Distance functions of carabids in crop fields depend on functional traits, crop type and adjacent habitat: a synthesis.

Natural pest and weed regulation are essential for agricultural production, but the spatial distribution of natural enemies within crop fields and its drivers are mostly unknown. Using 28 datasets comprising 1204 study sites across eight Western and Central European countries, we performed a quantitative synthesis of carabid richness, activity densities and functional traits in relation to field edges (i.e. distance functions). We show that distance functions of carabids strongly depend on carabid functional traits, crop type and, to a lesser extent, adjacent non-crop habitats. Richness of both carnivores and granivores, and activity densities of small and granivorous species decreased towards field interiors, whereas the densities of large species increased. We found strong distance decays in maize and vegetables whereas richness and densities remained more stable in cereals, oilseed crops and legumes. We conclude that carabid assemblages in agricultural landscapes are driven by the complex interplay of crop types, adjacent non-crop habitats and further landscape parameters with great potential for targeted agroecological management. In particular, our synthesis indicates that a higher edge-interior ratio can counter the distance decay of carabid richness per field and thus likely benefits natural pest and weed regulation, hence contributing to agricultural sustainability.

Reproduction of Varroa destructor depends on well-timed host cell recapping and seasonal patterns.

Resistance traits of honeybees (Apis mellifera) against their major parasite Varroa destructor have fascinated scientists and breeders for long. Nevertheless, the mechanisms underlying resistance are still largely unknown. The same applies to possible interactions between host behaviours, mite reproduction and seasonal differences. Two resistance traits, reproductive failure of mites and recapping of brood cells, are of particular interest. High rates of recapping at the colony level were found to correspond with low reproductive success of mites. However, the direct effect of recapping on mite reproduction is still controversial and both traits seem to be very variable in their expression. Thus, a deeper knowledge of both, the effect of recapping on mite reproduction and the seasonal differences in the expression of these traits is urgently needed. To shed light on this host-parasite interaction, we investigated recapping and mite reproduction in full-grown colonies naturally infested with V. destructor. Measurements were repeated five times per year over the course of 3 years. The reproductive success of mites as well as the recapping frequency clearly followed seasonal patterns. Thereby, reproductive failure of mites at the cell level was constantly increased in case of recapping. Interestingly, this did not apply to the occurrence of infertile mites. In line with this, recapping activity in fertile cells was most frequent in brood ages in which mite offspring would be expected. Our results suggest that mite offspring is the main target of recapping. This, in turn, leads to a significantly reduced reproductive success of the parasite.

Parasites, depredators, and limited resources as potential drivers of winter mortality of feral honeybee colonies in German forests.

Wild honeybees (Apis mellifera) are considered extinct in most parts of Europe. The likely causes of their decline include increased parasite burden, lack of high-quality nesting sites and associated depredation pressure, and food scarcity. In Germany, feral honeybees still colonize managed forests, but their survival rate is too low to maintain viable populations. Based on colony observations collected during a monitoring study, data on parasite prevalence, experiments on nest depredation, and analyses of land cover maps, we explored whether parasite pressure, depredation or expected landscape-level food availability explain feral colony winter mortality. Considering the colony-level occurrence of 18 microparasites in the previous summer, colonies that died did not have a higher parasite burden than colonies that survived. Camera traps installed at cavity trees revealed that four woodpecker species, great tits, and pine martens act as nest depredators. In a depredator exclusion experiment, the winter survival rate of colonies in cavities with protected entrances was 50% higher than that of colonies with unmanipulated entrances. Landscapes surrounding surviving colonies contained on average 6.4 percentage points more cropland than landscapes surrounding dying colonies, with cropland being known to disproportionately provide forage for bees in our study system. We conclude that the lack of spacious but well-protected nesting cavities and the shortage of food are currently more important than parasites in limiting populations of wild-living honeybees in German forests. Increasing the density and diversity of large tree cavities and promoting bee forage plants in forests will probably promote wild-living honeybees despite parasite pressure.

A dataset of occurrence of wild bees and their interaction with foraging plants along a livestock grazing gradient of northern Tanzania.

