Bumblebees Research Papers - Academia.edu (original) (raw)

This paper presents qualitative and quantitative analyses of the bumblebees' (Bom-bus) collection, which is kept in the Zoological Museum of Ivan Franko National University of Lviv. The collection includes 719 specimens of bumblebees, belonging to 23 species. The majority of these species were found in the western part of the territory of Ukraine (on the territory of eight regions), few specimens have been collected in Germany (1960) and in Egypt (2005). Unfortunately, there is a little part of specimens, which are lacking information on collecting locality. The basis of the collection is formed of the common and widespread bumblebee species, some rare species (Bombus argillaceus and B. muscorum) being available as well. The specimens have been collected during 1960–2017, the major part of the collection being made in the period od the last five years. The analysis of this collection shows us the species composition of the bumblebee fauna on the territory of Western Ukraine, and on the some others regions of Ukraine. This inventory will be a basis for a catalogue.

- by and +1
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- Collecting and Collections, Bumblebees
- by Sarina Jepsen
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- Conservation Biology, Bumblebees, Bombus

A short piece on the folklore surrounding bees - both honeybees and bumblebees

- by Ceri Norman
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- Ancient Egyptian Religion, Mythology And Folklore, Entomology, Folklore

RNA viruses, once considered specific to honey bees, are suspected of spilling over from managed bees into wild pollinators; however, transmission routes are largely unknown. A widely accepted yet untested hypothesis states that flowers serve as bridges in the transmission of viruses between bees. Here, using a series of controlled experiments with captive bee colonies, we examined the role of flowers in bee virus transmission. We first examined if honey bees deposit viruses on flowers and whether bumble bees become infected after visiting contaminated flowers. We then examined whether plant species differ in their propensity to harbor viruses and if bee visitation rates increase the likelihood of virus deposition on flowers. Our experiment demonstrated, for the first time, that honey bees deposit viruses on flowers. However, the two viruses we examined, black queen cell virus (BQCV) and deformed wing virus (DWV), were not equally distributed across plant species, suggesting that differences in floral traits, virus ecology and/or foraging behavior may mediate the likelihood of deposition. Bumble bees did not become infected after visiting flowers previously visited by honey bees suggesting that transmission via flowers may be a rare occurrence and contingent on multiplicative factors and probabilities such as infectivity of virus strain across bee species, immunocompetence, virus virulence, virus load, and the probability a bumble bee will contact a virus particle on a flower. Our study is among the first to experimentally examine the role of flowers in bee virus transmission and uncovers promising avenues for future research.

- by Samantha Alger, PhD
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- Bumblebees, Virus, Pollinators, Honey Bees

The main objectives of this research are: 1) the creation of an expert network for the evaluation of the extinction risk of wild bees species in Italy; 2) the evaluation of the extinction risk for the species potentially at risk; 3) the identification of the main threats and the conservation actions needed to tackle them. The assessments of extinction risk are based on the IUCN Red List Categories and Criteria and the most updated guidelines. The assessments have been carried out in a workshop with taxonomic focus and involving experts covering different regions of Italy and have been evaluated according to the IUCN standards. A total of 151 species of wild bees native to Italy, for which some indication of decline exists, have been included in the evaluation. The populations were evaluated in their Italian area, including large and small islands where necessary. Of the 151 species assessed, 5 are Critically Endangered and have not been recorded recently. For this reason they are classified as Possibly Extinct. Of the remaining species, 2 are Critically Endangered, 10 are Endangered, 4 are Vulnerable. An additional 13 species are Near Threatened, meaning that they are close to one of the three threat categories. The main threats to wild bees are related to land use change (agricultural intensification and expansion, urbanization, but also - for some species - natural reforestation following the abandonment of rural areas and overgrazing). Some species may be sensitive to climate change. The Red List is a fundamental tool for the identification of conservation priorities, but it is not a list of priorities on its own. Other elements instrumental to priority setting include the cost of action, the probability of success, and the proportion of the global population of each species living in Italy, which determines the national responsibility in the long term conservation of that species.

- by PAOLO BIELLA
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- Conservation Biology, Wildlife Conservation, Italy, Biodiversity Conservation
- by Atul Pandey
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- Bumblebees, Brain, Juvenile Hormone, Honey Bees

Many flowering plants engage in mutualistic interactions with animals in order to sexually reproduce, exchanging food rewards such as nectar and pollen for the service of pollen transfer between flowers. Floral reward variation strongly influences visitation patterns of both pollinating mutualists and non-mutualist consumers, with consequences for both male and female components of plant reproductive success. Despite the importance of pollination to ecological systems, the pollination ecology of many plants is poorly known. At seven sites over three years, we studied the mating system, floral visitors and pollen limitation of turtlehead (Chelone glabra L.), an eastern North America wetland herb. We found that the plant is autogamous, but requires pollinator visitation to set seed. C. glabra flowers are protandrous, with floral rewards that vary between male and female sex phases. We found diurnal variation in reward presentation that was a function of both floral phenology and consumer behaviour. Bombus vagans Smith, the most common visitor to C. glabra flowers, removed a large fraction of available pollen (> 36%) in single visits to newly opened flowers, and compared to other flower visitors, passively transported more pollen on flights between flowers and deposited more to conspecific stigmas, suggesting it was the most effective pollinator. The solitary bee Hylaeus annulatus L. made frequent visits to flowers, but contributed little to pollination due to morphological mismatch and because it avoided male-phase flowers. Despite high bee visitation rates, flowers were pollen limited for seed production, possibly indicating a negative effect of non-pollinating flower visitors on plant reproductive success.

