European Bumblebee Research Articles

Quantifying the impact of an invasive hornet on Bombus terrestris colonies

The invasive hornet Vespa velutina nigrithorax is considered a proliferating threat to pollinators in Europe and Asia. While the impact of this species on managed honey bees is well-documented, effects upon other pollinator populations remain poorly understood. Nonetheless, dietary analyses indicate that the hornets consume a diversity of prey, fuelling concerns for at-risk taxa. Here, we quantify the impact of V. velutina upon standardised commercially-reared colonies of the European bumblebee, Bombus terrestris terrestris. Using a landscape-scale experimental design, we deploy colonies across a gradient of local V. velutina densities, utilising automated tracking to non-invasively observe bee and hornet behaviour, and quantify subsequent effects upon colony outcomes. Our results demonstrate that hornets frequently hunt at B. terrestris colonies, being preferentially attracted to those with high foraging traffic, and engaging in repeated—yet entirely unsuccessful—predation attempts at nest entrances. Notably however, we show that B. terrestris colony weights are negatively associated with local V. velutina densities, indicating potential indirect effects upon colony growth. Taken together, these findings provide the first empirical insight into impacts on bumblebees at the colony level, and inform future mitigation efforts for wild and managed pollinators.

Non-compliance with the World Trade Organization agreements by exporters of the European bumblebee, Bombus terrestris

International companies commercially rear bumblebees worldwide, the trade of which is regulated through agreements established by the World Trade Organization (WTO). Scientific studies have shown multiple negative effects of introduced commercial bumblebees on native bees in Japan, Australia, Sweden, Israel, Chile, and Argentina, calling into question the compliance of exporting with some of the established WTO international sanitary regulations. We analyzed international WTO sanitary regulations focusing on the international trade of bumblebees from the European Union (EU) and Israel, especially regarding bumblebee exports to Chile and their side effects in neighboring Argentina. We have gathered evidence showing that exporters of bumblebees do not comply with WTO international trade agreements in at least two ways: (1) the quality of commercialized bumblebees differs from the quality declared in their certifications, and (2) the countries that sell the bumblebees violate sanitary agreements, producing negative effects on other native pollinating insects and causing a cascade of adverse impacts affecting both the environment and agriculture. This situation suggests that companies that raise bumblebees are currently in breach of WTO regulations and continue to contribute to major environmental damage in southern South America and elsewhere.

Projected decline in European bumblebee populations in the twenty-first century.

Habitat degradation and climate change are globally acting as pivotal drivers of wildlife collapse, with mounting evidence that this erosion of biodiversity will accelerate in the following decades1-3. Here, we quantify the past, present and future ecological suitability of Europe for bumblebees, a threatened group of pollinators ranked among the highest contributors to crop production value in the northern hemisphere4-8. We demonstrate coherent declines of bumblebee populations since 1900 over most of Europe and identify future large-scale range contractions and species extirpations under all future climate and landuse changescenarios. Around 38-76% of studied European bumblebee species currently classified as 'Least Concern' are projected to undergo losses of at least 30% of ecologically suitable territory by 2061-2080 compared to 2000-2014. All scenarios highlight that parts of Scandinavia will become potential refugia for European bumblebees; it is howeveruncertain whether these areas will remain clear of additional anthropogenic stressors not accounted for in present models. Our results underline the critical role of globalchange mitigation policies as effective levers to protect bumblebees from manmade transformation of the biosphere.

A narrow host-range and lack of persistence in two non-target insect species of a bacterial symbiont exploited to deliver insecticidal RNAi in Western Flower Thrips.

Insecticidal RNAi is a targeted pest insect population control measure. The specificity of insecticidal RNAi can theoretically be enhanced by using symbiotic bacteria with a narrow host range to deliver RNAi, an approach termed symbiont-mediated RNAi (SMR), a technology we have previously demonstrated in the globally-invasive pest species Western Flower Thrips (WFT). Here we examine distribution of the two predominant bacterial symbionts of WFT, BFo1 and BFo2, among genome-sequenced insects. Moreover, we have challenged two non-target insect species with both bacterial species, namely the pollinating European bumblebee, Bombus terrestris, and an insect predator of WFT, the pirate bug Orius laevigatus. Our data indicate a very limited distribution of either symbiont among insects other than WFT. Moreover, whereas BFo1 could establish itself in both bees and pirate bugs, albeit with no significant effects on insect fitness, BFo2 was unable to persist in either species. In terms of biosafety, these data, together with its more specific growth requirements, vindicate the choice of BFo2 for delivery of RNAi and precision pest management of WFT.