A dataset describing the occurrence of wild bees and their interaction with forage plants along livestock grazing gradient is critical in understanding bee-plant interaction networks and in developing conservation plans to ensure ecosystem services in human-modified landscapes. Despite this need, bee-plant datasets are scarce in Africa, and Tanzania is no exception. Therefore, in this article, we present a dataset of wild bee species richness, occurrence, and distribution collected across sites with different levels of livestock grazing intensity and forage resources thereby. The data presented in this paper supports a research article by Lasway et al., 2022 describing the effects of grazing intensity on East African bee assemblages. The paper presents primary data on bee species, collection method, date of collection, bee family, identifier, plant forage resource, forage plant life form, forage plant family, location (GPS coordinates), grazing intensity category, mean annual temperature (°C), and elevation (m asl). The data were collected intermittently between August 2018 and March 2020 from 24 study sites distributed along three levels of livestock grazing intensity with eight replicates for each: low, moderate, and high livestock grazing intensity. In each study site, two 50 × 50 m study plots were set from which bees and floral resources were sampled and quantified. The two plots were placed in a way to capture the overall structural heterogeneity of the respective habitat by placing the two plots in contrasting microhabitats where possible. For example, in moderately livestock-grazed habitats, plots were placed on sites with and without tree or shrub cover to ensure representativeness. This paper presents a dataset comprising 2,691 bee individuals from 183 species representing 55 genera of the five bee families: Halictidae (74), Apidae (63), Megachilidae (40), Andrenidae (5), and Colletidae (1). In addition, the dataset comprises 112 species of flowering plants that were identified as potential forage resources for bees. This paper supplements rare but critical data on bee pollinators in Northern Tanzania and advances our knowledge of the potential drivers of bee-pollinator whose populations diversity are declining globally. The dataset will also promote collaborations among researchers who would wish to combine and extend their data for further analysis to gain a broader understanding of the phenomenon on a larger spatial scale.

Birds and bats enhance cacao yield despite suppressing arthropod mesopredation.

Bird- and bat-mediated biocontrol benefits the productivity of tropical commodity crops such as cacao, but the ecological interactions driving these ecosystem services remain poorly understood. Whereas birds and bats prey on herbivorous arthropods, they may also prey on arthropod mesopredators such as ants, with poorly understood consequences for pest biocontrol. We used a full-factorial experiment excluding birds, bats, and ants to assess their effects on (a) the abundance of multiple arthropod groups; (b) predation pressure on arthropods evaluated through artificial sentinel caterpillars; and (c) cacao yield over 1 year in shaded agroforestry systems of native cacao varieties in Peru. Birds and bats increased cacao yield by 118%, which translates in smallholder benefits of ca. US $959 ha-1 year-1 . Birds and bats decreased predation by ants and other arthropods, but contributed to the control of phytophagous taxa such as aphids and mealybugs. By contrast, ant presence increased the abundance of these sap-sucking insects, with negative impacts for cacao yield. Notably, high abundances of the dominant ant Nylanderia sp., known to attend sap-sucking insects, were associated with lower cacao yield along a distance gradient from the closest forest edge. According to these results, arthropod predation by birds and bats, rather than mesopredation by arthropods, was most responsible for increases in cacao yield. Moving forward, detailed research about their trophic interactions will be necessary to identify the cause of such benefits. Retaining and restoring the large benefits of birds and bats as well as minimizing disservices by other taxa in cacao agroforests can benefit from management schemes that prioritize preservation of shade trees and adjacent forests within agroforestry landscapes.

Seasonal and elevational changes of plant-pollinator interaction networks in East African mountains.