- by Leif Richardson
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- Plant Ecology, Mating Systems, Ecology, Pollination ecology

Climate change is threatening species and habitats. Altitudinal shifts uphill and negative population trends are commonly observed in altitude-related taxa. The bumblebee Bombus alpinus (Linnaeus, 1758) has a disjoint distribution restricted to Fennoscandia and the Alps, and is considered threatened. We studied the ecology and distribution of B. alpinus in the Alps, where the endemic subspecies Bombus alpinus helleri Dalla Torre 1882 is found, as a case-model because of its rarity, habitat, and mutual dependence with the ecosystem for pollination and resources. We developed species distribution models including both climatic and habitat variables to obtain the surface suitable for this subspecies and quantified its protected portion. Our analyses indicate that this bumblebee is restricted to the upper altitudes and has a narrow niche mainly related to the presence of glaciers, the cool temperature, a low temperature variation, and a specific range of precipitation. A strong altitudinal shift is also taking place probably due to climate change. After years of no changes in altitudinal distribution, its lowest altitudinal limit has moved up 479 m since the year 1984, while its upper altitudinal limit has remained unchanged. Over half of the suitable area in the Alps is included within protected areas, but conservation has not been planned yet. However, rare species with narrow niche, such as B. alpinus, are highly threatened by climate change. Potential short-term mitigation actions are discussed, including exchange of males between locations and integral protection of prairies in the vicinity of glaciers.

- by PAOLO BIELLA and +1
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- Climate Change, Insect Ecology, Bumblebees, Species Distribution Modelling
- by Poissonnier Laure-Anne
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- Ethology, Animal Behavior, Bumblebees, Anaesthesia
- by Elaine Evans
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- Conservation Biology, Bumblebees, Bombus

The decline of many bumblebee species (Bombus spp.) has been linked to an increased prevalence of pathogens caused by spillover from managed bees. Although poorly understood , RNA viruses are suspected of moving from managed honeybees (Apis mellifera) into wild bumblebees through shared floral resources. We examined if RNA viruses spillover from managed honeybees, the extent to which viruses are replicating within bumblebees, and the role of flowers in transmission. Prevalence and active infections of deformed wing virus (DWV) were higher in bumblebees collected near apiaries and when neighboring hon-eybees had high infection levels. We found no DWV in bumblebees where honeybee forag-ers and honeybee apiaries were absent. The prevalence of black queen cell virus (BQCV) was also higher in bumblebees collected near apiaries. Furthermore, we detected viruses on 19% of flowers, all of which were collected within apiaries. Our results corroborate the hypothesis that viruses are spilling over from managed honeybees to wild bumblebees and that flowers may be an important route for transmission.

- by Samantha Alger, PhD and +1
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- Disease ecology, Pollination, Bumblebees, Virus

High-resolution numerical simulations of a tethered model bumblebee in forward flight are performed superimposing homogeneous isotropic turbulent fluctuations to the uniform inflow. Despite tremendous variation in turbulence intensity, between 17% and 99% with respect to the mean flow, we do not find significant changes in cycle-averaged aerodynamic forces, moments, or flight power when averaged over realizations, compared to laminar inflow conditions. The variance of aerodynamic measures, however, significantly increases with increasing turbulence intensity, which may explain flight instabilities observed in freely flying bees.

- by Thomas Engels and +2
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- Computational Fluid Dynamics, Turbulence, Aerodynamics, Low Speed Aerodynamics

From the study of the Greek bumblebee fauna (Hymenoptera: Apidae, Bombini), species lists have been published based on both literature records and original data from collected bees. Since 1995 a special effort to confirm with newly collected bees all bumblebee species reported in literature records for Greece has been in progress. Although numerous specimens have been collected and examined and in some instances yielding new Bombus species for the Greek insect fauna, some species, mainly those reported in older references, have not yet been found. Recently, identification of bumblebees collected in the Florina Prefecture - Northwest Macedonia, during the years 2006 and 2007 yielded information for two “literature cited” species, Bombus subterraneus (Linnaeus 1758) and Bombus cryptarum (Fabricius 1775). A B. subterraneus queen (collected at 40°47´38N, 21°26´10E on Vicia cracca) was distinguished by morphological characteristics and a worker B. cryptarum (collected at 40°41´58,7N, 21°28´18,5E on Echium spp) was revealed using mitochondrial DNA RFLP analysis of the CO1 gene. These new records from Florina are provided with comments, confirming the species presence in Greece for the first time after approximately 40 years.

