use should be improved by weighing benefits to agricultural productivity against risks for pollinators according to integrated pest and pollinator management principles. Our results emphasise that insect pollination can be an important factor for crop yield. The additive benefits of insect pollination and weed removal to crop yield indicates that they are crop production factors which can be managed for independently. • Insect pollination and weed removal increased faba bean yield additively. • Insect pollination enhanced yield more than weed removal. • Fungicide use did not affect yield components. • Bumble bees visited fungicide-sprayed plants more often than fungicide-free plants. [ABSTRACT FROM AUTHOR]

Pollinating insects rely on floral resources for survival and reproduction. Early flowering plants offer food resources for pollinating insects when floral resources are scarce, but they may also distract pollinating insects from pollination-dependent crops. Here we assessed how the abundance of bees and the pollination success of Korla fragrant pear (Pyrus sinkiangensis) is influenced by early flowering apricot trees within pear orchards or in the landscape at large, and how this influence is moderated by apricot flowering. The abundance of bees was measured using colored pan traps and pollination success was assessed by recording the initial fruit set and seed set. The density of apricot trees and land use types in radii of 0.5, 1.0, 1.5, and 2.0 km around focal pear orchards were assessed by landscape survey. The abundance of wild bees and honeybees was significantly higher in pear orchards with interspersed apricot trees than in mono-pear orchards. Pear trees next to an apricot tree row (5 m) had significantly higher wild bee abundance than pear trees at further distances (15 m, 30 m, 50 m, and 100 m). However, the positive effect of apricot trees on bee abundance in pear trees was only observed during apricot blooming, and the presence of apricot trees within or adjacent to pear orchards did not influence pear pollination success. The density of apricot trees in the surrounding landscape of pear orchards did not influence bee abundance and initial fruit set in pear orchards but it decreased seed set. Overall, our findings indicate that apricot trees in pear orchards can enhance bee abundance, but this effect only occurs at a relatively small spatial scale and during a short time span, and does not result in marked differences in pollination success. This indicates that flowering resources need to be close to or within the focal crop to have a positive effect on pollinating insect abundance. • Scattered apricot trees in pear orchards increased abundance of wild bees in pear orchards. • Apricot tree rows increased the abundance of wild bees on the adjacent pear trees, but not on pear trees further away. • The positive effect of apricot trees on bee abundance was only observed during apricot blooming. • Increased bee abundance did not lead to increased fruit set in pear. • Apricot tree density at the landscape scale did not influence bee abundance in pear orchards. [ABSTRACT FROM AUTHOR]

• Cayaponia (Cucurbitaceae) is a genus occurring in American and African continents, and contains bee- and bat-pollinated species. • Two species previously regarded as being bat-pollinated actually are bee-pollinated: Cayaponia cabocla and C. pilosa. • Both Cayaponia species are visited and pollinated by nocturnal and diurnal bees, the nocturnal ones arriving at dawn. • These findings allow to properly place these two Cayaponia species within the current evolutionary hypothesis. The evolution of pollination systems is unclear for many plant taxa due to the scarcity of field observations on floral visitors. Supposed bat- and bee-pollination is reported for species of the genus Cayaponia , but <5 % of these were observed in the field and their pollinators recorded. We studied the pollination biology of two early diverging sister species of Cayaponia, C. cabocla and C. pilosa , recording the floral biology, phenology, breeding system, floral visitors, and floral scent chemistry. Both species are monoecious and have bell-shaped white to greenish flowers. The length of the C. cabocla flowers was 2.33 ± 0.52 cm and of the C. pilosa flowers it was 2.75±0.95 cm. In C. cabocla nectar volume of male flowers was 180±57.15 μl and sugar concentration was 28.75±0.95%, whereas in female flowers the average volume was 46.5 ± 10.24 μl and sugar concentration was 22.5 ± 0.57%. Cayaponia cabocla flowers opened at late night, around 03:30 h, whereas those of C. pilosa opened around noon. Both species bloom in the austral summer (January-February) and depend on bees to set fruit, in addition to having a few floral visitor species in common. Whereas some of the flower traits resemble those of bat-pollinated plants (most notably the large nectar volume and nocturnal anthesis), the floral volatiles of both C. cabocla and C. pilosa are typical of flowers pollinated by bees. This study clarifies the pollination system of two Cayaponia species and provides new information that can be used to reconstruct pollination system transitions in this rich genus of cucurbits. [ABSTRACT FROM AUTHOR]

• Diversity and spatial arrangement of cultivars can influence pollination and yields. • Pollinator behavior interacts with spatial arrangement to affect pollination. • Blueberry yields were highest when cultivars were mixed within rows. • Yields were lowest in single-cultivar plots. • Bumble bees and honey bees switched between cultivars more when mixed within rows. Bees can facilitate cross-pollination in crops by moving pollen between distinct crop genotypes or cultivars, with pollination success dependent on both bee behavior and planting arrangement. Previous research suggests that bees forage primarily along crop rows, and deposit pollen relatively close to its source, which suggests that cross-pollination would be enhanced by mixing cultivars within crop rows at relatively fine spatial scales. However, minimal research has explored how bee-mediated cross-pollination is influenced by cultivar diversity and planting arrangement. In this study, we examined the effects of cultivar diversity and planting arrangement on bee-mediated cross-pollination in southern highbush blueberry. We used potted plants to create three arrangements including 1) single cultivar, 2) mixed cultivars across rows, and 3) mixed cultivars within rows, and observed bee visitation rates and behaviors across arrangements, and measured the number of fruit and fruit mass per flower across selected branches as indicators of pollination success and yield over two years. While the number of fruit was not affected by planting arrangement, fruit mass was highest in the mixed-within rows arrangement, 39 % higher than in the single cultivar arrangement. Mixing cultivars across rows resulted in intermediate fruit mass, which was 21 % higher than in the single cultivar arrangement. Additionally, we found that both bumble bees and honey bees were twice as likely to move between cultivars when cultivars were mixed within rows as compared to across rows. These results were further supported by a greenhouse experiment showing fruit mass per flower was higher with cross as compared to self-pollination by 20–38 % depending on pollen donor. Combined, data show that blueberries benefit from cross-pollination and mixed cultivar plantings and suggest that yields are optimized when cultivars are mixed within rows due to greater cross-cultivar movement by bees. [Display omitted] [ABSTRACT FROM AUTHOR]

Bees play a crucial role as pollinating insects in both natural and cultivated areas. However, the use of pesticides, such as thiamethoxam, has been identified as a contributing factor compromising bee health. The current risk assessment primarily relies on the model species Apis mellifera , raising concerns about the applicability of these assessments to other bee groups, including stingless bees. In this study, we investigated the acute toxicity of thiamethoxam on the stingless bee Frieseomelitta varia by determining the average lethal concentration (LC 50) and mean lethal time (LT 50). Additionally, we evaluated the enzymatic profile of Acetylcholinesterase (AChE), Carboxylesterase-3 (CaE-3), and Glutathione S-Transferase (GST), in the heads and abdomens of F. varia after exposure to thiamethoxam (LC 50/10). The LC 50 of thiamethoxam was determined to be 0.68 ng ai/μL, and the LT 50 values were 37 days for the control group, 25 days at LC 50/10 , and 27 days at LC 50/100. The thiamethoxam significantly decreased the survival time of F. varia. Furthermore, the enzymatic profile exhibited differences in CaE3 activity within one day in the heads and ten days in the abdomen. GST activity showed differences in the abdomen after one and five days of thiamethoxam exposure. These findings suggests that the abdomen is more affected than the head after oral exposure to thiamethoxam. Our study provides evidence of the toxicity of thiamethoxam at both the cellular and organismal levels, reinforcing the need to include non-Apis species in pollinator risk assessments. and provide solid arguments for bee protection. [Display omitted] • The LC 50 of thiamethoxam for the stingless bee Frieseomelitta varia is 0.68 ng ai/μL. • LC 50/10 and LC 50/100 of thiamethoxam shortened F. varia lifespan by 11 ± 1 days. • Thiamethoxam affected the enzymatic activity of GST in the abdomen of F. varia. • The enzymatic activity in the abdomen is more affected than in the heads of F. varia. [ABSTRACT FROM AUTHOR]