Across an elevation gradient, several biotic and abiotic factors influence community assemblages of interacting species leading to a shift in species distribution, functioning, and ultimately topologies of species interaction networks. However, empirical studies of climate-driven seasonal and elevational changes in plant-pollinator networks are rare, particularly in tropical ecosystems. Eastern Afromontane Biodiversity Hotspots in Kenya, East Africa. We recorded plant-bee interactions at 50 study sites between 515 and 2600 m asl for a full year, following all four major seasons in this region. We analysed elevational and seasonal network patterns using generalised additive models (GAMs) and quantified the influence of climate, floral resource availability, and bee diversity on network structures using a multimodel inference framework. We recorded 16,741 interactions among 186 bee and 314 plant species of which a majority involved interactions with honeybees. We found that nestedness and bee species specialisation of plant-bee interaction networks increased with elevation and that the relationships were consistent in the cold-dry and warm-wet seasons respectively. Link rewiring increased in the warm-wet season with elevation but remained indifferent in the cold-dry seasons. Conversely, network modularity and plant species were more specialised at lower elevations during both the cold-dry and warm-wet seasons, with higher values observed during the warm-wet seasons. We found flower and bee species diversity and abundance rather than direct effects of climate variables to best predict modularity, specialisation, and link rewiring in plant-bee-interaction networks. This study highlights changes in network architectures with elevation suggesting a potential sensitivity of plant-bee interactions with climate warming and changes in rainfall patterns along the elevation gradients of the Eastern Afromontane Biodiversity Hotspot.

Elevated ozone and carbon dioxide affects the composition of volatile organic compounds emitted by Vicia faba (L.) and visitation by European orchard bee (Osmia cornuta).

Recent studies link increased ozone (O3) and carbon dioxide (CO2) levels to alteration of plant performance and plant-herbivore interactions, but their interactive effects on plant-pollinator interactions are little understood. Extra floral nectaries (EFNs) are essential organs used by some plants for stimulating defense against herbivory and for the attraction of insect pollinators, e.g., bees. The factors driving the interactions between bees and plants regarding the visitation of bees to EFNs are poorly understood, especially in the face of global change driven by greenhouse gases. Here, we experimentally tested whether elevated levels of O3 and CO2 individually and interactively alter the emission of Volatile Organic Compound (VOC) profiles in the field bean plant (Vicia faba, L., Fabaceae), EFN nectar production and EFN visitation by the European orchard bee (Osmia cornuta, Latreille, Megachilidae). Our results showed that O3 alone had significant negative effects on the blends of VOCs emitted while the treatment with elevated CO2 alone did not differ from the control. Furthermore, as with O3 alone, the mixture of O3 and CO2 also had a significant difference in the VOCs' profile. O3 exposure was also linked to reduced nectar volume and had a negative impact on EFN visitation by bees. Increased CO2 level, on the other hand, had a positive impact on bee visits. Our results add to the knowledge of the interactive effects of O3 and CO2 on plant volatiles emitted by Vicia faba and bee responses. As greenhouse gas levels continue to rise globally, it is important to take these findings into consideration to better prepare for changes in plant-insect interactions.

Plant species composition and local habitat conditions as primary determinants of terrestrial arthropod assemblages.

Arthropods respond to vegetation in multiple ways since plants provide habitat and food resources and indicate local abiotic conditions. However, the relative importance of these factors for arthropod assemblages is less well understood. We aimed to disentangle the effects of plant species composition and environmental drivers on arthropod taxonomic composition and to assess which aspects of vegetation contribute to the relationships between plant and arthropod assemblages. In a multi-scale field study in Southern Germany, we sampled vascular plants and terrestrial arthropods in typical habitats of temperate landscapes. We compared independent and shared effects of vegetation and abiotic predictors on arthropod composition distinguishing between four large orders (Lepidoptera, Coleoptera, Hymenoptera, Diptera), and five functional groups (herbivores, pollinators, predators, parasitoids, detritivores). Across all investigated groups, plant species composition explained the major fraction of variation in arthropod composition, while land-cover composition was another important predictor. Moreover, the local habitat conditions depicted by the indicator values of the plant communities were more important for arthropod composition than trophic relationships between certain plant and arthropod species. Among trophic groups, predators showed the strongest response to plant species composition, while responses of herbivores and pollinators were stronger than those of parasitoids and detritivores. Our results highlight the relevance of plant community composition for terrestrial arthropod assemblages across multiple taxa and trophic levels and emphasize the value of plants as a proxy for characterizing habitat conditions that are hardly accessible to direct environmental measurements.

Enhancing the structural diversity between forest patches-A concept and real-world experiment to study biodiversity, multifunctionality and forest resilience across spatial scales.

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity-ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch ß-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, ß-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the ß-diversity of different trophic levels, as well as the ß-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and ß-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.