- by Ioannis T Anagnostopoulos
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- Entomology, Biodiversity, Greece, Bumblebees

Outreach article in spanish

- by Carolina Laura Morales
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- Conservation Biology, Invasive Species, Bumblebees, Bombus dahlbomii

Climate change and human activities are impacting species distribution, and thus, tracking species movements is a key aspect for their conservation and for understanding their biology. Among the bumblebees that are changing distribution, one of the most striking cases of a fast and natural range expansion is the eastern Mediterranean Bombus haematurus. Here we report the first Italian records of this species, with observations from the N-E Italy at a distance of 332 Km from the edge of the historical distribution. These are the westernmost known occurrences of this species and they are not far from a large series of records in several Central European countries of recent colonization. Here, we also obtained and made publicly available the reference COI barcode sequence of Bombus haematurus and shown that is significantly different from other similar species at this genetic marker. Coupling morphology, field-data and genetic identity should greatly improve the efficiency of tracking species movements and therefore also their knowledge in both recently colonized and historical areas.

- by PAOLO BIELLA
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- DNA Barcoding, Bumblebees, Mitochondrial DNA, Pollinators

The way pollinators gather resources may play a key role for buffering their population declines. Social pollinators like bumblebees could adjust their foraging after significant workforce reductions to keep provisions to the colony optimal, especially in terms of pollen diversity and quantity. To test what effects a workforce reduction causes on the foraging for pollen, commercially-acquired colonies of the bumblebee Bombus terrestris were allowed to forage in the field and they were experimentally manipulated by removing half the number of workers. For each bumblebee, the pollen pellets were taxonomically identified with DNA metabarcoding of the ITS2 region followed by a statistical filtering based on ROC curves to filter out underrepresented OTUs. Video cameras and network analyses were employed to investigate changes in foraging strategies and behaviour. After filtering out the false-posi-tives, HTS metabarcoding yielded a high plant diversity in the pollen pellets; for plant identity and pollen quantity traits no differences emerged between samples from treated and from control colonies, suggesting that plant choice was influenced mainly by external factors such as the plant phenology. The colonies responded to the removal of 50% of their workers by increasing the foraging activity of the remaining workers, while only negligible changes were found in diet breadth and indices describing the structure of the pollen transport network. Therefore, a consistency in the bumblebees' feeding strategies emerges in the short term despite the lowered workforce.

- by PAOLO BIELLA
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- Network Analysis, Animal Species Loss and Decline, Foraging ecology, Bumblebees
- by Anna Dornhaus
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- Animal Behavior, Pollination, Predator-Prey Interactions, Biological Sciences

Salvemos Nuestro Abejorro es una organización enfocada en la conservación del abejorro
nativo Bombus dahlbomii. A través de un modelo de ciencia ciudadana hemos recopilado
registros fotográficos de este insecto en todo el país. Se ha actualizado la información sobre
su distribución, permitiendo la postulación del abejorro como una especie con problemas de
conservación ante el Ministerio del Medio Ambiente. Adicionalmente hemos desarrollado
actividades de difusión para generar conocimiento y conciencia sobre la importancia de
conservar ésta especie

- by Jose Montalva and +2
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- Conservation Biology, Citizen Science, Bumblebees

Bumble bees (Bombus Latrielle) are significant pollinators of flowering plants due to their large body size, abundant setae, and generalist foraging strategies. However, shared setal coloration patterns among closely and distantly related bumble bee species makes identification notoriously difficult. The advent of molecular genetic techniques has increased our understanding of bumble bee evolution and taxonomy, and enables effective conservation policy and management. Individuals belonging to the North American Bombus fervidus species-complex (SC) are homogenous in body structure but exhibit significant body color phenotype variation across their geographic distribution. Given the uncertainty of the genea-logical boundaries within the SC, some authors have synonymized all members of the B. fer-vidus SC within a single taxon, while others propose an alternative two taxa hypothesis. Operating under the phylogenetic species concept, our analysis supports the hypothesis that there are two independent lineages of bumble bees within the B. fervidus SC. With the current evidence, however, it is not possible to assign valid names to either of them, because both lineages include the color phenotypes found in the original species descriptions of B. fervidus and B. californicus. Cryptic speciation does not seem to be the product of Mü llerian mimicry between the clades, because diverging coloration patterns are observed when the distribution of the clades overlaps. Furthermore, within each lineage there is evidence for strong population differentiation that is correlated with geographic distribution rather than color phenotype. In our study, we demonstrate the importance of obtaining a broad sample of multiple populations when conducting lower-level phylogenetic analyses. In addition to improving our knowledge of bumble bee diversification patterns, characterizing the evolutionary history of these pollinators provides the foundation needed to guide contemporary conservation assessments and management strategies.

- by Jonathan B . Koch and +1
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- Phylogenetics, Bees, Bumblebees, Mimicry

