Bee Visitation Research Articles

Plant virus diversity in bee and pollen samples from apple (Malus domestica) and sweet cherry (Prunus avium) agroecosystems.

Honey bee (Apis mellifera) pollination is widely used in tree fruit production systems to improve fruit set and yield. Many plant viruses can be associated with pollen or transmitted through pollination, and can be detected through bee pollination activities. Honey bees visit multiple plants and flowers in one foraging trip, essentially sampling small amounts of pollen from a wide area. Here we report metagenomics-based area-wide monitoring of plant viruses in cherry (Prunus avium) and apple (Malus domestica) orchards in Creston Valley, British Columbia, Canada, through bee-mediated pollen sampling. Plant viruses were identified in total RNA extracted from bee and pollen samples, and compared with profiles from double stranded RNA extracted from leaf and flower tissues. CVA, PDV, PNRSV, and PVF coat protein nucleotide sequences were aligned and compared for phylogenetic analysis. A wide array of plant viruses were identified in both systems, with cherry virus A (CVA), prune dwarf virus (PDV), prunus necrotic ringspot virus (PNRSV), and prunus virus F (PVF) most commonly detected. Citrus concave gum associated virus and apple stem grooving virus were only identified in samples collected during apple bloom, demonstrating changing viral profiles from the same site over time. Different profiles of viruses were identified in bee and pollen samples compared to leaf and flower samples reflective of pollen transmission affinity of individual viruses. Phylogenetic and pairwise analysis of the coat protein regions of the four most commonly detected viruses showed unique patterns of nucleotide sequence diversity, which could have implications in their evolution and management approaches. Coat protein sequences of CVA and PVF were broadly diverse with multiple distinct phylogroups identified, while PNRSV and PDV were more conserved. The pollen virome in fruit production systems is incredibly diverse, with CVA, PDV, PNRSV, and PVF widely prevalent in this region. Bee-mediated monitoring in agricultural systems is a powerful approach to study viral diversity and can be used to guide more targeted management approaches.

Optimizing coffee production: Increased floral visitation and bean quality at plantation edges with wild pollinators and natural vegetation

Abstract Animal pollination is important for more than 75% of agricultural crops, including coffee, whose productivity can increase with adequate pollination. Bees, including many solitary species, are diverse pollinators, with around 85% of them considered more effective than honeybees in pollen transfer. We assessed the coffee plantation and its surrounding vegetation for solitary bee nesting throughout the coffee flowering season and measured their impact on coffee productivity. We installed collection stations with trap nests inside a coffee plantation, on the border and inside the native vegetation in a farm in Diamantina, MG, Brazil. We used 10 weekly monitored replicates at least 1 km apart. We evaluated fruiting by autogamy in relation to natural pollination and used the increase in fruit set from pollinators to calculate the farmer's monetary gain. We recorded bee visits to the exposed flowers during coffee flowering considering both on the edge and inside the coffee plantation. Ripe fruits were dried, counted and weighed. We discovered 132 solitary bee nests outside the plantation, with 54% containing coffee pollen grains, indicating coffee as an essential resource for bees even outside the crop area. More bee visits occurred at the coffee plantation's edge, resulting in increased fruit production, denser fruits, and rounder fruits in that area. Bagged flowers produced consistent seeds in all locations. The farmer could earn an extra US$1736.37 per hectare if the entire area received the same level of pollination contribution from bees as observed at the coffee border. Synthesis and applications. Our study emphasises the key role of pollinators in coffee production and their impact on fruit and seed characteristics. Bee visits were more frequent on border areas, emphasising their reliance on natural nesting sites. Bee‐mediated pollination positively affected fruit traits and self‐pollinated fruits in plantation borders had reduced mass. Solitary bee nesting was primarily observed in native vegetation, underlining its importance for bee populations. Pollen composition in nests varied with proximity to coffee plantations, indicating landscape vegetation influences pollinator foraging. These findings support optimising coffee plantation design by preserving native vegetation to increase coffee yields and conserve biodiversity.

Pollen nutrition structures bee and plant community interactions.

