[Pollinator] Honeybees finding it harder to eat at US bee hot spot
David Inouye
dwinouye at gmail.com
Mon Jul 9 22:01:49 PDT 2018
Maybe one of these:
Cane, J. H. and V. J. Tepedino (2016). "Gauging the effect of honey bee
pollen collection on native bee communities." Conservation Letters: n/a-n/a.
Experimental demonstration of direct exploitative competition
between foraging honey bees and native bees in wildlands has proven
elusive, due to problems of experimental design, scale, and
context-dependence. We propose a different approach that translates
floral resources collected by a honey bee colony into progeny
equivalents of an average solitary bee. Such a metric is needed by
public land managers confronting migratory beekeeper demands for
insecticide-free, convenient, resource-rich habitats for summering. We
calculate that, from June–August, a strong colony gathers as much pollen
as could produce 100,000 progeny of an average solitary bee. Analogous
to the animal unit month (AUM) for livestock, a hive unit month (HUM) is
therefore 33,000 native bee progeny. By this calculation, a 40-hive
apiary residing on wildlands for 3 months collects the pollen equivalent
of four million wild bees. We introduce a rapid assessment metric to
gauge stocking of honey bees, and briefly highlight alternative
strategies to provide quality pasture for honey bees with minimal impact
on native bees.
Cane, J. H. and V. J. Tepedino (2017). "Gauging the effect of honey bee
pollen collection on native bee communities." Conservation Letters
10(2): 205-210.
Experimental demonstration of direct exploitative competition
between foraging honey bees and native bees in wildlands has proven
elusive, due to problems of experimental design, scale, and
context-dependence. We propose a different approach that translates
floral resources collected by a honey bee colony into progeny
equivalents of an average solitary bee. Such a metric is needed by
public land managers confronting migratory beekeeper demands for
insecticide-free, convenient, resource-rich habitats for summering. We
calculate that, from June–August, a strong colony gathers as much pollen
as could produce 100,000 progeny of an average solitary bee. Analogous
to the animal unit month (AUM) for livestock, a hive unit month (HUM) is
therefore 33,000 native bee progeny. By this calculation, a 40-hive
apiary residing on wildlands for 3 months collects the pollen equivalent
of four million wild bees. We introduce a rapid assessment metric to
gauge stocking of honey bees, and briefly highlight alternative
strategies to provide quality pasture for honey bees with minimal impact
on native bees.
Geldmann, J. and J. P. González-Varo (2018). "Conserving honey bees does
not help wildlife." Science 359(6374): 392-393.
Goras, G., et al. (2016). Impact of honeybee (Apis mellifera L.) density
on wild bee foraging behaviour. Journal of Apicultural Science. 60: 49.
Honey bees are globally regarded as important crop pollinators and
are also valued for their honey production. They have been introduced on
an almost worldwide scale. During recent years, however, several studies
argue their possible competition with unmanaged pollinators. Here we
examine the possible effects of honey bees on the foraging behaviour of
wild bees on Cistus creticus flowers in Northern Greece. We gradually
introduced one, five, and eight honey-bee hives per site, each
containing ca. 20,000 workers. The visitation frequency and visit
duration of wild bees before and after the beehive introductions were
measured by flower observation. While the visitation frequencies of wild
bees were unaffected, the average time wild bees spent on C. creticus
increased with the introduction of the honey-bee hives. Although
competition between honey bees and wild bees is often expected, we did
not find any clear evidence for significant effects even in honey-bee
densities much higher than the European-wide average of 3.1 colonies/km2.
Lindström, S. A. M., et al. (2016). "Experimental evidence that
honeybees depress wild insect densities in a flowering crop."
Proceedings of the Royal Society B: Biological Sciences 283(1843).
While addition of managed honeybees (Apis mellifera) improves
pollination of many entomophilous crops, it is unknown if it
simultaneously suppresses the densities of wild insects through
competition. To investigate this, we added 624 honeybee hives to 23
fields of oilseed rape (Brassica napus L.) over 2 years and made sure
that the areas around 21 other fields were free from honeybee hives. We
demonstrate that honeybee addition depresses the densities of wild
insects (bumblebees, solitary bees, hoverflies, marchflies, other flies,
and other flying and flower-visiting insects) even in a massive flower
resource such as oilseed rape. The effect was independent of the
complexity of the surrounding landscape, but increased with the size of
the crop field, which suggests that the effect was caused by spatial
displacement of wild insects. Our results have potential implications
both for the pollination of crops (if displacement of wild pollinators
offsets benefits achieved by adding honeybees) and for conservation of
wild insects (if displacement results in negative fitness consequences).
