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Land-use change and habitat loss have profoundly disturbed the resource availability for many organisms in farmlands, including bees. To counteract the resulting decline of bees and to maintain their pollination service to crops, bee pollinator-friendly schemes have been developed. We assessed the most established bee pollinator-friendly schemes which mainly aim at enhancing the availability of floral food resources and, or, nesting sites. We found that the availability of non-floral resources was typically overlooked in these schemes, although more than 30% of bee species worldwide depend on non-floral resources. In this opinion paper, we call for more attention on the role of non-floral resources in such conservation schemes. In fact, at least two of the most species rich Apoidea families, the Apidae and Megachilidae, need non-floral resources for nest building, defence, protection and health. For example, resin is known to improve health and resistance to pests and pathogens in stingless bees and the western honey bee Apis mellifera. Beyond social bees, many solitary bee species, in particularly within the Euglossini, Centridini and Megachilidae, also use resin, leaf pieces, trichome secretions and other materials for the construction and protection of brood cells and the nest. Besides protection, non-floral resources can also provide alternative food resources for bees, e.g. sugary secretions from other insects. Surprisingly little is known on this insect–insect interaction although some studies suggest that honey production by beekeepers can largely depend on this alternative food resource. The apparent knowledge gap on the role of non-floral resources for bees can thus directly concern stakeholders. Interestingly, many non-floral resources are provided by woody vegetation, but most of the bee pollinator-friendly schemes are currently orientated towards enhancing flower availability in field margins and flower strips. We therefore suggest more attention in the protection of trees and hedgerows in conservation, restoration and management schemes to best supporting bee health by providing combined access to nesting, floral and non-floral foraging resources.

Nonlethal exposure of honey bees to thiamethoxam (neonicotinoid systemic pesticide) causes high mortality due to homing failure at levels that could put a colony at risk of collapse. Simulated exposure events on free-ranging foragers labeled with a radio-frequency identification tag suggest that homing is impaired by thiamethoxam intoxication. These experiments offer new insights into the consequences of common neonicotinoid pesticides used worldwide.

Honey bees ( Apis mellifera ) are exposed to multiple stressors such as pesticides, lack of forage, and diseases. It is therefore a long-standing aim to develop robust and meaningful indicators of bee vitality to assist beekeepers While established indicators often focus on expected colony winter mortality based on adult bee abundance and honey reserves at the beginning of the winter, it would be useful to have indicators that allow detection of stress effects earlier in the year to allow for adaptive management. We used the established honey bee simulation model BEEHAVE to explore the potential of different indicators such as population size, number of capped brood cells, flight activity, abundance of Varroa mites, honey stores and a brood-bee ratio. We implemented two types of stressors in our simulations: 1) parasite pressure, i.e. sub-optimal Varroa treatment by the beekeeper (hereafter referred as Biotic stress) and 2) temporal forage gaps in spring and autumn (hereafter referred as Environmental stress). Neither stressor type could be detected by bee abundance or honey reserves at the end of the first year. However, all response variables used in this study did reveal early warning signals during the course of the year. The most reliable and useful measures seem to be related to brood and the abundance of Varroa mites at the end of the year. However, while in the model we have full access to time series of variables from stressed and unstressed colonies, knowledge of these variables in the field is challenging. We discuss how our findings can nevertheless be used to develop practical early warning indicators. As a next step in the interactive development of such indicators we suggest empirical studies on the importance of the number of capped brood cells at certain times of the year on bee population vitality.

Honey bees ( Apis spp.) play a crucial role in agricultural productivity and ecosystem functioning through pollination. However, their foraging behaviour is increasingly affected by pesticide exposure, including insecticides, acaricides, fungicides, and herbicides. Reported effects range from adverse to negligible or even stimulatory, depending on the compound, dose, and experimental design. To support more ecologically realistic risk assessments, we conducted a targeted scoping review of 26 studies examining pesticide impacts on honey bee foraging under semi-field and field-realistic conditions. These studies were evaluated based on pesticide type, exposure route and duration, Apis species, foraging type (nectar vs. pollen), behavioural endpoint, level of observation (individual vs. colony), and proposed mechanisms. Our synthesis reveals a pronounced research bias toward neonicotinoid insecticides and Apis mellifera , with minimal investigation of other pesticide classes, chronic exposures, or non- mellifera species such as A. cerana and A. dorsata . Most studies assessed individual-level effects and nectar foraging, while colony-level endpoints and pollen foraging remain underexplored. Additionally, small and inconsistent sample sizes reduce the statistical robustness and generalisability of many findings. We identify critical gaps in current pesticide risk assessments and call for standardised experimental methodologies, including harmonised behavioural metrics, consistent dosing protocols, and endpoints that link individual- to colony-level responses. Strengthening colony-level indicators under field-realistic exposures is essential for improving the predictive power of regulatory assessments, guiding targeted mitigation strategies, and promoting more sustainable pesticide use in agroecosystems. Graphical Abstract

