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Two studies provide evidence that bees cannot taste or avoid neonicotinoid pesticides, and that exposure to treated crops affects reproduction in solitary bees as well as bumblebee colony growth and reproduction.
Bee foraging options and pesticide exposure. Non-flowering crops and pasture cover large areas of rural land, but typically provide limited food resources for bee populations. Flowering crops can provide plentiful (although non-diverse) bee food, but are often treated with pesticides, a direct route for exposure. Flower-rich meadows provide a diverse bee diet, but these are becoming increasingly scarce, and small areas may support only low bee numbers. Furthermore, wild flowers in field margins may contain pesticide residues. Rundlöf et al.16 show that the growth rates and reproduction of bumblebee colonies are lower in neonicotinoid-treated fields than in control fields, and that reproduction of solitary bees can also be affected. However, the authors found no effect on honeybee colonies. These differences may result from different ecologies: honeybees can forage many kilometres from their hive, whereas bumblebees roam over smaller areas, and solitary bees fly less far from their nest. Honeybees also use the waggle dance to communicate the location of rewarding flower patches to nest-mates. Thus, honeybees may have reduced pesticide exposure from visiting a greater mixture of foraging sources or through a greater chance of avoiding treated crops. However, Kessler et al.15 show that neither honeybees nor bumblebees can taste neonicotinoids, suggesting that such avoidance behaviour is unlikely. (Nest sites, foraging ranges and the relative proportion of habitat types vary across landscapes — those depicted are representative only.)
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a ‘noisy’ image. Although a simple task, this
achievement is remarkable because the con-
tinuous conductance changes of memristors
are notoriously noisy and non-symmetric
— that is, increases in conductances often
have different amplitudes from analogous
decreases, which causes problems for learning
algorithms. The authors used two memristors
for each synaptic connection, such that the
strength of a synapse was given by the differ-
ence between two memristor conductances.
This differential implementation of synaptic
strengths has several benefits — for exam-
ple, it reduces the impact of non-symmetric
conductance changes because each synaptic
update involves the change of two conduct-
ances in opposite directions.
Prezioso and co-workers’ result is a proof-
of-concept for hybrid CMOS–memristor
neuromorphic circuits. If this design can be
scaled up to large network sizes, it will affect
the future of computing. Computer scientists
have struggled to design algorithms for jobs
that humans perform easily, such as visual
tasks (distinguishing objects in a scene, for
example), speech recognition and coordi na-
ting muscles and limbs to perform a motor
task. Large neural networks can learn such
tasks from massive data sets
. Brain-inspired
hardware would therefore complement the
strengths of conventional computers. In the
future, laptops, mobile phones and robots
could include ultra-low-power neuromorphic
chips that process visual, auditory and other
types of sensory information.
Of course, more research is necessary
to achieve these goals. With an area of
200 × 200 nanometres, the memristive devices
used by Prezioso etal. are still relatively large
compared with other state-of-the-art memris-
tors, and the network described is quite simple.
Much larger networks will need to be created,
with higher numbers of memristors per unit
area, for applications to be realized. Also, the
researchers used a batch-learning set-up, in
which the whole training data set had to be
processed for each update of memristive con-
ductances. This training set-up would there-
fore require many extra circuit components
to provide large amounts of memory outside
the memristive crossbar array. Future research
must explore how efficient learning procedures
for memristive crossbar arrays can be achieved
without the need for external memory.
Robert Legenstein is at the Institute
for Theoretical Computer Science, Graz
University of Technology, Graz 8010, Austria.
1. Prezioso, M. et al. Nature 521, 61–64 (2015).
2. Backus, J. Commun. ACM 21, 613–641 (1978).
3. McCulloch, W. S. & Pitts, W. H. Bull. Math. Biophys. 5,
115–133 (1943).
4. Rosenblatt, F. Psychol. Rev. 65, 386–408 (1958).
5. Schmidhuber, J. Neural Networks 61, 85–117 (2015).
6. Indiveri, G. et al. Nanotechnology 24, 384010
Tasteless pesticides
affect bees in the field
Two studies provide evidence that bees cannot taste or avoid neonicotinoid
pesticides, and that exposure to treated crops affects reproduction in solitary bees
as well as bumblebee colony growth and reproduction. S L .74  .77
nsects such as bees are crucial for the
pollination of agricultural crops and wild
plants1,2, helping to ensure food secu-
rity and maintain biodiversity. Yet a range of
environmental stressors are threatening bee
populations around the world3–6. The impact
of pesticide exposure, particularly from
neonicotinoid insecticides, has received sub-
stantial recent research attention7,8 and has
become a topic of public debate. Studies that
have reported adverse effects of neonicotinoids
on bees have been criticized for several rea-
sons: that exposure tests are carried out under
laboratory or semi-field settings rather than
in the field and use pesticide-treated foods
containing unrealistically high dosages; and
that bees can detect chemical residues on
treated crops and avoid foraging on them. Fur-
ther weight has been added to such criticisms
because the few field studies that have inves-
tigated potential impacts on honeybees and
bumblebees from exposure to neonicotinoid-
treated crops have been interpreted to show
little or no effect9–13, although limitations to
these studies have been highlighted7,14. Two
studies in this issue strike at the heart of these
evidence gaps and improve our understanding
of pesticide exposure risks to bees.
