More Like this

1. Honey bee (Apis mellifera) colony health and pathogen composition in migratory beekeeping operations involved in California almond pollination

   Glenny, W. ; Cavigli, I. ; Daughenbaugh, K.F. ; Radford, R. ; Kegeley, S. ; Flenniken, M.L. ( October 2017 , PloS one)

   Honey bees are important pollinators of agricultural crops. Pathogens and other factors have been implicated in high annual losses of honey bee colonies in North America and some European countries. To further investigate the relationship between multiple factors, including pathogen prevalence and abundance and colony health, we monitored commercially managed migratory honey bee colonies involved in California almond pollination in 2014. At each sampling event, honey bee colony health was assessed, using colony population size as a proxy for health, and the prevalence and abundance of seven honey bee pathogens was evaluated using PCR and quantitative PCR, respectively. In this sample cohort, pathogen prevalence and abundance did not correlate with colony health, but did correlate with the date of sampling. In general, pathogen prevalence (i.e., the number of specific pathogens harbored within a colony) was lower early in the year (January—March) and was greater in the summer, with peak prevalence occurring in June. Pathogen abundance in individual honey bee colonies varied throughout the year and was strongly associated with the sampling date, and was influenced by beekeeping operation, colony health, and mite infestation level. Together, data from this and other observational cohort studies that monitor individual honey bee colonies andmore »precisely account for sampling date (i.e., day of year) will lead to a better understanding of the influence of pathogens on colony mortality and the effects of other factors on these associations.« less
2. Local and landscape features constrain the trait and taxonomic diversity of urban bees

   https://doi.org/10.1007/s10980-021-01370-z  

   Cohen, Hamutahl ; Egerer, Monika ; Thomas, Summer-Solstice ; Philpott, Stacy M. ( December 2021 , Landscape Ecology)

   There is concern that urbanization threatens bees, a diverse group of economic importance. The impact of urbanization on bees is likely mediated by their phenotypic traits.

   We examine how urban cover and resource availability at local and landscape scales influences both species taxonomic and functional diversity in bees.

   We used a combination of aerial netting and pan traps across six sampling periods to collect wild bees in 18 urban gardens spanning more than 125 km of the California central coast. We identified 3537 specimens to genus and, when possible, to species to obtain species richness and abundance at each site. For each species we measured a suite of bee traits, including body size, sociality, nesting location, nesting behavior, pollen-carrying structure, parasitism, and lecty.

   We found that increased garden size was positively associated with bee species richness and abundance. Somewhat counterintuitively, we found that urban cover surrounding gardens (2 km) was positively associated with bee species richness. Urban cover was also associated with the prevalence of certain bee traits, such as bees that excavate nests over those who rent, and bees with non-corbiculate structures. We suggest that urban habitats such as gardens can host a high number of bee species, but urbanizationmore »selects for species with specific traits.

   These findings illustrate that local and landscape features both influence bee abundance, species richness, and the frequency of specific traits. We highlight the importance of trait-based approaches for assessing biodiversity in urban landscapes, and suggest conceptualizing urbanization as a process of habitat change rather than habitat loss.

   « less
3. Sunflower spines and beyond: Mechanisms and breadth of pollen that reduce gut pathogen infection in the common eastern bumble bee

   https://doi.org/10.1111/1365-2435.14320  

   Figueroa, Laura L. ; Fowler, Alison ; Lopez, Stephanie ; Amaral, Victoria E. ; Koch, Hauke ; Stevenson, Philip C. ; Irwin, Rebecca E. ; Adler, Lynn S. ( April 2023 , Functional Ecology)

   Plants have unique chemical and physical traits that can reduce infections in animals ranging from primates to caterpillars. Sunflowers (Helianthus annuus; Asteraceae) are one striking example, with pollen that suppresses infections by the trypanosomatid gut pathogenCrithidia bombiin the common eastern bumble bee (Bombus impatiens). However, the mechanism underlying this effect has remained elusive, and we do not know whether pollens from other Asteraceae species have similar effects.

   We evaluated whether mechanisms mediating sunflower pollen's antipathogenic effects are physical (due to its spiny exine), chemical (due to metabolites) or both. We also evaluated the degree to which pollen from seven other Asteraceae species reducedC. bombiinfection relative to pollen from sunflower and two non‐Asteraceae species, and whether pollen spine length predicted pathogen suppression.

   We found that sunflower exines alone reduced infection as effectively as whole sunflower pollen, while sunflower pollen metabolites did not. Furthermore, bees fed pollen from four of seven other Asteraceae had 62%–92% lowerC. bombiinfections than those fed non‐Asteraceae pollen. Spine length, however, did not explain variation in bumble bee infection.

   Our study indicates that sunflower pollen's capacity to suppressC. bombiis driven by its spiny exine, and that this phenomenon extends to several other Asteraceae species. Our results indicate that sunflower pollenmore »exines are as effective as whole pollen in reducing infection, suggesting that future studies should expand to assess the effects of other species with spiny pollen on pollinator–pathogen dynamics.