Pollinators are essential for crop pollination, but pollinators differ in their pollination efficiency. In urban areas, environmental filters such as soil sealing or the urban heat island lead to biotic homogenisation of pollinator communities, with generalist species being favoured while specialist species are filtered out. Therefore, efficient pollinators may be excluded from urban areas. In the context of the development of urban agriculture, urban areas require pollination by efficient pollinators. Here, we ask whether pollinators sustained in urban environments are equally efficient, and whether urbanisation impacts the efficiency of pollinators delivering pollination services. Using strawberry and raspberry as experimental plants, we carried out single visit experiments over 2 years (2023 and 2024) in spring and autumn, to assess pollination efficiency in densely urbanised and suburban sites in the region of Paris (France). We measured fruit mass, malformation and seed set of fruits which developed from flowers having received a single visit from a pollinator. We found that bumblebees were more efficient than honeybees as pollinators of raspberry, but not strawberry, as measured by fruit mass. Bumblebees were also more efficient than small and large solitary bees for pollinating strawberry, and more efficient than large solitary bees for pollinating raspberry. These differences were detected on mass for strawberries, and on mass, seed set and fruit malformation for raspberries. Practical implication: Environmental filters in urban environments tend to favour few generalist pollinator species. On one hand, these environments support honeybees, which we found were not necessarily the most efficient. On the other hand, wild pollinators, in particular bumblebees, were more efficient than honeybees for pollination of strawberry and raspberry. Thus, urban conservation strategies should focus on promoting these wild and efficient pollinators by planting beneficial plant species in flower beds and providing nesting habitats for ground nesting pollinators. This would promote diverse and efficient pollinators and thus enhance pollination services for urban agriculture. We evaluated single‐visit pollination efficiency, on strawberry and raspberry plants, in urban and suburban sites. Bumblebees were overall the most efficient pollinator. For strawberry, bumblebees had equivalent efficiency to honeybees, while for raspberry, bumblebees were more efficient than honeybees. Honeybees are often favoured in urbanised environments, but we show that they are not necessarily the most efficient, indicating that wild pollinators should be the target of urban landscape management in order to improve pollination in urban environments.

Automated 3D image‐based tracking systems are new and promising devices to investigate the foraging behavior of flying animals with great accuracy and precision. 3D analyses can provide accurate assessments of flight performance in regard to speed, curvature, and hovering. However, there have been few applications of this technology in ecology, particularly for insects. We used this technology to analyze the behavioral interactions between the Western honey bee Apis mellifera and its invasive predator the Asian hornet, Vespa velutina nigrithorax. We investigated whether predation success could be affected by flight speed, flight curvature, and hovering of the Asian hornet and honey bees in front of one beehive. We recorded a total of 603,259 flight trajectories and 5175 predator–prey flight interactions leading to 126 successful predation events, representing 2.4% predation success. Flight speeds of hornets in front of hive entrances were much lower than that of their bee prey; in contrast to hovering capacity, while curvature range overlapped between the two species. There were large differences in speed, curvature, and hovering between the exit and entrance flights of honey bees. Interestingly, we found hornet density affected flight performance of both honey bees and hornets. Higher hornet density led to a decrease in the speed of honey bees leaving the hive, and an increase in the speed of honey bees entering the hive, together with more curved flight trajectories. These effects suggest some predator avoidance behavior by the bees. Higher honey bee flight curvature resulted in lower hornet predation success. Results showed an increase in predation success when hornet number increased up to 8 individuals, above which predation success decreased, likely due to competition among predators. Although based on a single colony, this study reveals interesting outcomes derived from the use of automated 3D tracking to derive accurate measures of individual behavior and behavioral interactions among flying species. In this study, we used 3D image based tracking to analyse the behavioural interactions between the Western honey bee Apis melifera and its invasive predator the Asian hornet, Vespa velutina nigrithorax. We investigated whether predation success could be affected by flight speed, flight curvature, and hovering of the Asian hornet and honey bees in front of the beehive.