In their paper, Kessler etal.15 (page74)
present a carefully controlled laboratory study
Non-owering crop
Pesticide exposure: low
Nutrition: scarce
Wild-ower meadows
Pesticide exposure: low
Nutrition: less abundant
but diverse
Field margins
Pesticide exposure: medium
Nutrition: less abundant
but diverse
Flowering crop
Pesticide exposure: high
Nutrition: abundant
but non-diverse
Figure 1 | Bee foraging options and pesticide exposure. Non-flowering crops and pasture cover large
areas of rural land, but typically provide limited food resources for bee populations. Flowering crops can
provide plentiful (although non-diverse) bee food, but are often treated with pesticides, a direct route for
exposure. Flower-rich meadows provide a diverse bee diet, but these are becoming increasingly scarce, and
small areas may support only low bee numbers. Furthermore, wild flowers in field margins may contain
pesticide residues. Rundlöf etal.16 show that the growth rates and reproduction of bumblebee colonies are
lower in neonicotinoid-treated fields than in control fields, and that reproduction of solitary bees can also
be affected. However, the authors found no effect on honeybee colonies. These differences may result from
different ecologies: honeybees can forage many kilometres from their hive, whereas bumblebees roam
over smaller areas, and solitary bees fly less far from their nest. Honeybees also use the waggle dance to
communicate the location of rewarding flower patches to nest-mates. Thus, honeybees may have reduced
pesticide exposure from visiting a greater mixture of foraging sources or through a greater chance of
avoiding treated crops. However, Kessler etal.15 show that neither honeybees nor bumblebees can taste
neonicotinoids, suggesting that such avoidance behaviour is unlikely. (Nest sites, foraging ranges and the
relative proportion of habitat types vary across landscapes — those depicted are representative only.)
38 | NATURE | VOL 521 | 7 MAY 2015
© 2015 Macmillan Publishers Limited. All rights reserved
50 Years Ago
‘The sign of the constant of
gravitation. By Prof. W. H. McCrea
— A speaker in a recent broadcast
asserted that, were the gravitation-
constant negative instead of
positive, Newton’s apple would have
soared away into the sky instead of
falling on Newton’s head. However,
had that happened, Newton also
would have soared away and there
would have been no legend to
record. In fact, there cannot be a
world for which gravitation is not
attractive … We shall see that the
sign of the gravitation constant is
essentially a matter of convention.
From Nature 8 May 1965
100 Years Ago
It may be remembered that the
Royal Commission on Whisky,
which in 1908–9 gave a lengthy
consideration to the matter, did not
find a very satisfactory answer to
the query “What is whisky?” The
Government of Western Australia
… issued regulations under which
certain chemical standards for “pure
pot-still whisky” were proposed for
adoption. The proposals met with
some criticism. It was alleged, in
fact, that many pot-stills employed
in Great Britain could not produce
whisky which would comply with
the requirements … the proposals,
as now modified … are that, as
regards Scotch whisky, it shall have
been distilled at a strength not more
than 35 degrees above proof and
matured in wood for not less than
two years; and that “standard pot-
still whisky” shall contain at least
45 grams of esters, 3.5 of furfural,
and 180 of higher alcohols per
100litres of absolute alcohol … For
Irish whisky no furfural standard
is proposed at present, but the
proportion of esters is required to be
not less than 35 grams, and of higher
alcohols 200 grams, per 100 litres of
absolute alcohol.
From Nature 6 May 1915
testing the ability of both honeybees (Apis
mellifera) and bumblebees (Bombus terrestris)
to taste the three most commonly used neo-
nicotinoids — clothianidin, imidacloprid and
thiamethoxam. When hungry worker bees
could choose to collect from feeders contain-
ing either a solution of neonicotinoid-treated
sugar water or an untreated solution, neither
species avoided the treated food, which con-
tained neonicotinoid concentrations compa-
rable to those found in the nectar and pollen of
treated crops. Surprisingly, the bees in fact pre-
ferred the treated solution in the imidacloprid
and thiamethoxam tests, which the authors
suggest arises from the pharmacological action
of these insecticides on receptors in the bees’
brains. The authors corroborated their behav-
ioural results with neurophysiological meas-
urements showing that bees are unable to taste
neo nicotinoids in sugar water.
Scaling up from the laboratory, Rundlöf
etal .
(page77) undertook an ambitious study
to assess the impacts of neonicotinoid exposure
on bees placed near fields of treated oilseed rape
(also known as canola). The experiment — the
largest of its kind so far — involved 16fields
across southern Sweden: 8fields were planted
with seeds treated with the systemic insecti-
cide clothianidin, the pyrethroid insecticide
β-cyfluthrin and the fungicide thiram, and
8 control fields were treated solely with thiram.
Like Kessler etal., these researchers studied
both honeybees and bumble bees, but followed
entire colonies rather than individuals.
Furthermore, they monitored nests of a
species of solitary bee (Osmia bicornis ), as well
as surveying wild bees in field margins.
In treated fields, Rundlöf and colleagues
found fewer wild bees and observed reduced
growth rate and reproduction of bumblebee
colonies (which produced fewer males and
fewer new queens — consistent with previous
semi-field and field studies14,17,18) compared
to control fields. They also found that none
of the solitary bees that emerged from nests
placed next to treated fields came back to their
natal nest to build new brood cells, whereas
emergent females successfully produced brood
cells in six of eight untreated fields. By contrast,
there was no significant difference in honey-
bee colony growth between treated and control
fields. However, the authors’ power analysis
indicated that they would only have been able
to detect a minimum effect size of about 19%
for honeybees.