Acute lethal effect of the commercial formulation of the insecticides Imidacloprid, Spinosad y Thiocyclam hidrogenoxalate in Bombus atratus (Hymenoptera: Apidae) workers. The effect of insecticides on bees has gained great attention, however, there are few studies that explore this issue on Neotropical bees. Bombus atratus is a neotropical species broadly distributed in Colombia and is considered an important pol-linator of both Andean ecosystems and agroecosystems. However, as for many wild bees species, the effect of insecticides on B. atratus is unknow. In this study we determined the acute median lethal dose (LD50) of commercial formulations of insecticides Imidacloprid, Spinosad and Thiocyclam hydrogen oxalate, widely used in Colombia to control several pests of important crops. The LD50 was carried out by oral and contact routes, following and modifying the EPPO and OECD guidelines to perform LD50 on A. mellifera. We evaluated five doses for each route and insecticide, in a total of 25 medium-size workers for each dose by duplicate. Mortality was registered at 24, 48 and 72 hours after the experiment; and data were analyzed with the Probit regression model. For Imidacloprid, contacts and oral LD50 were 0.048 µg/bee and 0.010 µg/bee, respectively. For Thiocyclam hydrogen oxalate, topical and oral LD50 were 0.244 µg/bee and 0.056 µg/bee, respectively. For Spinosad, the oral LD50 corresponded to 0.28 µg/bee; it was not possible to establish the LD50 for the contact route. The Hazard Quotient (HQ) and Index of Relative Toxicity indicated that all three active ingredients are highly toxic. We discussed the risk of the insecticides use on B. atratus, considering their chemical nature. Rev. Biol. Trop. 64 (4): 1737-1745. Epub 2016 December 01.

- by Biología Tropical and +1
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- Conservation Biology, Toxicology, Ecology, Bumblebees
- by Daniel Papaj
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- Learning & Memory, Functional Ecology, Pollination, Learning
- by Michael Lattorff and +1
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- Population Genetics, Molecular Evolution, Social insects, Innate immunity

The structure of bumblebee communities has been studied in some ecosystems of Kunashir Island and Southern Sakhalin. The island taxocenes include five to eight bumblebee species. Bombus hypnorum is dominant in the majority of habitats. In geothermal areas near hot springs on Kunashir, the families of this species develop more rapidly than in areas without geothermal heating.

- by Grigory Potapov and +1
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- Pacific Island Studies, Island Biogeography, Bumblebees

We present details and characteristics of 123 novel polymorphic microsatellite DNA loci for Bombus terrestris. Thirty-four of these loci have been tested in nine other Bombus species and 25 of them showed polymorphisms in at least one species. These microsatellite DNA loci together with the already established 60 loci will be useful for characterizing wild and managed populations of B. terrestris and other Bombus species as well as for detailed genetic studies in including mapping studies and genome annotations.

- by Eckart Stolle
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- Bumblebees, Microsatellites, Pollinators

Species exist in complex biotic environments, engaging in a variety of antagonistic and cooperative interactions. While these interactions are generally recognized to be context-dependent, varying in outcome in the presence of other interactions, studies tend to focus on each interaction in isolation. One of the main classes of species interaction is mutualism, in which partner species gain a net benefit from their interaction. However, mutualisms are beset by a variety of species that can reduce or even eliminate the benefits of mutualism through exploitation of and competition for the resources and services offered by mutualists. These exploiter species potentially threaten the ecological stability of mutualisms and may alter selection on mutualistic traits. Thus, understanding the ecology and evolution of mutualisms requires consideration of interactions with exploiter species. In this dissertation, I investigated the effects of exploiter species on mutualisms between plants and pollinators using a combination of eco-evolutionary modeling, optimization theory, and behavioral studies. Using two adaptive dynamics models of coevolution in exploited pollinating seed parasite mutualisms, I found that exploiters reduce mutualist densities and select for more parasitic mutualists. Nevertheless, the models demonstrate that intraspecific competition for host resources and host defense of those resources restrict the ecological conditions that lead to extinction of the mutualism, as well as the chances of evolution to extinction. Thus, exploiters are unlikely to be the threat to mutualisms that has been assumed previously. On the other hand, in another type of exploitation, exploitative predators may pose a greater threat to investment in mutualism than has been presumed. Through both optimal foraging theory and behavioral experiments on bumble bees, I found that the risk from ambush predators can change pollinator floral preferences when predators preferentially use high-quality flowers to locate their prey. This research suggests that predators of mutualists may have important top-down effects and that further research is needed to investigate the effects of exploitative predators on selection on mutualist traits.

- by Emily Jones
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- Evolutionary Ecology, Mutualism, Bumblebees, Adaptive Dynamics

