single-clone and mixed-clone infections versus host environment in crithidia bombi infecting bumblebees.current theories assume that adaptive parasite evolution explains variation in the level of virulence and parasite success. in particular, mixed-genotype infections by parasites should generally be more virulent, and faster multiplying strains more successful, either because fixed strategies have evolved or because parasites facultatively alter virulence in response to co-infecting competitors. we compared several measures of parasite success and virulence between single-clone and mixed-clone in ...19989820854
the distribution of genotypes of the trypanosome parasite, crithidia bombi, in populations of its host, bombus terrestris.this study reports the distribution of parasite genotypes for the trypanosome crithidia bombi across individual units (the colonies) in host populations of a social insect, the bumble bee bombus terrestris. a number of microsatellite primers were developed and several of them were found to be polymorphic in our samples. furthermore, a simple algorithm was used to identify the likely multi-locus genotypes present in multiply infected host individuals. the results demonstrated a remarkably high de ...200415376774
the impact of host starvation on parasite development and population dynamics in an intestinal trypanosome parasite of bumble nutrition plays an important role in determining the development and success of parasitic infections. while studies of vertebrate hosts are accumulating, little is known about how host nutrition affects parasites of invertebrate hosts. crithidia bombi is a gut trypanosome parasite of the bumble bee, bombus terrestris and here we use it as a model system to determine the impact of host nutrition on the population dynamics and development of micro-parasites in invertebrates. pollen-starved be ...200515977900
bumble-bee foragers infected by a gut parasite have an impaired ability to utilize floral information.parasitic infection can influence a variety of behavioural mechanisms in animals, but little is known about the effects of infection on the cognitive processes underlying ecologically relevant behaviours. here, we examined whether parasitic infection alters cognitive aspects of foraging in a social insect, the bumble-bee (bombus impatiens). in controlled experiments, we assessed the ability of foraging bees to discriminate rewarding from non-rewarding flowers on the basis of colour and odour. we ...200616600883
serial passage of the parasite crithidia bombi within a colony of its host, bombus terrestris, reduces success in unrelated the wild, bombus spp. bees may contract infections of the trypanosome parasite crithidia bombi from their nestmates or from others while foraging on contaminated flowers. we expected that as c. bombi is transmitted repeatedly among related workers within a colony, the parasite population would become more successful in this relatively homogeneous host population and less successful in individuals from unrelated colonies of the same or different species. to test our prediction, we serially pas ...200616608683
within-host dynamics of an intestinal pathogen of bumble bees.the success of a pathogen depends not only on its transmission to new hosts, but also on its ability to colonize and persist within its current host. studies of within-host dynamics have focused on only a few diseases of humans, whereas little is known about the factors that influence pathogen populations as they develop inside non-human hosts. here, we investigate pathogen dynamics occurring within bumble bees (bombus impatiens) infected by the gut trypanosome crithidia bombi. infection by c. b ...200616948877
invasive bombus terrestris (hymenoptera: apidae) parasitized by a flagellate (euglenozoa: kinetoplastea) and a neogregarine (apicomplexa: neogregarinorida).the flagellate crithidia bombi and the neogregarine apicystis bombi have been found in individuals of bombus terrestris, a palaearctic species of bumble bee commercially reared and shipped worldwide for pollination services. b. terrestris has recently entered into the northwestern patagonia region of argentina from chile, where it was introduced in 1998. prevalence was 21.6% for c. bombi and 3.6% for a. bombi (n=111). the pathogens were not detected in 441 bumble bees belonging to five of the ei ...200919682459
infection with the trypanosome crithidia bombi and expression of immune-related genes in the bumblebee bombus bees and other insects are frequently parasitized by a large range of different microorganisms. among these is crithidia bombi (kinetoplastida: trypanosomatidae), a common gut parasite of bumblebees, bombus spp. (insecta: apidae). bumblebees are important pollinators in commercial and natural environments. there are clear detrimental effects of c. bombi infections on the fitness of bumblebees. however, little has been known about how the bee's immune system responds to infections with try ...201020144650
molecular divergence defines two distinct lineages of crithidia bombi (trypanosomatidae), parasites of bumblebees.this study provides, for the first time, sequence data for the protozoan flagellates crithidia bombi and crithidia mellificae (kinetoplastea: trypanosomatidae). we amplified the partial sequences of the small subunit ribosomal rna (ssu rrna), glycosomal glyceraldehyde phosphate dehydrogenase (ggapdh), cytochrome b (cyt b), and the complete internal transcribed spacer region 1 (its1) of the ribosomal rna gene region for 66 clones of c. bombi from switzerland and alaska. furthermore, we sequenced ...201020497286