Signals of adaptation to agricultural stress in the genomes of two European bumblebees.

Human-induced environmental impacts on wildlife are widespread, causing major biodiversity losses. One major threat is agricultural intensification, typically characterised by large areas of monoculture, mechanical tillage, and the use of agrochemicals. Intensification leads to the fragmentation and loss of natural habitats, native vegetation, and nesting and breeding sites. Understanding the adaptability of insects to these changing environmental conditions is critical to predicting their survival. Bumblebees, key pollinators of wild and cultivated plants, are used as model species to assess insect adaptation to anthropogenic stressors. We investigated the effects of agricultural pressures on two common European bumblebees, Bombus pascuorum and B. lapidarius. Restriction-site Associated DNA Sequencing was used to identify loci under selective pressure across agricultural-natural gradients over 97 locations in Europe. 191 unique loci in B. pascuorum and 260 in B. lapidarius were identified as under selective pressure, and associated with agricultural stressors. Further investigation suggested several candidate proteins including several neurodevelopment, muscle, and detoxification proteins, but these have yet to be validated. These results provide insights into agriculture as a stressor for bumblebees, and signal for conservation action in light of ongoing anthropogenic changes.

Invasion dynamics of the European bumblebee Bombus terrestris in the southern part of South America

Invasive species are one of the main biodiversity loss drivers. Some species can establish and thrive in novel habitats, impacting local communities, as is the case of managed pollinators. In this regard, an invasive species' expansion process over time is critical for its control and management. A good example is the European bumblebee Bombus terrestris, which has rapidly invaded the southern part of South America after being repeatedly introduced in Chile for crop pollination since 1997. We assessed the temporal dynamics of B. terrestris invasion in Argentina and Chile by compiling 562 occurrence points from 2000 to 2019. We used two estimators (minimum convex polygon and 95% fixed kernel) to estimate the increase of the invaded area over time. We found that the area invaded by B. terrestris in the southern part of South America presents a linear increase over time, which was consistent for both estimators. In this scenario, species traits, environmental characteristics, and introduction dynamics facilitate a rapid invasion process that will continue to expand, reaching other South American countries in the near future. As this bumblebee is a super-generalist, it probably will expand across South America, as climate niche modelling predicts, if no actions were taken.

Large variability in response to projected climate and land-use changes among European bumblebee species.

Bumblebees (Bombus ssp.) are among the most important wild pollinators, but many species have suffered from range declines. Land-use change, agricultural intensification, and the associated loss of habitat have been identified as drivers of the observed dynamics, amplifying pressures from a changing climate. However, these drivers are still underrepresented in continental-scale species distribution modeling. Here, we project the potential distribution of 47 European bumblebee species in 2050 and 2080 from existing European-scale distribution maps, based on a set of climate and land-use futures simulated through a regional integrated assessment model and consistent with the RCP-SSP scenario framework. We compare projections including (1) dynamic climate and constant land use (CLIM); (2) constant climate and dynamic land use (LU); and (3) dynamic climate and dynamic land use (COMB) to disentangle the effects of land use and climate change on future habitat suitability, providing the first rigorous continental-scale assessment of linked climate-land-use futures for bumblebees. We find that direct climate impacts, although variable across species, dominate responses for most species, especially under high-end climate change scenarios (up to 99% range loss). Land-use impacts are highly variable across species and scenarios, ranging from severe losses (up to 75% loss) to considerable gains (up to 68% gain) of suitable habitat extent. Rare species thereby tend to be disproportionally affected by both climate and land-use change. COMB projections reveal that land use may amplify, attenuate, or offset changes to suitable habitat extent expected from climate impact depending on species and scenario. Especially in low-end climate change scenarios, land use has the potential to become a game changer in determining the direction and magnitude of range changes, indicating substantial potential for targeted conservation management.