As bees' main source of protein and lipids, pollen is critical for their development, reproduction, and health. Plant species vary considerably in the macronutrient content of their pollen, and research in bee model systems has established that this variation both modulates performance and guides floral choice. Yet, how variation in pollen chemistry shapes interactions between plants and bees in natural communities is an open question, essential for both understanding the nutritional dynamics of plant-pollinator mutualisms and informing their conservation. To fill this gap, we asked how pollen nutrition (relative protein and lipid content) sampled from 109 co-flowering plant species structured visitation patterns observed among 75 subgenera of pollen-collecting bees in the Great Basin/Eastern Sierra region (USA). We found that the degree of similarity in co-flowering plant species' pollen nutrition predicted similarity among their visitor communities, even after accounting for floral morphology and phylogeny. Consideration of pollen nutrition also shed light on the structure of this interaction network: Bee subgenera and plant genera were arranged into distinct, interconnected groups, delineated by differences in pollen macronutrient values, revealing potential nutritional niches. Importantly, variation in pollen nutrition alone (high in protein, high in lipid, or balanced) did not predict the diversity of bee visitors, indicating that plant species offering complementary pollen nutrition may be equally valuable in supporting bee diversity. Nutritional diversity should thus be a key consideration when selecting plants for habitat restoration, and a nutritionally explicit perspective is needed when considering reward systems involved in the community ecology of pollination.

Are glyphosate and fipronil a threat to bees? Integrative literature review

Beekeeping has been growing and developing over the years. There are many products that can be explored with this activity, in addition to bringing great benefits to their producers and consumers. Apis mellifera L. bees carry out an extremely important activity for the productivity of many agricultural crops, which is the cross-pollination of vegetables. When bees visit crops in search of resources for their colony and, consequently, promoting pollination, they can come into contact with pesticides that are applied to crops to control pests, diseases and weeds. However, such pesticides can be harmful to bees, causing serious harm to the individual and the colony. Many of the pesticides are neurotoxic and have different modes of action, and have recently been identified as responsible for the decline in bee populations. Thus, this work carried out a bibliographical survey on the impact that the pesticides glyphosate and fipronil used in soybean cultivation affect bees in different aspects.

If you build it, will they come? Insect community responses to habitat establishment at solar energy facilities in Minnesota, USA

Global declines in insect populations have important implications for biodiversity and food security. To offset these declines, habitat restoration and enhancement in agricultural landscapes could mutually safeguard insect populations and their pollination services for crop production. The expansion of utility-scale solar energy development in agricultural landscapes presents an opportunity for the dual use of the land for energy production and biodiversity conservation through the establishment of grasses and forbs planted among and between the photovoltaic solar arrays (‘solar-pollinator habitat’). We conducted a longitudinal field study across 5 years (2018–2022) to understand how insect communities responded to newly established habitat on solar energy facilities in agricultural landscapes by evaluating (1) temporal changes in flowering plant abundance and diversity; (2) temporal changes in insect abundance and diversity; and (3) the pollination services of solar-pollinator habitat by comparing pollinator visitation to agricultural fields near solar-pollinator habitat with other agricultural field locations. We found increases over time for all habitat and biodiversity metrics: floral rank, flowering plant species richness, insect group diversity, native bee abundance, and total insect abundance, with the most noticeable temporal increases in native bee abundance. We also found positive effects of proximity to solar-pollinator habitat on bee visitation to nearby soybean (Glycine max) fields. Bee visitation to soybean flowers adjacent to solar-pollinator habitat were comparable to bee visitation to soybeans adjacent to grassland areas enrolled in the Conservation Reserve Program, and greater than bee visitation to soybean field interior and roadside soybean flowers. Our observations highlight the relatively rapid (<4 year) insect community responses to grassland restoration activities and provide support for solar-pollinator habitat as a feasible conservation practice to safeguard biodiversity and increase food security in agricultural landscapes.