These studies provide timely data to address
calls for further evidence about the environ-
mental risks of neonicotinoids. The insecti-
cides tested by the authors are currently subject
to a European Union moratorium for use as
seed treatments on crops attractive to bees, but
this usage restriction will be reviewed before
December2015. It is hard to say whether
the preferences observed by Kessler and col-
leagues for nectar containing imidacloprid
and thiamethoxam residues would occur in
a more complex field setting, where many
variables could interfere with foraging deci-
sions. However, their study does imply that
foraging bees are unlikely to avoid seed-treated
crops in the field, and supports previous
reports of honeybees and bumblebees bringing
back nectar and pollen from treated fields
If the preference for treated food does apply in
the field, these findings suggest that we could
be underestimating the exposure risk to bees
from treated crops.
Both studies also highlight the fact that
different bee species vary in their responses to
exposure. Current pesticide registrations rely
on ecotoxicological testing of just one spe-
cies, the honeybee, when assessing risks for all
insect pollinators. Yet Rundlöf and colleagues
found negative effects of neonicotinoids on
solitary bees and bumblebees in the field, but
not on honeybees, suggesting that a single
species might not represent the responses of
other pollinators. Potential explanations for
these apparent differences could include a vari-
able affinity of neuronal receptors for binding
neonicotinoids; differences in detoxification
capacities; and divergent foraging behaviours,
which influence levels of exposure (Fig.1).
Differences could also result from variation in
social organization and life-history strategies.
Even the smallest perennial honeybee colonies
contain a queen and several thousand work-
ers that overwinter as a group, whereas annual
bumblebee colonies rarely contain more than
a queen and a few hundred workers. Each
solitary bee is responsible for its own forag-
ing and reproduction during its few weeks of
adult life. The sheer number of workers in the
honeybee colony may better enable buffering
of stress over long periods, whereas the more
severe pinch points that bumblebees and soli-
tary bees experience could render them more
susceptible to environmental pressures19,20.
If field experiments to assess exposure are
deemed so important, why have so few been
carried out? Limiting factors include the
scale of such studies, the levels of replication
required to achieve appropriate statistical
power, and human and budgetary resources.
Even with 16 fields, Rundlöf and colleagues’
study had relatively low statistical power and,
as with other field studies, many environmen-
tal factors probably varied among their sites
and could not be standardized. Such studies
can provide only correlational evidence of
impacts, whereas controlled-exposure studies,
such as that of Kessler etal.15, are better suited
to determining causative relationships through
manipulative experimentation. The comple-
mentarity of these two approaches needs to be
considered by policy-makers and for future
research planning.
Although the two latest studies contribute
to our understanding of the risk neonicoti-
noids pose to bees, knowledge gaps remain.
For example, we need further evidence about
how neonicotinoid exposure might affect
7 MAY 2015 | VOL 521 | NAT URE | 39
© 2015 Macmillan Publishers Limited. All rights reserved
social bee colonies over multiple seasons, how
soil residues might affect ground-nesting bees
and how neonicotinoid exposure interacts with
other environmental stressors. We also need a
greater understanding of how neonicotinoids
affect other pollinators and natural enemies
of crop pests, and of the persistence of these
chemicals in soil and their take-up by untreated
plants growing in or next to treated fields.
Fundamentally, we must move towards
finding the right balance between the risks
of neonicotinoid exposure for insect pollina-
tors and the value these pesticides provide to
ensure crop yield and quality. Selective use of
neonicotinoid seed treatments, on the basis
of a demonstrable need for systemic pest
protection, might help to reduce non-target
exposure and slow the onset of pest resist-
ance. We also need to consider and evaluate
alternative options for pest control. It would
be unfortunate if the recent focus on the risks
from neonicotinoids led unintentionally to
broader use of alternative pesticides that prove
to be even more harmful to insect pollinators
and the essential ecosystem services that they
provide. SEE BOOKS & ARTS P.29
Nigel E. Raine is in the School of
Environmental Sciences, University of Guelph,
Guelph, Ontario N1G 2W1, Canada.
Richard J. Gill is in the Department of Life
Sciences, Silwood Park, Imperial College
London, Ascot SL5 7PY, UK.
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This article was published online on 22 April 2015.
Dinosaur up in the air
A new feathered dinosaur from China, belonging to an obscure and strange
carnivorous group, bears a seemingly bony wrist structure that may have
had a role in flight. S L .70
hen the first dinosaurs with feathers
or feather-like structures were
brought to light by Chinese
scientists in the mid-1990s, they cemented the
hypothesis of the dinosaurian origin of birds
and provided spectacular evidence about the
origin of flight and the primordial functions of
. In the ensuing two decades, the pic-
ture of the evolution of feathers and flight has
become richer and more complicated as other
feathered dinosaurs have been discovered,
seemingly on a monthly basis
. But things have
just gone from the strange to the bizarre. On
page70 of this issue, Xu etal.4 present a feath-
ered dinosaur from a completely un expected
branch of the dinosaur tree — and it sports a
never-before-seen skeletal element that the
authors think may be related to flight.
The dinosaur, named Yi qi, is a member of
the unusual group of theropod (carnivorous)
dinosaurs called Scansoriopterygidae
Although scansoriopterygids are not well
known — there are only three kinds, and only
incomplete remains of these — they seem to
be small (the skull of Yi qi is about 4centime-
tres long), with smaller and fewer teeth than
other theropods, and with long hands. Unusu-
ally for theropod dinosaurs, the third finger is
longer than the second. It is especially long in
Yiqi, and its forelimb is further distinguished
by a long ‘styliform element’ coming off the
wrist. The authors are refreshingly agnostic
about the exact function of this new struc-
ture, partly because it is so different from any-
thing previously known. However, their find
opens two cans of worms: about interpreting
unique structures in fossils and about what it
means to fly.