genetic exchange and emergence of novel strains in directly transmitted trypanosomatids.the breeding structure of protozoan infections, i.e. whether and how frequently parasites exchange genes ("sexual reproduction"), is a crucially important parameter for many important questions; it also matters for how new virulent strains might emerge. whether protozoan parasites are clonal or sexual is therefore a hotly debated issue. for trypanosomatids, few experimental tests of breeding structure exist to date and are limited to the vector-borne human diseases trypanosoma brucei, trypanosom ...201121252000
bumble bee parasite strains vary in resistance to phytochemicals.nectar and pollen contain diverse phytochemicals that can reduce disease in pollinators. however, prior studies showed variable effects of nectar chemicals on infection, which could reflect variable phytochemical resistance among parasite strains. inter-strain variation in resistance could influence evolutionary interactions between plants, pollinators, and pollinator disease, but testing direct effects of phytochemicals on parasites requires elimination of variation between bees. using cell cul ...201627883009
immune gene expression in bombus terrestris: signatures of infection despite strong variation among populations, colonies, and sister workers.ecological immunology relies on variation in resistance to parasites. colonies of the bumblebee bombus terrestris vary in their susceptibility to the trypanosome gut parasite crithidia bombi, which reduces colony fitness. to understand the possible origin of this variation in resistance we assayed the expression of 28 immunologically important genes in foraging workers. we deliberately included natural variation of the host "environment" by using bees from colonies collected in two locations and ...201323869212
bee pathogens found in bombus atratus from colombia: a case study.bombus atratus bumblebees from colombia that were caught in the wild and from breeding programs were screened for a broad set of bee pathogens. we discovered for the first time lake sinai virus and confirmed the infection by other common viruses. the prevalence of apicystis bombi, crithidia bombi and nosema ceranae was remarkably high. according to other studies the former two could have been co-introduced in south america with exotic bumble bees as bombus terrestris or bombus ruderatus. given t ...201526031564
unbiased rna shotgun metagenomics in social and solitary wild bees detects associations with eukaryote parasites and new viruses.the diversity of eukaryote organisms and viruses associated with wild bees remains poorly characterized in contrast to the well-documented pathosphere of the western honey bee, apis mellifera. using a deliberate rna shotgun metagenomic sequencing strategy in combination with a dedicated bioinformatics workflow, we identified the (micro-)organisms and viruses associated with two bumble bee hosts, bombus terrestris and bombus pascuorum, and two solitary bee hosts, osmia cornuta and andrena vaga. i ...201628006002
long-term prevalence of the protists crithidia bombi and apicystis bombi and detection of the microsporidium nosema bombi in invasive bumble initial survey in 2009 carried out at a site in northwestern patagonia region, argentina, revealed for the first time in south america the presence of the flagellate crithidia bombi and the neogregarine apicystis bombi, two pathogens associated with the palaearctic invasive bumble bee bombus terrestris. in order to determine the long-term persistence and dynamics of this microparasite complex, four additional collections at the same site (san carlos de bariloche) were conducted along the foll ...201728085231
differential gene expression and alternative splicing in insect immune specificity.ecological studies routinely show genotype-genotype interactions between insects and their parasites. the mechanisms behind these interactions are not clearly understood. using the bumblebee bombus terrestris/trypanosome crithidia bombi model system (two bumblebee colonies by two crithidia strains), we have carried out a transcriptome-wide analysis of gene expression and alternative splicing in bees during c. bombi infection. we have performed four analyses, 1) comparing gene expression in infec ...201425431190
recognition and avoidance of contaminated flowers by foraging bumblebees (bombus terrestris).bumblebee colonies are founded by a single-mated queen. due to this life history trait, bumblebees are more susceptible to parasites and diseases than polyandrous and/or polygynous social insects. a greater resistance towards parasites is shown when the genetic variability within a colony is increased. the parasite resistance may be divided into different levels regarding the step of the parasite infection (e.g. parasite uptake, parasite intake, parasite's establishment in the nest, parasite tra ...201122039462
