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First detection of the larval chalkbrood disease pathogen Ascosphaera apis (Ascomycota: Eurotiomycetes: Ascosphaerales) in adult bumble bees.

Maxfield-Taylor SA, Mujic AB, Rao S - PLoS ONE (2015)

Bottom Line: Queens that died during rearing or that did not lay eggs within one month of capture were dissected, and tissues were examined microscopically for the presence of pathogens.The identity of the fungus was confirmed using molecular markers and phylogenetic analysis.Thus, the discovery of A. apis in adult bumble bees in the current study has important implications for commercial production of bumble bee colonies and highlights potential risks to native bees via pathogen spillover from infected bees and infected pollen.

View Article: PubMed Central - PubMed

Affiliation: Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America.

ABSTRACT
Fungi in the genus Ascosphaera (Ascomycota: Eurotiomycetes: Ascosphaerales) cause chalkbrood disease in larvae of bees. Here, we report the first-ever detection of the fungus in adult bumble bees that were raised in captivity for studies on colony development. Wild queens of Bombus griseocollis, B. nevadensis and B. vosnesenskii were collected and maintained for establishment of nests. Queens that died during rearing or that did not lay eggs within one month of capture were dissected, and tissues were examined microscopically for the presence of pathogens. Filamentous fungi that were detected were plated on artificial media containing broad spectrum antibiotics for isolation and identification. Based on morphological characters, the fungus was identified as Ascosphaera apis (Maasen ex Claussen) Olive and Spiltoir, a species that has been reported earlier only from larvae of the European honey bee, Apis mellifera, the Asian honey bee, Apis cerana, and the carpenter bee Xylocopa californica arizonensis. The identity of the fungus was confirmed using molecular markers and phylogenetic analysis. Ascosphaera apis was detected in queens of all three bumble bee species examined. Of 150 queens dissected, 12 (8%) contained vegetative and reproductive stages of the fungus. Both fungal stages were also detected in two workers collected from colonies with Ascosphaera-infected B. nevadensis queens. In this study, wild bees could have been infected prior to capture for rearing, or, the A. apis infection could have originated via contaminated European honey bee pollen fed to the bumble bees in captivity. Thus, the discovery of A. apis in adult bumble bees in the current study has important implications for commercial production of bumble bee colonies and highlights potential risks to native bees via pathogen spillover from infected bees and infected pollen.

No MeSH data available.


Related in: MedlinePlus

Phylogeny of the internal transcribed spacer region for selected Ascosphaera species.The phylogeny was inferred under both the maximum likelihood methodology in RAxML and Bayesian methodology in MrBayes using the GTRGAMMA model of evolution. 1,000 RAxML bootstrap replicates were used and MrBayes was run for 1,000,000 generations with 1000 sample points. Bayesian posterior probabilities (PP) greater than 0.70 and Bootstrap support (BS) values greater than 50 are shown for major phylogram branches (PP/BS). Genbank accession numbers precede taxon name for those sequences that were derived from Genbank. Taxa denoted in bold face as “fungal culture” represent novel sequence data from this study that are derived from cultures of Ascosphaera apis isolated from bumble bee queens. Fungal culture A1 has been deposited at the USDA ARSEF insect pathogen collection (culture ID ST-OR11-A1) and the ITS sequence for this culture is deposited in Genbank (accession #KJ158165). Sequences for Aspergillus terreus and Ascosphaera apis USDA-ARSEF 7405 were derived from the genome sequences available at http://www.aspgd.org and http://www.beebase.org.
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pone.0124868.g002: Phylogeny of the internal transcribed spacer region for selected Ascosphaera species.The phylogeny was inferred under both the maximum likelihood methodology in RAxML and Bayesian methodology in MrBayes using the GTRGAMMA model of evolution. 1,000 RAxML bootstrap replicates were used and MrBayes was run for 1,000,000 generations with 1000 sample points. Bayesian posterior probabilities (PP) greater than 0.70 and Bootstrap support (BS) values greater than 50 are shown for major phylogram branches (PP/BS). Genbank accession numbers precede taxon name for those sequences that were derived from Genbank. Taxa denoted in bold face as “fungal culture” represent novel sequence data from this study that are derived from cultures of Ascosphaera apis isolated from bumble bee queens. Fungal culture A1 has been deposited at the USDA ARSEF insect pathogen collection (culture ID ST-OR11-A1) and the ITS sequence for this culture is deposited in Genbank (accession #KJ158165). Sequences for Aspergillus terreus and Ascosphaera apis USDA-ARSEF 7405 were derived from the genome sequences available at http://www.aspgd.org and http://www.beebase.org.

Mentions: The BLAST analysis conducted on the NCBI website found that ITS sequences from both of the selected fungal cultures possessed 100% sequence identity to ITS sequences from voucher strains of A. apis. The results of phylogenetic analysis in RAxML and MrBayes place the two fungal cultures in a single clade, along with the two voucher strains and the genome strain of A. apis (Fig 2). The ITS sequence alignment file used in these analyses along with maximum likelihood and Bayesian trees are available on Treebase (http://www.treebase.org/treebase-web/) under the accession number 16737 (http://purl.org/phylo/treebase/phylows/study/TB2:S16737).