The styliform element, which may be a
hypertrophied wrist bone or a neomorphic
calcified structure, is longer than any of the
animal’s fingers and is curved at both ends. It
is probably not a true finger, such as the fourth
finger that forms the main outboard spar of
the wing in pterosaurs — flying reptiles that
were related to their dinosaur contemporaries,
but that evolved flight independently of birds.
Instead, the styliform element of Yiqi has no
joints and comes directly off the carpal bones
without the intermediary of a meta carpal
(palm bone), so it is probably not a finger (the
authors confusingly label the three fingers of
the dinosaur-bird hand as II–III–IV instead
of the standard I–II–III, which corresponds
to our thumb, index and middle fingers6).
How the structure is attached to the wrist is
not clear, because its proximal end seems quite
squared off; this means that we also do not
know if or how it could move. Superficially, it
looks the same as the animal’s other bones, a
conclusion supported by the authors’ energy
dispersive spectrometry analysis. It would be
interesting to see if it has true bone cells, to
confirm that it is indeed bone and not calcified
cartilage or other calcified tissue.
What could this element be except a
support for some kind of aerofoil? The authors
infer this on the basis of its position and the
presence of membranous tissue in the wrist
area. But although they consider a variety of
analogous structures in living and extinct fly-
ing and gliding animals, none is exactly like
the styliform element in Yi qi. Furthermore,
Yi qi s body is not preserved below the ribcage,
so reconstructions of the pelvis, hindlimbs and
tail must be conjectured from what is known of
other scansoriopterygids (Fig.1). Further ana-
tomical analysis of this structure and how the
rest of the body related to it — such as whether
the tail created lift or drag — will require other
In the meantime, the authors do not
commit themselves to whether this animal
could flap or glide, or both, or neither. That
is a good position to take
, but we can parse it
further. To fly actively, an animal must be able
to execute a flight stroke that can generate a
vortex wake that propels it forward
. No evi-
dence presented so far suggests that Yi qi had
this ability. Furthermore, in flapping animals
the outboard skeletal elements (wrist, hand
and so on) are primarily responsible for thrust,
the essential component of powered flight8,9,
but these are not particularly long in Yi qi. So,
at present we can shelve the possibility that this
dinosaur flapped.
As for gliding, if Yi qi’s styliform element
helped to support a membranous aerofoil, it
can be used to reconstruct the planform of the
wing, as Xu and colleagues have done. But in a
gliding animal, the centre of lift of the aerofoil
should be fairly congruent with the centre of
gravity of the body — if the bulk of the animal’s
weight falls too far behind the centre of lift,
the back end will sag and the animal will stall
That is clearly the case in the authors’ recon
struction of Yi qi , but an aerofoil that was swept
back more, if anatomically possible, might
40 | NATURE | VOL 521 | 7 MAY 2015
© 2015 Macmillan Publishers Limited. All rights reserved
... Understanding how individual mobility traits such as flight motivation, endurance and velocity respond to temperature can highlight the capabilities of foraging individuals to reach increasingly patchy floral resources under projected climate change (Jha & Kremen, 2013;Senapathi et al., 2017). This is particularly relevant to eusocial bees such as bumblebees, which as central place foragers (have a fixed nest site), are unable to adaptively move to track within-season floral resource turnover and variation in microclimatic conditions (Bladon et al., 2020;Raine & Gill, 2015). ...
... With bumblebees being central place foragers, this is of particular concern, as a fixed nest site prevents within-season relocation of the 'central place' to track floral resource turnover or more favourable thermal microclimates (Bladon et al., 2020;Raine & Gill, 2015). ...
Full-text available
The effects of environmental temperature on components of insect flight determine life‐history traits, fitness, adaptability and, ultimately, organism ecosystem functional roles. Despite the crucial role of flying insects across landscapes, our understanding of how temperature affects insect flight performance remains limited. Many insect pollinators are considered under threat from climatic warming. Quantifying the relationship between temperature and behavioural performance traits allows us to understand where species are operating in respect to their thermal limits, helping predict responses to projected temperature increases and/or erratic weather events. Using a tethered flight mill, we quantify how flight performance of a widespread bumblebee, Bombus terrestris, varies over a temperature range (12–30℃). Given that body mass constrains insect mobility and behaviour, bumblebees represent a useful system to study temperature‐mediated size dependence of flight performance owing to the large intra‐colony variation in worker body size they exhibit. Workers struggled to fly over a few hundred metres at the lowest tested temperature of 12℃; however, flight endurance increased as temperatures rose, peaking around 25℃ after which it declined. Our findings further revealed variation in flight capacity across the workforce, with larger workers flying further, longer, and faster than their smaller nestmates. Body mass was also positively related with the likelihood of flight, although importantly this relationship became stronger as temperatures cooled, such that at 12℃ only the largest workers were successful fliers. Our study thus highlights that colony foraging success under variable thermal environments can be dependent on the body mass distribution of constituent workers, and more broadly suggests smaller‐bodied insects may benefit disproportionately more from warming than larger‐bodied ones in terms of flight performance. By incorporating both flight endurance and likelihood of flight, we calculated a simple metric termed ‘temperature‐mediated foraging potential’ to gain a clearer understanding of how temperature may constrain colony foraging. Of our tested temperatures, 27℃ supported the highest potential, indicating that for much of the range of this species, higher mean daily temperatures as forecasted under climate warming will push colonies closer to their thermal optimum for flight. Subsequently, warming may have positive implications for bumblebee foraging returns and pollination provision. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.