The genotypic structure of a multi-host bumblebee parasite suggests a role for ecological niche overlap.The genotypic structure of parasite populations is an important determinant of ecological and evolutionary dynamics of host-parasite interactions with consequences for pest management and disease control. Genotypic structure is especially interesting where multiple hosts co-exist and share parasites. We here analyze the natural genotypic distribution of Crithidia bombi, a trypanosomatid parasite of bumblebees (Bombus spp.), in two ecologically different habitats over a time period of three years ...201121853023
food-environment mediates the outcome of specific interactions between a bumblebee and its trypanosome parasite.specific host-parasite interactions, where the outcome of exposure to a parasite depends upon the genotypic identity of both parties, have implications for understanding host-parasite coevolution and patterns of genetic diversity. thus, grasping the extent to which these interactions are mediated by environmental changes in a spatially and temporally heterogeneous world is vital. in this study, it is shown that the environment can influence specific host-parasite interactions in the well-studied ...201121967438
differential diagnosis of the honey bee trypanosomatids crithidia mellificae and lotmaria passim.trypanosomatids infecting honey bees have been poorly studied with molecular methods until recently. after the description of crithidia mellificae (langridge and mcghee, 1967) it took about forty years until molecular data for honey bee trypanosomatids became available and were used to identify and describe a new trypanosomatid species from honey bees, lotmaria passim (evans and schwarz, 2014). however, an easy method to distinguish them without sequencing is not yet available. research on the r ...201526146231
Socially transmitted gut microbiota protect bumble bees against an intestinal parasite.Populations of important pollinators, such as bumble bees and honey bees, are declining at alarming rates worldwide. Parasites are likely contributing to this phenomenon. A distinct resident community of bacteria has recently been identified in bumble bees and honey bees that is not shared with related solitary bee species. We now show that the presence of these microbiota protects bee hosts against a widespread and highly virulent natural parasite (Crithidia bombi) in an experimental setting. W ...201122084077
effects of invasive parasites on bumble bee declines.bumble bees are a group of pollinators that are both ecologically and economically important and declining worldwide. numerous mechanisms could be behind this decline, and the spread of parasites from commercial colonies into wild populations has been implicated recently in north america. commercial breeding may lead to declines because commercial colonies may have high parasite loads, which can lead to colonization of native bumble bee populations; commercial rearing may allow higher parasite v ...201121771075
pathways to immunity: temporal dynamics of the bumblebee (bombus terrestris) immune response against a trypanosomal gut parasite.immune response dynamics in insects from natural host-parasite associations are poorly understood, despite accumulating evidence of ecological immune phenomena in these systems. using a gene discovery approach, we have identified genes relating to signalling, enzymatic processes and respiration that were up-regulated in the bumblebee, bombus terrestris, during infection with the trypanosomatid parasite, crithidia bombi. in addition, we have mapped dynamic changes in the temporal expression of th ...201121615578
protein-poor diet reduces host-specific immune gene expression in bombus terrestris.parasites infect hosts non-randomly as genotypes of hosts vary in susceptibility to the same genotypes of parasites, but this specificity may be modulated by environmental factors such as nutrition. nutrition plays an important role for any physiological investment. as immune responses are costly, resource limitation should negatively affect immunity through trade-offs with other physiological requirements. consequently, nutritional limitation should diminish immune capacity in general, but does ...201424850921
a draft genome of the honey bee trypanosomatid parasite crithidia mellificae.since 2006, honey bee colonies in north america and europe have experienced increased annual mortality. these losses correlate with increased pathogen incidence and abundance, though no single etiologic agent has been identified. crithidia mellificae is a unicellular eukaryotic honey bee parasite that has been associated with colony losses in the usa and belgium. c. mellificae is a member of the family trypanosomatidae, which primarily includes other insect-infecting species (e.g., the bumble be ...201424743507
gene expression differences underlying genotype-by-genotype specificity in a host-parasite many systems, host-parasite evolutionary dynamics have led to the emergence and maintenance of diverse parasite and host genotypes within the same population. genotypes vary in key attributes: parasite genotypes vary in ability to infect, host genotypes vary in susceptibility, and infection outcome is frequently the result of both parties' genotypic identities. these host-parasite genotype-by-genotype (gh × gp) interactions influence evolutionary and ecological dynamics in important ways. int ...201424550506