A worthy conservation target? Revising the status of the rarest bumblebee of Europe

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.

An invasive pest of bumblebee: A new record of the tracheal mite Locustacarus buchneri (Acari: Podapolipidae) from the European bumblebee, Bombus terrestris (Hymenoptera: Apidae) in Korea

• Bumblebees ( Bombus spp.) are important pollinators. • The endoparasitic mite, Locustacarus buchneri was discovered from Bombus terrestris. • It is the first report of the genus and species in Korea. • Morphological and molecular characteristics were detailed. • The ecological significances of the finding were discussed. Bumblebees ( Bombus spp.) are important pollinators of agricultural crops and wild plants, especially tomato and sweet pepper species requiring large-sized and buzzing pollinators. The endoparasitic mite Locustacarus buchneri Stammer 1951 (Acari; Podapolipidae) was identified from commercial populations of the introduced European bumblebee Bombus terrestris. We report the genus and species of this mite for the first time in Koran fauna. Identification was based on morphological and molecular characteristics. Morphological details were illustrated and compared with those to the original description. We analyzed partial cytochrome oxidase I gene to understand the phylogenetic relationship and possible source of invention. The maximum likelihood tree and haplotype network revealed that the Korean population is closely related to Japanese population than European population. The ecological significance of this finding and possible consequences of the invasive species to the native species are discussed.

Mass‐migrating bumblebees: An overlooked phenomenon with potential far‐reaching implications for bumblebee conservation

Abstract Bumblebees are one of the most commonly studied pollinators, but they are declining in large parts of their distribution. Whether bumblebees can cope with anthropogenic disturbances such as climate change and habitat loss depends largely on their dispersal capacity. While bumblebee queen dispersal is estimated to be only a few kilometres, bird migration sites have documented mass‐migration events with peak migration of 70 bumblebee queens per minute, indicating that bumblebees can migrate over larger distances than previously thought. The open‐access database trektellen.org contains 10 daily counts of >1,000 migrating queens past single points in the Netherlands, and one in the United Kingdom (total bumblebee records 65,430; range 1–11,142 individuals), mostly in early spring. Such mass‐migration events are poorly documented in the scientific literature, and usually when describing migrations of other insects such as syrphids and social wasps. Most common European bumblebee species were documented to migrate. Bumblebees were observed flying at sea, coming from sea and flying towards the sea, showing that they can cross large water bodies. The wind direction might have helped to concentrate migration at landscape bottlenecks. On 1 day, bumblebee mass‐migration was documented on two sites located 200 km apart. Together with the concentrated and directional flight this suggests that they can migrate for several hundreds of kilometres. Because most mass‐migration events occur in spring, large‐scale shortage in suitable nesting sites may be the trigger for mass‐migration (e.g. due to high queen survival or low vole numbers). Future studies should test whether this is the case, or whether bumblebees show annual seasonal migration. Synthesis and applications. Much remains unclear about bumblebee migration, but it may have large consequences for the conservation of bumblebees and the ecosystem services they provide. For example, bumblebees in highly disturbed areas like agricultural landscapes may be continuously supplemented by queens from far‐away productive natural areas. This suggests that large‐scale conservation initiatives are required to maintain viable populations of common and endangered species. Structured observations and modern‐day technology, like isotope analyses or radar monitoring, may shed light on the drivers and consequences of the overlooked phenomenon of bumblebee migration.

Level of Genetic Diversity in European Bumblebees is Not Determined by Local Species Abundance.

