Pollination Ecosystem Services Research Articles

Co-occurrence and abundance of pollinators and pests in horticultural systems in Africa using an integrated Earth observation-based approach

ABSTRACT Flower-visiting insects that are pollinators play a critical role in promoting biodiversity in agroecosystems and agricultural food production through their pollination ecosystem service. However, several factors affect the survival of these pollinators and flower visitors, including the heavy and indiscriminate application of agrochemicals to control crop insect pests, which is impacted by various cropping patterns in a landscape and by shifting environmental conditions. Thus, this study focused on investigating the influence of cropping patterns on the spatial distribution of pollinators (Apis mellifera, Hymenoptera other than A. mellifera, and Syrphidae), flower visitors (Calliphoridae), and pests, i.e. fruit fly (Bactrocera dorsalis) and false codling moth (Thaumatotibia leucotreta) of the avocado, a pollinator-dependent crop. Cropping patterns, earth observation data and relevant environmental variables were used as the predictor variables for modeling the potential distribution and abundance of avocado pollinators, flower visitors and pests in one of the leading regions in avocado production in Kandara, Maragua, and Gatanga sub-Counties in Murang’a County, Kenya. In specific, species distribution modeling (SDM) and species abundance modeling (SAM) techniques, i.e. the maximum entropy (MaxEnt) model (presence-only data) and negative binomial (NB) distribution in a generalized linear model (GLM) (abundance data) were used, respectively. Additionally, the spatial distribution probability of the co-occurrence of the pollinators, flower visitors and pests was also analyzed. This study revealed that cropping patterns was the most consistent influential predictor variables for the distribution of avocado pollinators, flower visitors and pests. A large area of Kandara and some parts of Maragua and Gatanga sub-Counties showed a high spatial distribution probability of the studied avocado pollinators, flower visitors and pests. However, only the majority of Kandara sub-County had a high spatial distribution probability score of the potential co-occurrence of the avocado pollinators, flower visitors and pests. Further, A. mellifera was the most abundant flower-visiting pollinator compared with the other studied pollinators, while B. dorsalis was the most abundant avocado pest compared with T. leucotreta. In addition, GLM analysis indicated that no environmental variable was significant in explaining the abundance of the studied avocado pollinators, whereas precipitation and elevation derivatives of aspect and hillshade were statistically significant (p ≤ 0.05) in explaining the abundance of B. dorsalis. Solar radiation was significant in explaining only the abundance of T. leucotreta. Our study revealed that SDM and SAM modeling outputs can be used to inform decision-making for the implementation of sustainable management efforts regarding pollinators, flower visitors, and insect pests.

Assessing pollinator habitat suitability considering ecosystem condition in the Hannover Region, Germany

Abstract Context Habitat suitability for pollinator species is an important indicator for pollination ecosystem service potential, i.e. for biodiversity and crop provision. Modelling habitat suitability using an expert- and process-based models such as ESTIMAP-pollination is a common and accepted approach to spatially analyse pollination service potential and to make recommendations for planning. Objectives However, the suitability as a pollinator habitat depends not only on the land use type. It is also important to consider the condition of the habitat. For this reason, ecosystem condition information was used as a parameter for ESTIMAP modelling for the first time. Ecosystem condition data was used besides the commonly (in ESTIMAP) used information from expert assessments and from land use data. Methods As parameters for ecosystem condition, the management intensity in agro ecosystems, the management of forests and the proportion of green space in urban areas were included and affected the modelled habitat suitability for wild bees. Results Not all ecosystem types of the region were equally affected by the inclusion of the ecosystem condition parameter in the model. The most affected types were agricultural areas, such as arable and horticultural biotopes, whose suitability values decreased by 25.7%. As a result, areas with low suitability account for 41% of the region and 76.6% of the agro ecosystems. In forest, shrubs and woody plants land use types, the suitability decreased respectively by 4.3 and 6%. On the other hand, urban ecosystems in the city of Hannover were characterised by relatively good habitat suitabilities, especially in the proximity of wide urban forests. In 3.4% of the agricultural land, measures to support pollinators have been established. 1.6% of these measures are located in areas with low suitability. Conclusions The results show that ecosystem condition is, in addition to land use type, an important parameter to indicate habitat suitability for pollinators. Especially for ecosystem types with varying habitat suitabilities, such as agro ecosystems, the implementation of ecosystem condition parameters is recommendable. However, the selection of suitable ecosystem condition indicators still requires further research and concise definitions.