a quantitative in vitro cultivation technique to determine cell number and growth rates in strains of crithidia bombi (trypanosomatidae), a parasite of bumblebees.the protozoan parasite crithidia bombi and its host, the bumblebee bombus terrestris, are used as a model system for the study of the evolutionary ecology of host-parasite interactions. in order to study these interactions we established a method for in vitro cultivation of single parasite strains. additionally, a high-throughput method is developed for the determination of cell numbers in cultures by means of optical density (od) measurements. the protocol for in vitro cultivation allowed for g ...201021129082
multiplex pcr detection of slowly-evolving trypanosomatids and neogregarines in bumblebees using broad-range primers.the aims of this study were to design universal markers for different protozoan parasites of bombus spp. based on the phylogenetic position of two important bumblebee parasites crithidia bombi and apicystis bombi.201020015206
differential expression of immune defences is associated with specific host-parasite interactions in insects.recent ecological studies in invertebrates show that the outcome of an infection is dependent on the specific pairing of host and parasite. such specificity contrasts the long-held view that invertebrate innate immunity depends on a broad-spectrum recognition system. an important question is whether this specificity is due to the immune response rather than some other interplay between host and parasite genotypes. by measuring the expression of putative bumblebee homologues of antimicrobial pept ...200919859547
consumption of a nectar alkaloid reduces pathogen load in bumble has a significant effect on pathogen infections in animals and the consumption of secondary metabolites can either enhance or mitigate infection intensity. secondary metabolites, which are commonly associated with herbivore defense, are also frequently found in floral nectar. one hypothesized function of this so-called toxic nectar is that it has antimicrobial properties, which may benefit insect pollinators by reducing the intensity of pathogen infections. we tested whether gelsemine, a ne ...201019711104
does pathogen spillover from commercially reared bumble bees threaten wild pollinators?the conservation of insect pollinators is drawing attention because of reported declines in bee species and the 'ecosystem services' they provide. this issue has been brought to a head by recent devastating losses of honey bees throughout north america (so called, 'colony collapse disorder'); yet, we still have little understanding of the cause(s) of bee declines. wild bumble bees (bombus spp.) have also suffered serious declines and circumstantial evidence suggests that pathogen 'spillover' fro ...200818648661
contact networks and transmission of an intestinal pathogen in bumble bee (bombus impatiens) socially living animals, individuals interact through complex networks of contact that may influence the spread of disease. whereas traditional epidemiological models typically assume no social structure, network theory suggests that an individual's location in the network determines its risk of infection. empirical, especially experimental, studies of disease spread on networks are lacking, however, largely due to a shortage of amenable study systems. we used automated video-tracking to quan ...200717713789
natural variation in the genetic architecture of a host-parasite interaction in the bumblebee bombus terrestris.the genetic architecture of fitness-relevant traits in natural populations is a topic that has remained almost untouched by quantitative genetics. given the importance of parasitism for the host's fitness, we used qtl mapping to study the genetic architecture of traits relevant for host-parasite interactions in the trypanosome parasite, crithidia bombi and its host, bombus terrestris. the three traits analysed were the parasite's infection intensity, the strength of the general immune response ( ...200717391417
specific versus nonspecific immune defense in the bumblebee, bombus terrestris l.hosts vary in both their strength of response to a general immunological insult and in their specific susceptibility to different parasite species or different strains of the same parasite. the variation in the general immune response is considered a result of the costs imposed by selection on defended individuals. the variation in the specific response may originate from variation in host and parasite genotypes and is a requirement for frequency-dependent selection. the relationship between the ...200312894951
activation of host constitutive immune defence by an intestinal trypanosome parasite of bumble bees.many parasites, including important species that affect humans and livestock, must survive the harsh environment of insect guts to complete their life-cycle. hence, understanding how insects protect themselves against such parasites has immediate practical implications. previously, such protection has been thought to consist mainly of mechanical structures and the action of lectins. however, recently it has become apparent that gut infections may interact with the host immune system in more comp ...200312666884
unexpected consequences of polyandry for parasitism and fitness in the bumblebee, bombus terrestris.multiple mating by females (polyandry) is taxonomically widespread but the evolution of such behaviors is not clearly understood given potential costs of polyandry such as time, energy, or predation risk. the genetic variability versus parasites hypothesis predicts a reduction of parasitism due to increased genetic variability among offspring and an associated fitness gain. we tested this hypothesis with a field experiment in the bumblebee, bombus terrestris l. worker heterogeneity within the co ...200111580023