The ecological success of social insects is frequently ascribed to improvements in task performance due to division of labour amongst workers. While much research has focused on improvements associated with lifetime task specialization, members of colonies can specialize on a given task over shorter time periods. Eusocial bees in particular must collect pollen and nectar rewards to survive, but most workers appear to mix collection of both rewards over their lifetimes. We asked whether bumblebees specialize over timescales shorter than their lifetime. We also explored factors that govern such patterns, and asked whether reward specialists made more foraging bouts than generalists. In particular, we described antennal morphology and size of all foragers in a single colony and related these factors to each forager's complete foraging history, obtained using radio frequency identification (RFID). Only a small proportion of foragers were lifetime specialists; nevertheless, >50% of foragers specialized daily on a given reward. Contrary to expectations, daily and lifetime reward specialists were not better foragers (being neither larger nor making more bouts); larger bees with more antennal olfactory sensilla made more bouts, but were not more specialized. We discuss causes and functions of short and long-term patterns of specialization for bumblebee colonies. Task specialization is a hallmark of insect societies 1,2. Eusocial bees, some of our most important pollinators, must engage in a variety of tasks over their lifetime, including nest construction, brood care, and foraging from flowers to feed themselves and their nest mates. Specialization on different foraging tasks in particular has been well studied (e.g., refs 3 and 4). Because switching between tasks can incur temporal, cognitive, and/or energetic costs, specialization is thought to maximize task efficiency 3–6. For instance, bees often have to learn new nectar collection routines each time they shift to a new plant species 3,7. Cognitive costs associated with learning and recalling such collection routines are thought to make it advantageous for foraging bees to specialize in the short term on a given plant species 3–8. In addition, individuals can vary in their task performance as a result of fixed physiological or morphological differences; for example, honeybees vary in their sucrose sensitivity 4,9. In fact, intrinsic differences among foragers are thought to explain lifetime patterns of specialization on the collection of nectar, water, and pollen in foraging honeybees 9,10. These and other studies suggest that patterns of foraging task specialization by individual worker bees might differ when we examine the short term (e.g., hours or days) versus the long-term (e.g., lifetime). Yet almost no research has examined specialization by the same foragers over different timescales. Patterns of foraging specialization over different timescales have important implications for how individuals and, for social bee species, colonies manage the collection of multiple floral rewards. The two most common floral rewards collected by bees are pollen and nectar 11,12. Flowering plants offer pollen and nectar in all combinations and qualities. For instance, the flowers of some plant species offer pollen and nectar, only pollen, only nectar, or even vary the availability of one or the other reward over the floral lifecycle or as a result of prior collection. Thus a forager might not always be able to collect pollen and nectar on a single floral visit (e.g., refs 13 and 14). Further, collecting both rewards during a single foraging bout may not be efficient if, for instance, the bee has to travel far to collect both rewards. In addition, colony needs vary over lifetime. Bees rely on nectar as their primary

- by Avery Russell and +2
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- Bumblebees, Pollen, RFID Technology, Specialization

A bumblebee community was studied at Pymvashor, the only thermal spring in North European Russia. The bumblebee fauna comprised 12 species, which is a large number when compared to other native tundra ecosystems. Most of the species recorded were ubiquitous, 3 were forest species and 2 were typical tundra species. The presence of the ubiquitous and forest species in the bumblebee community appears to be due to the landscape features and the perennial impact of the hot springs, under the influence of which specific extrazonal ecosystems arise that are different from those typical of the tundra zone.

- by Ivan Bolotov and +1
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- Bumblebees, Alpine and Arctic Research
- by Leif Richardson and +2
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- Pollination, Pollination ecology, Behavioral Ecology, Parasite Ecology
- by Ioannis T Anagnostopoulos
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- Bumblebees, Bombus, Εντομολογία, Μέλισσες

learning multimodal cue pollen poricidal anther signal interaction Signals used in communication are frequently complex, being composed of multiple signal components that in combination improve information transfer. A variety of morphological parts are typically used to transmit components of any given complex signal. Our understanding of why a given morphological part is used to transmit a given signal component is poor. We hypothesized that the function of a given signal component is improved by its association with its morphological part and that such parts interact functionally to transmit information. In a laboratory study we characterized the function of different floral signal components transmitted by associated floral parts and the interaction of those signal components. Using Solanum houstonii flowers, we focused on two major floral parts, corolla and anthers, involved in signalling bumblebee, Bombus impatiens, visitors. We further examined how experience affected the relationship between signal component and floral part. Floral visits involve a stepwise process in which bees approach, land and acquire pollen. We found that the corolla plays the dominant role in eliciting approaches by bees, whether naïve or experienced. Landing is elicited by corolla signals and, to a lesser but additive degree, anther signals. Following experience, anther signals nearly completely dominate corolla signals in eliciting landing. The anthers convey signals mediating pollen acquisition, regardless of the bee's experience level. Our findings suggest there is selection for specific relationships between signal components and morphological parts, which in turn might drive complex signal evolution.

- by Avery Russell
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- Animal Behavior, Pollination, Bumblebees, Foraging Behavior

The study of foraging behaviour in plant-pollinator mutualisms has benefitted from the use of artificial flowers to manipulate floral display traits and the delivery of floral rewards. The two most common floral rewards are pollen and nectar; some pollinators, such as bees, are obliged to collect both for survival and reproduction. While flexible designs for artificial flowers providing nectar rewards abound, useful designs for artificial flowers that dispense pollen are few. This disparity mirrors a heavy emphasis on nectar collection in the study of pollinator foraging behaviour. In this study we describe a novel, easily constructed and modifiable artificial flower that dispenses flexible amounts of pollen via an 'anther' composed of a chenille stem. Using controlled lab assays, we show that more pulverized honeybee pollen is collected by bumblebee (Bombus impatiens) workers at chenille stem feeders than at dish-type feeders. We suggest that the paucity of studies examining pollinator cognition in the context of pollen rewards might be partly remedied if researchers had access to inexpensive and easily adjustable pollen-offering surrogate flowers.