• Honey bees increased yield for five commonly planted blueberry varieties • Blueberry yields still show a pollen deficit • Honey bees can be effective pollinators of blueberries in areas which lack bumble bees • Benefit of bees and pollination deficit differs between varieties Agricultural crops are often dependent on insect pollination for commercially viable yields. Blueberries are an example of such a crop and owing to their proposed health benefits they are grown around the world, including locations where their native bumble bee pollinators do not occur. In the absence of bumble bees, blueberry pollination in South Africa and many other parts of the non-native, commercial range is performed primarily by honey bees. Despite this, the effectiveness of honey bee pollination on blueberries remains understudied. This study determined the effect of honey bee pollination on components of fruit yield (fruit set and mass) of five blueberry varieties that are extensively planted in South Africa. For each variety, two metrics were calculated: 1) the benefit of bees — a comparison of fruit yields after exposure to honey bees and fruit yields after honey bee exclusion, 2) the pollination deficit — the difference in yield between hand pollination (maximum yield potential) and yields after exposure to honey bee pollinators. Honey bee pollination consistently resulted in improved yields, although the magnitude of this improvement (i.e., the benefit of bees) was dependent on the variety considered. Similarly, the pollination deficit also varied considerably across varieties and while some varieties appeared to perform close to maximum potential (small pollination deficit), others yielded well below their maximum potential under honey bee pollination. This study demonstrates that honey bees are functional pollinators of blueberries in areas where native blueberry pollinators are absent. However, in such areas, it is important that special focus is given to selecting blueberry varieties that perform well with honey bees as their primary pollinator. Further research is necessary to determine how the pollination deficit of blueberry varieties can be decreased as well as how to increase the effectiveness of honey bee pollination. [ABSTRACT FROM AUTHOR]

The yield of many agricultural crops depends on pollination services provided by wild and managed bees, many of which are experiencing declines due to factors such as reductions in floral resources. Thus, improving pollinator habitat on farmlands using management strategies like planting wildflower strips is vital for wild bee conservation and sustainable crop pollination. Yet, few studies have examined whether and at what spatial scales wildflower strips enhance crop pollination and yields, and most research has been conducted in large-scale commercial agriculture. Therefore, we investigated the effects of wildflower strips on crop pollination on small, diversified farms (i.e., those growing a variety of crop species) where wild bee diversity and abundance is predicted to be comparatively high. Over three years, on four diversified farms in Montana USA, we tested the hypothesis that distance (20, 60, and 180 m) of crops from native perennial wildflower strips planted alongside crop fields affected wild bee visitation, pollination, and yields of squash and sunflower crop plants. We found that distance to wildflower strips did not affect bee visitation or pollination in crops. Squash yield was pollen-limited in the growing season prior to wildflower strip establishment, and in one of the two years after wildflower strip establishment, but proximity to wildflower strips did not influence the magnitude of pollen limitation. Sunflower seed production was not pollen-limited in any year. Our findings demonstrate that even on diverse farms with wildflower strips and a demonstrated high diversity of bees, some crops do not necessarily receive maximum pollination, regardless of distance from the wildflower strips. However, the value of wildflower strips for supporting wild bee diversity, and other ecological or economic benefits, needs consideration for a full understanding of this pollinator habitat management strategy. [ABSTRACT FROM AUTHOR]

The Mesozoic is a key era for the rise of the modern insect fauna. Among the most important evolutionary events in Mesozoic insects are the radiation of holometabolous insects, the origin of eusocial and parasitoid insects, diversification of pollinating insects, and development of advanced mimicry and camouflage. These events are closely associated with the diversification of insect ecological behaviors and colonization of new ecospaces. At the same time, insects had evolved more complex and closer ecological associations with various plants and animals. Mesozoic insects played a key and underappreciated ecological role in reconstructing and maintaining terrestrial ecosystems. A greater understanding of the history of insects may help to mitigate future changes in insect diversity and abundance. Holometabolous insects underwent a distinct radiation during the Early–Middle Triassic because they were probably more resilient to environmental disturbance. Four lineages of insects (termites, ants, corbiculate bees, and wasps) had evolved eusociality at least by the Cretaceous. The Mid-Mesozoic Parasitoid Revolution, a dramatic radiation of parasitoid lineages during the Middle Jurassic to Early Cretaceous, is a major biological event in terrestrial food-web history. Insect pollination of gymnosperms was already widespread prior to the rise of angiosperms and was an evolutionary and ecological prelude to later interactions between early angiosperms and their insect pollinators during the mid-Cretaceous. Mimicry and camouflage among insects went through an increasingly sophisticated evolution in the Mesozoic in response to selective pressures. [ABSTRACT FROM AUTHOR]

Bees provide valuable pollination services by increasing crop yields. However, pollination services to crop quality – which often determines nutritional and financial value – have been less studied, particularly in tropical commodities such as coffee. Understanding how pollination affects coffee quality is critical because high-quality coffee on the specialty market fetches higher prices, which can potentially benefit farmers more than just focusing on yield alone. This study aimed to test the effects of bee pollination on coffee yield and quality and to evaluate possible trade-offs within them. We conducted bee-exclusion experiments on 30 coffee plants in the Tarrazú region of Costa Rica, controlling for several factors associated with coffee quality. At the end of the growing season, we harvested the berries and compared yield (that is, fruit set and weight) and quality (that is, the cup profiles of certified coffee tasters) among treatments. Our results indicate that bee pollination can lead to trade-offs in coffee production. Bee pollination significantly increased final fruit set by 9 % and the desired aroma scores by 2 %. However, these fruits weighed 7 % less than self-pollinated berries and displayed more body but less balance in their cup profiles. This is one of the first experimental studies to evaluate pollination services for coffee, considering not just yield but also its cup profile. We provide early evidence suggesting bee pollination improves coffee aroma, a critical quality attribute in specialty coffee. Our research emphasizes the importance of protecting or restoring bee habitats in coffee farms, which can not only improve income for coffee producers but also conserve biodiversity. Integrating these ecological insights into initiatives like 'bee-friendly' coffee production presents an innovative approach for stakeholders in the coffee supply chain and can serve as a strategic nexus of agricultural, economic, and ecological interests. [Display omitted] • Bee pollination not only increases coffee yields but also improves the quality of the roasted beans. • Bee-pollinated plants exhibited a 9 % higher fruit set and a 2 % enhancement in aroma and body, as assessed by professional cuppers, compared to self-pollinated plants. • Potential trade-offs exist: while aroma, body, and fruit set improve, the weight of the coffee berries is slightly reduced, and their balance scores in cupping decrease. • The importance of bees in coffee production expands beyond yield enhancement, as they also positively influence aroma—a crucial factor in the pricing of specialty coffee. • Protecting bee habitats on coffee farms can lead to better quality coffee and greater profits for farmers, while also contributing to biodiversity conservation efforts. [ABSTRACT FROM AUTHOR]

Insects contribute considerably to global crop pollination, with pollination deficits being documented for multiple entomophilous or pollinator-dependent crops. Different cultivars of crops are being cultivated within and across production regions, so it is essential to understand the cultivar variability of pollination deficits. Here, we used a dataset from 286 sites from multiple production regions to develop a synthesis on pollination deficits in two widely cultivated highbush blueberry cultivars, 'Bluecrop' and 'Duke'. Additionally, we determined if bee visitation or bee richness reduces pollination deficits in these cultivars. On average, neither cultivar showed pollination deficits regarding fruit set. However, for 'Bluecrop' we found pollination deficits for berry weight and seed set, which was not the case for 'Duke'. Increasing total bee visitation reduced pollination deficits of both berry weight and seed set for 'Bluecrop'. More specifically, a non-linear, negative exponential model best predicted this relation between bee visitation and pollination deficits. Our results highlight that pollination deficits and responses to pollinator visitation are variable between different cultivars of a single crop, which suggests opportunities to use certain cultivars that are less dependent on insect-mediated pollination in landscapes and regions where pollination services have been compromised. In addition, the non-linear response between bee visitation and pollination deficits suggests that optimal bee visitation rates need to be determined to improve pollination management and crop yield and to support accurate economic valuations of pollination services. • We synthesized pollination deficits for two cultivars of a single crop. • Pollination deficits were not detected for fruit set for both cultivars. • Berry weight and seed set deficits were detected and cultivar-dependent. • The relation of the pollination deficits with bee visitation was cultivar-dependent. • The latter was best predicted by a non-linear model, suggesting a saturation effect. [ABSTRACT FROM AUTHOR]