immune response and gut microbial community structure in bumblebees after microbiota transplants.microbial communities are a key component of host health. as the microbiota is initially 'foreign' to a host, the host's immune system should respond to its acquisition. such variation in the response should relate not only to host genetic background, but also to differences in the beneficial properties of the microbiota. however, little is known about such interactions. here, we investigate the gut microbiota of the bumblebee, bombus terrestris, which has a protective function against the bee's ...201627226466
pollination services enhanced with urbanization despite increasing pollinator parasitism.animal-mediated pollination is required for the reproduction of the majority of angiosperms, and pollinators are therefore essential for ecosystem functioning and the economy. two major threats to insect pollinators are anthropogenic land-use change and the spread of pathogens, whose effects may interact to impact pollination. here, we investigated the relative effects on the ecosystem service of pollination of (i) land-use change brought on by agriculture and urbanization as well as (ii) the pr ...201627335419
robustness of the outcome of adult bumblebee infection with a trypanosome parasite after varied parasite exposures during larval development.the outcome of defence by the invertebrate immunity has recently been shown to be more complex than previously thought. in particular, the outcome is affected by biotic and abiotic environmental variation, host genotype, parasite genotype and their interaction. knowledge of conditions under which environmental variation affects the outcome of an infection is one important question that relates to this complexity. we here use the model system of the bumblebee, bombus terrestris, infected by the t ...201222487556
species-specific diagnostics of apis mellifera trypanosomatids: a nine-year survey (2007-2015) for trypanosomatids and microsporidians in serbian honey this study, honey bees collected in serbia over 9 consecutive years (2007-2015) were retrospectively surveyed to determine the prevalence of eukaryotic gut parasites by molecular screening of archival dna samples. we developed species-specific primers for pcr to detect the two known honey bee trypanosomatid species, crithidia mellificae and the recently described lotmaria passim. these primers were validated for target specificity under single and mixed-species conditions as well as against t ...201627392956
evolution of resistance to single and combined floral phytochemicals by a bumble bee parasite.repeated exposure to inhibitory compounds can drive the evolution of resistance, which weakens chemical defence against antagonists. floral phytochemicals in nectar and pollen have antimicrobial properties that can ameliorate infection in pollinators, but evolved resistance among parasites could diminish the medicinal efficacy of phytochemicals. however, multicompound blends, which occur in nectar and pollen, present simultaneous chemical challenges that may slow resistance evolution. we assesse ...201727783434
synergistic effects of floral phytochemicals against a bumble bee parasite.floral landscapes comprise diverse phytochemical combinations. individual phytochemicals in floral nectar and pollen can reduce infection in bees and directly inhibit trypanosome parasites. however, gut parasites of generalist pollinators, which consume nectar and pollen from many plant species, are exposed to phytochemical combinations. interactions between phytochemicals could augment or decrease effects of single compounds on parasites. using a matrix of 36 phytochemical treatment combination ...201728331591
the relationship between managed bees and the prevalence of parasites in bumblebees.honey bees and, more recently, bumblebees have been domesticated and are now managed commercially primarily for crop pollination, mixing with wild pollinators during foraging on shared flower resources. there is mounting evidence that managed honey bees or commercially produced bumblebees may affect the health of wild pollinators such as bumblebees by increasing competition for resources and the prevalence of parasites in wild bees. here we screened 764 bumblebees from around five greenhouses th ...201425165632
insect antimicrobial peptides act synergistically to inhibit a trypanosome parasite.the innate immune system provides protection from infection by producing essential effector molecules, such as antimicrobial peptides (amps) that possess broad-spectrum activity. this is also the case for bumblebees, bombus terrestris, when infected by the trypanosome, crithidia bombi furthermore, the expressed mixture of amps varies with host genetic background and infecting parasite strain (genotype). here, we used the fact that clones of c. bombi can be cultivated and kept as strains in mediu ...201627160603
