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Bacterial and Fungal Symbionts in Pollen Provisions of a Native Solitary Bee in Urban and Rural Environments

DOI:10.1007/s00248-022-02164-9
Authors:
Lila Rose Westreich at University of Washington Seattle
Lila Rose Westreich
Sam Westreich at DNAnexus
Sam Westreich
Patrick C. Tobin
Patrick C. Tobin
Patrick C. Tobin
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Among insects, symbionts such as bacteria and fungi can be linked to their physiology and immature development, and in some cases are part of a defense system against parasites and diseases. Current bacterial and fungal symbiont associations in solitary bees are understudied, especially in the Pacific Northwest region of the USA. We collected pollen provisions from the native spring-foraging solitary bee, Osmia lignaria Say, across two distinct foraging periods over 2 years at 22 sites along an urban-to-rural gradient in western Washington. We then used next-generation sequencing to identify bacterial and fungi within pollen provisions and assessed the effect of their richness and diversity on O. lignaria larval development success and adult emergence. We detected a significantly positive relationship between bacterial diversity in pollen with O. lignaria larval developmental success, and higher bacterial richness and diversity during the later foraging period. Fungal generic richness and diversity decreased with increasing plant richness. Although neither was associated with O. lignaria developmental success, we did detect Ascosphaera spp. known to be pathogenic to O. lignaria and other bee species. Neither bacterial or fungal richness or diversity was affected by site type when classified as urban or rural. This study provides new information on bacterial and fungal symbionts present in pollen provisions of a native solitary bee when foraging across urban and rural areas of the Pacific Northwest.
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Vol:.(1234567890)
Microbial Ecology (2023) 86:1416–1427
https://doi.org/10.1007/s00248-022-02164-9
1 3
HOST MICROBE INTERACTIONS
Bacterial andFungal Symbionts inPollen Provisions ofaNative
Solitary Bee inUrban andRural Environments
LilaR.Westreich1 · SamuelT.Westreich2 · PatrickC.Tobin1
Received: 21 March 2022 / Accepted: 20 December 2022 / Published online: 28 December 2022
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2022
Abstract
Among insects, symbionts such as bacteria and fungi can be linked to their physiology and immature development, and in
some cases are part of a defense system against parasites and diseases. Current bacterial and fungal symbiont associations
in solitary bees are understudied, especially in the Pacific Northwest region of the USA. We collected pollen provisions
from the native spring-foraging solitary bee, Osmia lignaria Say, across two distinct foraging periods over 2years at 22
sites along an urban-to-rural gradient in western Washington. We then used next-generation sequencing to identify bacterial
and fungi within pollen provisions and assessed the effect of their richness and diversity on O. lignaria larval development
success and adult emergence. We detected a significantly positive relationship between bacterial diversity in pollen with O.
lignaria larval developmental success, and higher bacterial richness and diversity during the later foraging period. Fungal
generic richness and diversity decreased with increasing plant richness. Although neither was associated with O. lignaria
developmental success, we did detect Ascosphaera spp. known to be pathogenic to O. lignaria and other bee species. Neither
bacterial or fungal richness or diversity was affected by site type when classified as urban or rural. This study provides new
information on bacterial and fungal symbionts present in pollen provisions of a native solitary bee when foraging across
urban and rural areas of the Pacific Northwest.
Keywords DNA Metabarcoding· Native bee conservation· Osmia lignaria· Pollination ecology
Introduction
The role of microorganisms in affecting the health of host
species is an increasingly engaging area of research, in part
due to the availability of molecular tools to ascertain these
relationships [29]. In insect species, microbial symbionts
play key roles in development and survival, and are linked
to population success [22]. The connection between symbi-
otic microbes and pollinator health has also received much
attention, especially in the European honey bee, Apis mel-
lifera L. and in response to Colony Collapse Disorder [13].
Among bees (Hymenoptera: Anthophila), foraging females
collect pollen and nectar during the flowering season to
bring back to their offspring. Symbionts such as bacteria
and fungi are often present on flowering plants, particularly
on the surface of flowers [30], and may occur naturally or be
deposited by insect species that visit the flower [3]. Because
social and solitary bees visit numerous flowering plant spe-
cies during their foraging periods, they create a network
of visitations and consequently facilitate the movement of
microorganisms among flowers [14].
Bacteria associated with the health of social bee species
have been linked across seasons and geographic areas, pro-
viding evidence of a core microbiome distinct across time
and space [41, 45, 53]. Bacterial diversity has also been
linked to the health and survival in several bee species. For
example, beneficial gut bacteria in bumble bees reduce the
infection rate and presence of the gut parasite Crithidia
bombi [32]. Stress tolerance, disease resistance, and stronger
* Patrick C. Tobin
pctobin@uw.edu
Lila R. Westreich
lilawestreich@gmail.com
Samuel T. Westreich
swestreich@gmail.com
1 School ofEnvironmental andForest Sciences, University
ofWashington, 3715 W. Stevens Way NE, Seattle,
WA98195, USA
2 DNAnexus Inc, 1975 El Camino Real, MountainView,
CA94041, USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... A more diverse microbial community would be predicted to provide a broader enzymatic repertoire, increasing the variety of pollen types that can be accessed. Indeed, increased microbial diversity within pollen provisions confers benefits for certain solitary bees: it has been shown that, with increasing bacterial diversity [61] and microbial abundance [15], larval fitness can be enhanced. ...
View
... In environments where access to floral resources changes or provisioning requirements becomes more limited, both plant and bee microbiota may experience dysbiosis and a harmful reduction in important microbiota [83,86]. Visiting an array of plants may also allow bees to become exposed to diverse bacteria and result in improved larval developmental success, as is the case with Osmia lignaria pollen provisions with higher bacterial diversity [87]. However, this matter is worsened when considering that pollen and nectar in wild flowers can harbour pesticides, which pollinators bring back to their nests, both in agricultural and urban landscapes [88,89]. ...
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