Temperature and photoperiod are important Zeitgebers for plants and pollinators to synchronize growth and reproduction with suitable environmental conditions and their mutualistic interaction partners. Global warming can disturb this temporal synchronization since interacting species may respond differently to new combinations of photoperiod and temperature under future climates, but experimental studies on the potential phenological responses of plants and pollinators are lacking. We simulated current and future combinations of temperature and photoperiod to assess effects on the overwintering and spring phenology of an early flowering plant species (Crocus sieberi) and the Western honey bee (Apis mellifera). We could show that increased mean temperatures in winter and early spring advanced the flowering phenology of C. sieberi and intensified brood rearing activity of A. mellifera but did not advance their brood rearing activity. Flowering phenology of C. sieberi also relied on photoperiod, while brood rearing activity of A. mellifera did not. The results confirm that increases in temperature can induce changes in phenological responses and suggest that photoperiod can also play a critical role in these responses, with currently unknown consequences for real‐world ecosystems in a warming climate. This study analyzed whether differences in the importance of temperature and photoperiod as Zeitgebers could lead to different phenological responses of the early‐season flowering geophyte Crocus sieberi and Apis mellifera colonies under future climates. Increased mean temperatures in winter and early spring advanced the flowering phenology of C. sieberi and intensified brood rearing activity of A. mellifera but did not advance their brood rearing activity. Flowering phenology of C. sieberi also relied on photoperiod, while brood rearing activity of A. mellifera did not. Increases in temperature can induce changes in phenological responses and photoperiod can also play a critical role in these responses. ​

Recent studies reveal the use of tree cavities by wild honeybee colonies in European forests. This highlights the conservation potential of forests for a highly threatened component of the native entomofauna in Europe, but currently no estimate of potential wild honeybee population sizes exists. Here, we analyzed the tree cavity densities of 106 forest areas across Europe and inferred an expected population size of wild honeybees. Both forest and management types affected the density of tree cavities. Accordingly, we estimated that more than 80,000 wild honeybee colonies could be sustained in European forests. As expected, potential conservation hotspots were identified in unmanaged forests, and, surprisingly, also in other large forest areas across Europe. Our results contribute to the EU policy strategy to halt pollinator declines and reveal the potential of forest areas for the conservation of so far neglected wild honeybee populations in Europe.

Pollination services provided by a diversity of pollinators are critical in agriculture because they enhance the yield of many crops. However, few studies have assessed pollination services in urban agricultural systems. We performed flower–visitor observations and pollination experiments on strawberries (Fragaria × ananassa) in an urban area near Paris, France, in order to assess the effects of (i) insect-mediated pollination service and (ii) potential pollination deficit on fruit set, seed set, and fruit quality (size, weight, and malformation). Flower–visitor observations revealed that the pollinator community solely comprised unmanaged pollinators, despite the presence of beehives in the surrounding landscape. Based on the pollination experiments, we found that the pollination service mediated by wild insects improved the fruit size as a qualitative value of production, but not the fruit set. We also found no evidence of pollination deficit in our urban environment. These results suggest that the local community of wild urban pollinators is able to support strawberry crop production and thus plays an important role in providing high-quality, local, and sustainable crops in urban areas.

The Asian hornet is an invasive predator of honey bees in Western Europe. The Asian hornet-related risk of bee colony mortality has motivated the development of biological and physical control methods over the past years. Although the technical cost–benefit ratio has been established for most of these control methods, it is still unclear whether such methods can reduce the detrimental effects of the Asian hornet on European honey bees. In this study, we investigated the potential benefits of a biodiversity-friendly control method, the beehive muzzle. We observed the flight activity of bees and the predation behaviour of the Asian hornets at the beehive entrance of 22 pairs of honey bee colonies, each with one muzzle-equipped colony and one control colony without muzzle, in France. We measured HF (bee homing failure due to hornet predation of bees) and FP (foraging paralysis: the stop of flight activity in beehives due to hovering hornets), and estimated the mortality probability of the colonies using a mechanistic modelling approach. The beehive muzzle did not reduce the hornet-related HF, but drastically reduced FP. Moreover, the muzzle increased the survival probability of hornet-stressed colonies up to 51% in context of high abundance of Asian hornets based on theoretical simulations. These results suggest that installing beehive muzzles can mitigate the detrimental effect of the Asian hornet on European honey bees. This low-cost technique does not lead to any environmental impacts and could therefore be recommended to beekeepers as an effective biodiversity-friendly method of Asian hornet control.