Magrach, A., et al. (2017). "Honeybee spillover reshuffles pollinator
diets and affects plant reproductive success." Nature Ecology &
Evolution 1(9): 1299-1307.
During the past decades, managed honeybee stocks have increased
globally. Managed honeybees are particularly used within mass-flowering
crops and often spill over to adjacent natural habitats after crop
blooming. Here, we uniquely show the simultaneous impact that honeybee
spillover has on wild plant and animal communities in flower-rich
woodlands via changes in plant–pollinator network structure that
translate into a direct negative effect on the reproductive success of a
dominant wild plant. Honeybee spillover leads to a re-assembly of
plant–pollinator interactions through increased competition with other
pollinator species. Moreover, honeybee preference for the most abundant
plant species reduces its seed set, driven by high honeybee visitation
rates that prevent pollen tube growth. Our study therefore calls for an
adequate understanding of the trade-offs between providing pollination
services to crops and the effects that managed pollinators might have on
wild plants and pollinators.
Mallinger, R. E., et al. (2017). "Do managed bees have negative effects
on wild bees?: A systematic review of the literature." PLoS ONE 12(12):
e0189268.
Managed bees are critical for crop pollination worldwide. As the
demand for pollinator-dependent crops increases, so does the use of
managed bees. Concern has arisen that managed bees may have unintended
negative impacts on native wild bees, which are important pollinators in
both agricultural and natural ecosystems. The goal of this study was to
synthesize the literature documenting the effects of managed honey bees
and bumble bees on wild bees in three areas: (1) competition for floral
and nesting resources, (2) indirect effects via changes in plant
communities, including the spread of exotic plants and decline of native
plants, and (3) transmission of pathogens. The majority of reviewed
studies reported negative effects of managed bees, but trends differed
across topical areas. Of studies examining competition, results were
highly variable with 53% reporting negative effects on wild bees, while
28% reported no effects and 19% reported mixed effects (varying with the
bee species or variables examined). Equal numbers of studies examining
plant communities reported positive (36%) and negative (36%) effects,
with the remainder reporting no or mixed effects. Finally, the majority
of studies on pathogen transmission (70%) reported potential negative
effects of managed bees on wild bees. However, most studies across all
topical areas documented the potential for impact (e.g. reporting the
occurrence of competition or pathogens), but did not measure direct
effects on wild bee fitness, abundance, or diversity. Furthermore, we
found that results varied depending on whether managed bees were in
their native or non-native range; managed bees within their native range
had lesser competitive effects, but potentially greater effects on wild
bees via pathogen transmission. We conclude that while this field has
expanded considerably in recent decades, additional research measuring
direct, long-term, and population-level effects of managed bees is
needed to understand their potential impact on wild bees.
Müller, H. T. (2016). Interaction between Bombus terrestris and
honeybees in red clover fields reduces abundance of other bumblebees and
red clover yield Oslo, Norwegian University of Life Sciences M.Sc.
Pollinator dependent crops have increased by 300% the last 50
years. At the same time many pollinator species are declining, including
honeybees and bumblebees. Red clover is one of the crops dependent on
bees for seed set. It is the single most important leguminous crop for
milk and meat production in Norway, but over the last years crops have
declined, and insufficient pollination is a likely hypothesis to explain
this. Long tongued bumblebees are the most efficient pollinators of this
crop, and are simultaneously the bumblebee species declining the most.
To improve yields, honeybees and another bumblebee, B. terrestris, is
added to fields. Evidence on how this affects the other bumblebee
species, especially long tongued species, and yield is conflicting.
However, honeybees are considered poorer pollinators of red clover than
bumblebees, and B. terrestris is a known nectar robber. The aim of this
study was to identify whether competition occurs between honeybees, B.
terrestris and other bumblebee species in red clover fields, and how
these interactions may affect red clover yield. To that objective the
composition of pollinator communities in 40 red clover fields over two
years were examined, and estimates for red clover yield were obtained.