Effect of Indigenous Bee Attractants on Bee Visitation and Seed Production of Sesame (Sesamum indicum Linnaeus)

An experiment to determine the effect of various bee attractants on bee visitation and quantitative parameters in sesame crops was conducted during the kharif season in Amritsar, Punjab. The 10% concentration of each bee attractant (honey solution, jaggary solution, sugar solution, sugar+jaggary solution, and glucon-D+milk powder) was sprayed twice at 10 and 50% flowering of the crop, and bee visitation (no. of bees/5 minutes/m2 area) was recorded three times a day at 0800, 1100 and 1400 hrs. After the first spray, a gradual increase in bee visitation was recorded from 1st to 5th day of observation, whereas after the second spray, bee visitation increased till 2nd day followed by a steady decline afterwards. The bee species, including Apis mellifera, Apis cerana, Apis dorsata and Megachile lanata, were observed at a maximum on plots sprayed with honey solution (4.49±0.49, 3.91±0.39, 3.17±0.28, 3.59±0.25 bees/m2/5 min, respectively), followed by jaggary solution, sugar solution, sugar+jaggary solution, and glucon-D+milk powder. Among the quantitative parameters, the maximum number of capsules per plant (141.86±0.93), seeds per capsule (68.80±0.15), test weight (4.22±0.12 g), and seed yield (5.99 q/ha) were recorded with honey solution.

Flower morphology and nectar quality traits in faba bean affect attraction to bees

AbstractLegumes provide nutritious floral resources for bees thus are commonly considered for use in schemes to enhance pollinators in agroecosystems. In particular, legume landraces are important elements in practices towards sustainable agriculture. Differences in flower morphology and nectar may affect the attraction of pollinators. The aim of the present study was to investigate possible differences in pollinator attraction between a Vicia faba L. landrace and a commercial variety and to indicate differences in floral characteristics and nectar quality traits which can be associated with bee visits. To assess this, floral morphological trait measurements and chemical analysis using high‐resolution mass spectrometry‐based non‐targeted screening of the flower nectar were carried out and bee visits on faba bean flowers were recorded. Floral traits that contributed to the separation of the two accessions were ‘intensity of streaks’ and ‘extent of anthocyanin colouration’ on standard petal which were more pronounced in the landrace. All nectar traits examined contributed to the separation of the two V. faba accessions. Chemical substances such as amino acids and sugars which are important for bee nutrition are differentially increased in the landrace compared with the commercial variety. The landrace attracted more bee genera (Apis, Anthophora, Eucera) and bee visits compared with the commercial variety (only Eucera) supporting that the floral and nectar differences between the accessions of the same plant species are important to bees. The well‐fitting interrelation of the landrace flowers and bee visits can have possible implications in agricultural practices such as crop breeding for pollinator friendly varieties through selecting floral traits, improvement of foraging resources for pollinators in agroecosystems and subsequently food production. Exploitation of the V. faba landrace in agroecological schemes to support conservation of flora and fauna genetic resources in situ should be considered also for the benefit of future food stability and security.

Effects of a field-sprayed antibiotic on bee foraging behavior and pollination in pear orchards

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.

Synthesis of highbush blueberry pollination research reveals region‐specific differences in the contributions of honeybees and wild bees

Abstract Highbush blueberry production has expanded worldwide in recent decades. To safeguard future yields, it is essential to understand if insect pollination is limiting current blueberry production and which insects contribute to pollination in different production regions. We present a systematic review including a set of meta‐analyses on insect‐mediated pollination in highbush blueberry. We summarize the geographic distribution of research, the abundance of different pollinator taxa and their relative pollination contributions. Using raw data from 21 studies, totalling 496 site replicates, we determine the degree of pollination service and pollen limitation (i.e. combining open pollination levels with experimental bagged and/or hand pollination treatments), as well as the contribution of honeybees and wild bees to pollination (i.e. observational, open pollination). Most studies originate from North America, focusing on only a few cultivars. Honeybees are the dominant pollinator, and wild bees are occasionally abundant. Wild bees are more efficient pollinators on a single‐visit basis compared to honeybees, which increases their relative pollination contribution compared to their relative abundance. Insect‐mediated pollination services increased blueberry fruit set, berry weight and seed set (R2 values: 64.8%, 75.9% and 75.2% respectively). We often detected pollen limitation, indicated by an increase in fruit set, berry weight and seed set (R2: 10.1%, 18.2% and 21.5%, respectively), with additional hand pollination. Increasing visitation of honeybees and wild bees contributed to blueberry pollination by increasing fruit set (R2: 5.4% and 3.5%), berry weight (R2: 6.5% and 2.8%) and seed set (R2: 6.4% and 3.8%) respectively. Bee contributions to fruit set and berry weight were variable across regions. Synthesis and application: A diverse community of insects, primarily bees, contributes to highbush blueberry pollination and yield. However, pollination deficits are common. The finding that both honeybees and wild bees enhance pollination highlights the possibility of adopting different management strategies that utilize honeybees, wild bees or both depending on the specific context and region. This further emphasizes the general importance of conserving pollinator health and diversity. Our synthesis highlights data gaps and areas for future research to better understand the pollination contribution of different pollinators to crops that are expanding globally.