... In these studies, bumblebees showed a greater propensity to collect focal crop (oilseed rape (Brassica napus) and blueberry (Vaccinium corymbosum), respectively) pollen compared to honey bees, indicating that bumblebees may have greater exposure to pesticides when nesting in the vicinity of crop fields. Whether bumblebees are more inclined to collect pollen from contaminated crop flowers needs to be confirmed by further research (Kessler et al., 2015;Raine & Gill, 2015). Moreover, pollen and nectar collected by colonies of Bombus huntii foraging in a commercial cherry (Prunus avium) orchard in Oregon (USA) contained very high concentrations of boscalid (up to 440 ppb in nectar and 60,500 ppb in pollen) and pyraclostrobin (up to 240 ppb in nectar and 32,000 in pollen), two fungicides applied when cherry trees were in bloom (Kuivila et al., 2021). ...
Full-text available
Fungicides account for more than 35% of the global pesticide market and their use is predicted to increase in the future. While fungicides are commonly applied during bloom when bees are likely foraging on crops, whether real-world exposure to these chemicals – alone or in combination with other stressors – constitutes a threat to the health of bees is still the subject of great uncertainty. The first step in estimating the risks of exposure to fungicides for bees is to understand how and to what extent bees are exposed to these active ingredients. Here we review the current knowledge that exists about exposure to fungicides that bees experience in the field, and link quantitative data on exposure to acute and chronic risk of lethal endpoints for honey bees (Apis mellifera). From the 702 publications we screened, 76 studies contained quantitative data on residue detections in honey bee matrices, and a further 47 provided qualitative information about exposure for a range of bee taxa through various routes. We compiled data for 90 fungicides and metabolites that have been detected in honey, beebread, pollen, beeswax, and the bodies of honey bees. The risks posed to honey bees by fungicide residues was estimated through the EPA Risk Quotient (RQ) approach. Based on residue concentrations detected in honey and pollen/beebread, none of the reported fungicides exceeded the levels of concern (LOC) set by regulatory agencies for acute risk, while 3 and 12 fungicides exceeded the European Food Safety Authority (EFSA) chronic LOC for honey bees and wild bees, respectively. When considering exposure to all bees, fungicides of most concern include many broad-spectrum systemic fungicides, as well as the widely used broad-spectrum contact fungicide chlorothalonil. In addition to providing a detailed overview of the frequency and extent of fungicide residue detections in the bee environment, we identified important research gaps and suggest future directions to move towards a more comprehensive understanding and mitigation of the risks of exposure to fungicides for bees, including synergistic risks of co-exposure to fungicides and other pesticides or pathogens.
... This can contaminate nearby non-treated wildflowers too [22]. Previously, most of the impact studies assaying pesticides were carried out under laboratory or semi-field settings rather than in the field and used pesticide-treated foods containing unrealistically high dosages [23]. The present study was conducted as an organised field experiment to explore Indian honey bee, A. c. indica foraging preference to neonicotinoid treated and untreated sunflower crops. ...
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Aim: Forage preference of Indian honey bee on neonicotinoid insecticides treated sunflower Study Design: Randomized Block Design (RBD) Place and Duration of Study: Insectary, Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore between August 2021 to December 2021 during the Adipattam season Methodology: Bee activity was recorded by in situ counting method. Seven treatments with three replications (5flowers/replication) in Randomized Block Design were followed. Different treatments viz., Imidacloprid 17.8 SL @ 280µl/l, Clothianidin 50 WDG @ 80µg/l, Thiamethoxam 25 WG @ 250µg/l, Thiacloprid 21.7 SC @ 1100/µl, Dimethoate 30 EC @ 1400µl/l (chemical check), Water control (Water spray) and Absolute control (no spray) were given at 50% flowering period using Knapsack sprayer. The number of bees visiting 5 flowers per 5 minutes was observed during morning (09.00-11.00), afternoon (13.00-15.00) and evening (16.00-18.00) hours of the day for seven days after spray (DAS). DAS. Statistical Analysis Software (SAS) academics was used to statistically analyse the data. Results: The mean population of Apis cerana indica Fab. was more in absolute control (5.97) followed by water control (4.77), imidacloprid (4.10), clothianidin (3.40), thiacloprid (3.21), thiamethoxam (3.14) and dimethoate (1.90) during morning hours (09.00-11.00) of the day. The mean bee visitation rate was high in control (3.40), followed by water control (2.65), imidacloprid (1.77), clothianidin (1.52), thiacloprid (1.55), thiamethoxam (1.40) and dimethoate (1.17) during afternoon hours (13.00-15.00) of the day. In the evening hours (16.00-18.00), mean bee activity was high in control (4.95) followed by water control (4.27), imidacloprid (3.40), clothianidin (3.13), thiamethoxam (2.75), thiacloprid (2.53) and dimethoate (1.88). Among these different hours, morning forage activity of the bees are high in morning hours of the day followed by evening and very less in afternoon hours. Conclusion: The present study revealed that Indian honey bees preferred to forage both on neonicotinoid treated, however at a reduced rate, and untreated flowers. Since, neonicotinoids are odourless, tasteless compounds that increase the risk of pesticide exposure for the bee colony owing to less capability for segregation of insecticide treated surfaces.
... The exact reason for the loss remains unclear. But bee disease and pesticide residues in colonies are one of the main reasons (Henry et al., 2012;Raine and Gill, 2015;Sánchez-Bayo et al., 2016). ...