Shading effects in agrivoltaic systems can make the difference in boosting food security in climate change

Photovoltaic (PV) systems play an important role in the sustainable energy transition, but their impact on food security is ambiguous due to the shift in land use from agriculture to energy production. Currently, agrivoltaic is emerging as an alternative sustainable energy source that optimises multifunctional land use by simultaneously supporting electricity generation and agricultural activities. While many studies have extolled the benefits of shade provided by agrivoltaic on crop water balance and evapotranspiration, plant ecological adaptation, such as Shade Avoidance Syndrome (SAS), and its implications for food security remain relatively unexplored. In this context, we have investigated the influence of a panel-generated shadow on chicory crop production in terms of plant biomass yield and its quality for human health under different water irrigation regimes. For each chicory plant, fresh weight and leaf dimensions were measured to estimate edible biomass, while leaf water content, chlorophylls a and b, carotenoids, metabolite profile and antioxidant capacity were evaluated to assess food quality. Our results show that the shading system has a remarkable capacity to increase edible chicory biomass production compared to full sunlight conditions of 69% and 23%, respectively for high water supply and low water supply, and greater capacity to promote pollination ecosystem services. The shade, provided by a well-designed agrivoltaic system, improves SAS and directly increase yield without altering food quality. Thus, agrivoltaic systems can combine renewable energy strategies with food security, while enhancing ecosystem services for human well-being.

Impacts of degraded pollination ecosystem services on global food security and nutrition

Nutrient resource loss in human food due to an ecological shock in terms of the depletion of insect pollination services may become a global concern. Inspired by the international trade theory, we use a bioeconomic model to estimate the impact of crop price changes on nutrient consumption as crop supply and demand vary under different scenarios of pollinators decline. Our findings show that the average global crop price will increase by about 187% if pollinators go extinct at a global scale and worldwide nutrient consumption from crops may decrease in all scenarios studied, exacerbating food insecurity where food shortage already exists. We argue that the consequences of pollinators decline on human well-being is not only a matter of the crop production quantity in exporting countries but also the global demand of nutrients contained in pollinator-dependent crops as their supply decline.

Where the bee sucks: a dynamic Bayesian network approach to decision support for pollinator abundance strategies

Abstract For policymakers wishing to make evidence-based decisions, one of the challenges is how to combine the relevant information and evidence in a coherent and defensible manner in order to formulate and evaluate candidate policies. Policymakers often need to rely on experts with disparate fields of expertise when making policy choices in complex, multi-faceted, dynamic environments such as those dealing with ecosystem services. The pressures affecting the survival and pollination capabilities of honey bees (Apis mellifera), wild bees, and other pollinators is well documented, but incomplete. In order to estimate the potential effectiveness of various candidate policies to support pollination services, there is an urgent need to quantify the effect of various combinations of variables on the pollination ecosystem service, utilising available information, models and expert judgement. In this paper, we present a new application of the integrating decision support system methodology, using dynamic Bayesian networks, for combining inputs from multiple panels of experts to evaluate policies to support an abundant pollinator population.