Bees visiting the broad bean (Vicia faba L.) and the impact of border planting on their abundance and the yield improvement in Ismailia, Egypt

Incorporating flowering plants into cropping systems has the potential to actively enhance pollination and crops yields. This study evaluated whether the introduction of border planting affects bee visitation and yield of a broad bean (Vicia faba L.). Experiments were carried out in 2018 and 2019 in Ismailia, Egypt. Bee visitation and broad bean yields were compared between plots with and without border planting. Results showed that open flowers achieved higher yields than netted flowers. Apis mellifera L. was the dominant visitor, followed by four solitary bee species, Chalicodoma siculum (Rossi), Colletes lacunatus Dours, 1872, Andrena ovatula and Xylocopa pubescens (Kirby, 1802). The addition of border planting was associated with a significant increase in the abundance of all five bee visitors and the associated yields. Findings showed that flowering border plants adjacent to broad bean can actively enhance pollination services and yields of this commercially valuable crop, whilst helping to conserve vulnerable bee populations.

Visiting of Carpenter Bees Xylocopa latipes Drury to The Bean Crop in Central Sulawesi

Xylocopa latipes Drury are one species of bee found in the Hymenoptera order, in the family Anthophoridae. Carpenter bees, which are essential for plant pollination, build their nests in decaying wood and bark. Carpenter bees visit the bean crop to collect pollen and nectar for their hives. This study aims to determine the visit of the wood bee X. latipes on long bean plants in Central Sulawesi. The study employed a descriptive survey methodology that involved field sampling at bean planting and direct observation of X. latipes in the field. measured the temperature and the light intensity. The findings revealed that X. latipes visits to the bean crop at Desa Nambaru, Kecamatan Parigi Selatan, Kabupaten Parigi Moutong average 58,3 people each visit. The morning at 08.30 am averages 21 X. latipes visits; the afternoon at 15.30 pm averages 9 Xylocopa latipe visits; and the afternoon at 11.30 am averages 2 Xylocopa latipe visits. The amount of light present during X. latipes visit to the bean crop has a significant impact. Weather variables like temperature, humidity, and wind speed had an impact on the multivariate regression's very real relationship to X. latipes visit to bean planting.

Erythritol sprays reduce D. suzukii infestation without impacting honey bee visitation nor fruit quality.

Spotted-wing drosophila, Drosophila suzukii, is an economic pest of small fruits and cherries. Insecticides primarily control this pest while alternative controls are in development. Laboratory studies show that erythritol is insecticidal to D. suzukii and other pests while safe for human consumption. Moreover, erythritol combined with sucrose or non-caloric sucralose can stimulate feeding and quicken mortality. Before growers can use erythritol, the impact on crop protection, non-target insects, and fruit quality need evaluation. In three blueberry and cherry field cage trials, oviposition on fruit sprayed with erythritol:sucrose or erythritol:sucralose formulations was lowered by 59-81% compared to unsprayed controls. Fly infestation (larval or adult counts from fruit) was 90% lower in a greenhouse blueberry trial, and 49% lower in an open field blueberry trial with 2M erythritol: 0.5M sucrose. Infestation was also 57% lower in an open field cherry trial with 1.5M erythritol: 0.5M sucrose. Other field trials with very low pest pressure or frequent rains revealed no differences from controls. Field trials consistently revealed that honey bees did not preferentially visit plants sprayed with either erythritol formulation, although yellow jackets visited erythritol:sucrose-sprayed plants more frequently. Erythritol formulations consistently led to more leaf spotting, but there was no reduction in quality of treated blueberries or cherries in terms of mold development, firmness, diameter, epidermal penetration force, and Brix° (total soluble solids; TSS) at harvest. Eleven trials conducted over four years show that erythritol formulations can reduce D. suzukii pressure without attracting foraging honey bees nor negatively impacting fruit quality. This article is protected by copyright. All rights reserved.