Native plants in Western Australia have been highly valued in urban environments due to their endemicity, adaptivity to local conditions and their positive impact on local identity. However, the process of urbanisation often leads to the destruction or significant alteration of native landscapes to meet amenity demands and diverse aesthetic preferences, ecological and functional requirements that vary across societies and over time. This paper examines the role of native and non-native plant species in urban areas of Western Australia with particular reference to the needs of bees (both honeybees and Australian native bees). The analysis draws on the perspectives, vision, and practical experiences of landscape practitioners, beekeepers, and ecologists specialising in native bees and plant pollination. The findings suggest that urban biodiversity in Western Australia inherently involves a combination of native and non-native plant species. Consequently, designing plant arrangements that attract a diverse range of pollinators, including both native and non-native bees, necessitates a specific approach. The results showing that all landscape practitioner respondents have used non-native plants in design practices and acknowledged them as a part of urban biodiversity in Western Australia. All ecologist respondents and 31 % of beekeeper respondents agreed on the existence of competition between native and non-native bees. While ecologist respondents emphasised the significance of native plants for native bees, they still hold positive attitude towards the use of non-native plants in urban landscapes. This research provides valuable guidance for designing urban landscapes that support a diverse range of pollinators and contribute to the conservation of biodiversity in Western Australia. Three key guidance for bee botanic garden plant selections are: (1) Promoting interdisciplinary research and collaboration; (2) Maximising site value and ecosystem integration when considering plant selections; and (3) Incorporating diverse plant collections for varied purposes, such as native plant collection, spontaneous gardens, orchards and preserved remnant bush gardens. [ABSTRACT FROM AUTHOR]

Protective crop covers are used extensively to protect high-value crops from bird and hail damage, however, these structures may present challenges for honey bees (Apis mellifera L.), the main pollinators in these systems. Some studies have indicated that protective covers result in declines in colony size and resource storage, but few replicated field trials exist. To determine the impact of protective cropping structures on honey bee brood production and resource storage, 14 honey bee colonies were placed inside and outside of protective covers on four blueberry (Vaccinium corymbosum and V. virgatum) farms in northern New South Wales, Australia. We measured changes in brood production, pollen and honey storage, hive weight and ambient hive temperature fortnightly over a 12-week period. Brood production, pollen and honey storage, and hive weight all displayed greater reductions within four weeks of placement under net cover, compared to hives outside of net cover. Although brood and honey metrics gradually increased in all hives during the remainder of the 12-week monitoring period, hives located under protective netting had relatively smaller gains in brood production and pollen storage when compared to hives located outside the protective covering. Hives under protective netting that were in the shade and/or whose entrances were facing south were most impacted by the end of the monitoring period. Our findings highlight the need for protected crop management strategies to consider pollinator health as well as crop pollination needs so that both bee health and pollination services are maintained in these systems. • The reported decline of bee colony strength under protective covers was tested. • Bee hives inside and outside protective covers were studied on blueberry farms. • Protective covers restricted bee access to diverse resources. • Brood production, pollen storage and hive weight declined under protective covers. • Protected crop management strategies must consider pollinator resilience. [ABSTRACT FROM AUTHOR]

[Display omitted] • The contribution of bees and syrphids to interaction network attributes is unclear. • We simulate the removal of bees with different traits and syrphids. • Bees have a key role increasing nestedness, interaction diversity, and stability. • Syrphids increase network specialization but have an overall secondary role. • Smaller bees and bees active for longer contribute more to temporal stability. Insect pollinators are key to maintaining biodiversity and providing important ecosystem services. Among them, bee species (i.e., Apidae) and hoverflies (i.e., Syrphidae) are two of the most important and well-studied taxa worldwide. Yet, their relative contribution to the structural and dynamic properties of plant-pollinator interaction networks remains poorly understood. This is an important gap in knowledge given that these phylogenetically and functionally different groups might play different roles within their communities and respond in contrasting ways to anthropogenic perturbations. Here, we study the relative contribution of bee species (with different traits) and syrphids to maintain network properties (i.e., nestedness, network specialization (H2), and interaction diversity) and their influence on the temporal dynamics of these network metrics. To this end, we simulate species removals in community-wide flower-arthropod visitor interaction networks. These interactions were extensively sampled across four years in two different near-pristine temperate ecosystems in Japan. We found that bee species contribute significantly more than syrphids or any random combination of species to network nestedness, low specialization, and interaction diversity across months and years. In addition, bees also played a particularly important role in maintaining the observed temporal dynamics over time. Conversely, although syrphids were an abundant and species-rich group, they did not contribute so prominently to network metrics or temporal dynamics, with the exception of network complementary specialization, to which they contributed positively. In addition, smaller bee species and those that were active for longer periods were particularly important for interaction diversity and the number of interactions, respectively, and to maintain observed network temporal dynamics. Our results support that bee species, and especially the small ones, are cornerstone contributors to plant-visitor communities by shaping network properties and network temporal dynamics in natural ecosystems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Varroa destructor prefers to invade the worker and drone larvae of Apis mellifera rather than Apis cerana. • There is a significant difference between the cuticular hydrocarbon profiles of worker and drone larvae of the two bee hosts. • Apis mellifera worker and drone larvae express significantly higher amounts of methyl-alkanes. • Apis cerana worker and drone larvae produce higher levels of alkenes. • The cuticular hydrocarbons on the larval body surface mediate the preferential cell invasion of Varroa mites. Honey bees (Apis) are important pollinators for food crops and wild plants, but are facing great threats from pathogens and parasites, especially an obligate ectoparasitic mite, Varroa destructor. Cell invasion is a key step for V. destructor to reproduce, and the parasite displays remarkable host preference in this process. Varroa destructor made its host-shift from its original host, the Asian honey bee Apis cerana, to the new host, the European honey bee Apis mellifera several decades ago. However, it remains largely unstudied whether V. destructor shows a cell invasion preference between the two host species. Using cell invasion bioassays on a modified four-well arena, we showed that V. destructor significantly preferred to invade the worker and drone larvae of A. mellifera rather than A. cerana , suggesting that the new host is much more attractive to the parasite than the original one. Using gas chromatography-mass spectrometry (GC-MS), we revealed significant differences between the cuticular hydrocarbon (CHC) profiles of worker and drone larvae of the two bee hosts. The amounts of methyl-branched alkanes and alkenes (unsaturated CHCs), but not n -alkanes, were significantly different, and A. mellifera worker and drone larvae were found to express significantly higher amounts of methyl-alkanes, while A. cerana larvae produced higher amounts of alkenes. Cell invasion bioassays with glass dummies showed that the mites preferred the glass dummies coated with the CHCs of A. mellifera worker or drone larvae, which indicates a role of larval CHCs in mediating the preferential cell invasion of Varroa. The findings from this study extend our understanding of the host preference of V. destructor , and can potentially contribute to the development of effective strategies for mite control. [ABSTRACT FROM AUTHOR]

• Aloe reitzii var. reitzii bears red flowers in summer, suggesting bird pollination. • Four specialist and five generalist nectar-feeding bird species visit the aloe. • Temporally separated sunbirds and weavers co-dominate day visitation. • Nectar properties reflect generalist nectivorous bird preferences. • Honeybees and beetles also visit during the day, and hawkmoths visit at night. Aloe reitzii var. reitzii is a summer-flowering (February–March) succulent, endemic to a restricted range within the heavily transformed grasslands of eastern South Africa. Floral structure and nectar properties suggest bird-pollination. This study investigated the temporal visitation events of birds to this aloe. Extensive camera observations during the 2017 flowering season (23 days) identified both specialist and generalist nectarivorous birds (n = four and five species respectively) as regular diurnal aloe visitors. Malachite Sunbirds (Nectarinia famosa) accounted for 49% of all visits, while Cape Weavers (Ploceus capensis) made up 41% of all visits; these species co-dominate visitation of the specialist and generalist avian feeding guilds respectively. In addition, visitation by each guild was separated temporally to some extent, with generalists mostly visiting early in the day, while specialists dominate afternoon visitation. Nectar volume (overall unbagged mean = 48.67 ± 4.70 µL) and concentration (overall unbagged mean = 10.68 ± 0.21% w/w) remains consistent throughout the day, and are within generalist nectar-feeding bird preferences, which may explain the abundance of Cape Weavers, despite floral morphological traits matching those of specialist nectar feeders. While many summer-flowering aloes are primarily insect- or sunbird-pollinated, Cape Weavers may be supplementing their diets with A. reitzii var. reitzii nectar, and potentially playing a crucial role in pollination. [ABSTRACT FROM AUTHOR]