First detection of the larval chalkbrood disease pathogen Ascosphaera apis (Ascomycota: Eurotiomycetes: Ascosphaerales) in adult bumble bees.

Maxfield-Taylor SA, Mujic AB, Rao S - PLoS ONE (2015)

Phylogeny of the internal transcribed spacer region for selected Ascosphaera species.The phylogeny was inferred under both the maximum likelihood methodology in RAxML and Bayesian methodology in MrBayes using the GTRGAMMA model of evolution. 1,000 RAxML bootstrap replicates were used and MrBayes was run for 1,000,000 generations with 1000 sample points. Bayesian posterior probabilities (PP) greater than 0.70 and Bootstrap support (BS) values greater than 50 are shown for major phylogram branches (PP/BS). Genbank accession numbers precede taxon name for those sequences that were derived from Genbank. Taxa denoted in bold face as “fungal culture” represent novel sequence data from this study that are derived from cultures of Ascosphaera apis isolated from bumble bee queens. Fungal culture A1 has been deposited at the USDA ARSEF insect pathogen collection (culture ID ST-OR11-A1) and the ITS sequence for this culture is deposited in Genbank (accession #KJ158165). Sequences for Aspergillus terreus and Ascosphaera apis USDA-ARSEF 7405 were derived from the genome sequences available at http://www.aspgd.org and http://www.beebase.org.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401763&req=5

pone.0124868.g002: Phylogeny of the internal transcribed spacer region for selected Ascosphaera species.The phylogeny was inferred under both the maximum likelihood methodology in RAxML and Bayesian methodology in MrBayes using the GTRGAMMA model of evolution. 1,000 RAxML bootstrap replicates were used and MrBayes was run for 1,000,000 generations with 1000 sample points. Bayesian posterior probabilities (PP) greater than 0.70 and Bootstrap support (BS) values greater than 50 are shown for major phylogram branches (PP/BS). Genbank accession numbers precede taxon name for those sequences that were derived from Genbank. Taxa denoted in bold face as “fungal culture” represent novel sequence data from this study that are derived from cultures of Ascosphaera apis isolated from bumble bee queens. Fungal culture A1 has been deposited at the USDA ARSEF insect pathogen collection (culture ID ST-OR11-A1) and the ITS sequence for this culture is deposited in Genbank (accession #KJ158165). Sequences for Aspergillus terreus and Ascosphaera apis USDA-ARSEF 7405 were derived from the genome sequences available at http://www.aspgd.org and http://www.beebase.org.
Mentions: The BLAST analysis conducted on the NCBI website found that ITS sequences from both of the selected fungal cultures possessed 100% sequence identity to ITS sequences from voucher strains of A. apis. The results of phylogenetic analysis in RAxML and MrBayes place the two fungal cultures in a single clade, along with the two voucher strains and the genome strain of A. apis (Fig 2). The ITS sequence alignment file used in these analyses along with maximum likelihood and Bayesian trees are available on Treebase (http://www.treebase.org/treebase-web/) under the accession number 16737 (http://purl.org/phylo/treebase/phylows/study/TB2:S16737).

Bottom Line: Queens that died during rearing or that did not lay eggs within one month of capture were dissected, and tissues were examined microscopically for the presence of pathogens.The identity of the fungus was confirmed using molecular markers and phylogenetic analysis.Thus, the discovery of A. apis in adult bumble bees in the current study has important implications for commercial production of bumble bee colonies and highlights potential risks to native bees via pathogen spillover from infected bees and infected pollen.

View Article: PubMed Central - PubMed

Affiliation: Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America.

ABSTRACT
Fungi in the genus Ascosphaera (Ascomycota: Eurotiomycetes: Ascosphaerales) cause chalkbrood disease in larvae of bees. Here, we report the first-ever detection of the fungus in adult bumble bees that were raised in captivity for studies on colony development. Wild queens of Bombus griseocollis, B. nevadensis and B. vosnesenskii were collected and maintained for establishment of nests. Queens that died during rearing or that did not lay eggs within one month of capture were dissected, and tissues were examined microscopically for the presence of pathogens. Filamentous fungi that were detected were plated on artificial media containing broad spectrum antibiotics for isolation and identification. Based on morphological characters, the fungus was identified as Ascosphaera apis (Maasen ex Claussen) Olive and Spiltoir, a species that has been reported earlier only from larvae of the European honey bee, Apis mellifera, the Asian honey bee, Apis cerana, and the carpenter bee Xylocopa californica arizonensis. The identity of the fungus was confirmed using molecular markers and phylogenetic analysis. Ascosphaera apis was detected in queens of all three bumble bee species examined. Of 150 queens dissected, 12 (8%) contained vegetative and reproductive stages of the fungus. Both fungal stages were also detected in two workers collected from colonies with Ascosphaera-infected B. nevadensis queens. In this study, wild bees could have been infected prior to capture for rearing, or, the A. apis infection could have originated via contaminated European honey bee pollen fed to the bumble bees in captivity. Thus, the discovery of A. apis in adult bumble bees in the current study has important implications for commercial production of bumble bee colonies and highlights potential risks to native bees via pathogen spillover from infected bees and infected pollen.

No MeSH data available.


Related in: MedlinePlus