B. terrestris abundance was manipulated in five fields. The results
suggest that B. terrestris act as nectar robbers, facilitating honeybees
and other short tongued bumblebees acting as secondary robbers.
Honeybees negatively affects abundance of both long and short tongued
bumblebees, indicating that competition occurs. Interaction between
increased abundance of honeybees and B. terrestris seems to reduces long
tongued bumblebee abundance and red clover yield.
Nielsen, A., et al. (2017). "Effects of competition and climate on a
crop pollinator community." Agriculture, Ecosystems & Environment 246:
253-260.
Plant-pollinator interactions are ubiquitous in nature where both
wild and domesticated pollinators interact with wild plant communities
and entomophilous crops. Honeybees are important pollinators in many
crop systems, but recent declines in honeybee stocks in Europe and the
US have caused concern about the sustainability of crop systems solely
depending on honeybees. In addition, several studies have shown that
honeybees might negatively affect native pollinator populations,
bumblebees in particular. Here we have studied flower visitation to two
raspberry farms and surrounding wildflower communities in SE Norway.
Bumblebees were excluded from the raspberry field by means of
exploitative competition from honeybees ( >97% of flower visits in the
raspberry fields were conducted by honeybees). More than 55% of the
visits recorded in wild plant communities surrounding the farms were
conducted by bumblebees, showing that bumblebees were present in the
system. Pollinator taxa were affected differently by temperature;
honeybee visits showed a unimodal relationship with maximum flower
visitation activity at a temperature of 24.1°C, while flower visits by
bumblebees showed a positive, linear relationship with temperature. The
effect of temperature was much weaker for bumblebees than for honeybees
(∼2.2% of the variation was explained by temperature, compared to ∼46%
for honeybees). Farming practice affected flower visitation, as flowers
within growing tunnels received fewer visits. However, the number of
flower visits, also within the growing tunnels, was far above what other
studies have shown to be sufficient for optimal pollination in
raspberry. We conclude that the raspberry fields were sufficiently
pollinated by honeybees but that the system should be considered
vulnerable as it is solely dependent on this particular pollinator
species. The honeybees were sensitive to ambient temperature suggesting
that they might suffer more from future climate change than bumblebees.
Thomson, D. M. (2016). "Local bumble bee decline linked to recovery of
honey bees, drought effects on floral resources." Ecology Letters
19(10): 1247-1255.
Time series of abundances are critical for understanding how
abiotic factors and species interactions affect population dynamics, but
are rarely linked with experiments and also scarce for bee pollinators.
This gap is important given concerns about declines in some bee species.
I monitored honey bee (Apis mellifera) and bumble bee (Bombus spp.)
foragers in coastal California from 1999, when feral A. mellifera
populations were low due to Varroa destructor, until 2014. Apis
mellifera increased substantially, except between 2006 and 2011,
coinciding with declines in managed populations. Increases in A.
mellifera strongly correlated with declines in Bombus and reduced diet
overlap between them, suggesting resource competition consistent with
past experimental results. Lower Bombus numbers also correlated with
diminished floral resources. Declines in floral abundances were
associated with drought and reduced spring rainfall. These results
illustrate how competition with an introduced species may interact with
climate to drive local decline of native pollinators.
Torné-Noguera, A., et al. (2016). "Collateral effects of beekeeping:
Impacts on pollen-nectar resources and wild bee communities." Basic and
Applied Ecology 17(3): 199-209.
Due to the contribution of honey bees (Apis mellifera) to wild
flower and crop pollination, beekeeping has traditionally been
considered a sustainable practice. However, high honey bee densities may
have an impact on local pollen and nectar availability, which in turn
may negatively affect other pollinators. This is exacerbated by the
ability of honey bees to recruit foragers to highly rewarding flower
patches. We measured floral resource consumption in rosemary (Rosmarinus
officinalis) and thyme (Thymus vulgaris) in 21 plots located at
different distances from apiaries in the scrubland of Garraf Natural
Park (Barcelona), and related these measures to visitation rates of
honey bees, bumblebees (Bombus terrestris) and other pollinators. In the
same plots, we measured flower density, and used pan traps to
characterize the wild bee community. Flower resource consumption was
largely explained by honey bee visitation and marginally by bumblebee
visitation. After accounting for flower density, plots close to apiaries
had lower wild bee biomass. This was due to a lower abundance of large
bee species, those more likely to be affected by honey bee competition.