Colletes hederae bees are equally attracted by visual and olfactory cues of inconspicuous Hedera helix flowers

Wild bees are heavily declining worldwide except for a few species, such as Colletes hederae, which is spreading in its distribution throughout Europe. Colletes hederae mainly forages on ivy (Hedera helix) which is widespread in Europe and the plants’ availability is thought to contribute to the successful spread of C. hederae. A rapid location of the plants using visual and/or olfactory floral cues would allow the bee to efficiently forage. Beside bee visitors, the flowers attract a high variety of other insects, such as Vespula wasps that were recently investigated regarding their floral-cue preferences. The aim of this study was to investigate the communication between C. hederae and its H. helix host flowers, and to compare the results with that previously obtained with V. germanica wasps. We identified headspace compounds detectable by the bees using gas chromatography coupled to electroantennography (GC-EAD) and performed behavioral experiments to both compare the attractiveness of visual and olfactory floral cues and to determine the attractiveness of a synthetic mixture composed of physiologically active compounds. In the GC-EAD analyses, bees responded to 15 flower-specific compounds of various chemical classes, of which 4-oxoisophorone, (E)-linalool-oxide furanoid, and acetophenone were the most abundant in the floral scent. In the bioassays, visual and olfactory flower cues were equally attractive for bees, but a combination of both cues was needed to elicit not only approach responses but also landings. A synthetic mixture of the EAD-active compounds was attractive to the bees, but to a lesser extent than the natural scent of H. helix flowers. The bees’ integrations of different floral-cue modalities in its search image and its strong antennal responses elicited by various floral scent compounds make C. hederae highly effective in finding its host flowers. In comparison to V. germanica wasps, the bees relied stronger on visual cues than the wasps do, but both species showed the highest attraction when presented with a combination of the cues.

Effectiveness of honeybee (Apis mellifera) visit on the pollination of different sunflower cultivars

BackgroundUtilizing pollinators is one of the most dependable, economical, and environmentally friendly ways to improve cross-pollination, boost crop output, and improve crop quality. Bees are regarded as the best pollinators among all other pollinators. MethodsThe current study was conducted to elucidate the impact of honeybee (Apis mellifera) visits on the pollination of various sunflower cultivars including Hysum-33, Hysun-38, and FH-106. ResultsOur finding revealed that the highest average number of honeybee visits was observed in the morning followed by noon and afternoon on different sunflower cultivars. The maximum number of honeybee visits was recorded on Hysun-38, while the minimum was recorded on the FH-106 cultivar, which was 87.85 and 73.6, respectively. In (Hysun-33) and (FH-106), the maximum average time spent by the honeybee noticed in the morning on the flower was 34.24 and 32.67 min, whereas the maximum average time spent in the evening on the flower of (Hysun-38), which was 36.41 min. Regression analysis demonstrated that a significant effect between the head diameter of sunflower cultivars and the number of honey bee visits (p < 0.05). In addition, a significant effect was observed between the number of honeybees visited and the number of seed settings on all cultivars of sunflower (p < 0.05). There was a highly strong positive correlation between the number of seed sets and the head diameter of all cultivars. ConclusionIt is concluded that farmers should maintain honeybee colonies close to the desired crop to increase pollination and increase output.

Use of olive pomace extract as a pollinator attractant to increase onion (Allium cepa L.) seed crop production

Onion is an allogamous species with protandry, as anthers release pollen before the stigma is receptive. Thus, insect pollination is needed to produce seeds. When male sterile lines are used, an efficient pollinator is important to ensure pollen transfer to the stigma. Therefore, increasing seed yield depends on increasing bee activity. Seed yield is variable in hybrid lines and lower than open-pollinated varieties, with a decrease of up to 60%. Bee attractants sometimes are used to influence worker bees towards flowers for pollination. The objective of this work is to use a food industry waste, such as olive pomace, as bee attractant upon application of the water extract on onion umbels. The effectiveness of this by-product in enhancing pollination efficiency was evaluated and compared to untreated controls. Male-sterile lines, as well as a fertile line, were used in commercial fields and environmental variables were registered. Pollination effectiveness was measured by seed yield. Olive pomace water extracts (OPWE), rich in bioactive compounds, from local industries were evaluated. Some compounds present in the OPWE were analyzed, identified and quantified. The OPWEs were applied during flowering, at different times and correlated with seed yield and the frequency of bee visits. After 3 years of study, we can assert that the application of OPWE enhances honeybee pollination efficiency, and as consequence improves onion seed yield.