Bumblebee species with declining population trends tend to show lower genetic diversity levels than stable species. The observed difference might be explained by abundance differences, with declining bumblebee species having lower genetic diversity levels simply due to their lower local species abundances. However, whether this holds true is not known. Here, we investigated whether bumblebee local abundances determines population genetic diversity levels. Therefore, local species abundances were measured for bumblebee species at four locations in Belgium and two locations in Estonia during bumblebee foraging years 2013–2017. These locations and countries were chosen to ensure the greatest possible variance in both local abundances and population trends for these species. Hence, genetic diversity levels were obtained for seven species by genotyping collected specimens with 16 microsatellites. Our results showed that the observed patterns in genetic diversity did not depend on local species abundance. So, although declining bumblebee species can become locally abundant, they will still show lower genetic diversity levels than stable species. This result implies that measuring bumblebees’ local abundance cannot be used to directly determine the health status of a population. Furthermore, this result has also major impact on future conservation strategies as increasing the genetic diversity levels of declining species will be very difficult, and habitat quality should be high to maintain their populations, otherwise these species are doomed to disappear first.

Narrow pollen diets are associated with declining Midwestern bumble bee species.

Many species of bumble bee (Bombus) have declined in range and abundance across Europe, the Americas, and Asia, whereas other species have persisted and remain common and widespread. One explanation as to why some species have declined, based primarily on studies of the European bumble bee fauna, is that declining species have relatively narrow pollen-foraging niches and are less able to use alternative host plants in the absence of their preferred hosts. Though extensively explored in Europe, this hypothesis has not been investigated in North America, in part due to incomplete information on the foraging niche of many species. We selected 12 bumble bee species found in Michigan and quantified their pollen diets using museum specimens. We also extensively resurveyed the state to understand their contemporary status and distribution. Compared to a pre-2000 baseline, six species remain relatively common and widespread, whereas six species show range contractions of over 50%. There was a significant relationship between dietary breadth and distributional range change, with declined or declining species collecting around one-third fewer pollen types than stable species. Though there were significant compositional differences, we found no differences in the number of pollen types collected by species with differing tongue lengths. Overall, these results support the hypothesis that species with narrower dietary niches are at greater risk of decline. However, it is not clear if narrow dietary niches are a cause of declines, or if both are driven by an underlying factor such as proximity to the edge of climatic niches. Further research is needed to improve our understanding of dietary niche in bumble bees, and how it interacts with other factors to influence population trajectories of stable and at-risk species.

Habitat suitability for the invasion of Bombus terrestris in East Asian countries: A case study of spatial overlap with local Chinese bumblebees

Invasive species such as Bombus terrestris represent a severe threat that can result in the decline of local biodiversity. We examined the habitat suitability for B. terrestris invasion in East Asian countries and the risk of habitat overlap with 24 bumblebee species from different groups in China. All East Asian countries were predicted to be susceptible to invasion by B. terrestris, with the highest habitat suitability occurring in China followed by Japan, North Korea, South Korea and Mongolia. Within China, which is a global biodiversity hotspot for bumblebees, three different regions, north-west, central to south-east and north-east, were predicted as being highly suitable for invasion. In China, the group of species closely related to B. terrestris showed higher sensitivity (89%) to habitat overlap with B. terrestris than did the group of non-closely related species (73%). The risk of overlap for the three major regional bumblebees within China decreased in the order southern region, northern region and Tibetan Plateau region. Due to the sensitivity of habitat suitability and overlap, the use of the introduced European bumblebee B. terrestris for pollination services should be discouraged in regions with overlapping habitats in China, and management strategies should be implemented to conserve the vulnerable bumblebees in all East Asian countries.

Microbiome Structure Influences Infection by the Parasite Crithidia bombi in Bumble Bees.