Designing wildflower habitats to support beneficial insects providing pollination and pest control services is important for supporting sustainable crop production. It is often desirable to support both groups of insects, making the selection of resource plants for insect conservation programs more challenging. Moreover, the process of selecting resource plants is complicated by the array of possible options in each region, and the need to provide resources over the entire growing season. Identifying traits shared by resource plants that are attractive to both bees and natural enemies can reduce the need to evaluate new plants in each region, by providing a guide for the types of plants expected to be rewarding to these insects. Using insect visitation data collected from replicated common garden plantings of native wildflower and shrub species from the Great Lakes region of the United States, we found a high degree of correlation between the abundance of bees and natural enemies visiting native plant species. These results were used to identify a set of 15 plant species that can provide resources for these insects throughout the summer. Across all tested species, pollen quantity per flower and the week of bloom were positively correlated with some, but not all, taxonomic groupings of beneficial insects. In contrast, floral area was consistently positively associated with visitation of both natural enemies and wild bees. This trait is easy to document and can allow for efficient local testing of potential resource plants, providing a faster path to implementing insect conservation in working landscapes. [ABSTRACT FROM AUTHOR]

Camellia oleifera Abel is an economically-important, cross-pollinated oil tree grown commercially in China. Fruit set is greatly enhanced when animal pollinators are available in this system. Prior studies have shown that bees are the primary pollinators of Camellia oleifera , but we do not know which are the most effective. This study was conducted in Xinyu, Jiangxi province, China. Through tracking observation, we measured visit duration and the tendency of bees to visit new plants, critical for the self-incompatible C. oleifera. Further, we assessed pollen loads, pollen removal rates and pollen deposition per single visit to C. oleifera , as measures of pollination efficiency for comparing the managed honey bee (A. cerana) with wild bees (C. gigas and four Andrena species). Determining the pollination efficiency of bees is important for increasing fruit set and crop yield.The managed hongeybee Apis cerana has the longest single-visit time (92.40±8.31s) with a higher visit frequency to flowers on the same tree. The difference in duration was not significant between Apis cerana and three wild bee species (A. camellia, A. hunanensis and A. striata). Conversely, the pollen deposition of A. cerana was the lowest, significantly lower than that of four species of Andrena. Further, there were significant differences in the pollen load of six species: the amount of pollens on hind legs and body surface of A. cerana was much lower than in the wild bees. Compared with the four species of Andrena, Colletes gigas moved between plants more frequently. Given its large size, it also had the highest pollen load size, pollen removal and higher deposition rates, meaning it can essentially deposit more pollen across more flowers per unit time. The efficiency of Andrena striata Wu was relatively low compared to its congeners, which were similar. [ABSTRACT FROM AUTHOR]

To achieve maximised and sustainable crop productivity, it is critical that we develop crop-specific strategies for managing pollination. Honey bees (Apis mellifera) and stingless bees (Tetragonula carbonaria) are considered effective pollinators of macadamia (Macadamia integrifolia). The introduction of managed honey bee or stingless bee hives into orchards is likely to boost the numbers of these insects visiting flowers; however, there is a lack of published information and consensus regarding their management for pollination. Here, we identify factors that affect the distribution of both honey bees and stingless bees across cultivated macadamia, and establish whether increased flower visitation leads to higher nut set. A gradient of bee visitation rates was created by placing colonies on the ends of a four-hectare block, and mixed-effect models were applied to assess forager abundance and nut set with respect to distance from hive, time of day, cultivar, and floral display size. Distance from colony had a strong effect on stingless bee numbers, with >96% of individuals recorded within 100 metres of colonies, whereas the distribution of honey bees was more closely related to daily floral display: trees with greater numbers of flowers attracted more honey bees. Simplified surveys conducted in a further 17 macadamia blocks confirm that these are broadly occurring distribution patterns. Bee abundance alone did not significantly predict nut production; however, an indirect effect of bee visits to flowers is inferred, as nut production increased with size of floral display. To encourage a more even distribution of bees and uniform pollination, we recommend placement of stingless bee hives to maximise their distribution through a block (e.g. at 100-m intervals) and management practices that promote even distributions of flowers across trees. [ABSTRACT FROM AUTHOR]

[Display omitted] • Livestock pastures support diverse communities of wild bees and other insects. • Sheep grazing affects the diversity and community of wild bees and other insects. • Abundance and diversity of wild bees were higher in non-grazed relative to grazed plots. • Non-bee insects were more abundant in non-grazed compared with grazed pasture plots. Pollinators contribute to the establishment of perennial native forages, but little is known about the effect of grazing practices on pollinator abundance and diversity in livestock pasture ecosystems. Grazing reduces floral resources available to bees and other insects, and as a result, may influence their communities. The main objective of this study was to examine the impact of sheep grazing on bees and other non-bee insects in livestock pasture established with seed mixes of native forb/legume/grass and warm season grasses. Each pasture was divided into two halves (in a split-plot design) using an electric fence in which one plot was grazed and the other plot was non-grazed. Blue vane traps and a pair of yellow and blue pan traps were used for sampling bees and non-bee insects. A diverse array of bees (59 species) and non-bee insects (at least 93 species) were found in the livestock pastures. The abundance, diversity, and evenness of bee and non-bee communities were greater in non-grazed plots as compared to grazed plots. However, species richness, as measured by rates of species accumulation relative to sampling effort, was not different among treatments. Results show that a diverse community of bees and non-bee insects may be found in livestock pasture systems, but reduction in bee and non-bee insect diversity in grazed areas highlight the importance of strategic pasture management to support persistence of native forages and sufficient floral resources for pollinators at relevant scales. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pesticides contribute to decline of wild bees. • Pesticide mixtures can result in unpredictable interaction effects. • Development of new method for testing pesticide mixtures on bumblebees. • No effect of pesticide mixture on learning ability and flight activity of bumblebees. • Effects on solitary wild bees cannot be excluded. Bumblebees are among the most important wild bees for pollination of crops and securing wildflower diversity. However, their abundance and diversity have been on a steady decrease in the last decades. One of the most important factors leading to their decline is the frequent use of plant protection products (PPPs) in agriculture, which spread into forests and natural reserves. Mixtures of different PPPs pose a particular threat because of possible synergistic effects. While there is a comparatively large body of studies on the effects of PPPs on honeybees, we still lack data on wild bees. We here investigated the influence of the frequent fungicide Cantus® Gold (boscalid/dimoxystrobin), the neonicotinoid insecticide Mospilan® (acetamiprid) and their combination on bumblebees. Cognitive performance and foraging flights of bumblebees were studied. They are essential for the provisioning and survival of the colony. We introduce a novel method for testing four treatments simultaneously on the same colony, minimizing inter-colony differences. For this, we successfully quartered the colony and moved the queen daily between compartments. Bumblebees appeared astonishingly resilient to the PPPs tested or they have developed mechanisms for detoxification. Neither learning capacity nor flight activity were inhibited by treatment with the single PPPs or their combination. [ABSTRACT FROM AUTHOR]

The conservation of biodiversity hinges on the value humans place upon it. However, knowledge of how ordinary people perceive and value biodiversity remains limited. To address this gap, we conducted a multinational survey assessing people's perceptions of crop-pollination services provided by insects, one of the most economically significant ecosystem services provided by biodiversity. We administered a questionnaire in eight countries (Australia, Japan, Peru, the Philippines, South Africa, Spain, Turkey, and the United States) and investigated the perceived significance of crop-pollination services delivered by nine major groups of insects. We also estimated the actual economic contributions of crop-pollination services provided by each insect group by conducting a literature review and database analysis. We found large variations in perceived importance of insects' role in crop pollination among the eight countries, with recognition generally lower in more economically developed nations. Differences in perception levels were evident among the insect groups: insects estimated to have greater economic benefits through crop pollination tended to be identified as more important by respondents. However, the perceived contributions of insects favoured by people often exceeded their estimated actual economic importance. Conversely, the contributions of less-favoured insects such as flies and bugs to crop pollination were consistently underestimated. Our results underscore the existence of a gap between the actual value biodiversity provides and how people perceive it. Addressing this gap seems critically important, as it can lead to ineffective conservation efforts. • Perception of insect-mediated crop pollination services was assessed in eight countries. • This perception was lower in more economically developed nations. • Differences in perception levels were evident among different insect groups. • Insects favoured by people were overestimated in their role in crop pollination. • Biases in perceiving the value of biodiversity may influence future conservation efforts. [ABSTRACT FROM AUTHOR]