Comparing levels of geitonogamous visitation by honey bees and other pollinators

Geitonogamy, the transfer of pollen from one flower to another on the same plant, is often the primary means of self-pollination in flowering plants. For self-compatible plants, self-fertilization may lead to greatly reduced offspring fitness via inbreeding depression. For self-incompatible plants, geitonogamous pollen transfer can result in low seed set, even when stigmatic pollen loads are substantial. For multiple self-compatible, native California plants, we found that honey bees visited more flowers per plant than native insects, and that offspring resulting from pollination by honey bees had reduced fitness relative to those resulting from native insect pollination. Here we investigate whether honey bees generally make more geitonogamous visits than other pollinators using data from a global survey of 41 manuscripts that reported floral visitation data. Compared to the average of all non-honey bee visitors in a plants pollinator assemblage, honey bees visit significantly more flowers per plant, though they do not differ from the non-honey bee visitor with the highest rate of geitonogamous visitation. However, the disparity between rates of geitonogamous visitation by honey bees and non-honey bee visitors is a function of the frequency of honey bees relative to non-honey bee visitors. As honey bees become increasingly numerically dominant, there is a trend for their rates of geitonogamous visitation to increase, accompanied by a significant decline in flowers visited per plant by non-honey bee visitors. While we found that honey bees visited more flowers per plant compared to the average of other visitors, large or eusocial pollinators were as likely as honey bees to be the most geitonogamous visitor.

The major role of spring trees in Ohio honey production for bees located in high and low agricultural intensity

Nectar is the resource that sustains honey bee colonies through periods of dearth and provides the surplus honey beekeepers harvest for human consumption. While extensive information is available for plants that honey bees visit for pollen and nectar, we lack knowledge on which nectars are stored long-term as honey for harvest and support of colonies through winter. Here, we used citizen science methods and pollen metabarcoding analysis to identify the plants contributing most to honey samples harvested by beekeepers from apiaries with variable intensities of surrounding agriculture. A total of 36 samples were collected from 36 apiaries in Ohio in 2019, with an average of 3 plant genera detected per sample. We found similarity in honey samples collected from all apiaries, regardless of the proportion of agricultural land within a 2-km foraging range, with substantial amounts of honey stored from spring trees, including Salix (willow) and Prunus (cherry). This result suggests the importance of early-season resources regardless of agricultural intensity in the surrounding landscape. This study contributes to a body of work aiming to identify the nectars making it to long-term honey storage and those that are being consumed within the hive shortly after collection.

Forest conservation maximises açaí palm pollination services and yield in the Brazilian Amazon

Abstract Agricultural expansion is one of the main drivers of global pollinator loss. Paradoxically, this occurs while agriculture is becoming increasingly dependent on biotic pollination, raising concerns about food production. Integrated Crop Pollination (ICP), the use of both wild and managed pollinators in crop fields, can help conserve pollinator diversity while ensuring effective pollination services for growers. However, given the context‐dependent nature of this approach, there is an urgent need to evaluate its application across different landscapes and crops. We apply the ICP approach to açaí palm (Euterpe oleracea Mart.) production in the eastern Brazilian Amazon to explore effects of a native stingless bee, Scaptotrigona aff. postica (Apidae: Meliponini), and landscape‐level forest conservation on yield and socioeconomic outcomes for açaí fruit growers. We assessed flower visitor assemblages and fruit production on 18 plantations across a landscape forest cover gradient, with bee colonies introduced on nine plantations. Field data were combined with information from semistructured interviews of growers to estimate yield and profit per hectare under different pollinator management scenarios. Bee colonies and forest cover enhanced flower visitor abundance on palm inflorescences, but abundance increases attributed to managed bees were associated with shifts in flower visitor evenness and diversity (species richness), due to reduced visitation of wild bees near managed colonies. Fruit production on inflorescences was positively related to bee abundance and bee diversity. Consequently, overall pollination performance was lower in plantations with bee colonies. This was repeated at the hectare scale, where yield and profit were associated with surrounding forest cover and not bee colonies. Synthesis and applications. Managed bees can increase pollinator densities and fruit production, but the increased environmental and socioeconomic risks associated with this activity means açaí growers should prioritise forest conservation to safeguard pollination services and improve overall sustainability of açaí production in the eastern Brazilian Amazon.