Can macroplastics affect riparian vegetation blooming and pollination? First observations from a temperate South-European river

Since plastics are a global growing concern that persists in nature, they threaten ecosystem conservation and human health. Particularly, pollination is one of the most important ecological services being pivotal to the ecosystem’s long-term functioning and human welfare. However, pollination is threatened by pesticides, urbanisation, habitat loss, and contaminants. As interactions between plastics and biota or ecosystem service remain neglected, the major challenge would be to research it. Our achievement was a first attempt to assess the effects of macroplastics on riparian vegetation and the ecosystem service of pollination. Here, (i) while investigating macroplastics entrapped by riparian vegetation, (ii) we propose the new field observation of the flower’s coverage by macroplastics. Then, (iii) we indirectly assessed the possible interaction between macroplastic litter and the ecosystem service of pollination. Finally, (iv) we performed a meta-analysis search to understand better how many studies were carried out on this topic. To achieve our aim, surveys of riverine macroplastic litter entrapped in riparian vegetation were carried out in the urban tract of the Aniene River. To assess if pollination was possibly reduced by macroplastics covering flowers, we observed the visitation of pollinators on flowers. Overall, we observed that flowers of riparian vegetation were covered by macroplastics, preventing them from being pollinated by insects, and pollination success (i.e., successful pollination) was potentially reduced to 81.4% by a factor of 18.6%. Our research highlights that macroplastics on vegetation indicate a new stress to plant reproduction, reducing blooming (i.e., flowering or flower production) and pollination. These recent observations urge new studies to evaluate how macroplastic litter accumulates and might affect ecosystem services in long-term research. Our findings could be of particular concern as pollination in agricultural crops and riverine habitats is central to human welfare as an ecosystem service. Considering that most global food crops depend on pollination by insects, crops and fruits (e.g., coffee, cocoa, apples) would not be present without the essential ecosystem service of pollination. Our findings highlight for the first time a new threat (i.e., macroplastic litter) to the blooming with possible implications for the pollination process.

Imidacloprid: Impact on Africanized Apis mellifera L. (Hymenoptera: Apidae) workers and honey contamination

Apis mellifera L. (Hymenoptera: Apidae) is fundamental in the production chain, ensuring food diversity through the ecosystem service of pollination. The aim of this work was to evaluate the impact of imidacloprid, orally, topically, and by contact, on A. mellifera workers and to verify the presence of this active ingredient in honey. Toxicity levels were verified by bioassays. In bioassay 1, the levels correspond to the percentages of 100, 10, 1, 0.1, and 0.01% of the recommended concentration for field application of the commercial product Nortox® (active ingredient imidacloprid), with which we obtained the mean lethal concentration (LC50) in 48 h for A. mellifera, determining the concentration ranges to be used in the subsequent bioassays. Bioassays 2 and 3 followed the guidelines of the Organization for Economic Cooperation and Development, which specify the LC50 (48 h). In bioassay 4, the LC50 (48 h) and the survival rate of bees for a period of 120 h were determined by contact with a surface contaminated with imidacloprid, and in bioassay 5, the interference of the insecticide with the flight behavior of bees was evaluated. Honey samples were collected in agroecological and conventional georeferenced apiaries and traces of the imidacloprid were detected by means of high-performance liquid chromatography (HPLC-UV) with extraction by SPE C18. Bee survival was directly affected by the concentration and exposure time, as well behavioral performance, demonstrating the residual effect of imidacloprid on A. mellifera workers. Honey samples from a conventional apiary showed detection above the maximum residue limits (MRL) allowed by the European Union (0.05 μg mL−1), but samples from other apiaries showed no traces of this insecticide. Imidacloprid affects the survival rate and behavior of Africanized A. mellifera and honey quality.