The supply of multiple ecosystem services requires biodiversity across spatial scales.

The impact of local biodiversity loss on ecosystem functioning is well established, but the role of larger-scale biodiversity dynamics in the delivery of ecosystem services remains poorly understood. Here we address this gap using a comprehensive dataset describing the supply of 16 cultural, regulating and provisioning ecosystem services in 150 European agricultural grassland plots, and detailed multi-scale data on land use and plant diversity. After controlling for land-use and abiotic factors, we show that both plot-level and surrounding plant diversity play an important role in the supply of cultural and aboveground regulating ecosystem services. In contrast, provisioning and belowground regulating ecosystem services are more strongly driven by field-level management and abiotic factors. Structural equation models revealed that surrounding plant diversity promotes ecosystem services both directly, probably by fostering the spill-over of ecosystem service providers from surrounding areas, and indirectly, by maintaining plot-level diversity. By influencing the ecosystem services that local stakeholders prioritized, biodiversity at different scales was also shown to positively influence a wide range of stakeholder groups. These results provide a comprehensive picture of which ecosystem services rely most strongly on biodiversity, and the respective scales of biodiversity that drive these services. This key information is required for the upscaling of biodiversity-ecosystem service relationships, and the informed management of biodiversity within agricultural landscapes.

Nutritional resources modulate the responses of three bee species to pesticide exposure.

The response of bee species to various stressors is assumed to depend on the availability of sufficient nutrients in their environment. We compare the response of three bee species (Apis mellifera, Bombus terrestris, Osmia bicornis) under laboratory conditions. Survival, physiology, and sensitivity, after exposure to the fungicide prochloraz, the insecticide chlorantraniliprole, and their mixture with different nutritional resources (sugar only, sugar with amino acids or pollen) were observed. Prochloraz reduced the bee survival of A. mellifera and O. bicornis fed with pollen, but not with other diets. Chlorantraniliprole impaired the survival of A. mellifera fed with sugar or pollen diet, but not with amino acid diet. The mixture impaired survival of A. mellifera and O. bicornis in association with every diet. B. terrestris was only affected by chlorantraniliprole and its mixture with prochloraz fed with sugar diet. The activity of P450 reductase was higher in A. mellifera fed with amino acids in all treatments, whereas no effect emerged in O. bicornis and B. terrestris. Our results indicate that the sensitivity of bee species after exposure to agrochemicals is affected by diet. Thus, balanced and species-dependent nutrition ameliorated the effects. Further field studies are necessary to evaluate the potential effects of such mixtures on bee populations.

Socio-ecological benefits of fine-flavor cacao in its center of origin.

In the tropics, combining food security with biodiversity conservation remains a major challenge. Tropical agroforestry systems are among the most biodiversity-friendly and productive land-use systems, and 70% of cocoa is grown by >6 million smallholder farmers living on <2$ per day. In cacao's main centre of diversification, the western Amazon region, interest is growing to achieve premium prices with the conversion of high-yielding, but mostly bulk-quality cacao to native fine-flavor cacao varieties, culturally important since pre-Columbian times. Conversion to native cacao can be expected to favor adaptation to regional climate and growth conditions, and to enhance native biodiversity and ecosystem services such as biological pest control and pollination, but possibly also imply susceptibility to diseases. Experience from successful conversion of non-native cacao plantations to fine-flavor cacao agroforestry with rejuvenation by grafting and under medium-canopy cover levels (30%-40%) can ensure a smooth transition with only minor temporary productivity gaps. This includes ongoing selection programs of high yielding and disease resistant native fine-flavor cacao genotypes and organizing in cooperatives to buffer the high market volatility. In conclusion, the recent interest on converting bulk cacao to a diversity of native fine-flavor varieties in countries like Peru is a challenge, but offers promising socio-ecological perspectives.

Corrigendum: Honeybees are buffered against undernourishment during larval stages.

[This corrects the article DOI: 10.3389/finsc.2022.951317.].

Bacterial gut microbiomes of aculeate brood parasites overlap with their aculeate hosts', but have higher diversity and specialization.