- by Avery Russell
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- Animal Behavior, Bumblebees, Pollen, Pollinators
- by Liz Day
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- Bumblebees

"1. Animal hosts harbour diverse and often specific bacterial communities (“microbiota”) in their gut. These microbiota can provide crucial services to the host, such as aiding in digestion of food and immune defence. However, the ecological factors correlating with and eventually shaping these microbiota under natural conditions are poorly understood.
2. Bumble bees have recently been shown to possess simple and highly specific microbiota. We here examine the dynamics of these microbiota in field colonies of the bumble bee Bombus terrestris over one season. The gut bacteria were assessed with culture-independent methods, i.e. with terminal restriction fragment length profiles (TRFLPs) of the 16S rRNA gene.
3. To further understand the factors that affect the microbiota, we experimentally manipulated field-placed colonies in a fully factorial experiment by providing additional food, or by priming the workers’ immune system by injecting heat killed bacteria. We furthermore looked at possible correlates of diversity and composition of the microbiota for a) natural infections with the microbial parasites Crithidia bombi and Nosema bombi; b) bumble bee worker size; c) colony identity, and d) colony age.
4. We found an increase in diversity of the microbiota in individuals naturally infected with either C. bombi or N. bombi. C. bombi infections, however, appear to be only indirectly linked with higher microbial diversity when comparing colonies. The treatments of priming the immune system with heat-killed bacteria, and additional food supply, as well as host body size had no effect on the diversity or composition of the microbiota. Host colony identity had only a weak effect on the composition of the microbiota at the level of resolution of our method. We found both significant increases and decreases in the relative abundance of selected bacterial taxa over the season.
5. We present the first study on the ecological dynamics of gut microbiota in bumble bees and identify parasite infections, colony identity and colony age as important factors influencing the diversity and composition of the bacterial communities. The
absence of an effect of our otherwise effective experimental treatments suggests a remarkable ability of the host to maintain a homeostasis in this community under widely different environments."

- by Hauke Koch
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- Parasitology, Microbial Ecology, Ecology, Evolutionary Ecology

The natural wind environment that volant insects encounter is unsteady and highly complex, posing significant flight-control and stability challenges. It is critical to understand the strategies insects employ to safely navigate in natural environments. We combined experiments on free flying bumblebees with high-fidelity numerical simulations and lower-order modeling to identify the mechanics that mediate insect flight in unsteady winds. We trained bumblebees to fly upwind towards an artificial flower in a wind tunnel under steady wind and in a von Kármán street formed in the wake of a cylinder. Analysis revealed that at lower frequencies in both steady and unsteady winds the bees mediated lateral movement with body roll - typical casting motion. Numerical simulations of a bumblebee in similar conditions permitted the separation of the passive and active components of the flight trajectories. Consequently, we derived simple mathematical models that describe these two motion components. Comparison between the free-flying live and modeled bees revealed a novel mechanism that enables bees to passively ride out high-frequency perturbations while performing active maneuvers at lower frequencies. The capacity of maintaining stability by combining passive and active modes at different timescales provides a viable means for animals and machines to tackle the challenges posed by complex airflows.

- by Dmitry Kolomenskiy and +3
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- Computational Fluid Dynamics, Numerical Modeling, Numerical Modelling, Bumblebees

We examined the function of floral traits associated with buzz pollination through studies of Rhexia virginica (Melastomataceae) in the Muskoka region of Ontario, Canada. Controlled pollinations demonstrated that the species is self-compatible, but dependent on insects for pollen transfer. Bumble bees made 82 and 90% of observed insect visits to R. virginica in 1996 and 1997, respectively, and effectively buzzed flowers. Buzz pollination did not appear to be highly ‘‘specialized’’ since various species of bumble bee were capable of pollination, and pollen transfer efficiency appeared to be relatively low. Experimental manipulations provided little support for the hypothesis that the yellow color of melastome anthers mimics abundant pollen, thereby deceiving pollinators to visit regardless of whether most pollen has been removed. Fruit set averaged 52.6% among populations, owing largely to infrequent pollinator visits and pollen limitation. Flowers of R. virginica were infertile after a single day of anthesis, but petals were subsequently maintained for 1–2 d and stamens underwent a color change from bright yellow to red. Second-day flowers may function to increase floral display size and hence fertility, without a concomitant increase in pollen discounting. Studies of bumble bee foraging behavior and correlates of seed set provided indirect support for this hypothesis.

- by Brendon Larson and +1
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- Pollination, Pollination ecology, Bumblebees
- by Diego Riaño
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- Conservation Biology, Toxicology, Ecology, Bumblebees

Ecological partnerships, or mutualisms, are globally widespread, sustaining agriculture and biodiversity. Mutualisms evolve through the matching of functional traits between partners, such as tongue length of pollinators and flower tube depth of plants. Long-tongued pollinators
specialize on flowers with deep corolla tubes, whereas shorter-tongued pollinators generalize across tube lengths. Losses of functional guilds because of shifts in global climate may disrupt mutualisms and threaten partner species.We found that in two alpine bumble bee species,
decreases in tongue length have evolved over 40 years. Co-occurring flowers have not become shallower, nor are small-flowered plants more prolific.We argue that declining floral resources because of warmer summers have favored generalist foraging, leading to a mismatch between shorter-tongued bees and the longer-tubed plants they once pollinated.