Forest insect pollination ecosystem services and climate change: A review

Forest insect pollination ecosystem services and climate change: A review

Trouble in the tropics: Pathogen spillover is a threat for native stingless bees

Pathogen spillover is a major threat to biodiversity. Insect pollinators, important providers of the ecosystem service of pollination that are in global decline, are no exception to this threat, with mounting evidence of pathogen spillover from managed into wild bee species in temperate regions. The phenomenon is likely global in scope, though poorly documented, and its consequences for recipient species are largely unknown. To address these knowledge gaps, we investigated viral spillover in the neotropics from the honey bee (Apis mellifera), where it is a managed and invasive species, into native stingless bees, a biodiverse taxon of pollinators. We furthermore exposed stingless bees to honey bee viruses to test for their impact on host survival. High viral prevalence in honey bees and low prevalence of identical viral haplotypes in stingless bees supports ongoing spillover from managed to native species. The survival of native stingless bees was reduced when inoculated with virus by feeding, a plausible route of natural infection. We conclude that viral spillover from managed to wild insect pollinators is likely a global phenomenon and poses a serious threat worldwide to native insect species. If negative impacts are detected in the field, conservation management needs to be developed to reduce spillover, including better control of pathogens in managed species and legislation on their movement.

How Informed Design Can Make a Difference: Supporting Insect Pollinators in Cities

Pollinators are responsible for the reproduction of many plant and crop species and provide important diversity for food webs and cultural value. Despite the critical ecosystem services provided by pollinators, rapid pollinator declines are occurring in response to anthropogenic activities that cause the loss of suitable habitat. There is an opportunity for urban green space to support pollination ecosystem services locally and across the landscape. However, there is a lack of practical but evidence-based guidance on how urban green space can be designed effectively to provide floral resources and other habitat needs to a diverse assemblage of pollinators. We examine the existing pollinator research in this paper to address the following questions specific to insect pollinators in temperate urban settings: (1) Which pollinators can be the focus of efforts to increase pollinator ecosystem services in cities? (2) Which plants and what arrangements of plants are most attractive and supportive to urban pollinators? (3) What do urban pollinators need beyond floral resources? (4) How can the surrounding landscape inform where to prioritize new habitat creation within cities? Using these questions as a framework, we provide specific and informed management and planning recommendations that optimize pollinator ecosystem value in urban settings.

Evaluation of the Pollination Ecosystem Service of the Honey Bee (Apis mellifera) Based on a Beekeeping Model in Hungary

Apiaries must be ecologically and economically sustainable to provide pollination as a unique ecosystem service. Pollination as an ecosystem service is economically, socially, and environmentally irreplaceable. Therefore, it is essential to improve the profitability of beekeeping activities, which are mainly carried out in rural areas. With this in mind, the main objective of this article is to assess pollination as one of the ecosystem services provided by bees, based on the specificities of Hungarian honey production. The authors’ analysis is based on a Hungarian apiary with 300 colonies active in migratory beekeeping. The model farm produces a wide variety of honey thanks to its migratory beekeeping, visiting several bee pastures during the beekeeping season. This paper presents an approach to quantify the ecosystem services provided by honey bees (Apis mellifera) using two economic valuation methods (productivity change and surrogate market goods) belonging to the family of cost-based valuation. The results of the monetary valuation of the ecosystem services provided by bees can provide a starting point for further research to help decision-makers and farmers to calculate a fair “pollination fee” for beekeepers, which will significantly help beekeepers to maintain beekeeping, an important and beneficial activity for all of us.

Bees and pollination in grassland habitats in Helsinki (Finland) are diverse but dominated by polylectic species

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.

Relationship between the Abundance of Native Honey Bee Species (<i>Apis cerana</i>) and Distance to Natural Forests in Hyuganatsu (<i>Citrus tamurana</i>) Orchards in Aya Town, Japan

This study aimed to examine the relationship between the ecosystem services of pollination offered by native honey bees (Apis cerana) and the distance to natural forests (as an indicator of landscape structure) in hyuganatsu (Citrus tamurana) orchards in Aya Town, Miyazaki Prefecture, Japan. Two statistical models were developed to predict the number of visits of native honey bees to hyuganatsu tree. The area-distaince model (AD-model) considered the area of natural forests and distance from natural forests and the area model (A-model) considered the total area of the surrounding natural forests, and the results of the two models were compared. The estimated parameters of both models suggested a positive effect of natural forests on pollination services. Further, the estimated effect of the landscape structure of the AD-model was greater than that of the A-model. These results suggested that the distance to natural forests is an important landscape factor for evaluating pollination services by native honey bees.