To mitigate the effects of habitat loss on bee conservation and crop pollination, farmers are encouraged to plant flowers along the edges of crop fields. However, it is unclear where and to what degree these flower plantings are effective. Recent studies suggest that flower plantings may be less effective if they are established in landscapes with either very low or very high amounts of non-crop habitat. Moreover, while field edge flower plantings often increase the abundance and richness of bees in field edges, it is unclear whether this improves crop pollination or bee nesting success, which could increase bee populations over time. In this study we examined how field edge flower plantings and the landscape context in which they are established affect wild bee conservation and crop pollination. Across two years we established flower plantings of 0.1–0.5 ha along the edges of 17 of 34 commercial cucumber fields arranged across a gradient of landscape complexity. We then measured wild bee abundance, richness, and crop pollination in and around cucumber fields with and without plantings and assessed the nesting success of stem-nesting bees. We found that both field edge flowers and landscape-scale non-crop habitat had independent, positive effects on bee abundance, richness, nesting, or crop pollination in one of the two years of the study, and that the effects of field edge flowers on bees and crop pollination were not influenced by the surrounding landscape. We also found that managing field edges in a way that maintains naturally-occurring flowers may matter as much or more than flower plantings for short-term increases in bee abundance and richness. However, certain species of planted flowers might be associated with improved bee nesting success, an outcome important for both bee conservation and sustained crop pollination. • Examined how flower plantings and landscape affect wild bees and crop pollination. • Local flowers and surrounding landscape had positive effects in 1 of 2 study years. • Effects of field edge flowers were not influenced by the surrounding landscape. • Managing field edges to maintain naturally occurring flowers is important. • Local flowers may improve success of stem-nesting bees. [ABSTRACT FROM AUTHOR]

• Honey bees significantly increase yield in blueberry variety Ventura. • Blueberry yields still show a pollen deficit. • Honey bees can be effective pollinators of blueberries in areas which lack bumble bees. Animal-mediated pollination is an essential ecosystem service on which over a third of the world's agricultural crops depend. Blueberry fruit production is highly dependent on animal pollination and although visited by a range of bee species in their native range and agricultural settings, bumble bees are thought to be their primary native pollinators. Demand for blueberries has increased in recent years due to their perceived health benefits. Consequently, blueberry cultivation has expanded well beyond their native and original agricultural range, including several regions where bumble bees are not present. In South Africa, like many areas in the world, honey bees are the only commercially available pollinators for blueberries because many countries ban the importation of bumble bees. This study aimed to determine the benefits of honey bee pollination on blueberry fruit yield for the variety Ventura by comparing yields of honey bee-pollinated flowers to flowers where pollinators were excluded. Our results show that honey bees significantly increased berry mass and diameter. We conclude that Ventura in South Africa can be pollinated by honey bees, and that honey bee pollination can be an effective substitute for bumble bees in areas where bumble bees are unavailable. We also determined the extent to which blueberry yields could be improved by comparing fruit yield under honey bee pollination to fruit yield achieved through hand pollination. We found that honey bee pollinated blueberry yields were lower than yields achieved through hand pollination, suggesting that there is potentially room to improve honey bee pollination. Furthermore, we offer a conceptual figure to demonstrate how yield obtained through pollinator exclusion, open pollination, and hand pollination relate to each other. Additional research is required to study how beneficial honey bees are to fruit yield on other blueberry varieties as the benefits of honey bees are likely to vary depending on the variety. [ABSTRACT FROM AUTHOR]

• Introduced honey bees dominated bee assemblages in protected Australian heathlands. • Metabarcoding revealed that honey bee pollen diets overlap with Tetragonula (stingless bees) and species of braUnsapis. • On average, honey bee individuals carried significantly more species of pollen than individuals of all other bee species. • Collectively, Australian native bees visited more plant species than introduced honey bees. The decline of both managed and wild bee populations has been extensively reported for over a decade now, with growing concerns amongst the scientific community. Also, evidence is growing that both managed and feral honey bees may exacerbate threats to wild bees. In Australia, there are over 1600 native bee species and introduced European honey bees (Apis mellifera) have established throughout most landscapes. There is a major gap in knowledge of the interactions between honey bees and native bees in Australian landscapes, especially floral resource use. Here we report on the pollen diets of wild bees in protected areas of coastal heathland, an ecosystem characterised by mass flowering in late winter and spring. We sampled bees within three sites and DNA metabarcoding was used to compare the pollen diets of honey bees and native bees. We recorded 2, 772 bees in total, with 13 genera and 18 described species identified. Apis mellifera was the most common species across all locations, accounting for 42% of all bees collected. Native bee genera included eusocial Tetragonula (stingless bees) (37%), and semi-social Exoneura and Braunsapis (19.8% combined). Metabarcoding data revealed both Tetragonula and honey bees have wide foraging patterns, and the bipartite network overall was highly generalised (H 2 ' = 0.24). Individual honey bees carried pollen of 7–29 plant species, and significantly more species than all other bees. We found niche overlap in the diets of honey bees and native bees generally (0.42), and strongest overlap with stingless bees (0.70) and species of Braunsapis (0.62). A surprising finding was that many species carried pollen from Restionaceae and Cyperaceae , families generally considered to be predominantly wind-pollinated in Australia. Our study showed introduced honey bee use of resources overlaps with that of native bees in protected heathlands, but there are clear differences in their diet preferences. [ABSTRACT FROM AUTHOR]

• Pollinator conservation is a topic of public concern. This study analyses public comments on policy to determine stance, sources, and main concerns. • We found the greatest concerns were for bees and pollination, but that the diversity of bees their role in pollination was not well understood. • Regulation of neonics and other actions to protect pollinators have broad which creates a rare opportunity for conservation policy and action. • We found very strong support for neonicotinoid regulation, with less than 5% opposed to the proposed policy. • We conclude to be effective support will need to be translated into evidence-based policy that addresses the threats at-risk pollinators face. Pollinator conservation is a major focus of current conservation attention and public policy. However, an understanding of the social dimensions of pollinator conservation is urgently needed for effective action. In 2014, Ontario became the first jurisdiction in North America to propose to regulate neonicotinoid pesticides, and the proposal included a draft Pollinator Health Action Plan with additional measures to protect pollinator species. We analyzed the 972 comments submitted on the proposal by individual citizens, determining each commenter's stance, source of information (if applicable), and main concerns. We found very strong support for neonicotinoid regulation, with less than 5% opposed. We also found that the greatest concerns were for bees and pollination services, but that the diversity of pollinating species and the relative contributions of various taxa to pollination was not well understood. Government regulation of neonicotinoid pesticides and other actions to protect pollinator health clearly have the broad support and great interest of the general public, which creates a rare opportunity for conservation policy and action. We conclude that, in order to be effective, broad support will need to be translated into nuanced, evidence-based policy that is focussed on native species and addresses the many threats at-risk pollinators face. [ABSTRACT FROM AUTHOR]

• Two co-flowering Erica species are both predominantly pollinated by Cape honey bees. • The two Erica species deposit their pollen on similar parts of the honey bee body. • Honey bees exhibit high levels of constant, non-random foraging. • Pollen purity on both honey bees and stigmas is high. Erica is the largest genus of the Cape Floristic Region (CFR) of South Africa, and multiple species often coexist. Species that co-flower and share a pollinator may suffer from reproductive interference through heterospecific pollen deposition, especially when such species are closely related. However, little is known about the mechanisms that enable coexistence of co-flowering Erica species that share pollinators. Here we focus on a site where two co-flowering Erica species which are both predominantly pollinated by Cape honey bees grow intermingled, to ask whether this is associated with flower constancy and/or differences in pollen deposition sites. Despite minor differences in sites of pollen deposition on honey bees, most pollen of both Erica species was found on the head and ventral thorax regions. Subsequent visits of honey bees were almost always to the same Erica species from which they departed, and were significantly more constant than expected from random foraging in two consecutive years. Based on differences in pollen types between the two species, we established that pollen loads carried by honey bees were between 67% and 99% species-specific, whereas pollen loads on stigmas were on average over 93% pure. We conclude that despite the superficial similarities of small-flowered Erica species, honeybees can use species-specific cues for constant foraging, which is associated with almost complete absence of heterospecific pollen transfer. Future analyses of pollen carryover rates could help to quantify the benefit of pollinator behaviour for plant fecundity, and inclusion of more study sites sampled throughout the Erica flowering season could shed further light on the importance of flower constancy for facilitating coexistence of Erica species in the CFR. [ABSTRACT FROM AUTHOR]

