| 1. |
- Gérard, Maxence, et al.
(författare)
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Impact of landscape fragmentation and climate change on body size variation of bumblebees during the last century
- 2021
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 44:2, s. 255-264
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Tidskriftsartikel (refereegranskat)abstract
- Body size is a key parameter of organism fitness. While the impact of climate change on body size has received increasing attention, the long-term consequences of landscape fragmentation are still poorly known. These two major global threats may potentially induce opposite trends: the decrease of body size in warmer environments (e.g. individuals developing faster) or the selection of larger individuals in fragmented habitats (e.g. large individuals more capable of reaching distant patches). We assessed the relationship between temperature and landscape fragmentation with mean body size during the last century, within four European regions (Austria, Belgium, England and above the Arctic circle in Scandinavia) and among queens of five bumblebee species. At the regional scale, we first analysed the variation over time of body size and the two hypothesised drivers, temperature and landscape fragmentation. Then, at the local landscape scale, we tested whether body size varied according to these drivers irrespective of the region. At the regional level, we observed a statistically clear increase of queen body size corresponding to an increase of landscape fragmentation (i.e. in Belgium and England). There was no increase of size when fragmentation did not increase (i.e. in Austria and above the Arctic Circle). Temperature also increased through time in all regions. At the local landscape scale, we found that all species were impacted by changes in both climate and landscape fragmentation but show different trends. The body size of the two largest species significantly increased at landscape level with higher fragmentation while body size of the two smallest species decreased with higher fragmentation. We highlight that, in a context of global changes, landscape fragmentation can also be a major driver of body size clines. Depending on the dispersal abilities of species, larger species could be positively selected for and overcome landscape fragmentation.
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| 2. |
- Ghisbain, Guillaume, et al.
(författare)
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A worthy conservation target? Revising the status of the rarest bumblebee of Europe
- 2021
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Ingår i: Insect Conservation and Diversity. - : Wiley. - 1752-458X .- 1752-4598. ; 14:5, s. 661-674
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Tidskriftsartikel (refereegranskat)abstract
- Against the context of global wildlife declines, targeted mitigation strategies have become critical to preserve what remains of biodiversity. However, the effective development of conservation tools in order to counteract these changes relies on unambiguous taxonomic determination and delineation.In this study, we focus on an endemic bumblebee species recorded only from the highest altitudes of the Sierra Nevada (Spain), Bombus reinigiellus (Rasmont, 1983). The species has the smallest range of any European bumblebee, along with a restricted diet and an inability to disperse because of its isolated montane distribution, making it an appropriate conservation target. However, through an integrative taxonomic approach including genetics, morphometrics and semio-chemistry, we demonstrate the conspecificity of this taxon with one of the most common and widespread bumblebee species of Europe, Bombus hortorum (L. 1761). We assign a subspecies status to this endemic taxon (Bombus hortorum reinigiellus comb. nov.) shown to be different in colour and morphology but also in wing shape and relative wing size compared to the other conspecific subspecies.Following our taxonomic revision, we reassessed the IUCN conservation status of Bombus hortorum both at the continental and Spanish scale. We then propose how historic climatic oscillations of the last Ice age could explain such a phenotypic divergence in a post-glacial refugium and highlight the critical role of establishing unambiguous taxonomic revision prior to any conservation assessment.
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| 3. |
- Ghisbain, Guillaume, et al.
(författare)
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Expanding insect pollinators in the Anthropocene
- 2021
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Ingår i: Biological Reviews. - : Wiley. - 1464-7931 .- 1469-185X. ; 96:6, s. 2755-2770
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Tidskriftsartikel (refereegranskat)abstract
- Global changes are severely affecting pollinator insect communities worldwide, resulting in repeated patterns of species extirpations and extinctions. Whilst negative population trends within this functional group have understandably received much attention in recent decades, another facet of global changes has been overshadowed: species undergoing expansion. Here, we review the factors and traits that have allowed a fraction of the pollinating entomofauna to take advantage of global environmental change. Sufficient mobility, high resistance to acute heat stress, and inherent adaptation to warmer climates appear to be key traits that allow pollinators to persist and even expand in the face of climate change. An overall flexibility in dietary and nesting requirements is common in expanding species, although niche specialization can also drive expansion under specific contexts. The numerous consequences of wild and domesticated pollinator expansions, including competition for resources, pathogen spread, and hybridization with native wildlife, are also discussed. Overall, we show that the traits and factors involved in the success stories of expanding pollinators are mostly species specific and context dependent, rendering generalizations of 'winning traits' complicated. This work illustrates the increasing need to consider expansion and its numerous consequences as significant facets of global changes and encourages efforts to monitor the impacts of expanding insect pollinators, particularly exotic species, on natural ecosystems.
