scholarly journals Exposure to nectar‐realistic sugar concentrations negatively impacts the ability of the trypanosome parasite ( Crithidia bombi ) to infect its bumblebee host

2020 ◽  
Vol 45 (6) ◽  
pp. 1495-1498 ◽  
Author(s):  
Arran J. Folly ◽  
Marta Barton‐Navarro ◽  
Mark J. F. Brown
Keyword(s):  
Crithidia Bombi

scholarly journals Eristalis flower flies can be mechanical vectors of the common trypanosome bee parasite, Crithidia bombi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abby E. Davis ◽  
Kaitlin R. Deutsch ◽  
Alondra M. Torres ◽  
Mesly J. Mata Loya ◽  
Lauren V. Cody ◽  
...  
Keyword(s):  
Theoretical Work ◽  
Floral Resources ◽  
Active Infection ◽  
Osmia Lignaria ◽  
Crithidia Bombi ◽  
Large Populations ◽  
Bee Health ◽  
The Common ◽  
Flower Flies ◽  
Bee Communities

AbstractFlowers can be transmission platforms for parasites that impact bee health, yet bees share floral resources with other pollinator taxa, such as flies, that may be hosts or non-host vectors (i.e., mechanical vectors) of parasites. Here, we assessed whether the fecal-orally transmitted gut parasite of bees, Crithidia bombi, can infect Eristalis tenax flower flies. We also investigated the potential for two confirmed solitary bee hosts of C. bombi, Osmia lignaria and Megachile rotundata, as well as two flower fly species, Eristalis arbustorum and E. tenax, to transmit the parasite at flowers. We found that C. bombi did not replicate (i.e., cause an active infection) in E. tenax flies. However, 93% of inoculated flies defecated live C. bombi in their first fecal event, and all contaminated fecal events contained C. bombi at concentrations sufficient to infect bumble bees. Flies and bees defecated inside the corolla (flower) more frequently than other plant locations, and flies defecated at volumes comparable to or greater than bees. Our results demonstrate that Eristalis flower flies are not hosts of C. bombi, but they may be mechanical vectors of this parasite at flowers. Thus, flower flies may amplify or dilute C. bombi in bee communities, though current theoretical work suggests that unless present in large populations, the effects of mechanical vectors will be smaller than hosts.

scholarly journals Antimicrobial peptides play a functional role in bumblebee anti-trypanosome defense

2014 ◽  
Author(s):  
Soni Deshwal ◽  
Eamonn Mallon
Keyword(s):  
Gene Expression ◽  
Gut Microbiota ◽  
Antimicrobial Peptides ◽  
Functional Role ◽  
Immune Gene ◽  
Ecological Immunology ◽  
Previous Evidence ◽  
Immune Gene Expression ◽  
Crithidia Bombi ◽  
First Time

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 (AMPs) have a functional role in anti-Crithidia defense.

scholarly journals Behavioural evidence for self-medication in bumblebees?

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 73 ◽  
Author(s):  
David Baracchi ◽  
Mark J. F. Brown ◽  
Lars Chittka
Keyword(s):  
Secondary Metabolites ◽  
Sucrose Solution ◽  
Parasite Load ◽  
Foraging Activity ◽  
Self Medication ◽  
Crithidia Bombi ◽  
Nicotine Consumption ◽  
Behavioural Experiments ◽  
Behavioural Tests ◽  
Behavioural Evidence

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 slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan’s viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony.  Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.

scholarly journals Weak and contradictory effects of self-medication with nectar nicotine by parasitized bumblebees

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 73 ◽  
Author(s):  
David Baracchi ◽  
Mark J. F. Brown ◽  
Lars Chittka
Keyword(s):  
Secondary Metabolites ◽  
Sucrose Solution ◽  
Parasite Load ◽  
Foraging Activity ◽  
Plant Metabolites ◽  
Self Medication ◽  
Crithidia Bombi ◽  
Nicotine Consumption ◽  
Behavioural Experiments ◽  
Behavioural Tests

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 Solenaceae 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 [TI1] had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion the protozoan’s viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in food-stressed bees (starved) but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nonetheless we did not find a benefit of nicotine consumption in terms of life expectancy of infected bees, making these findings difficult to interpret. Our results indicate that caution is warranted in interpreting impacts of plant metabolites on insect parasites and suggest that the conditions under which nicotine consumption provides benefits to either bees or plants remain to be identified. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.

scholarly journals Pollination services enhanced with urbanization despite increasing pollinator parasitism

2016 ◽  
Vol 283 (1833) ◽  
pp. 20160561 ◽  
Author(s):  
Panagiotis Theodorou ◽  
Rita Radzevičiūtė ◽  
Josef Settele ◽  
Oliver Schweiger ◽  
Tomás E. Murray ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Urban Areas ◽  
Negative Effects ◽  
Pollination Services ◽  
Pollination Success ◽  
Flower Visitation ◽  
Visitation Rates ◽  
Crithidia Bombi ◽  
Agricultural Areas

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 prevalence of pollinator parasites, using experimental insect pollinator-dependent plant species in natural pollinator communities. We found that pollinator habitat (i.e. availability of nesting resources for ground-nesting bees and local flower richness) was strongly related to flower visitation rates at the local scale and indirectly influenced plant pollination success. At the landscape scale, pollination was positively related to urbanization, both directly and indirectly via elevated visitation rates. Bumblebees were the most abundant pollinator group visiting experimental flowers. Prevalence of trypanosomatids, such as the common bumblebee parasite Crithidia bombi, was higher in urban compared with agricultural areas, a relationship which was mediated through higher Bombus abundance. Yet, we did not find any top-down, negative effects of bumblebee parasitism on pollination. We conclude that urban areas can be places of high transmission of both pollen and pathogens.