- by Jennifer Geib
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- Evolutionary Biology, Climate Change, Evolution, Evolutionary Ecology

Pollinators use multiple cues whilst foraging including direct cues from flowers and indirect cues from other pollinators. The use of indirect social cues is common in social insects, such as honey-bees and bumblebees, where a social environment facilitates the ability to use such cues. Bumblebees use cues to forage on flowers according to previous foraging experiences. Flowers are an essential food source for pollinators but also pose a high risk of parasite infection through the shared use of flowers leading to parasite spillover. Nevertheless, bumblebees have evolved be-havioral defense mechanisms to limit parasite infection by avoiding contaminated flowers. Mechanisms underlying the avoidance of contaminated flowers by bumblebees are poorly understood. Bumblebees were recorded having the choice to forage on non-contaminated flowers and flowers contaminated by a trypan osome gut parasite, Crithidia bombi. The use of different treatments with presence or absence of conspecifics on both contaminated and non-contaminated flowers allowed to investigate the role of social visual cues on their pathogen avoidance behavior. Bumblebees are expected to use social visual cues to avoid contaminated flowers. Our study reveals that the presence of a conspecific on flowers either contaminated or not does not help bumblebee foragers avoiding contaminated flowers. Nevertheless, bumblebees whereas gaining experience tend to avoid their conspecific when placed on contaminated flower and copy it when on the non-contaminated flower. Our experiment suggests a detrimental impact of floral scent on disease avoidance behavior.

- by Michael Lattorff
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- Social insects, Foraging ecology, Parasite Ecology, Bumblebees

Pollinators frequently use complex motor routines to find and extract floral rewards. Studies of polli-nators foraging for nectar rewards indicate these routines are typically learned, and that constraints associated with learning and memory give pollinators incentive to continue foraging on these flowers. However, plants offer rewards besides nectar, including pollen, lipids and essential oils. In particular, bees use a complex motor routine termed floral sonication to extract pollen, their primary source of protein, from the more than 6% of flowering plant species (>22 000 species) that conceal pollen rewards within tube-like poricidal anthers. If floral sonication requires learning, this pollen extraction behaviour could contribute to floral fidelity. However, no studies have quantified the effect of experience on flower handling for bees extracting pollen from poricidal species. We therefore examined the degree to which floral sonication behaviour was modified by experience. We found that the key elements of the soni-cation motor routine appeared in full-blown form in a flower-naïve bee's first visit to a flower. We additionally found consistent, albeit modest, effects of experience on certain aspects of sonication behaviour. The latency to sonicate slightly decreased with experience. Bees also adjusted the length and amplitude of their sonication buzzes in response to pollen receipt. We conclude that the role of experience in foraging for concealed pollen rewards is different from that reported for nectar rewards. We offer an alternative explanation for its function in sonication. Finally, we discuss alternative hypotheses for the function of poricidal anthers and for how pollen-bearing plants may ensure floral fidelity even in the absence of a significant impact of experience on pollen extraction behaviour.

- by Avery Russell and +1
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- Cognition, Mutualism, Bumblebees, Experience

Greek bumblebee fauna records (Bombus LATREILLE 1802) are known from published studies on Greek insects and from publications concerning bumblebees or pollinators in general. From the published information concerning Greek bumblebees 23 species are presented with their valid names and with comments. Wherever noted, the locality region of each record is also mentioned. Original data are presented from the identification of specimens collected from Greece (with greater sampling effort in Florina - Northwest Macedonia). This material confirmed the presence of 17 out of the 23 species recorded in the literature, provided various new locality records and yielded five species new to the Greek entomofauna: Bombus (Psithyrus) bohemicus SEIDL 1837, B. (Ps.) campestris (PANZER 1801), B. (Ps.) maxillosus KLUG 1817, B. (Thoracobombus) deuteronymus SCHULZ 1906, B. (Th.) sylvarum (LINNAEUS 1761). An updated species list is provided for the 28 bumblebee species known currently for Greece.

- by Ioannis T Anagnostopoulos
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- Entomology, Biodiversity, Bumblebees, Entomologia
- by Sarah Arnold and +1
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- Colour Vision, Pollination, Bumblebees, Insect Behaviour
- by Kate S E Henson
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- Conservation Biology, Restoration Ecology, Ecology, Plant-Animal Interactions

Context There have been dramatic global declines in pollinating insects. A common land management intervention to support wild pollinators is to plant non-crop flowering plants (‘pollinator planting’). However, there are limited data on which species or spatial arrangement of planting provide maximum benefit to wild pollinators. Objectives Here we investigate which flowering species and locations are visited by free-foraging Bombus terrestris (buff-tailed bumblebees) in species-rich semi-natural grassland and woodland. Methods Two study nests of buff-tailed bumblebees were established in Wytham Woods, UK. Pollen analogue pigments were sprayed on open flowers in the study area over a period of two months, with unique colours used to identify separate sections of the study area. Pollen load analysis was used to identify forage species and foraging locations. Results Bumblebees showed low flower constancy, visiting five flower species per trip on average, and as a group the sampled bum...