Fluvalinate has been heavily used to control the pest Varroa destructor and residues in honeybee colony causing long-term exposure threat for bees. But, little is known about the lifetime trips and homing ability of worker bees under fluvalinate stresses during the development period. In this study, honeybees from 2-day-old larvae to 7-day-old adults were continuously fed with different concentrations of fluvalinate (0, 0.5, 5 and 50 mg/kg) and the effects of fluvalinate on the development of larvae were examined. And then, all the treated bees were reintroduced into the original source colony and were monitored, and the homing ability of 20 days old bees at 1000 and 2000 m away from the beehive were tested using the radio frequency identification (RFID). We found that fluvalinate significantly activates the superoxide dismutase (SOD) activities of larvae and 5 mg/kg fluvalinate reduced the homing rate of workers at 2000 m away from colony. 50 mg/kg fluvalinate reduced proportion of capped worker cells, activated Cytochrome P450 (CYP450) activity of larvae, affected the foraging times, influenced the homing rate and homing time of one trip at 2000 m away from colony. Our results showed that the larvae can activate the activities of SOD and detoxification enzymes in detoxification of fluvalinate and reduce the influence on honeybees. But, when the concentration is higher than 5 mg/kg fluvalinate, it is difficult for bees to detoxify fluvalinate completely, which affect the homing rate. The results reflect the potential risk for honeybees in the development stage continuously exposed to fluvalinate.
... Pesticides have negative effects on biodiversity, which could change in the function of ecosystem, moreover; it has impact on bees' learning and foraging behaviors (Boff et al., 2020). Bees are important for the pollination of plants; they assist in maintaining biodiversity and ensure food security (Raine and Gill, 2015). Herein study concentrate on farmers' behaviors on using chemical substances in the rural area in Sulaimani and the impacts of these chemicals on environment and human health. ...
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Human activates especially farmers can have impacts on the environment via using chemical substances, these effects can be directly on human or indirectly through food, wildlife, climate, crops, or livestock. Chemical substances which are created to introduce into delicately balanced ecosystems, they could have led to damage in motion that reverberates via the food for years. Nevertheless, it wreaks havoc, biodiversity and the natural system that human survival depends on. The aim of this study is to evaluate farmer’s behaviour in using pesticides and fertilizers to prevent the environment pollution and the harm to the human beings. Primary data was used to achieve the objective which using a semi-structure questionnaire, that administered in a random sampling technique, face to face administration. The total number of farmers in the sample was 200 farmers in 31 villages. The analysis is conducted with SPSS and Excel Spread sheets. The results illustrated that great number of farmers in rural area of Sulaimani uses chemical pesticides and fertilizers in huge amounts, they still with the adage, “if little is good, a lot more will be better”. In addition, the great number of farmers don’t follow the product’s labels, or believe that these chemical substances impact on the environment, or adopt new techniques in applying chemical substances. So, farmers require knowledge and informations to understand the negative influences of these chemical substances on the biotic and abiotic components of the environment to use organic fertilizers and pesticides instead of toxic chemicals with the recommended standard levels.
Since the loss of honeybees in hives could have a greater impact on colony health than those of their foraging bees, it is imperative to know beehives' pesticide exposure via oral ingestion of contaminated in-hive matrices. Here, a 4-year monitoring survey of 64 pesticide residues in pollen, nectar and related beehive matrices (beebread and honey) from China's main honey producing areas was carried out using a modified version of the QuEChERS multi-residue method. The results showed that 93.6% of pollen, 81.5% of nectar, 96.6% of beebread, and 49.3% of honey containing at least one target pesticide were detected either at or above the method detection limits (MDLs), respectively, with up to 19 pesticides found per sample. Carbendazim was the most frequently detected pesticide (present in >85% of the samples), and pyrethroids were also abundant (median concentration = 134.3–279.0 μg/kg). The transfer of pesticides from the environment into the beehive was shown, but the pesticide transference ratio may be affected by complex factors. Although the overall risk to colony health from pesticides appears to be at an acceptable level, the hazard quotient/hazard index (HQ/HI) value revealed that pyrethroids were clearly the most influential contributor, accounting for up to 45% of HI. Collectively, these empirical findings provide further insights into the extent of contamination caused by agricultural pesticide use on honeybee colonies.
In the studies on dihydroxy intermediate synthesis, a serendipitous reaction of introducing nitro group from nitromethylene has been observed. Instead of expected dihydroxy compounds, dinitration structures with nitromethylene analogues were prepared under mild conditions by using a metal-free catalyst B(OH)3. In this reaction, the extra nitro group was suggested to be from starting material. Bioassays indicated that compound 3a showed good insecticidal activities against cowpea aphid (Aphis craccivora) and armyworm (Mythimna separata), with LC50 values were 4.9 mg/L and 7.1 mg/L, respectively.
Insecticide synergists are sought-after due to their potential in improving the pesticide control efficacy with a reduced dose of an active ingredient. We previously reported that a cis-configuration neonicotinoid (IPPA08) exhibited specific synergistic activity toward neonicotinoid insecticides. In this study, we synthesized a series of structural analogues of IPPA08 by converting the pyridyl moiety of IPPA08 into phenyl groups, via facile double-Mannich condensation reactions between nitromethylene compounds and glutaraldehyde. All of the oxabridged neonicotinoid compounds were found to increase the toxicity of imidacloprid against Aphis craccivora. Notably, compound 25 at 0.75 mg/L lowered the LC50 value of imidacloprid against A. craccivora by 6.54-fold, while a 3.50-fold reduction of the LC50 value was observed for IPPA08. The results of bee toxicity test showed that compound 25 display selectivity in its effects on imidacloprid toxicity against the honey bee (Apis mellifera L.). In summary, replacing the pyridyl ring with a phenyl ring was a viable approach to obtain a novel synergist with oxabridged moiety for neonicotinoid insecticides.