Infection with the trypanosome Crithidia bombi and expression of immune-related genes in the bumblebee Bombus terrestris

2010 ◽  
Vol 34 (7) ◽  
pp. 705-709 ◽  
Author(s):  
Helge Schlüns ◽  
Ben M. Sadd ◽  
Paul Schmid-Hempel ◽  
Ross H. Crozier
Keyword(s):  
Bombus Terrestris ◽  
Crithidia Bombi ◽  
Immune Related Genes

scholarly journals Revealing mechanisms of infectious disease spread through empirical contact networks

2021 ◽  
Vol 17 (12) ◽  
pp. e1009604
Author(s):  
Pratha Sah ◽  
Michael Otterstatter ◽  
Stephan T. Leu ◽  
Sivan Leviyang ◽  
Shweta Bansal
Keyword(s):  
Infectious Disease ◽  
Incomplete Data ◽  
Model Comparison ◽  
Transmission Rate ◽  
Disease Spread ◽  
Contact Network ◽  
Statistical Tool ◽  
Contact Networks ◽  
Crithidia Bombi ◽  
Transmission Pathways

The spread of pathogens fundamentally depends on the underlying contacts between individuals. Modeling the dynamics of infectious disease spread through contact networks, however, can be challenging due to limited knowledge of how an infectious disease spreads and its transmission rate. We developed a novel statistical tool, INoDS (Identifying contact Networks of infectious Disease Spread) that estimates the transmission rate of an infectious disease outbreak, establishes epidemiological relevance of a contact network in explaining the observed pattern of infectious disease spread and enables model comparison between different contact network hypotheses. We show that our tool is robust to incomplete data and can be easily applied to datasets where infection timings of individuals are unknown. We tested the reliability of INoDS using simulation experiments of disease spread on a synthetic contact network and find that it is robust to incomplete data and is reliable under different settings of network dynamics and disease contagiousness compared with previous approaches. We demonstrate the applicability of our method in two host-pathogen systems: Crithidia bombi in bumblebee colonies and Salmonella in wild Australian sleepy lizard populations. INoDS thus provides a novel and reliable statistical tool for identifying transmission pathways of infectious disease spread. In addition, application of INoDS extends to understanding the spread of novel or emerging infectious disease, an alternative approach to laboratory transmission experiments, and overcoming common data-collection constraints.

scholarly journals Cross-infectivity of honey and bumble bee-associated parasites across three bee families

Parasitology ◽  
2020 ◽  
Vol 147 (12) ◽  
pp. 1290-1304 ◽  
Author(s):  
Lyna Ngor ◽  
Evan C. Palmer-Young ◽  
Rodrigo Burciaga Nevarez ◽  
Kaleigh A. Russell ◽  
Laura Leger ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Bumble Bees ◽  
Floral Resources ◽  
Bumble Bee ◽  
Broad Host Range ◽  
Osmia Lignaria ◽  
Social Bees ◽  
Crithidia Bombi ◽  
Halictus Ligatus ◽  
Parasite Replication

AbstractRecent declines of wild pollinators and infections in honey, bumble and other bee species have raised concerns about pathogen spillover from managed honey and bumble bees to other pollinators. Parasites of honey and bumble bees include trypanosomatids and microsporidia that often exhibit low host specificity, suggesting potential for spillover to co-occurring bees via shared floral resources. However, experimental tests of trypanosomatid and microsporidial cross-infectivity outside of managed honey and bumble bees are scarce. To characterize potential cross-infectivity of honey and bumble bee-associated parasites, we inoculated three trypanosomatids and one microsporidian into five potential hosts – including four managed species – from the apid, halictid and megachilid bee families. We found evidence of cross-infection by the trypanosomatids Crithidia bombi and C. mellificae, with evidence for replication in 3/5 and 3/4 host species, respectively. These include the first reports of experimental C. bombi infection in Megachile rotundata and Osmia lignaria, and C. mellificae infection in O. lignaria and Halictus ligatus. Although inability to control amounts inoculated in O. lignaria and H. ligatus hindered estimates of parasite replication, our findings suggest a broad host range in these trypanosomatids, and underscore the need to quantify disease-mediated threats of managed social bees to sympatric pollinators.

scholarly journals Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen

2019 ◽  
Vol 6 (4) ◽  
pp. 190279 ◽  
Author(s):  
George M. LoCascio ◽  
Luis Aguirre ◽  
Rebecca E. Irwin ◽  
Lynn S. Adler
Keyword(s):  
Helianthus Annuus ◽  
Fagopyrum Esculentum ◽  
Bombus Impatiens ◽  
Crithidia Bombi ◽  
Bee Health ◽  
Bee Disease ◽  
Gut Pathogen ◽  
Pollinator Declines

Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) ofBombus impatienspreviously, but the breadth of this effect was unknown. We tested whether pollen from nineH. annuuscultivars, four wildH. annuuspopulations,H. petiolarus, H. argophyllusand twoSolidagospp., reducedCrithidiainB. impatienscompared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. AllHelianthusandSolidagopollen reducedCrithidiaby 20–40-fold compared to buckwheat pollen, and all but three taxa reducedCrithidiacompared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduceCrithidiainfection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease.

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