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| 4. |
- Guiraud, Marie, et al.
(författare)
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Higher developmental temperature increases queen production and decreases worker body size in the bumblebee Bombus terrestris
- 2021
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Ingår i: Journal of Hymenoptera Research. - : Pensoft Publishers. - 1070-9428 .- 1314-2607. ; 88, s. 39-49
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and increasing average temperatures are now affecting most ecosystems. Social insects such as bumblebees are especially impacted because these changes create spatial, temporal and morphological mismatches that could impede their ability to find food resources and mate. However, few studies have assessed how the colony and life cycle are affected when temperatures rise above optimal rearing temperature. It has become imperative to understand how heat stress affects the life history traits of insect pollinators as well as how changes in life history interact with other traits like morphology. For example, a decrease in the number of foraging workers could be balanced by producing larger workers, able to forage at longer distances and gather more resources. Here, we investigated the impact of temperature on colony production and body size in the bumblebee Bombus terrestris. Colonies were exposed to two temperatures: 25 degrees C, which is around the optimal temperature for larval development and 33 degrees C, which is slightly above the set-point that is considered stressful for bumblebees. Although the production of males and workers wasn't significantly affected by these different temperatures, queen production and reproductive investment were much higher for colonies placed in 33 degrees C than in 25 degrees C. We also found that, in agreement with the temperature-size rule, workers were significantly smaller in the higher temperature. The decrease in worker body size could affect resource collection and pollination if their foraging distance and the quantity of food they are taking back to the colony decreases. While in our controlled conditions the bumblebees were fed ad libitum, the decrease of resource collection in field conditions could prevent colonies from producing as many queens as in our study. Together with the decrease of worker body size, our results suggest that elevated temperatures could ultimately have a negative impact on bumblebee colony fitness. Indeed, smaller workers are known to have weaker flight performance which could affect foraging performance and consequently colony development.
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| 5. |
- Lhomme, Patrick, et al.
(författare)
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Diversification Pattern of the Widespread Holarctic Cuckoo Bumble Bee, Bombus flavidus (Hymenoptera: Apidae) : The East Side Story
- 2021
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Ingår i: Insect Systematics and Diversity. - : Oxford University Press (OUP). - 2399-3421. ; 5:2, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Recent bumble bee declines have made it increasingly important to resolve the status of contentious species for conservation purposes. Some of the taxa found to be threatened are the often rare socially parasitic bumble bees. Among these, the socially parasitic bumble bee, Bombus flavidus Eversmann, has uncertain species status. Although multiple separate species allied with B. flavidus have been suggested, until recently, recognition of two species, a Nearctic Bombus fernaldae (Franklin) and Palearctic B. flavidus, was favored. Limited genetic data, however, suggested that even these could be a single widespread species. We addressed the species status of this lineage using an integrative taxonomic approach, combining cytochrome oxidase I (COI) and nuclear sequencing, wing morphometrics, and secretions used for mate attraction, and explored patterns of color polymorphism that have previously confounded taxonomy in this lineage. Our results support the conspecificity of fernaldae and flavidus; however, we revealed a distinct population within this broader species confined to eastern North America. This makes the distribution of the social parasite B. flavidus the broadest of any bumble bee, broader than the known distribution of any nonparasitic bumble bee species. Color polymorphisms are retained across the range of the species, but may be influenced by local mimicry complexes. Following these results, B. flavidusEversmann, 1852 is synonymized with Bombus fernaldae (Franklin, 1911) syn. nov. and a subspecific status, Bombus flavidus appalachiensisssp. nov., is assigned to the lineage ranging from the Appalachians to the eastern boreal regions of the United States and far southeastern Canada.