Despite growing interest in gut microbiomes of aculeate Hymenoptera, research so far focused on social bees, wasps, and ants, whereas non-social taxa and their brood parasites have not received much attention. Brood parasitism, however, allows to distinguish between microbiome components horizontally transmitted by spill-over from the host with such inherited through vertical transmission by mothers. Here, we studied the bacterial gut microbiome of adults in seven aculeate species in four brood parasite-host systems: two bee-mutillid (host-parasitoid) systems, one halictid bee-cuckoo bee system, and one wasp-chrysidid cuckoo wasp system. We addressed the following questions: (1) Do closely related species possess a more similar gut microbiome? (2) Do brood parasites share components of the microbiome with their host? (3) Do brood parasites have different diversity and specialization of microbiome communities compared with the hosts? Our results indicate that the bacterial gut microbiome of the studied taxa was species-specific, yet with a limited effect of host phylogenetic relatedness and a major contribution of shared microbes between hosts and parasites. However, contrasting patterns emerged between bee-parasite systems and the wasp-parasite system. We conclude that the gut microbiome in adult brood parasites is largely affected by their host-parasite relationships and the similarity of trophic food sources between hosts and parasites.

Dung-visiting beetle diversity is mainly affected by land use, while community specialization is driven by climate.

Dung beetles are important actors in the self-regulation of ecosystems by driving nutrient cycling, bioturbation, and pest suppression. Urbanization and the sprawl of agricultural areas, however, destroy natural habitats and may threaten dung beetle diversity. In addition, climate change may cause shifts in geographical distribution and community composition. We used a space-for-time approach to test the effects of land use and climate on α-diversity, local community specialization (H 2') on dung resources, and γ-diversity of dung-visiting beetles. For this, we used pitfall traps baited with four different dung types at 115 study sites, distributed over a spatial extent of 300 km × 300 km and 1000 m in elevation. Study sites were established in four local land-use types: forests, grasslands, arable sites, and settlements, embedded in near-natural, agricultural, or urban landscapes. Our results show that abundance and species density of dung-visiting beetles were negatively affected by agricultural land use at both spatial scales, whereas γ-diversity at the local scale was negatively affected by settlements and on a landscape scale equally by agricultural and urban land use. Increasing precipitation diminished dung-visiting beetle abundance, and higher temperatures reduced community specialization on dung types and γ-diversity. These results indicate that intensive land use and high temperatures may cause a loss in dung-visiting beetle diversity and alter community networks. A decrease in dung-visiting beetle diversity may disturb decomposition processes at both local and landscape scales and alter ecosystem functioning, which may lead to drastic ecological and economic damage.

Quantifying services and disservices provided by insects and vertebrates in cacao agroforestry landscapes.

Animals provide services such as pollination and pest control in cacao agroforestry systems, but also disservices. Yet, their combined contributions to crop yield and fruit loss are mostly unclear. In a full-factorial field experiment in northwestern Peru, we excluded flying insects, ants, birds and bats from cacao trees and assessed several productivity indicators. We quantified the contribution of each group to fruit set, fruit loss and marketable yield and evaluated how forest distance and canopy closure affected productivity. Fruit set dropped (from 1.7% to 0.3%) when flying insects were excluded and tripled at intermediate (40%) compared to high (greater than 80%) canopy cover in the non-exclusion treatment. Fruit set also dropped with bird and bat exclusion, potentially due to increased abundances of arthropods preying on pollinators or flower herbivores. Overall, cacao yields more than doubled when birds and bats had access to trees. Ants were generally associated with fruit loss, but also with yield increases in agroforests close to forest. We also evidenced disservices generated by squirrels, leading to significant fruit losses. Our findings show that several functional groups contribute to high cacao yield, while trade-offs between services and disservices need to be integrated in local and landscape-scale sustainable cacao agroforestry management.

Population demography of feral honeybee colonies in central European forests.