The impact of pesticides on insect pollinators has caused worldwide concern. Both global bee decline and stopping the use of pesticides may have serious consequences for food security. Automated and accurate prediction of chemical poisoning of honey bees is a challenging task owing to a lack of understanding of chemical toxicity and introspection. Deep learning (DL) shows potential utility for general and highly variable tasks across fields. Here, we developed a new DL model of deep graph attention convolutional neural networks (GACNN) with the combination of undirected graph (UG) and attention convolutional neural networks (ACNN) to accurately classify chemical poisoning of honey bees. We used a training dataset of 720 pesticides and an external validation dataset of 90 pesticides, which is one order of magnitude larger than the previous datasets. We tested its performance in two ways: poisonous versus non-poisonous and GACNN versus other frequently-used machine learning models. The first case represents the accuracy in identifying bee poisonous chemicals. The second represents performance advantages. The GACNN achieved ~6% higher performance for predicting toxic samples and more stable with ~7% Matthews Correlation Coefficient (MCC) higher compared to all tested models, demonstrating GACNN is capable of accurately classifying chemicals and has considerable potential in practical applications. In addition, we also summarized and evaluated the mechanisms underlying the response of honey bees to chemical exposure based on the mapping of molecular similarity. Moreover, our cloud platform (http://beetox.cn) of this model provides low-cost universal access to information, which could vitally enhance environmental risk assessment. [ABSTRACT FROM AUTHOR]

The parasitic mite, Varroa destructor , has shaken the beekeeping and pollination industries since its spread from its native host, the Asian honey bee (Apis cerana), to the naïve European honey bee (Apis mellifera) used commercially for pollination and honey production around the globe. Varroa is the greatest threat to honey bee health. Worrying observations include increasing acaricide resistance in the varroa population and sinking economic treatment thresholds, suggesting that the mites or their vectored viruses are becoming more virulent. Highly infested weak colonies facilitate mite dispersal and disease transmission to stronger and healthier colonies. Here, we review recent developments in the biology, pathology, and management of varroa, and integrate older knowledge that is less well known. Varroa destructor is an underestimated parasite: it is genetically labile, with multiple hybridization and dispersal events. Varroa is also a highly efficient vector of honey bee viruses and drives changes in virus distribution, prevalence, and virulence. Despite this, some Apis mellifera populations can survive without human intervention on all continents where varroa has dispersed. Scientists and specialist breeders are advancing marker-assisted selection techniques to enrich naturally occurring varroa-resistance traits in commercial stock – an approach predicted to be most effective when combined with culling susceptible colonies. Culling is identified as an effective means of removing both undesirable genetics and varroa-related virulence. [ABSTRACT FROM AUTHOR]

• Many traits are involved in the survival of honey bee populations towards Varroa. • Honey bee survival with Varroa infestations is largely explained by resistance mechanisms. • No common molecular pathways for resistance and tolerance were identified. • Understanding of the potential link between the different traits is needed. • Finding proxies of complex traits will facilitate phenotyping for honey bee survival against Varroa. The ectoparasitic mite Varroa destructor is the most significant pathological threat to the western honey bee, Apis mellifera , leading to the death of most colonies if left untreated. An alternative approach to chemical treatments is to selectively enhance heritable honey bee traits of resistance or tolerance to the mite through breeding programs, or select for naturally surviving untreated colonies. We conducted a literature review of all studies documenting traits of A. mellifera populations either selectively bred or naturally selected for resistance and tolerance to mite parasitism. This allowed us to conduct an analysis of the diversity, distribution and importance of the traits in different honey bee populations that can survive V. destructor globally. In a second analysis, we investigated the genetic bases of these different phenotypes by comparing 'omics studies (genomics, transcriptomics, and proteomics) of A. mellifera resistance and tolerance to the parasite. Altogether, this review provides a detailed overview of the current state of the research projects and breeding efforts against the most devastating parasite of A. mellifera. By highlighting the most promising traits of Varroa -surviving bees and our current knowledge on their genetic bases, this work will help direct future research efforts and selection programs to control this pest. Additionally, by comparing the diverse populations of honey bees that exhibit those traits, this review highlights the consequences of anthropogenic and natural selection in the interactions between hosts and parasites. [ABSTRACT FROM AUTHOR]

The preservation of pollinator habitat on croplands in the form of hedgerows, wildflower strips, and natural and semi-natural areas can help maintain and enhance wild bee populations in agricultural landscapes. However, there have been few comparisons of the effectiveness of different types of field-margin pollinator habitat in maintaining bee diversity and pollination of the focal crops. We compared wild bee abundance, species richness and community composition between strawberry crops bordered by hedgerows, and those bordered by larger expanses of natural land (forests). Strawberry is an ideal crop in which to investigate pollinator export from field margins as the rows are covered with straw, which reduces habitat for ground-nesting bees within the crop; thus, most wild pollinators need to enter the crop from the margins. We sampled bees in six strawberry fields with hedgerow margins and six strawberry fields with forested margins of at least 200 m in length, using a paired design. We examined strawberry pollen deposition at regular intervals into the fields, and the magnitude of pollinator export from the field margins towards the centre of the crops. We found that bees as a group were no more species-rich or abundant in crops bordered by forests than in crops bordered by hedgerows, although large-bodied bees were more abundant in the former than the latter. Regardless of field-margin type, we found that small wild bee abundance declined significantly from the edge to the centre of the crop, but honey bee (Apis mellifera L.) and large-bodied bee abundance did not. Strawberry pollen deposition also did not decline with distance into the crop. Although previous work indicates that small wild bees are more effective (yield-increasing) pollinators of strawberry on a per-visit basis, their limited foraging ranges suggest they may only pollinate areas near the crop margins, given typical field sizes in our area. [ABSTRACT FROM AUTHOR]

• The pollination behaviour of bumble bees is different than that of honey bees. • Bumble bee richness and abundance improve the pollination behaviour of honey bees. • Bumble' bees pollination behaviour was not influenced by bee richness or abundance. Pollination service in agricultural crops increases significantly with pollinator diversity and wild pollinator abundance. Differences in the foraging behaviour of pollinating insects are one of the reasons why pollinator diversity and abundance enhances crop pollination. Here, we focused on the foraging behaviour of honey bees and bumble bees in sweet cherry orchards. In addition, we studied the influence of bee diversity and abundance on the foraging behaviour of honey bees and bumble bees. Honey bees were found to visit fewer flowers than bumble bees. Bumble bees also showed a higher probability of changing trees between rows than honey bees. Both visitation rate and probability of row changes of honey bees increased with bumble bee diversity and with bumble bee abundance. We also found that the probability of row changes of honey bees increased with increasing bumble bee abundance. These effects of bumble bee richness and abundance on the pollination behaviour of honey bees can improve the pollination performance of honey bees in crops that depend on cross pollination. Our results highlight the higher pollination performance of bumble bees and the facilitative effect of wild pollinators to crop pollination. [ABSTRACT FROM AUTHOR]

Insects can exhibit flexible olfaction that is sensitive to complex natural chemical environments. Odorant-binding proteins (OBPs) in insects' antennal chemosensilla can act as transporters of plant volatiles and pheromones across the sensillar lymph. Although the physiological functions of OBPs have been widely reported, it is still unclear how OBP binds to ligands with various structures in detail. Here, we further investigated the ligand-binding modes and characteristics of AcerOBP2 from the Eastern honey bee (Apis cerana). The results showed that, as a specific protein distributed below the base of chemosensilla on the antennal surface, AcerOBP2 was strongly bound with the candidate floral volatiles and bee pheromones. By docking analysis and site-directed mutagenesis, four different binding modes were found in the five AcerOBP2 mutants between six ligands. Two key amino acids, Ser123 and Lys51, play a key role in AcerOBP2 binding to odors, depending on the presence or absence of hydrogen bonds. In addition, the binding modes depend on their chemical structures and the binding poses of the diverse ligands. These results not only further prompted the functional basis of the relationship between the chemical structures of odorants and bee OBPs, but also revealed the complexity of the flexible behavioral modes of odor binding in insect olfactory systems. • OBP2 is a specific protein distributed below the base of antennal chemosensilla. • OBP2 was strongly bound with the floral volatiles and bee pheromone components. • Four different binding modes were found in five OBP2 mutants between six ligands. • Ser123 and Lys51 play a key role in the binding of OBP2 to odors through H-bond. [ABSTRACT FROM AUTHOR]

• A two-archive-guided multiobjective artificial bee colony algorithm was designed. • The algorithm's convergence and exploitation abilities are enhanced. • Two archives are employed to enhance the search capability of the algorithm. • Results have shown that TMABC-FS is an efficient and robust optimization method. Since different features may require different costs, the cost-sensitive feature selection problem become more and more important in real-world applications. Generally, it includes two main conflicting objectives, i.e. , maximizing the classification performance and minimizing the feature cost. However, most existing approaches treat this task as a single-objective optimization problem. To satisfy various requirements of decision-makers, this paper studies a multi-objective feature selection approach, called two-archive multi-objective artificial bee colony algorithm (TMABC-FS). Two new operators, i.e. , convergence-guiding search for employed bees and diversity-guiding search for onlooker bees, are proposed for obtaining a group of non-dominated feature subsets with good distribution and convergence. And two archives, i.e. , the leader archive and the external archive are employed to enhance the search capability of different kinds of bees. The proposed TMABC-FS is validated on several datasets from UCI, and is compared with two traditional algorithms and three multi-objective methods. Results have shown that TMABC-FS is an efficient and robust optimization method for solving cost-sensitive feature selection problems. [ABSTRACT FROM AUTHOR]