Evidence of exploitative competition between honey bees and native bees in two California landscapes.

Human-mediated species introductions provide real-time experiments in how communities respond to interspecific competition. For example, managed honey bees Apis mellifera (L.) have been widely introduced outside their native range and may compete with native bees for pollen and nectar. Indeed, multiple studies suggest that honey bees and native bees overlap in their use of floral resources. However, for resource overlap to negatively impact resource collection by native bees, resource availability must also decline, and few studies investigate impacts of honey bee competition on native bee floral visits and floral resource availability simultaneously. In this study, we investigate impacts of increasing honey bee abundance on native bee visitation patterns, pollen diets, and nectar and pollen resource availability in two Californian landscapes: wildflower plantings in the Central Valley and montane meadows in the Sierra. We collected data on bee visits to flowers, pollen and nectar availability, and pollen carried on bee bodies across multiple sites in the Sierra and Central Valley. We then constructed plant-pollinator visitation networks to assess how increasing honey bee abundance impacted perceived apparent competition (PAC), a measure of niche overlap, and pollinator specialization (d'). We also compared PAC values against null expectations to address whether observed changes in niche overlap were greater or less than what we would expect given the relative abundances of interacting partners. We find clear evidence of exploitative competition in both ecosystems based on the following results: (1) honey bee competition increased niche overlap between honey bees and native bees, (2) increased honey bee abundance led to decreased pollen and nectar availability in flowers, and (3) native bee communities responded to competition by shifting their floral visits, with some becoming more specialized and others becoming more generalized depending on the ecosystem and bee taxon considered. Although native bees can adapt to honey bee competition by shifting their floral visits, the coexistence of honey bees and native bees is tenuous and will depend on floral resource availability. Preserving and augmenting floral resources is therefore essential in mitigating negative impacts of honey bee competition. In two California ecosystems, honey bee competition decreases pollen and nectar resource availability in flowers and alters native bee diets with potential implications for bee conservation and wildlands management.

Effect of herbicides on pollinator foraging behavior and flower morphology in white clover (Trifolium repens L.)–infested turfgrass

AbstractThe recent decline in pollinator abundance is a cause of concern for sustaining global food production. Several common weeds of managed turfgrass systems attract honeybees and other wild pollinators. As turfgrass often requires treatment with insecticides that harm bees, best practices are needed to prevent bees from visiting weed-infested turf areas that will be treated for insect pests. Weed control tactics can protect pollinator exposure to insecticides by reducing the floral resources afforded to bees from turfgrass weeds. Three field studies were conducted in 2021 and 2022 to evaluate the effect of various herbicides and herbicide formulation constituents on pollinator foraging and white clover floral morphology in managed tall fescue turfgrass. Treatments included a nontreated control; MCPP; 2,4-D; dicamba; Trimec Classic™ (2,4-D, MCPP, dicamba); Speedzone™ (carfentrazone, 2,4-D, MCPP, dicamba); and an herbicide-formulation constituent (inert ingredients of Speedzone™). All response variables were evaluated for 8 d, starting from one day before treatment and ending 6 d after treatment (DAT). The herbicide formulation constituent did not alter white clover flower density, floral discoloration, floral quality, or insect visitation compared to nontreated plots. Herbicides reduced flower density and floral quality to the same extent, but MCPP discolored white clover floral tissue 16% per day and less than all other herbicides except dicamba. Floral quality completely declined in approximately 5 d following any herbicide treatment. Bee visitation to white clover–infested turf increased by 3 bees min–1 for every 100 white clover blooms m–2. Honeybees and other insects vacated herbicide-treated areas in less than 2 d, despite minimal effects on floral quality and density at that time. The data suggest that practitioners could apply insecticides 2 d after auxin herbicide treatment and avoid harm to pollinators, but additional work is needed to directly measure pollinator exposure following such treatments.