The effect of landscape composition on stingless bee (Melipona fasciculata) honey productivity in a wetland ecosystem of Eastern Amazon, Brazil

Humanity depends on the processes and resources of natural ecosystems, such as natural grassland fields and forests. These ecosystems depend on pollinators, especially bees, to ensure crossbreeding and plant productivity. Faced with deforestation and the fragmentation of forest remnants, meliponiculture plays an important role in biodiversity conservation, ecological restoration, and generating income for family farmers. Little is known about the effect of landscape on the productivity of native tiúba bees (Melipona fasciculata Smith, 1854) in the Baixada Maranhense Environmental Protection Area (APA) in the Brazilian Amazon. This study aimed to evaluate the landscape effect on M. fasciculata honey productivity in APA. We selected 34 stingless beekeepers, mapped and classified landscapes within a 2,000 m radius around the meliponaries, measured honey productivity, and identified the pollen types. We analyzed honey productivity as a function of landscapes and floral origin. Our results show that honeys from forest landscapes have greater richness and abundance of species, indicating more pollination ecosystem services in these landscapes, but have lower honey productivity. The highest productivity occurs in landscapes with a greater percentage of natural grassland fields and a composition dominated by shrubs. Melissopalynology and geographical information from landscape mapping provided ecological dimensioning of M. fasciculata honey productivity in the APA, which can guide conservation, management, and restoration actions in this region, and enhance the recognition of environmental services provided by stingless beekeepers.

Stable pollination service in a generalist high Arctic community despite the warming climate.

Insects provide key pollination services in most terrestrial biomes, but this service depends on a multistep interaction between insect and plant. An insect needs to visit a flower, receive pollen from the anthers, move to another conspecific flower, and finally deposit the pollen on a receptive stigma. Each of these steps may be affected by climate change, and focusing on only one of them (e.g., flower visitation) may miss important signals of change in service provision. In this study, we combine data on visitation, pollen transport, and single-visit pollen deposition to estimate functional outcomes in the high Arctic plant-pollinator network of Zackenberg, Northeast Greenland, a model system for global warming-associated impacts in pollination services. Over two decades of rapid climate warming, we sampled the network repeatedly: in 1996, 1997, 2010, 2011, and 2016. Although the flowering plant and insect communities and their interactions varied substantially between years, as expected based on highly variable Arctic weather, there was no detectable directional change in either the structure of flower-visitor networks or estimated pollen deposition. For flower-visitor networks compiled over a single week, species phenologies caused major within-year variation in network structure despite consistency across years. Weekly networks for the middle of the flowering season emerged as especially important because most pollination service can be expected to be provided by these large, highly nested networks. Our findings suggest that pollination ecosystem service in the high Arctic is remarkably resilient. This resilience may reflect the plasticity of Arctic biota as an adaptation to extreme and unpredictable weather. However, most pollination service was contributed by relatively few fly taxa (Diptera: Spilogona sanctipauli and Drymeia segnis [Muscidae] and species of Rhamphomyia [Empididae]). If these key pollinators are negatively affected by climate change, network structure and the pollination service that depends on it would be seriously compromised.

Combination of organic farming and flower strips in agricultural landscapes – A feasible method to maximise functional diversity of plant traits related to pollination