• Quality of watermelon fruits produced on Panama crops increased with bee visits on flowers. • Flowers required a large number of visits to produce the best quality fruits, requiring at least 16 visits per flower. • The bee species depositing most pollen grains on the stigmas were Trigona corvina, Apis mellifera, and Nannotrigona perilampoides. • T. corvina contributed to the formation of more fruits, heavier fruits, and fruits with more seeds inside. • Bee Pollination efficiency didn't seem to depend on the bee size, but on bee behavior. This study evaluated the bee pollination efficiency of wild neotropical bees visiting watermelon flowers in Azuero, Panama. We determined the quantity of pollen grains deposited on stigmas of excluded flowers by Apis mellifera, Nannotrigona perilampoides, Trigona corvina, Trigona fulviventris , and Lasioglossum spp. We also determined the number of produced fruits and their quality by weighing and counting the seeds inside the fruits produced by 1, 8, 12, and 16 visits of A. mellifera, N. perilampoides, and T. corvina. Finally, we calculated Spear's Pollination Efficiency Index. We found differences in the pollen grain number deposited by the studied bee species. On average, T. corvina deposited the largest amount of pollen (n = 379 ± 35), and T. fulviventris deposited the least (n = 86± 20). The fruit weight and seed number showed a positive correlation with the number of visits the flowers received. No differences were observed in weight and seed number in the fruits visited by the three bee species. The best quality fruits were obtained with 16 visits and no visit restriction treatment, with no differences between them. Our results show the studied bee species are capable of efficiently pollinating watermelon flowers, and have the potential for being used in the pollination of local crops. However, the best production results are obtained when the bee species act together. [ABSTRACT FROM AUTHOR]

• Pan-traps were used to study the phenology of floral visitors and its resources. • The relationship between floral richness and floral visitor's abundance vary among orders. • Correlation between floral visitors' abundance and its resources vary between years. • Species composition of floral visitors and flowers varied between spring and summer. • Coastal ecosystems had an extended flowering season stabilizing inland communities. Precise monitoring of insect floral visitors and their relationship with floral resources throughout the flowering season provides baseline information to help us understand long-term changes in plant-pollinator interactions and improve pollinator conservation strategies. Pan traps are one of the methods most used for monitoring insect floral visitors and several studies have already linked the abundance and richness of these floral visitors with floral resources. However, less research has been conducted into the effectiveness of pan traps for monitoring phenological changes in the floral visitor community with regard to floral resources. We used pan traps to study the species composition and the abundance of insect floral visitors and their relationship with flower richness in a coastal forest throughout the entire flowering season for two consecutive years. Captures were confirmed to be floral visitors through field survey studies. Pan traps were effective for revealing changes in the abundance and species composition of floral visitor communities during and between years that correlated with changes in floral richness and species composition. Changes in floral visitor abundance showed a different bias in their association with floral richness. Thus, while Hymenoptera and Diptera abundance tended to be negatively correlated with floral richness, Coleoptera abundance tended to be positively correlated, although such correlations could change from year to year. There were two significantly different groups of flowering plant and floral visitor species: one in spring and the other in summer. Each period was characterized by unique overlap between some floral visitors and their floral resources, suggesting that to monitor floral visitors effectively both communities need to be considered. Interestingly, the floral phenology in this coastal forest extended longer than that of more inland communities, so reliable monitoring of floral visitors throughout the floral season may help us to better understand the role of coastal plant communities in the stabilization of the pollinator networks of more inland communities. Overall, phenology patterns need to be taken into account for pan trapping to become an effective methodology for monitoring floral visitor communities, considering both intra-year (spring and summer communities) and inter-year variations. [ABSTRACT FROM AUTHOR]

• Bee pollination is the most frequent pollination type in the studied vereda. • Flowering occurs throughout the year with a peak in September to November. • Resource availability differed among pollination types indicating temporal variation. • Pollination modes vary in their occurrence indicating habitat complementarity. Floral resource distribution, pollinator community structure, and flowering season are essential for maintaining and preserving pollination services in ecosystems. In humid Cerrado areas, veredas are considered hygrophilous communities, marked by the presence of the Mauritia flexuosa palm tree emerging in the wetter zones. Waterlogged portions present dense hygrophilous forests, whereas open areas predominant present herbaceous and shrubby components. We identified the pollination syndromes of woody species in a vereda ecosystem and characterized the pollination resource availability between habitats (hygrophilous forest and open area). The study was conducted on a vereda located in the north of Minas Gerais, Brazil. We characterized pollination syndromes using information on floral attributes, pollinator observations, and a literature survey. We performed phenological monitoring for 24 months and examined the occurrence of flowering using circular statistics. The differences in pollination syndrome occurrence among months and habitats were determined using modularity analysis. We found eight pollination syndromes, with melittophily being the most frequent pollination type among the woody species in the studied vereda. Flowering occurs throughout the year in the community and peaks from September to November during the transition from the dry to the wet season. In hygrophilous forest the species flowered preferentially in November, whereas in open area, preferentially between September and October. The syndromes distribution differed between the habitats, as well as resource availability. This difference between habitats can influence pollinator diversity. Modularity showed complementarity among the habitats, with continuous resource availability throughout the entire ecosystem. Species present in the hygrophilous forest provide their resources mainly during the rainy season, whereas species from the open area, during the dry season. Information on these interactions is necessary to understand the functionality of a vereda ecosystem, through the characterization of the resource's availability, and maintenance of pollination services in the ecosystem. In addition, our results demonstrate the importance of the vereda ecosystem as an important area in the availability of resources for the Cerrado formation. This information can strengthen protection laws and contribute to sustainable practices that boost the conservation of pollinators in the biome. [ABSTRACT FROM AUTHOR]

Broadcast spraying of antibiotics in crops is widely used for controlling bacterial plant pathogens. The effects of antibiotics on non-target (and especially beneficial) organisms in cropping systems, however, are not well studied. Pollinators are of particular concern because in pear and apple crops, antibiotics for controlling fire blight (Erwinia amylovora) are sprayed during bloom, likely exposing pollinators. This is especially relevant as laboratory evidence suggests that antibiotics could have sublethal effects on bee foraging behavior and colony health. But to our knowledge these potential impacts have not been studied in field settings. Here, we compared the effects of two fire blight control methods, a single spray of an antibiotic (oxytetracycline) and a biological antagonist (Aureobasidium pullulans), on honey bee (Apis mellifera) foraging, pollination, and fruit set in pear orchards. Complementing these field assessments, we conducted laboratory experiments to examine the effects of these treatments on locomotion and foraging behavior of a bumble bee species, Bombus vosnesenskii. We found that honey bees visited fewer flowers and foraged longer on each flower in orchards sprayed with antibiotics than with a biological product, but there were no differences in crop pollination and seed set. The pear cultivars we worked in, however, can self-pollinate. In the lab, we found that feeding on high doses of either the antibiotic or the biological antagonist reduced bumble bee foraging relative to controls. The limited impact of antibiotics on pear pollination observed in this study suggest that antibiotics pose a low economic risk to pear growers, especially for self-compatible cultivars. Still, crops with higher pollinator dependence may be affected by reductions in bee visitation. Future studies should examine the impacts of multiple antibiotic sprays within a season, which are common during warm springs, and their long-term health impacts on both individual bees and colonies. • Antibiotics are sprayed on many crops to control plant bacterial pathogens. • Research on the impacts of antibiotics on beneficial arthropods in agriculture is limited. • We studied antibiotic impacts on bee behavior and pollination function in pears. • Bees exposed to antibiotics visit fewer flowers and this could impact bee fitness. • Despite decreased bee visitation, we did not detect a reduction in crop pollination. [ABSTRACT FROM AUTHOR]