Recent declines in bumble bee populations are of great concern and have prompted critical evaluations of the role of pathogen introductions and host resistance in bee health. One factor that may influence host resilience when facing infection is the gut microbiota. Previous experiments with Bombus terrestris, a European bumble bee, showed that the gut microbiota can protect against Crithidia bombi, a widespread trypanosomatid parasite of bumble bees. However, the particular characteristics of the microbiome responsible for this protective effect have thus far eluded identification. Using wild and commercially sourced Bombus impatiens, an important North American pollinator, we conducted cross-wise microbiota transplants to naive hosts of both backgrounds and challenged them with a Crithidia parasite. As with B. terrestris, we find that microbiota-dependent protection against Crithidia operates in B. impatiens Lower Crithidia infection loads were experimentally associated with high microbiome diversity, large gut bacterial populations, and the presence of Apibacter, Lactobacillus Firm-5, and Gilliamella spp. in the gut community. These results indicate that even subtle differences between gut community structures can have a significant impact on a microbiome's ability to defend against parasite infections.IMPORTANCE Many wild bumble bee populations are under threat due to human activity, including through the introduction of pathogens via commercially raised bees. Recently, it was found that the bumble bee gut microbiota can help defend against a common parasite, Crithidia bombi, but the particular factors contributing to this protection are unknown. Using both wild and commercially raised bees, we conducted microbiota transplants to show that microbiome diversity, total gut bacterial load, and the presence of certain core members of the microbiota may all impact bee susceptibility to Crithidia infection. Bee origin (genetic background) was also a factor. Finally, by examining this phenomenon in a previously uninvestigated bee species, our study demonstrates that microbiome-mediated resistance to Crithidia is conserved across multiple bumble bee species. These findings highlight how intricate interactions between hosts, microbiomes, and parasites can have wide-ranging consequences for the health of ecologically important species.

Genetic structure of the bumble bee Bombus hypocrita sapporoensis, a potential domestic pollinator for crops in Japan

The European bumble bee, Bombus terrestris, is an excellent commercial pollinator. In Japan, B. terrestris is categorized as an invasive alien species, and the use of the bee is restricted. In this study, we identify the native bumble bee Bombus hypocrita sapporoensis as a candidate commercial pollinator in Hokkaido Island. To evaluate the risk of disturbing the natural genetic structure if this bee is used as a commercial pollinator, we sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene to elucidate the phylogenetic relationship of B. h. sapporoensis in Hokkaido Island and the Asian continent. In addition, we analyzed six microsatellites to further investigate the population genetic structure in Hokkaido Island. The mitochondrial analyses revealed that there is little differentiation within Hokkaido Island; however, there is considerable differentiation between Hokkaido and the Asian continent. Microsatellite analyses using STRUCTURE showed that B. h. sapporoensis in Hokkaido was divided into two genetic groups. Individuals belonging to each group were distributed throughout Hokkaido Island, and no clear geographical differentiation was observed. These results indicate that there would be little risk of genetic disturbance if bees from Hokkaido Island were used. However, it would be advisable to avoid importing continental bees as a pollinating insect in Hokkaido Island.

The interplay of climate and land use change affects the distribution of EU bumblebees.

Bumblebees in Europe have been in steady decline since the 1900s. This decline is expected to continue with climate change as the main driver. However, at the local scale, land use and land cover (LULC) change strongly affects the occurrence of bumblebees. At present, LULC change is rarely included in models of future distributions of species. This study's objective is to compare the roles of dynamic LULC change and climate change on the projected distribution patterns of 48 European bumblebee species for three change scenarios until 2100 at the scales of Europe, and Belgium, Netherlands and Luxembourg (BENELUX). We compared three types of models: (1) only climate covariates, (2) climate and static LULC covariates and (3) climate and dynamic LULC covariates. The climate and LULC change scenarios used in the models include, extreme growth applied strategy (GRAS), business as might be usual and sustainable European development goals. We analysed model performance, range gain/loss and the shift in range limits for all bumblebees. Overall, model performance improved with the introduction of LULC covariates. Dynamic models projected less range loss and gain than climate-only projections, and greater range loss and gain than static models. Overall, there is considerable variation in species responses and effects were most pronounced at the BENELUX scale. The majority of species were predicted to lose considerable range, particularly under the extreme growth scenario (GRAS; overall mean: 64%±34). Model simulations project a number of local extinctions and considerable range loss at the BENELUX scale (overall mean: 56%±39). Therefore, we recommend species-specific modelling to understand how LULC and climate interact in future modelling. The efficacy of dynamic LULC change should improve with higher thematic and spatial resolution. Nevertheless, current broad scale representations of change in major land use classes impact modelled future distribution patterns.

