http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html?WT.ec_id=NATURE-20150423
- Sébastien C. Kessler
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html?WT.ec_id=NATURE-20150423#auth-1>
,et al
Nature (2015) doi:10.1038/nature14414 Received 24 January 2015 / Accepted
20 March 2015 / Published online 22 April 2015 Abstract:
The impact of neonicotinoid insecticides on insect pollinators is highly
controversial. Sublethal concentrations alter the behaviour of social bees
and reduce survival of entire colonies1
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#ref1>,
2
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#ref2>,
3
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#ref3>.
However, critics argue that the reported negative effects only arise from
neonicotinoid concentrations that are greater than those found in the
nectar and pollen of pesticide-treated plants4
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#ref4>.
Furthermore, it has been suggested that bees could choose to forage on
other available flowers and hence avoid or dilute exposure4
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#ref4>,
5
<http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#ref5>.
Here, using a two-choice feeding assay, we show that the honeybee, *Apis
mellifera*, and the buff-tailed bumblebee, *Bombus terrestris*, do not
avoid nectar-relevant concentrations of three of the most commonly used
neonicotinoids, imidacloprid (IMD), thiamethoxam (TMX), and clothianidin
(CLO), in food. Moreover, bees of both species prefer to eat more of
sucrose solutions laced with IMD or TMX than sucrose alone. Stimulation
with IMD, TMX and CLO neither elicited spiking responses from gustatory
neurons in the bees' mouthparts, nor inhibited the responses of
sucrose-sensitive neurons. Our data indicate that bees cannot taste
neonicotinoids and are not repelled by them. Instead, bees preferred
solutions containing IMD or TMX, even though the consumption of these
pesticides caused them to eat less food overall. This work shows that bees
cannot control their exposure to neonicotinoids in food and implies that
treating flowering crops with IMD and TMX presents a sizeable hazard to
foraging bees.
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