   Read the freePlain Language Summaryfor this article on the Journal blog.

   « less
4. The costs and benefits of sunflower pollen diet on bumble bee colony disease and health

   https://doi.org/10.1002/ecs2.3663  

   Giacomini, Jonathan J. ; Connon, Sara J. ; Marulanda, Daniel ; Adler, Lynn S. ; Irwin, Rebecca E. ( July 2021 , Ecosphere)

   Pathogen transmission between domesticated and wild host species has important implications for community ecology, agriculture, and wildlife conservation. Bumble bees provide valuable pollination services that are vital for both wildflowers and agricultural production. Intense concerns about pathogen spillover from commercial bumble bees to wild bee populations, and the potential harmful effects of pathogen spillback to commercial bees, has stimulated a need for practical strategies that effectively manage bumble bee infectious diseases. Here, we assessed the costs and benefits of a medicinal sunflower pollen diet (Helianthusannuus) on whole‐colony bumble bee disease and performance using commercial colonies of the common eastern bumble bee,Bombus impatiens, and its protozoan pathogen,Crithidia bombi(Trypanosomatida). We first found that a 1:1 mixture of sunflower combined with wildflower pollen reducedC. bombiinfection prevalence and intensity within individualB. impatiensworkers by nearly 4‐fold and 12‐fold, respectively, relative to wildflower pollen. At the colony level, a 1:1 mixture of sunflower and wildflower pollen reducedC. bombiinfection prevalence by 11% averaged over a 10‐week period and infection intensity by 30% relative to wildflower pollen. Colony performance was similar between pollen diets and infection treatments, including the number of workers and immatures produced, and size and weight of workers, drones, and queens. Infection significantly reduced the probabilitymore »of queen production in colonies fed a pure wildflower pollen diet, but not colonies fed a mixed sunflower pollen diet, suggesting that the medicinal benefits of a mixed sunflower pollen diet can reverse the negative effects of infection on reproductive success. This study provides evidence that sunflower pollen as part of a mixed pollen diet can reduce infection in individual bees and whole colonies with no significant nutritional trade‐offs for colony worker production and most aspects of colony reproduction. A supplemental mixed sunflower pollen diet may provide a simple and effective solution to reduce disease and improve the health of economically and ecologically important pollinators.

   « less
5. Elevational Constraints on the Composition and Genomic Attributes of Microbial Communities in Antarctic Soils

   https://doi.org/10.1128/msystems.01330-21  

   Dragone, Nicholas B. ; Henley, Jessica B. ; Holland-Moritz, Hannah ; Diaz, Melisa ; Hogg, Ian D. ; Lyons, W. Berry ; Wall, Diana H. ; Adams, Byron J. ; Fierer, Noah ( February 2022 , mSystems)

   Mackelprang, Rachel (Ed.)

   ABSTRACT The inland soils found on the Antarctic continent represent one of the more challenging environments for microbial life on Earth. Nevertheless, Antarctic soils harbor unique bacterial and archaeal (prokaryotic) communities able to cope with extremely cold and dry conditions. These communities are not homogeneous, and the taxonomic composition and functional capabilities (genomic attributes) of these communities across environmental gradients remain largely undetermined. We analyzed the prokaryotic communities in soil samples collected from across the Shackleton Glacier region of Antarctica by coupling quantitative PCR, marker gene amplicon sequencing, and shotgun metagenomic sequencing. We found that elevation was the dominant factor explaining differences in the structures of the soil prokaryotic communities, with the drier and saltier soils found at higher elevations harboring less diverse communities and unique assemblages of cooccurring taxa. The higher-elevation soil communities also had lower maximum potential growth rates (as inferred from metagenome-based estimates of codon usage bias) and an overrepresentation of genes associated with trace gas metabolism. Together, these results highlight the utility of assessing community shifts across pronounced environmental gradients to improve our understanding of the microbial diversity found in Antarctic soils and the strategies used by soil microbes to persist at the limits of habitability.more »IMPORTANCE Antarctic soils represent an ideal system to study how environmental properties shape the taxonomic and functional diversity of microbial communities given the relatively low diversity of Antarctic soil microbial communities and the pronounced environmental gradients that occur across soils located in reasonable proximity to one another. Moreover, the challenging environmental conditions typical of most Antarctic soils present an opportunity to investigate the traits that allow soil microbes to persist in some of the most inhospitable habitats on Earth. We used cultivation-independent methods to study the bacterial and archaeal communities found in soil samples collected from across the Shackleton Glacier region of the Transantarctic Mountains. We show that those environmental characteristics associated with elevation have the greatest impact on the structure of these microbial communities, with the colder, drier, and saltier soils found at higher elevations sustaining less diverse communities that were distinct from those in more hospitable soils with respect to their composition, genomic attributes, and overall life-history strategies. Notably, the harsher conditions found in higher-elevation soils likely select for taxa with lower maximum potential growth rates and an increased reliance on trace gas metabolism to support growth.« less