Microsatellite analysis supports the existence of three cryptic species within the bumble bee Bombus lucorum sensu lato

Mitochondrial cytochrome oxidase I (COI) partial sequences are widely used in taxonomy for species identification. Increasingly, these sequence identities are combined with modelling approaches to delineate species. Yet the validity of species delineation based on such DNA ‘barcodes’ is rarely tested and may be called into question by phenomena such as ancestral polymorphisms in DNA sequences, phylogeographic divergence, mitochondrial introgression and hybridization, or distortion of mitochondrial inheritance through such factors as Wolbachia infection. The common and widespread European bumble bee Bombus lucorum s. lato contains three distinct mitochondrial DNA lineages that are assumed to represent three cryptic species, namely Bombus cryptarum, B. lucorum s. str. and B. magnus. To test whether nuclear gene pools of the three putative species were differentiated, we genotyped 304 sympatric members of the lucorum complex (54 B. cryptarum females, 168 B. lucorum s. str. females and 82 B. magnus females, as defined using mtDNA COI haplotypes) from 11 localities spread across the island of Ireland at seven nuclear microsatellite loci. Multilocus genotypes clustered into three discrete groups that largely corresponded to the three mtDNA lineages: B. cryptarum, B. lucorum s. str. and B. magnus. The good fit of mitochondrial haplotype to nuclear (microsatellite) genotypic data supports the view that these three bumble bee taxa are reproductively isolated species, as well as providing a vindication of species identity using so-called DNA barcodes.

Geographic distribution and trait-mediated causes of nectar robbing by the European bumblebee Bombus terrestris on the Patagonian shrub Fuchsia magellanica

Invasive floral visitors may obtain nectar rewards from native plants exerting nectar robbing. Nevertheless, the probability of a plant to be robbed will ultimately depend upon the accessibility constraints imposed by the phenotypes of flowers and animals, and putatively upon the abundance of animals. The alien bumblebee B. terrestris is widely distributed in the temperate forests of Chile, where it is exerting nectar robbing on flowers of F. magellanica. Its geographic distribution and the causes of nectar robbing, however, are currently unknown. The aim of this study is to evaluate the distribution of nectar robbing in a wide range of distribution of plants and animals, and the causes of nectar robbing in terms of floral and animal phenotypes, and in terms of animal abundances. The primary nectar robbing did not correlate with the latitude, longitude or altitude of populations, thus indicating an absence of cline variation in the causes of nectar robbing. The variability of primary nectar robbing seemingly showed a bimodal distribution, since the most represented categories were the low and high incidence of primary nectar robbing. Petal length, rather than other flora traits, coupled to the glossa length of animals, played a pivotal role in the probability of flowers to experience nectar robbing. The putative negative consequences upon the population persistence and the evolution and maintenance of floral phenotypes of hummingbird-pollinated plants strongly encourage new assessments.

Effective population size as a driver for divergence of an antimicrobial peptide (Hymenoptaecin) in two common European bumblebee species

Social insects are the target of numerous pathogens. This is because the high density of closely-related individuals frequently interacting with each other enhances the transmission and establishment of pathogens. This high selective pressure results in the rapid evolution of immune genes, which might be counteracted by a reduced effective population size (Ne) lowering the effectiveness of selection. We tested the effect of Ne on the evolutionary rate of an important immune gene for the antimicrobial peptide Hymenoptaecin in two common central European bumblebee species: Bombus terrestris and Bombus lapidarius. Both species are similar in their biology and are expected to be under similar selective pressures because pathogen prevalence does not differ between species. However, previous studies indicated a higher Ne in B. terrestris compared to B. lapidarius. We found high intraspecific variability in the coding sequence but low variability for silent polymorphisms in B. lapidarius. Estimates of long- and short-term Ne were three- to four-fold higher Ne in B. terrestris, although the species did not differ in census population sizes. The difference in Ne might result in less efficient selection and suboptimal adaptation of immune genes (e.g. hymenoptaecin) in B. lapidarius, and thus this species might become less resistant and more tolerant, turning into a superspreader of diseases.

Addressing bumblebee faunistic and ecology using Citizen Science – reviewing a two years’ experience

Addressing bumblebee faunistic and ecology using Citizen Science – reviewing a two years’ experience