colony pace: a life-history trait affecting social insect epidemiology.among colonies of social insects, the worker turnover rate (colony 'pace') typically shows considerable variation. this has epidemiological consequences for parasites, because in 'fast-paced' colonies, with short-lived workers, the time of parasite residence in a given host will be reduced, and further transmission may thus get less likely. here, we test this idea and ask whether pace is a life-history strategy against infectious parasites. we infected bumblebees (bombus terrestris) with the inf ...201626763696
possible synergistic effects of thymol and nicotine against crithidia bombi parasitism in bumble bees.floral nectar contains secondary compounds with antimicrobial properties that can affect not only plant-pollinator interactions, but also interactions between pollinators and their parasites. although recent work has shown that consumption of plant secondary compounds can reduce pollinator parasite loads, little is known about the effects of dosage or compound combinations. we used the generalist pollinator bombus impatiens and its obligate gut parasite crithidia bombi to study the effects of ne ...201526657643
testing dose-dependent effects of the nectar alkaloid anabasine on trypanosome parasite loads in adult bumble bees.the impact of consuming biologically active compounds is often dose-dependent, where small quantities can be medicinal while larger doses are toxic. the consumption of plant secondary compounds can be toxic to herbivores in large doses, but can also improve survival in parasitized herbivores. in addition, recent studies have found that consuming nectar secondary compounds may decrease parasite loads in pollinators. however, the effect of compound dose on bee survival and parasite loads has not b ...201526545106
behavioural evidence for self-medication in bumblebees?the presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. we tested whether nicotine, a nectar secondary metabolite common in solanaceae and tilia species, is used by parasitized bumblebees as a source of self-medication , using a series of toxicological, microbiological and behavioural experiments. caged bees infected with crithidia bombi had a ...201525949807
secondary metabolites in floral nectar reduce parasite infections in bumblebees.the synthesis of secondary metabolites is a hallmark of plant defence against herbivores. these compounds may be detrimental to consumers, but can also protect herbivores against parasites. floral nectar commonly contains secondary metabolites, but little is known about the impacts of nectar chemistry on pollinators, including bees. we hypothesized that nectar secondary metabolites could reduce bee parasite infection. we inoculated individual bumblebees with crithidia bombi, an intestinal parasi ...201525694627
variable effects of nicotine, anabasine, and their interactions on parasitized bumble bees.secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. we tested for interactions between the effects of two alkaloids found in the nectar of nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( ...201526998225
few colonies of the host bombus terrestris disproportionately affect the genetic diversity of its parasite, crithidia and recombination have long been considered as necessary means for hosts to keep up with and resist to their faster reproducing parasites. on the other hand, comparatively little attention has been paid to potential benefits of recombination for the parasites. using as model organisms the bumblebee bombus terrestris and its genetically highly variable trypanosomatid parasite crithidia bombi we analysed the infection dynamics as well as the relative frequency of parasite recombinants over tim ...201424263111
the invasion of southern south america by imported bumblebees and associated parasites.the palaearctic bombus ruderatus (in 1982/1983) and bombus terrestris (1998) have both been introduced into south america (chile) for pollination purposes. we here report on the results of sampling campaigns in 2004, and 2010-2012 showing that both species have established and massively expanded their range. bombus terrestris, in particular, has spread by some 200 km year(-1) and had reached the atlantic coast in argentina by the end of 2011. both species, and especially b. terrestris, are infec ...201424256429
genetic diversity, parasite prevalence and immunity in wild bumblebees.inbreeding and a consequent loss of genetic diversity threaten small, isolated populations. one mechanism by which genetically impoverished populations may become extinct is through decreased immunocompetence and higher susceptibility to parasites. here, we investigate the relationship between immunity and inbreeding in bumblebees, using hebridean island populations of bombus muscorum. we sampled nine populations and recorded parasite prevalence and measured two aspects of immunity: the encapsul ...201020926436
antimicrobial peptides play a functional role in bumblebee anti-trypanosome defense.bumblebees, amongst the most important of pollinators, are under enormous population pressures. one of these is disease. the bumblebee and its gut trypanosome crithidia bombi are one of the fundamental models of ecological immunology. although there is previous evidence of increased immune gene expression upon crithidia infection, recent work has focussed on the bumblebee's gut microbiota. here, by knocking down gene expression using rnai, we show for the first time that antimicrobial peptides ( ...201424060502