- by Angélica E. Martínez Bauer
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- Landscape Ecology, Earth Sciences, Biology, Agriculture

Invasive social bees can alter plant-pollinator interactions with detrimental effects on both partners. However, most studies have focused on one invasive bee species, while the interactions among two or more species remain poorly understood. Also, many study sites had a history of invasive bees, being hard to find sites with historical low abundances. In Patagonia, Bombus ruderatus (F.) invasion begun in 1993 and B. terrestris (L.) in 2006. Though honey bees (Apis mellifera L.) introduction started in 1859, their density is still low in some parts. By experimentally increasing honey bee densities, we evaluated the effect of honey bees and bumblebees floral visitation on native pollinator floral visitation, pollen deposition, and reproductive success of three plant species in mixed Nothofagus antarctica forests of northern Patagonia: Oxalis valdiviensis, Mutisia spinosa and Cirsium vulgare. Our results show that exotic bees became the main floral visitors. No negative association was found between invasive bee and native pollinator visitation rates, but there was evidence of potential competition between honey bees and bumblebees. Floral neighborhood diversity played an important role in pollinator behavior. Conspecific pollen deposition was high for all species, while deposition of heterospecific pollen was very high in M. spinosa and C. vulgare. Not as expected, honey bees visitation rate had a negative effect on heterospecific pollen deposition in C. vulgare. For O. valdiviensis, exotic visitation rates increased conspecific pollen deposition, which was positively related to reproductive success. Although exotic bees became main floral visitors, their contribution to reproductive success was only clear for one species.

- by Lucas Garibaldi
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- Pollination, Bumblebees, Honey Bees

Species range expansions are crucial for understanding niche formation and the interaction with the environment. Here, we studied the bumblebee Bombus haematu-rus Kriechbaumer, 1870, a species historically distributed from northern Serbia through northern Iran which has very recently started expanding northwestward into Central Eu-rope without human-mediated dispersal (i.e., it is a natural spread). After updating the global distribution of this species, we investigated if niche shifts took place during this range expansion between newly colonized and historical areas. In addition, we have explored which climatic factors may have favored the natural range expansion of the species. Our results indicated that Bombus haematurus has colonized large territories in 7 Euro-pean countries outside the historical area in the period from the 1980s to 2018, a natural expansion over an area that equals 20% of the historical distribution. In addition, this bumblebee performs generalism in flower visitation and it occurs in different habitats, although a preference for forested areas clearly emerges. The land-use associated with the species in the colonized areas is similar to the historical distribution, indicating that no major niche shifts occurred during the spread. Furthermore, in recently colonized localities, the range expansion was associated with warming temperatures during the winter and also during both queen overwintering and emergence phases. These findings document a case of natural range expansion due to environmental change rather than due to niche shifts, and specifically they suggest that warmer winters could be linked to the process of natural colonization of new areas.

- by PAOLO BIELLA and +4
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- Rangeland Ecology, Biogeography, Pollination ecology, Niche Construction Theory

Bumble bees are the most efficient pollinators not only for the wild plants, but also for pollination services, used in both outdoor and greenhouse horticulture and orchards. In this experiment the influence of the bumble bee Bombus haemorrhoidalis Smith (Hymenoptera: Apidae) was analyzed and compared to honeybee pollination, hand-pollination, open-pollination and control (crop without pollinators) kiwifruit (Actinidia deliciosa Chev., a buzz pollinated species) grown under insect proof nylon cages. Buzz pollination resulted in higher fruit set (79.43%), longer fruits (59.56 mm/fruits), higher fruit breadth (40.58 mm/fruit), heavier fruits (68.14 g/fruit), higher total fruit yield (8.14 kg/vine), higher healthy fruits (94.60%), higher seed number (560.13 seeds/fruit) and test weight (1.67 g/1000 seed) in kiwifruit and accounted an increase of 46.05, 41.53, 37.00, 180, 191.75, 107.33, 25.34 and 57.54 per cent, respectively over control. Only A-grade and B-grade fruits were yielded in bumble bee pollinated fruit vines. Chemical parameters viz. TSS, TSS/acidity ratio, total sugars, reducing sugars and non-reducing sugars of kiwifruits were also found effected with buzz pollination. In kiwifruit, buzz pollination was observed as better mode of pollination next to hand-pollination. Bumble bee (B. haemorrhoidalis) pollination proved superior over control (crop without pollinator), open/natural pollination and equally good (at par) to hand-pollination, with respect to all quantitative as well as qualitative parameters. The preliminary present studies indicate that bumble bee pollination is helpful to enhance the quality and quantity of kiwifruit and will definitely increase farmer’s income.

- by rohit kumar nayak
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- Pollination, Bumblebees, Kiwifruit, TSS
- by Melissa Vogt
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- Ecology, European Union, United Kingdom, Insecticides

This study was conducted during 2017-18 to explore the genus Bombus Latreille, 1802 from the
Himalayan region of Pakistan. As a result, we found 771 specimens of bumblebees, among them nine
species viz. Bombus asiaticus Morawitz, 1875, B. lucorum subsp. jacobsoni Skorikov, 1912, B.
rufofasciatus Smith, 1852, B. tunicatus Smith, 1852, B. kashmirensis Friese, 1909, B. semenovianus
Skorikov, 1914, B. melanurus Lepeleitier, 1836, B. lepidus Skorikov, 1912 and B. ferganicus
Radoszkowski, 1893. Of these, B. semenovianus Skorikov, 1914, B. ferganicus Radoszkowski, 1893, B.
kashmirensis Friese, 1909 and B. lepidus Skorikov, 1912 are new records for Gilgit-Baltistan. Most of
the bumblebees were collected in altitudinal ranges of 6000ft-9000ft. Diagrams of each bumblebee cast
have been listed with distribution.

- by Saleem Jaffar
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- Taxonomy, DISTRIBUTION, Hymenoptera, Bumblebees