Agri-environment schemes (AES) are valuable instruments to support pollination in agricultural landscapes. Evaluating AES based on their effects on pollinators has high practical relevance for agricultural production and nature conservation. In our two-year assessment, we studied the effectiveness of two AES (organic farming vs flower strips) on plant traits associated with pollinator attraction (flower size, colour, and ultraviolet pattern) and reward accessibility (flowering duration, and nectar quantity). We selected ten landscapes along a landscape-scale field size gradient in Central Germany. Three types of winter wheat fields (organic, and conventional fields with and without flower strips) were chosen in each landscape. We sampled the vegetation in transects designated in characteristic field parts, i.e. grassy margins, field edges (or flower strips), and field interiors in the growing seasons of 2016 and 2017. We calculated community-weighted means and functional diversity of plant traits and tested the effects of field size, management, and within-field position with linear mixed-effects models. We showed that organic fields and flower strips provided more abundant and functionally more diverse flowers than conventional fields. Flower strips were superior with the highest insect-pollinated plant cover and the highest ratio of plants with flowers showing ultraviolet patterns. Although grassy margins next to flower strips harboured twice as many species as those without flower strips, this positive effect did not emerge in conventional field interiors. Landscape configuration expressed as mean field size did not affect pollination traits in our study. Our results highlighted that both organic farming and flower strips maintained abundant and functionally diverse insect-pollinated flora, and thus they can potentially support larger pollinator communities. However, only organic farming could maintain high functional diversity of pollination-related plant traits in field interiors. Hence flower strips and organic farming in combination might be a good option for sustaining diverse pollinator communities and their services. • Organic fields and annual wildflower strips can boost pollinator-friendly flora. • Plant pollination trait diversity is high in both agro-environmental schemes. • Both schemes can supposedly maintain high pollination ecosystem service. • There is little spill-over from flower strips to intensive field interiors. • Plant functional diversity of grassy field margins benefited from flower strips.

Enhancing pollination ecosystem service in urban green areas: An opportunity for the conservation of pollinators

The rapid growing urbanization is one of the main threats to urban biodiversity and the ecosystem services (ES) that they provide. Pollination is one of the most affected ES in urban areas mainly due to the decline in urban green areas (UGAs) and other factors derived from urbanization itself. Considering this and the already existing global pollinator crisis, the aim of this work is the evaluation of urban green infrastructure as an opportunity for pollinator conservation. For that purpose, the ornamental vegetation of a medium-sized Mediterranean city (Granada, south-eastern Spain) was determined. The floral origin, phenology and floral traits of the conforming species and the pollinator species that they attract were analysed. Additionally, NMDS analysis were performed in order to determine if the “Pollination Syndromes” are a useful tool to actually predict the pollinator group attracted to a certain plant species. It was found that UGAs have huge potential for pollinator conservation as the major part of its ornamental species have an entomophilic pollination strategy. However, there is an imbalance in the availability of flower resources throughout the year. Hence, the addition of species flowering out of the main flowering season would be advisable in order to get a continuous supply of floral resources for pollinators. A current disproportion in the potentially attracted pollinator groups was also found out, being bees the predominantly attracted ones. However, results showed that the “Pollination Syndromes” are a tool with limitations at the moment and needs to be used with considerations. Thus, the specific plant-pollinator relationship should be determined through field work in each case-study. Further studies considering key factors such as urban connectivity and fragmentation would be desirable to ensure a comprehensive management for urban pollinators.

DNA metabarcoding unveils the effects of habitat fragmentation on pollinator diversity, plant-pollinator interactions, and pollination efficiency in Maldive islands.

Habitat fragmentation affects biodiversity, but with unclear effects on pollinators and their interactions with plants in anthropized landscapes. Islands could serve as open air laboratories, suitable to disentangle how land-use alteration impacts pollination ecology. In Maldive islands we investigated how pollinator richness, plant-pollinator interactions and pollination efficiency are influenced by the green area fragmentation (i.e., gardens and semi-natural patches). Moreover, we considered the mediating role of pollinator body size and the plant trait of being invasive in shaping interactions. To do this, we surveyed pollinator insects from 11 islands representing a gradient of green area fragmentation. A DNA metabarcoding approach was adopted to identify the pollen transported by pollinators and characterize the plant-pollinator interactions. We found that intermediate levels of green area fragmentation characterized pollinator communities and increased their species richness, while decreasing interaction network complexity. Invasive plants were more frequently found on pollinator bodies than native or exotic noninvasive ones, indicating a concerningly higher potential for pollen dispersal and reproduction of the former ones. Intriguingly, pollinator body size mediated the effect of landscape alteration on interactions, as only the largest bees expanded the foraging diet in terms of plant richness in the transported pollen at increasing fragmentation. In parallel, the pollination efficiency increased with pollinator species richness in two sentinel plants. This study shows that moderate landscape fragmentation of green areas shapes many aspects of the pollination ecosystem service, where despite interactions being less complex and mediated by pollinator body size, pollinator insect biodiversity and potential plant reproduction are supported.