qualitatively different immune response of the bumblebee host, bombus terrestris, to infection by different genotypes of the trypanosome gut parasite, crithidia bombi.insects have a complex and highly successful immune system that responds specifically to different types of parasites. different genotypes of a parasite species can differ in infectivity and virulence; which is important for host-parasite co-evolutionary processes, such as antagonistic, fluctuating selection. such coevolution obviously requires a genetic basis, but little is known about how hosts immunologically respond to different genotypes. the common european bumblebee bombus terrestris is i ...201324055962
indirect effects on mutualisms: parasitism of bumble bees and pollination service to plants.researchers increasingly recognize the important role of mutualisms in structuring communities and view positive interactions in a community context rather than as simple pairwise interactions. indirect effects, such as those that predators have on lower trophic levels, are a key process in community ecology. however, such top-down indirect effects have rarely been extended to mutualisms. antagonists of one mutualist have the potential to negatively affect the second mutualist through negative e ...201323691664
seasonal variability of prevalence and occurrence of multiple infections shape the population structure of crithidia bombi, an intestinal parasite of bumblebees (bombus spp.).ergonomic growth phases of annual social insect societies strongly influence horizontally transmitted parasites. herein, we focused on the impact of temporal changes in host demography on the population structure of a horizontally transmitted parasite. seasonal fluctuations in prevalence and the occurrence of multiple infections of the gut parasite crithidia bombi were analyzed in repeatedly sampled populations of two common bumblebee (bombus spp.) species. prevalence of c. bombi was greatest in ...201223233373
probing mixed-genotype infections i: extraction and cloning of infections from hosts of the trypanosomatid crithidia bombi.we here present an efficient, precise and reliable method to isolate and cultivate healthy and viable single crithidia bombi cells from bumblebee faeces using flow cytometry. we report a precision of >99% in obtaining single trypanosomatid cells for further culture and analysis ("cloning"). in the study, we have investigated the use of different liquid media to cultivate c. bombi and present an optimal medium for obtaining viable clones from all tested, infected host donors. we show that this me ...201223155449
probing mixed-genotype infections ii: high multiplicity in natural infections of the trypanosomatid, crithidia bombi, in its host, bombus spp.mixed-genotype infections have major consequences for many essential elements of host-parasite interactions. with genetic exchange between co-infecting parasite genotypes increased diversity among parasite offspring and the emergence of novel genotypes from infected hosts is possible. we here investigated mixed- genotype infections using the host, bombus spp. and its trypanosome parasite crithidia bombi as our study case. the natural infections of c. bombi were genotyped with a novel method for ...201223145099
social scent marks do not improve avoidance of parasites in foraging bumblebees.foraging is a result of innate and acquired mechanisms, and is optimized in order to increase fitness. during foraging, an animal faces many threats, such as predation and infection. the uptake of parasites and diseases while foraging is common and an individual should be adapted to detect and avoid such threats, using cues from either the abiotic environment or the parasite. social animals possess an additional cue to detect such contaminated food sources: information provided by conspecifics. ...201323038725
sex, horizontal transmission, and multiple hosts prevent local adaptation of crithidia bombi, a parasite of bumblebees (bombus spp.).local adaptation within host-parasite systems can evolve by several non-exclusive drivers (e.g., host species-genetic adaptation; ecological conditions-ecological adaptation, and time-temporal adaptation). social insects, especially bumblebees, with an annual colony life history not only provide an ideal system to test parasite transmission within and between different host colonies, but also parasite adaptation to specific host species and environments. here, we study local adaptation in a mult ...201222837838
ecological effects on gut bacterial communities in wild bumblebee colonies.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. bumblebees have recently been shown to possess simple and highly specific microbiota. we here examine the dynamics of these microbiota in field co ...201222708631
gut microbiota instead of host genotype drive the specificity in the interaction of a natural host-parasite system.specific interactions between parasite genotypes and host genotypes (g(p) × g(h)) are commonly found in invertebrate systems, but are largely lacking a mechanistic explanation. the genotype of invertebrate hosts can be complemented by the genomes of microorganisms living on or within the host ('microbiota'). we investigated whether the bacterial gut microbiota of bumble bees (bombus terrestris) can account for the specificity of interactions between individuals from different colonies (previousl ...201222765311
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