European honeybee populations are considered to consist only of managed colonies, but recent censuses have revealed that wild/feral colonies still occur in various countries. To gauge the ecological and evolutionary relevance of wild-living honeybees, information is needed on their population demography. We monitored feral honeybee colonies in German forests for up to 4 years through regular inspections of woodpecker cavity trees and microsatellite genotyping. Each summer, about 10% of the trees were occupied, corresponding to average densities of 0.23 feral colonies km-2 (an estimated 5% of the regional honeybee populations). Populations decreased moderately until autumn but dropped massively during winter, so that their densities were only about 0.02 colonies km-2 in early spring. During the reproductive (swarming) season, in May and June, populations recovered, with new swarms preferring nest sites that had been occupied in the previous year. The annual survival rate and the estimated lifespan of feral colonies (n = 112) were 10.6% and 0.6 years, respectively. We conclude that managed forests in Germany do not harbour self-sustaining feral honeybee populations, but they are recolonized every year by swarms escaping from apiaries.

The role of diversity, body size and climate in dung removal: A correlative and experimental approach.

The mechanisms by which climatic changes influence ecosystem functions, that is, by a direct climatic control of ecosystem processes or by modifying richness and trait compositions of species communities, remain unresolved. This study is a contribution to this discourse by elucidating the linkages between climate, land use, biodiversity, body size and ecosystem functions. We disentangled direct climatic from biodiversity-mediated effects by using dung removal by dung beetles as a model system and by combining correlative field data and exclosure experiments along an extensive elevational gradient on Mt. Kilimanjaro, Tanzania. Dung removal declined with increasing elevation, being associated with a strong reduction in the richness and body size traits of dung beetle communities. Climate influenced dung removal rates by modifying biodiversity rather than by direct effects. The biodiversity-ecosystem effect was driven by a change in the mean body size of dung beetles. Dung removal rates were strongly reduced when large dung beetles were experimentally excluded. This study underscores that climate influences ecosystem functions mainly by modifying biodiversity and underpins the important role of body size for dung removal.

Plant richness, land use and temperature differently shape invertebrate leaf-chewing herbivory on plant functional groups.

Higher temperatures can increase metabolic rates and carbon demands of invertebrate herbivores, which may shift leaf-chewing herbivory among plant functional groups differing in C:N (carbon:nitrogen) ratios. Biotic factors influencing herbivore species richness may modulate these temperature effects. Yet, systematic studies comparing leaf-chewing herbivory among plant functional groups in different habitats and landscapes along temperature gradients are lacking. This study was conducted on 80 plots covering large gradients of temperature, plant richness and land use in Bavaria, Germany. We investigated proportional leaf area loss by chewing invertebrates ('herbivory') in three plant functional groups on open herbaceous vegetation. As potential drivers, we considered local mean temperature (range 8.4-18.8 °C), multi-annual mean temperature (range 6.5-10.0 °C), local plant richness (species and family level, ranges 10-51 species, 5-25 families), adjacent habitat type (forest, grassland, arable field, settlement), proportion of grassland and landscape diversity (0.2-3 km scale). We observed differential responses of leaf-chewing herbivory among plant functional groups in response to plant richness (family level only) and habitat type, but not to grassland proportion, landscape diversity and temperature-except for multi-annual mean temperature influencing herbivory on grassland plots. Three-way interactions of plant functional group, temperature and predictors of plant richness or land use did not substantially impact herbivory. We conclude that abiotic and biotic factors can assert different effects on leaf-chewing herbivory among plant functional groups. At present, effects of plant richness and habitat type outweigh effects of temperature and landscape-scale land use on herbivory among legumes, forbs and grasses.

Interactive effects of climate and land use on pollinator diversity differ among taxa and scales.

Changes in climate and land use are major threats to pollinating insects, an essential functional group. Here, we unravel the largely unknown interactive effects of both threats on seven pollinator taxa using a multiscale space-for-time approach across large climate and land-use gradients in a temperate region. Pollinator community composition, regional gamma diversity, and community dissimilarity (beta diversity) of pollinator taxa were shaped by climate-land-use interactions, while local alpha diversity was solely explained by their additive effects. Pollinator diversity increased with reduced land-use intensity (forest < grassland < arable land < urban) and high flowering-plant diversity at different spatial scales, and higher temperatures homogenized pollinator communities across regions. Our study reveals declines in pollinator diversity with land-use intensity at multiple spatial scales and regional community homogenization in warmer and drier climates. Management options at several scales are highlighted to mitigate impacts of climate change on pollinators and their ecosystem services.