City climate and landscape structure shape pollinators, nectar and transported pollen along a gradient of urbanization

Abstract Urbanization gradients influence both landscape and climate and provide opportunity for understanding how plants and pollinators respond to artificially driven environmental transitions, a relevant aspect for the ecosystem service of pollination. Here, we investigated several aspects of pollination along an urbanization gradient in landscape and climate. We quantified wild hoverfly and bee abundances with trapping, standing crop of nectar with spectrophotometer, and the pollen transported by flower visitors with DNA metabarcoding, in 40 independent sites from semi‐natural to built‐up areas in Northern Italy. Direct and indirect effects were fitted considering landscape and climate variables. Linear and nonlinear relationships were detected along the urbanization gradient. Pollinator abundances increased quadratically and peaked at 22% of impervious cover with an 81% growth, and they decreased with green‐patch distance by 37% and urban park largeness by 60%. This indicates that pollinators are more abundant at intermediate levels of urbanization. Climatically, pollinators diminished by up to 46% in areas with low spring–summer temperature seasonality: urban areas likely posing thermic stress. Furthermore, the sugar mass available in nectar increased by 61% with impervious cover and by 79% with precipitations, indicating that city nectars were less consumed or flowers more productive. Furthermore, the species richness of pollen decreased by 32% in highly urbanized areas, and contained a high incidence of exotic plants, hinting for anthropized, simplified plant communities. Synthesis and applications. Urbanization influences pollinator abundances, nectar resources and transported pollen in direct and indirect ways. Pollinators are negatively affected by a thermally harsh climate in highly urbanized areas with isolated green areas and large parks. Suburban landscapes demonstrated the highest pollinator presence. In the city core, flowers contained more nectary sugar in association with more precipitations, while pollinators collected pollen from a small number of plants, mainly exotic. These findings highlight the strong influence of urban landscape and climate on pollinators and plants, showing that cities are heterogenous realities. Patterns from this study will serve as basis for pollinator‐friendly planning, mitigation and management of urban landscapes.

Anthropogenic air pollutants reduce insect-mediated pollination services

Common air pollutants, such as nitrogen oxides (NOx), emitted in diesel exhaust, and ozone (O3), have been implicated in the decline of pollinating insects. Reductionist laboratory assays, focused upon interactions between a narrow range of flowering plant and pollinator species, in combination with atmospheric chemistry models, indicate that such pollutants can chemically alter floral odors, disrupting the cues that foraging insects use to find and pollinate flowers. However, odor environments in nature are highly complex and pollination services are commonly provided by suites of insect species, each exhibiting different sensitivities to different floral odors. Therefore, the potential impacts of pollution-induced foraging disruption on both insect ecology, and the pollination services that insects provide, are currently unknown. We conducted in-situ field studies to investigate whether such pollutants could reduce pollinator foraging and as a result the pollination ecosystem service that those insects provide. Using free-air fumigation, we show that elevating diesel exhaust and O3, individually and in combination, to levels lower than is considered safe under current air quality standards, significantly reduced counts of locally-occurring wild and managed insect pollinators by 62–70% and their flower visits by 83–90%. These reductions were driven by changes in specific pollinator groups, including bees, flies, moths and butterflies, and coincided with significant reductions (14–31%) in three different metrics of pollination and yield of a self-fertile test plant. Quantifying such effects provides new insights into the impacts of human-induced air pollution on the natural ecosystem services upon which we depend.