Recent studies have emphasized the role of the western honey bee, Apis mellifera , as a managed agricultural species worldwide, but also as a potential threat to endangered wild pollinators. This has resulted in the suggestion that honey bees should be regulated in natural areas to conserve wild pollinators. We argue that this perspective fails to appreciate the multifaceted nature of honey bees as native or introduced species with either managed or wild colonies. Wild populations of A. mellifera are currently imperiled, and natural areas are critical for the conservation of local subspecies and genotypes. We propose that a differentiation between managed and wild populations is required and encourage integrated conservation planning for all endangered wild bees, including A. mellifera. The western honey bee, Apis mellifera , is globally the most prominent pollinator used for pollination services in crops and is often known only as a domesticated species managed by beekeepers. Recent studies suggest that the presence of large numbers of introduced managed colonies can threaten wild bee populations. Therefore, proposals to exclude A. mellifera colonies from protected areas have arisen. The diversity of honey bee subspecies in Europe, Africa, and western Asia as a threatened component of the native fauna is underappreciated. In Europe, wild honey bee populations are endangered, due to lack of nesting sites and hybridization between and the transfer of pathogens and parasites from managed to wild populations. Natural areas, especially protected areas, are critical for the conservation of the wild populations of the western honey bee in its native range. [ABSTRACT FROM AUTHOR]

• We tested the effect of commercial bumblebees on strawberry pollination and quality. • Commercial bees increased high grade fruit by 25% in an early-flowering variety. • In two other varieties commercial bees had no effect on fruit quality. • Commercial bumblebees do not always provide the benefit they are assumed to. • Commercial bumblebees can be very effective when used in the right circumstance. Both wild and managed pollinators significantly contribute to global food production by providing pollination services to crops. Colonies of commercially-reared honey bees and bumblebees are two of the largest groups of managed pollinators. Bumblebees in particular are increasingly used on soft fruit crops, such as strawberry, an economically important crop globally. Despite the use of commercial bumblebees in strawberry crops, there is little quantitative evidence that they provide a benefit to farmers. Given the negative impacts that commercial colonies can have on wild bee populations, it is vital that the benefits of commercial bumblebees are quantified, so reasoned management decisions can be made that provide maximum benefit to both farmers and wild bees. In this study, commercial colonies of the UK native subspecies Bombus terrestris audax were placed into June-bearer (flowering March-April, varieties 'Malling Centenary' and 'Flair') and everbearer (flowering May-June) strawberry polytunnels on a soft-fruit farm in the south east of England, and opened and closed at weekly intervals. The flower-visiting assemblage inside polytunnels was quantified, and fruit was harvested and quality assessed. In the June-bearer variety Malling Centenary, the presence of commercial bumblebees increased the amount of high commercial grade fruit by 25%. In contrast, no benefit of commercial bees on pollination or fruit quality was observed in the June-bearer variety Flair and the everbearer crop. The increase in quality of fruit in the Malling Centenary crop may be driven by the higher B. terrestris audax flower visitation rates seen in this crop in combination with varietal differences in pollination dependency. The number of flower visits by wild pollinators was not a well-supported predictor of strawberry quality, thus the benefit they provide in this system remains to be elucidated. The results presented here suggest that commercial bumblebees can greatly increase the quality and subsequent value of a strawberry crop, when deployed on a suitable variety at a time when wild pollinator numbers are low. However, the results also raise the possibility that commercial colonies do not always provide the benefits to strawberry crops that they are thought to. For growers to make informed decisions on commercial bumblebee use, further research is required into the effect of commercial bumblebees on the major strawberry varieties, in different locations and seasons. This study is an important step in gaining this understanding. [ABSTRACT FROM AUTHOR]

Trade-offs are considered a major factor in the evolution of ecological specialization, as organisms can rarely specialize on more than one niche. Here we ask whether flowers can be specialized for more than one pollinator group. We studied an outcrossing plant, Aloe kraussii (Asphodelaceae), whose floral morphology is intermediate between that of exclusively bird- and exclusively insect-pollinated aloes. Previous field experiments showed that bees effectively pollinate A. kraussii ; while sunbirds are frequent visitors their effectiveness as pollinators was unknown, especially as their long bills prevent head feathers—the normal location of pollen transfer by birds—from touching A. kraussii 's relatively short anthers and stigmas. We tested whether sunbirds can pollinate A. kraussii , and whether this might be facilitated by flowers' narrow corolla opening, which could increase pollen transfer via narrow sunbird bills. Aviary experiments showed that a Malachite sunbird's bill can successfully pick up and deposit A. kraussii pollen, so long-billed sunbirds can be effective pollinators despite the apparent mismatch between bill and corolla length. Flowers with experimentally widened corolla openings experienced lower pollen removal and deposition by sunbirds than unmanipulated flowers with narrow openings. Aloe kraussii' s floral morphology therefore enables dual specialization on two divergent pollinator guilds; short corollas facilitate bee pollination by enabling access to nectar, while narrow corolla openings facilitate pollen transfer via sunbird bills. • Aloe kraussii has short yellow flowers intermediate to bee- and bird-pollinated aloes. • Previous work found it is fully pollinated by bees but also visited by long-billed sunbirds. • Aviary experiments show long-billed sunbirds can effectively pollinate short A. kraussii flowers. • Floral manipulations show narrow corolla mouths help sunbird bills transfer pollen. • Short corollas with narrow mouths enable dual specialization on divergent pollinators. [ABSTRACT FROM AUTHOR]

• Oilseed rape area reduces the seed set of Cardamine pratensis in grasslands. • Seed set in grasslands is unaffected by oilseed rape configuration in the landscape. • Oilseed rape area and configuration drive solitary bee abundance in grasslands. Mass-flowering crops such as oilseed rape (Brassica napus) are attractive for some pollinators. Consequently, flowering oilseed rape fields may compete for pollinators with co-flowering wild plants occurring in adjacent non-crop habitats. We evaluated the influence of flowering oilseed rape through both its area and its configuration in the landscape on pollinator abundance and on the reproductive success of a co-flowering wild plant functionally close to oilseed rape in surrounding grasslands. We monitored the production of seeds of a pollinator-generalist plant, Cardamine pratensis , and sampled pollinator communities in 22 permanent grasslands. To understand the landscape effect of oilseed rape, we quantified its area and aggregation in the landscape at 1 000 m around each grassland. We measured the flower abundance in the grasslands and C. pratensis conspecific plant abundance to consider local influences. At the landscape scale, C. pratensis seed set was unaffected by the aggregation of oilseed rape patches but it was reduced by increasing oilseed rape area in the landscape. At the local scale, the conspecific plant abundance enhanced seed set (i.e. facilitation effect), whereas flower abundance in the grassland reduced it (i.e. competition effect). Analyses revealed a significant positive correlation between seed set and honeybee abundance, but no correlation was found between seed set and solitary bee abundance. Oilseed rape aggregation and the area of semi-natural habitats in the landscape had a weak negative effect on honeybee abundance. Oilseed rape area had either a positive or a negative effect on solitary bee abundance depending on oilseed rape aggregation in the landscape. Flowering oilseed rape can either enhance or reduce the pollinator abundance and the reproductive success of wild plants depending on its quantity and spatial arrangement. Guidance for plant and pollinator conservation should therefore consider both landscape aspects. [ABSTRACT FROM AUTHOR]

• Increased patch size increases social and solitary bee densities. • Solitary bees are waylaid by mass-flowering vetch patches. • Semi-natural habitats do not influence concentration effect or waylaying effect. • Nesting resources increase concentration effect and waylaying effect. • Landscape-modified concentration and waylaying effects cascade to pollination. Landscape composition is assumed to modify spatial foraging patterns of bees in agricultural ecosystems which subsequently influence pollination services provided to crops. However, empirical evidence to support this prediction is scarce. We investigated the influences of semi-natural habitats and nesting resources on concentration effect and waylaying effect of bees, as well as their consequences on crop pollination in landscapes. Ninety-seven vetch patches with independent gradients of size and distances to nesting sites were selected from 11 agricultural landscapes with independent gradients of surrounding semi-natural habitats and nesting resources. Semi-natural habitats and nesting resources were quantified either by field inspections or from satellite images; flower visitor densities and vetch pollination services were measured across overall flowering seasons. The proportion of semi-natural habitats did not modify the concentration effect or waylaying effect of the abundant and highly social honey bees or the solitary species Anthophora waltoni. The increase in area of brick walls, acting as nesting resources of A. waltoni , increased the concentration effect and the waylaying effect. For other solitary bees, the proportion of semi-natural habitats and the proportion of buildings did not influence the concentration effect or the waylaying effect. Honey bee density, A. waltoni density and other solitary bee density positively predict vetch pollination services. The landscape-modified concentration effect and waylaying effect cascaded to vetch pollination by modifying A. waltoni density. Our findings indicated that landscape composition could modify the spatial foraging patterns of bees and influence pollination services provided to crops, but those varied among different taxonomic groups. [ABSTRACT FROM AUTHOR]