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<font size=2>Piiroinen, S. and D. Goulson (2016). "Chronic
neonicotinoid pesticide exposure and parasite stress differentially
affects learning in honeybees and bumblebees." <u>Proceedings of the
Royal Society of London B: Biological Sciences</u> <b>283</b>(1828).<br>
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Learning and memory are crucial functions which enable insect pollinators
to efficiently locate and extract floral rewards. Exposure to pesticides
or infection by parasites may cause subtle but ecologically important
changes in cognitive functions of pollinators. The potential interactive
effects of these stressors on learning and memory have not yet been
explored. Furthermore, sensitivity to stressors may differ between
species, but few studies have compared responses in different species.
Here, we show that chronic exposure to field-realistic levels of the
neonicotinoid clothianidin impaired olfactory learning acquisition in
honeybees, leading to potential impacts on colony fitness, but not in
bumblebees. Infection by the microsporidian parasite Nosema ceranae
slightly impaired learning in honeybees, but no interactive effects were
observed. Nosema did not infect bumblebees (3% infection success).
Nevertheless, Nosema-treated bumblebees had a slightly lower rate of
learning than controls, but faster learning in combination with
neonicotinoid exposure. This highlights the potential for complex
interactive effects of stressors on learning. Our results underline that
one cannot readily extrapolate findings from one bee species to others.
This has important implications for regulatory risk assessments which
generally use honeybees as a model for all bees.<br><br>
<br>
</dl>Ziska, L. H., et al. (2016). "Rising atmospheric CO2 is
reducing the protein concentration of a floral pollen source essential
for North American bees." <u>Proceedings of the Royal Society of
London B: Biological Sciences</u> <b>283</b>(1828).<br>
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present, there is substantive evidence that the nutritional content of
agriculturally important food crops will decrease in response to rising
levels of atmospheric carbon dioxide, Ca. However, whether Ca-induced
declines in nutritional quality are also occurring for pollinator food
sources is unknown. Flowering late in the season, goldenrod (Solidago
spp.) pollen is a widely available autumnal food source commonly
acknowledged by apiarists to be essential to native bee (e.g. Bombus
spp.) and honeybee (Apis mellifera) health and winter survival. Using
floral collections obtained from the Smithsonian Natural History Museum,
we quantified Ca-induced temporal changes in pollen protein concentration
of Canada goldenrod (Solidago canadensis), the most widespread Solidago
taxon, from hundreds of samples collected throughout the USA and southern
Canada over the period 1842(i.e. a Ca from approx. 280 to 398 ppm). In
addition, we conducted a 2 year in situ trial of S. canadensis
populations grown along a continuous Ca gradient from approximately 280
to 500 ppm. The historical data indicated a strong significant
correlation between recent increases in Ca and reductions in pollen
protein concentration (r2 = 0.81). Experimental data confirmed this
decrease in pollen protein concentration, and indicated that it would be
ongoing as Ca continues to rise in the near term, i.e. to 500 ppm (r2 =
0.88). While additional data are needed to quantify the subsequent
effects of reduced protein concentration for Canada goldenrod on bee
health and population stability, these results are the first to indicate
that increasing Ca can reduce protein content of a floral pollen source
widely used by North American bees.<br><br>
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