Publications by authors named "Fabrice Requier"

The dataset contains information on plant-bee interactions in an agricultural landscape with diverse intensities of land use management, in Germany and Belgium. It was collected during spring and early summer in 2020 and 2021 using two complementary types of sampling: standardized transects (5 transects of 50 m long in 1 h of netting) and targeted sampling in which flowers were observed for diverse periods of times, anywhere in an area of 50 to 150 m. The species identity was obtained with field keys and DNA barcoding.

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In recent decades, worldwide concerns about the health of honey bees motivated the development of surveys to monitor the colony losses, of which Sub-Saharan Africa has had limited representation. In the context of climate change, understanding how climate affects colony losses has become fundamental, yet literature on this subject is scarce. For the first time, we conducted a survey to estimate the livestock decrease of honey bee colonies in Kenya for the year 2021-2022 to explore the effects of environmental conditions, such as temperature and precipitation, on livestock decrease.

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Due to the increasing pressures on bees, many beekeepers currently wish to move their managed livestock of into little disturbed ecosystems such as protected natural areas. This may, however, exert detrimental competitive effects upon local wild pollinators. While it appears critical for land managers to get an adequate knowledge of this issue for effective wildlife conservation schemes, the frequency of this competition is not clear to date.

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Landscape simplification and the loss of semi-natural habitats are identified as important drivers of insect pollinator decline in farmlands, by disrupting the availability of floral resources and facilitating the occurrence of food shortages. Food shortages can lead to accelerated behavioral maturation in honey bees, with potential consequences for colony survival. However, little is known about the magnitude of behavioral maturation mediated by to food shortage under real field conditions, and whether it could be mitigated by the presence of semi-natural habitats.

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High winter mortality of honey bees () has been observed in temperate regions over the past 30 years. Several biotic and abiotic stressors associated with winter colony losses have been identified, but the mechanisms and interactions underlying their effects remain unclear. We reviewed the effects of stressors on key overwintering biological traits, distinguishing between individual and colony traits.

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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.

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Article Synopsis
  • A large-scale survey conducted in Latin America found that on average, 30.4% of managed honey bee colonies and 39.6% of stingless bee colonies were lost each year over a two-year period (2016-2018).
  • Summer losses for stingless bees (30.9%) were higher compared to winter losses (22.2%), while honey bee losses did not show the same seasonal pattern.
  • The survey revealed significant differences in colony loss rates between countries and over the years, indicating challenges in maintaining bee colony health and economic viability for those involved in beekeeping.
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Apis mellifera was used as a model species for ecotoxicological testing. In the present study, we tested the effects of acetone (0.1% in feed), a solvent commonly used to dissolve pesticides, on bees exposed at different developmental stages (larval and/or adult).

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The Western honey bee Apis mellifera is a managed species that provides diverse hive products and contributing to wild plant pollination, as well as being a critical component of crop pollination systems worldwide. High mortality rates have been reported in different continents attributed to different factors, including pesticides, pests, diseases, and lack of floral resources. Furthermore, climate change has been identified as a potential driver negatively impacting pollinators, but it is still unclear how it could affect honey bee populations.

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Social insects' nests harbor intruders known as inquilines, which are usually related to their hosts. However, distant non-social inquilines may also show convergences with their hosts, although the underlying genomic changes remain unclear. We analyzed the genome of the wingless and blind bee louse fly Braula coeca, an inquiline kleptoparasite of the western honey bee, Apis mellifera.

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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 () 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).

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Article Synopsis
  • Biological invasions, particularly by the Yellow-legged hornet, pose significant ecological and economic threats, especially to honey bees and beekeeping practices.
  • The study used field data and modeling to assess the mortality risk to bee colonies and estimated that up to 29.2% of colonies could face mortality annually due to these hornets, leading to potential economic losses of €30.8 million per year for beekeepers.
  • Findings indicate that there's a pressing need for better financial assessments of the impacts of invasive species on biodiversity to inform conservation policies.
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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.

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Pollinators are critical for food security; however, their contribution to the pollination of locally important crops is still unclear, especially for non-bee pollinators. We reviewed the diversity, conservation status, and role of bee and non-bee pollinators in 83 different crops described either as important for the global food market or of local importance. Bees are the most commonly recorded crop floral visitors.

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Environmental gradients generate and maintain biodiversity on Earth. Mountain slopes are among the most pronounced terrestrial environmental gradients, and the elevational structure of species and their interactions can provide unique insight into the processes that govern community assembly and function in mountain ecosystems. We recorded bumble bee-flower interactions over 3 years along a 1400-m elevational gradient in the German Alps.

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Biotic pollination and pest control are two critical insect-mediated ecosystem services that support crop production. Although management of both services is usually treated separately, the new paradigm of Integrated Pest and Pollinator Management (IPPM) suggests synergetic benefits by considering them together. We reviewed the management practices in two major tropical perennial crops: cocoa and coffee, to assess IPPM applications under the tropics.

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Pesticide risk-assessment guidelines for honeybees (Apis mellifera) generally require determining the acute toxicity of a chemical over the short-term through fix-duration tests. However, potential long-lasting or delayed effects resulting from an acute exposure (e.g.

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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 () and the Western honey bee ().

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Context: Global pollinator decline has motivated much research to understand the underlying mechanisms. Among the multiple pressures threatening pollinators, habitat loss has been suggested as a key-contributing factor. While habitat destruction is often associated with immediate negative impacts, pollinators can also exhibit delayed responses over time.

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Assessing the various anthropogenic pressures imposed on honeybees requires characterizing the patterns and drivers of natural mortality. Using automated lifelong individual monitoring devices, we monitored worker bees in different geographical, seasonal and colony contexts creating a broad range of hive conditions. We measured their life-history traits and notably assessed whether lifespan is influenced by pre-foraging flight experience.

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Measuring time-activity budgets over the complete individual life span is now possible for many animals with the recent advances of life-long individual monitoring devices. Although analyses of changes in the patterns of time-activity budgets have revealed ontogenetic shifts in birds or mammals, no such technique has been applied to date on insects. We tested an automated breakpoint-based procedure to detect, assess and quantify shifts in the temporal pattern of the flight activities in honeybees.

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Article Synopsis
  • Stakeholders play a crucial role in managing environmental issues in areas affected by human activity, but they often act on personal observations rather than scientific advice, especially during biological invasions.
  • The study of European beekeepers battling the invasive Asian hornet shows that their actions are influenced by immediate risk perceptions, but these actions can mismatch with delayed scientific recommendations, leading to negative impacts on local species.
  • The findings stress the importance of better communication between scientists and stakeholders to ensure that management strategies are effective and sustainable from the outset.
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Resource availability in agricultural landscapes has been disturbed for many organisms, including pollinator species. Abundance and diversity in flower availability benefit bee populations; however, little is known about which of protein or carbohydrate resources may limit their growth and reproductive performance. Here, we test the hypothesis of complementary resource limitation using a supplemental feeding approach.

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When honey bees () feed on flowers, they extend their proboscis to absorb the nectar, i.e. they perform the proboscis extension response (PER).

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