We conclude that honey bees are the main contributors to pollen/nectar
consumption of the two main flowering plants in the scrubland, and that
at the densities currently occurring in the park (3.5 hives/km2) the
wild bee community is being affected. Our study supports the hypothesis
that high honey bee densities may have an impact on other pollinators
via competition for flower resources.
Wojcik, V. A., et al. (2018). "Floral resource competition between honey
bees and wild bees: Is there clear evidence and can we guide management
and conservation?" Environ Entomol: nvy077-nvy077.
Supporting managed honey bees by pasturing in natural landscapes
has come under review due to concerns that honey bees could negatively
impact the survival of wild bees through competition for floral
resources. Critique and assessment of the existing body of published
literature against our criteria focussing on studies that can support
best management resulted in 19 experimental papers. Indirect measures of
competition examining foraging patterns and behavior yielded equivocal
results. Direct measures of reproduction and growth were investigated in
only seven studies, with six indicating negative impacts to wild bees
from the presence of managed honey bees. Three of these studies examined
fitness impacts to BombusLatreille and all three indicated reduced
growth or reduced reproductive output. Because there is a severe lack of
literature, yet potential that honey bee presence could negatively
impact wild bees, exemplified with bumble bee studies, we advocate for
further research into the fitness impacts of competition between managed
and wild pollinators. Conservative approaches should be taken with
respect to pasturing honey bees on natural lands with sensitive bumble
bee populations. Correspondingly, forage opportunities for honey bees in
managed, agricultural landscapes, should be increased in an effort to
reduce potential pressure and infringement on wild bee populations in
natural areas.
On 7/9/2018 9:41 PM, Barbara Passero wrote:
> Hi David and others,
> I’m looking for an article I read on this listserv that described how
> honey bees are outcompeting domestic bumble bees.
> It seems to me that development of open space is speeding up just as
> it becomes even more critical to save the land.
> I wonder whether the public would rally if they knew that their “all
> you can eat buffet” would eventually consist of all the rice you could
> eat.
> Thanks, Barbara
> Barbara Passero, Director
> MEADOWSCAPING for Biodiversity
> 174 Moody St. #244
> Waltham, MA 02453
> Office: 781-209-0052 Cell: 617-999-9546
> bpassero at meadowmaking.org
> http://www.meadowmaking.org
> *From:* David Inouye <mailto:dwinouye at gmail.com>
> *Sent:* Tuesday, July 03, 2018 9:21 AM
> *To:* pollinator at coevolution.org <mailto:pollinator at coevolution.org>
> *Subject:* [Pollinator] Honeybees finding it harder to eat at US bee
> hot spot
>
>
> Honeybees finding it harder to eat at US bee hot spot
> <https://ehn.us16.list-manage.com/track/click?u=73be43273a8ebb733ab2696c7&id=66d66dd6bf&e=df8f3d14a2>
>
> www.cbc.ca
> <https://ehn.us16.list-manage.com/track/click?u=73be43273a8ebb733ab2696c7&id=c47eceac28&e=df8f3d14a2>
>
> Bees are having a much harder time finding food in the Northern Great
> Plains of the Dakotas, known as America's last honeybee refuge,
> according t...
>
> https://www.cbc.ca/news/technology/honeybees-harder-to-eat-1.4731277
>
> --
> Dr. David W. Inouye
> Professor Emeritus
> Department of Biology
> University of Maryland
> College Park, MD 20742-4415
> inouye at umd.edu
>
> Principal Investigator
> Rocky Mountain Biological Laboratory
> PO Box 519
> Crested Butte, CO 81224
>
> ------------------------------------------------------------------------
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--
Dr. David W. Inouye
Professor Emeritus
Department of Biology
University of Maryland
Principal Investigator
Rocky Mountain Biological Laboratory
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