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| 6. |
- Schatz, Bertrand, et al.
(författare)
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Pollinator conservation in the context of global changes with a focus on France and Belgium
- 2021
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Ingår i: Acta Oecologica. - : Elsevier BV. - 1146-609X .- 1873-6238. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- The decline of pollinators has been demonstrated scientifically and this phenomenon is widely recognized by both the general public and by stakeholders. Since pollinators face different threats that are all linked to human activities, there is a unique and unprecedented responsibility for people to conserve pollinators, requiring political action to counter the substantial worldwide risk of pollinator loss. As our perception of the situation is rapidly changing, as a result of the steady accumulation of international and national reports as well as new scientific findings, we propose here to provide an updated overview of pollinator conservation globally. We present the key messages and the proposed solutions found in international reports and assessments, how European countries have interpreted these solutions proposed in the context of existing international frameworks. Next, we analyze how scientific research is addressing the issue of pollinator conservation through different international, European and national programs. The analysis of the keywords used in published scientific articles also allows us to characterize how the scientific community has engaged with this issue over time. Finally, we focus on how France and Belgium have reacted to the observed decline of pollinators, and examine their national interpretations, conservation actions and research contributions.
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| 7. |
- Sculfort, Ombeline, et al.
(författare)
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Specialized Metabolites in Floral Resources : Effects and Detection in Buff-Tailed Bumblebees
- 2021
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The selection of appropriate food resources by bees is a critical aspect for the maintenance of their populations, especially in the current context of global change and pollinator decline. Wild bees have a sophisticated ability to forage selectively on specific resources, and can assess the quality of pollen using contact chemosensory perception (taste). While numerous studies have investigated the detection of pollen macronutrients in bees and their impact on bee health and reproductive success, only a few studies have described the gustatory responses of bees toward specialized metabolites. In addition, these studies mostly focused on the response to nectar and neglected pollen, which is the main food resource for both bee imagines and larvae. Whether bees have the ability to detect specialized toxic metabolites in pollen and then rapidly adapt their foraging behavior to avoid them is very little studied. In this study, we tested whether pollen specialized metabolites affect bumblebees at both the micro-colony and individual levels (i.e., bioassays using supplemented pollen), and whether foragers detect these specialized metabolites and potentially display an avoidance behavior (i.e., preference tests using supplemented syrup). Bumblebees were fed with either amygdalin-, scopolamine- or sinigrin-supplemented pollen diets in ratios that mimic 50%, 100%, and 200% of naturally occurring concentrations. We found no effect of these specialized metabolites on resource collection, reproductive success and stress response at the micro-colony level. At the individual level, bumblebees fed on 50%-amygdalin or 50%-scopolamine diets displayed the highest scores for damage to their digestive systems. Interestingly, during the preference tests, the solution with 50%-scopolamine displayed a phagostimulatory activity, whereas solution with 50%-amygdalin had a deterrent effect and could trigger an active avoidance behavior in bumblebees, with a faster proboscis retraction. Our results suggest that regulation of toxin intake is not as well-established and effective as the regulation of nutrient intake in bees. Bees are therefore not equally adapted to all specialized pollen metabolites that they can come into contact with.
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| 8. |
- Vanderplanck, Maryse, et al.
(författare)
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Monitoring bee health in European agroecosystems using wing morphology and fat bodies
- 2021
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Ingår i: One Ecosystem. - : Pensoft Publishers. - 2367-8194. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Current global change substantially threatens pollinators, which directly impacts the pollination services underpinning the stability, structure and functioning of ecosystems. Amongst these threats, many synergistic drivers, such as habitat destruction and fragmentation, increasing use of agrochemicals, decreasing resource diversity, as well as climate change, are known to affect wild and managed bees. Therefore, reliable indicators for pollinator sensitivity to such threats are needed. Biological traits, such as phenotype (e.g. shape, size and asymmetry) and storage reserves (e.g. fat body size), are important pollinator traits linked to reproductive success, immunity, resilience and foraging efficiency and, therefore, could serve as valuable markers of bee health and pollination service potential.
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