The ubiquitous presence of neonicotinoid insecticides in the environment poses potential health concerns across all biomes, aquatic systems, and food chains. This global environmental challenge requires robust, advanced materials to efficiently scavenge and remove these harmful neonicotinoids. In this work, we engineered nanocomposite hydrogels based on sustainable cellulose acetate for water treatment. The nanocomposite hydrogels were incorporated with small quantities of polymers of intrinsic microporosity (PIM-1) and graphene oxide (GO). We prepared the hydrogels using green solvents such as Cyrene and MeTHF via simple dropwise phase inversion. High adsorption capacity and fast kinetic behavior toward acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam were observed. We also developed a rapid and sustainable ultrasound-assisted regeneration method for the hydrogels. Molecular dynamics of the complex quaternary system revealed the synergistic effects of the components, and the presence of PIM-1 was found to increase the GO surface area available for neonicotinoid scavenging. We demonstrated the robustness and practicality of the nanocomposites in continuous environmental remediation by using the hydrogels to treat contaminated groundwater from the Adyar river in India. The presented methodology is adaptable to other contaminants in both aqueous environments and organic media.
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Dar, S.A., Dukku, U.H., Ilyasov, R.A., Kandemir, I., Lee, M.L., Özkan Koca, A. 2019. Chapter 4. The classic taxonomy of Asian and European honey bees. 107-137 pp. In: R.A. Ilyasov and H.W. Kwon. [eds.]. Phylogenetics of Bees. CRC Press, Taylor and Francis Group, Boca Raton, London, New-York, USA. 290 pp. ISBN 9781138504233. Abstract. Honey bees of the genus Apis, belonging to the family Apidae and the superfamily Apoidea in the order of insects Hymenoptera. The number of Apis species and their identification methods are discussed. According to different authors, the number of species of the genus varied from 6 to 24. While Apis mellifera inhabits West Asia, Africa and Europe, the ranges of all other species, including Apis cerana, are limited to Asia. A. mellifera and A. cerana are two species widely used in agriculture for the pollination, the production of honey and other products. They have adapted to wide climatic conditions. Intraspecific taxonomy for both species is incomplete and contradictory. In this review, all available studies of A. mellifera and A. cerana are analyzed to ordering the modern taxonomy of honey bees. We found that there are 27 subspecies for A. mellifera and 7 subspecies for A. cerana. However, these data are not ultimate, since some subspecies of A. mellifera and A. cerana remain unexplored.
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Overall, 9.2% of bees are considered threatened in all of Europe, while at the EU 27 level, 9.1% are threatened with extinction. A further 5.2% and 5.4% of bees are considered Near Threatened in Europe and the EU 27, respectively (101 species at both levels). However, for 1,101 species (56.7%) in Europe and 1,048 species (55.6%) at the EU 27, there was not enough scientific information to evaluate their risk of extinction and thus, they were classified as Data Deficient. When more data become available, many of these might prove to be threatened as well. Looking at the population trends of European bee species, 7.7% (150 species) of the species have declining populations, 12.6% (244 species) are more or less stable and 0.7% (13 species) are increasing. The population trends for 1,535 species (79%) remains unknown. A high proportion of threatened bee species are endemic to either Europe (20.4%, 400 species) or the EU 27 (14.6%, 277 species), highlighting the responsibility that European countries have to protect the global populations of these species. Almost 30% of all the species threatened (Critically Endangered, Endangered, or Vulnerable) at the European level are endemic to Europe (e.g., found nowhere else in the world). The species richness of bees increases from north to south in Europe, with the highest species richness being found in the Mediterranean climate zone. In particular, the Iberian, Italian and Balkan peninsulas are important areas of species richness. Regarding the distribution of endemic species, southern Europe shows the highest concentration of endemism. The largest numbers of threatened species are located in south-central Europe and the pattern of distribution of Data Deficient species is primarily concentrated in the Mediterranean region. The main threat to European bees is habitat loss as a result of agriculture intensification (e.g., changes in agricultural practices including the use of pesticides and fertilisers), urban development, increased frequency of fires and climate change.
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The causes of bee declines remain hotly debated, particularly the contribution of neonicotinoid insecticides. In 2013 the UK's Food & Environment Research Agency made public a study of the impacts of exposure of bumblebee colonies to neonicotinoids. The study concluded that there was no clear relationship between colony performance and pesticide exposure, and the study was subsequently cited by the UK government in a policy paper in support of their vote against a proposed moratorium on some uses of neonicotinoids. Here I present a simple re-analysis of this data set. It demonstrates that these data in fact do show a negative relationship between both colony growth and queen production and the levels of neonicotinoids in the food stores collected by the bees. Indeed, this is the first study describing substantial negative impacts of neonicotinoids on colony performance of any bee species with free-flying bees in a field realistic situation where pesticide exposure is provided only as part of normal farming practices. It strongly suggests that wild bumblebee colonies in farmland can be expected to be adversely affected by exposure to neonicotinoids.
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Pollinators are fundamental to maintaining both biodiversity and agricultural productivity, but habitat destruction, loss of flower resources, and increased use of pesticides are causing declines in their abundance and diversity. Using historical records, we assessed the rate of extinction of bee and flower-visiting wasp species in Britain from the mid-19th century to the present. The most rapid phase of extinction appears to be related to changes in agricultural policy and practice beginning in the 1920s, before the agricultural intensification prompted by the Second World War, often cited as the most important driver of biodiversity loss in Britain. Slowing of the extinction rate from the 1960s onward may be due to prior loss of the most sensitive species and/or effective conservation programs.
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In summer 2012, we initiated a large-scale field experiment in southern Ontario, Canada, to determine whether exposure to clothianidin seed-treated canola (oil seed rape) has any adverse impacts on honey bees. Colonies were placed in clothianidin seed-treated or control canola fields during bloom, and thereafter were moved to an apiary with no surrounding crops grown from seeds treated with neonicotinoids. Colony weight gain, honey production, pest incidence, bee mortality, number of adults, and amount of sealed brood were assessed in each colony throughout summer and autumn. Samples of honey, beeswax, pollen, and nectar were regularly collected, and samples were analyzed for clothianidin residues. Several of these endpoints were also measured in spring 2013. Overall, colonies were vigorous during and after the exposure period, and we found no effects of exposure to clothianidin seed-treated canola on any endpoint measures. Bees foraged heavily on the test fields during peak bloom and residue analysis indicated that honey bees were exposed to low levels (0.5-2 ppb) of clothianidin in pollen. Low levels of clothianidin were detected in a few pollen samples collected toward the end of the bloom from control hives, illustrating the difficulty of conducting a perfectly controlled field study with free-ranging honey bees in agricultural landscapes. Overwintering success did not differ significantly between treatment and control hives, and was similar to overwintering colony loss rates reported for the winter of 2012-2013 for beekeepers in Ontario and Canada. Our results suggest that exposure to canola grown from seed treated with clothianidin poses low risk to honey bees.
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We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (Apis mellifera) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earth-worms), Apoidae sensu lato (bumblebees, solitary bees) and the section "other invertebrates" review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.
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Neonicotinoid insecticides have been studied as possible contributors to bumble bee declines in North America and Europe. This has potential significance in corn agro-ecosystems since this crop is frequently treated with neonicotinoids and dominates much of the agricultural landscape in North America and Europe where bumble bees and other pollinators are commonplace. We conducted an experiment where commercial bumble bee (Bombus impatiens) hives were placed during pollen shed next to corn (Zea mays) fields that were grown from "conventional" seed that was treated with neonicotinoids, or "organic" seed that was not treated with pesticides. Samples of pollen were collected from corn plants for neonicotinoid residue analysis, pollen types carried by worker bees returning to hives were determined, and in autumn hives were dissected to measure various endpoints that serve as markers of colony vigor. Clothianidin was detected (0.1-0.8 ng/g) in pollen collected from all conventional fields, but was not detected in pollen from organic fields. Corn pollen was only rarely collected from bumble bee foragers and the vast majority of pollen was from wild plants around the corn fields. All hives appeared healthy and neonicotinoid seed treatments had no effect on any hive endpoints measured, except the number of workers, where significantly fewer workers were recovered from hives placed next to conventional fields (96 ± 15 workers per hive) compared to organic fields (127 ± 17 workers per hive). The results suggest that exposure during pollen shed to corn grown from neonicotinoid-treated shed poses low risk to B. impatiens.
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Insect pollination is a vital ecosystem service that maintains biodiversity and sustains agricultural crop yields. Social bees are essential insect pollinators, so it is concerning that their populations are in global decline.Although pesticide exposure has been implicated as a possible cause for bee declines, we currently have a limited understanding of the risk these chemicals pose. Whilst environmental exposure to pesticides typically has non-lethal effects on individual bees, recent reports suggest that sublethal exposure can affect important behavioural traits such as foraging. However, at present, we know comparatively little about how natural foraging behaviour is impaired and the relative impacts of acute and chronic effects.Using Radio-Frequency Identification (RFID) tagging technology, we examined how the day-to-day foraging patterns of bumblebees (Bombus terrestris) were affected when exposed to either a neonicotinoid (imidacloprid) and/or a pyrethroid (λ-cyhalothrin) independently and in combination over a four-week period. This is the first study to provide data on the impacts of combined and individual pesticide exposure on the temporal dynamics of foraging behaviour in the field over a prolonged period of time.Our results show that neonicotinoid exposure has both acute and chronic effects on overall foraging activity. Whilst foragers from control colonies improved their pollen foraging performance as they gained experience, the performance of bees exposed to imidacloprid became worse: chronic behavioural impairment. We also found evidence, suggesting that pesticide exposure can change forager preferences for the flower types from which they collect pollen.Our findings highlight the importance of considering prolonged exposure (which happens in the field) when assessing the risk that pesticides pose to bees. The effects of chronic pesticide exposure could have serious detrimental consequences for both colony survival and also the pollination services provided by these essential insect pollinators.
Understanding the effects of neonicotinoid insecticides on bees is vital because of reported declines in bee diversity and distribution and the crucial role bees have as pollinators in ecosystems and agriculture. Neonicotinoids are suspected to pose an unacceptable risk to bees, partly because of their systemic uptake in plants, and the European Union has therefore introduced a moratorium on three neonicotinoids as seed coatings in flowering crops that attract bees. The moratorium has been criticized for being based on weak evidence, particularly because effects have mostly been measured on bees that have been artificially fed neonicotinoids. Thus, the key question is how neonicotinoids influence bees, and wild bees in particular, in real-world agricultural landscapes. Here we show that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees. In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions. Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.
The impact of neonicotinoid insecticides on insect pollinators is highly controversial. Sublethal concentrations alter the behaviour of social bees and reduce survival of entire colonies. 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 plants. Furthermore, it has been suggested that bees could choose to forage on other available flowers and hence avoid or dilute exposure. 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.