The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Nigel E Raine - One of the best experts on this subject based on the ideXlab platform.

  • Pesticide reduces bumblebee colony initiation and increases probability of population extinction
    Nature Ecology & Evolution, 2017
    Co-Authors: Gemma L. Baron, Vincent A A Jansen, Mark J. F. Brown, Nigel E Raine
    Abstract:

    Thiamethoxam, a Neonicotinoid Pesticide, is shown to reduce the rate of colony initiation by bumblebee queens. Modelling shows that this effect could increase colony extinction rates. Pollinators are in global decline and agricultural Pesticides are a potential driver of this. Recent studies have suggested that Pesticides may significantly impact bumblebee colonies—an important and declining group of pollinators. Here, we show that colony-founding queens, a critical yet vulnerable stage of the bumblebee lifecycle, are less likely to initiate a colony after exposure to thiamethoxam, a Neonicotinoid insecticide. Bombus terrestris queens were exposed to field-relevant levels of thiamethoxam and two natural stressors: the parasite Crithidia bombi and varying hibernation durations. Exposure to thiamethoxam caused a 26% reduction in the proportion of queens that laid eggs, and advanced the timing of colony initiation, although we did not detect impacts of any experimental treatment on the ability of queens to produce adult offspring during the 14-week experimental period. As expected from previous studies, the hibernation duration also had an impact on egg laying, but there was no significant interaction with insecticide treatment. Modelling the impacts of a 26% reduction in colony founding on population dynamics dramatically increased the likelihood of population extinction. This shows that Neonicotinoids can affect this critical stage in the bumblebee lifecycle and may have significant impacts on population dynamics.

  • bumblebee colony development following chronic exposure to field realistic levels of the Neonicotinoid Pesticide thiamethoxam under laboratory conditions
    Scientific Reports, 2017
    Co-Authors: Dara A Stanley, Nigel E Raine
    Abstract:

    Neonicotinoid Pesticides are used in agriculture to reduce damage from crop pests. However, beneficial insects such as bees can come into contact with these Pesticides when foraging in treated areas, with potential consequences for bee declines and pollination service delivery. Honeybees are typically used as a model organism to investigate insecticide impacts on bees, but relatively little is known about impacts on other taxa such as bumblebees. In this experiment, we chronically exposed whole mature bumblebee (Bombus terrestris) colonies to field-realistic levels of the Neonicotinoid thiamethoxam (2.4ppb & 10ppb) over four weeks, and compared colony growth under laboratory conditions. We found no impact of insecticide exposure on colony weight gain, or the number or mass of sexuals produced, although colonies exposed to 2.4ppb produced larger males. As previous studies have reported Pesticide effects on bumblebee colony growth, this may suggest that impacts on bumblebee colonies are more pronounced for colonies at an earlier stage in the reproductive cycle. Alternatively, it may also indicate that thiamethoxam differs in toxicity compared to previously tested Neonicotinoids in terms of reproductive effects. In either case, assessing bumblebee colony development under field conditions is likely more informative for real world scenarios than tests conducted in laboratory conditions.

  • investigating the impacts of field realistic exposure to a Neonicotinoid Pesticide on bumblebee foraging homing ability and colony growth
    Journal of Applied Ecology, 2016
    Co-Authors: Dara A Stanley, Nigel E Raine, Avery L Russell, Sarah J Morrison, Catherine Rogers
    Abstract:

    Summary The ability to forage and return home is essential to the success of bees as both foragers and pollinators. Pesticide exposure may cause behavioural changes that interfere with these processes, with consequences for colony persistence and delivery of pollination services. We investigated the impact of chronic exposure (5–43 days) to field-realistic levels of a Neonicotinoid insecticide (2·4 ppb thiamethoxam) on foraging ability, homing success and colony size using radio frequency identification (RFID) technology in free-flying bumblebee colonies. Individual foragers from Pesticide-exposed colonies carried out longer foraging bouts than untreated controls (68 vs. 55 min). Pesticide-exposed bees also brought back pollen less frequently than controls indicating reduced foraging performance. A higher proportion of bees from Pesticide-exposed colonies returned when released 1 km from their nests; this is potentially related to increased orientation experience during longer foraging bouts. We measured no impact of Pesticide exposure on homing ability for bees released from 2 km, or when data were analysed overall. Despite a trend for control colonies to produce more new workers earlier, we found no overall impacts of Pesticide exposure on whole colony size. Synthesis and applications. This study shows that field-realistic Neonicotinoid exposure can have impacts on both foraging ability and homing success of bumblebees, with implications for the success of bumblebee colonies in agricultural landscapes and their ability to deliver crucial pollination services. Pesticide risk assessments should include bee species other than honeybees and assess a range of behaviours to elucidate the impact of sublethal effects. This has relevance for reviews of Neonicotinoid risk assessment and usage policy world-wide.

  • Neonicotinoid Pesticide exposure impairs crop pollination services provided by bumblebees
    Nature, 2015
    Co-Authors: Dara A Stanley, Michael P D Garratt, Jennifer B Wickens, Victoria J Wickens, Simon G Potts, Nigel E Raine
    Abstract:

    Recent concern over global pollinator declines has led to considerable research on the effects of Pesticides on bees. Although Pesticides are typically not encountered at lethal levels in the field, there is growing evidence indicating that exposure to field-realistic levels can have sublethal effects on bees, affecting their foraging behaviour, homing ability and reproductive success. Bees are essential for the pollination of a wide variety of crops and the majority of wild flowering plants, but until now research on Pesticide effects has been limited to direct effects on bees themselves and not on the pollination services they provide. Here we show the first evidence to our knowledge that Pesticide exposure can reduce the pollination services bumblebees deliver to apples, a crop of global economic importance. Bumblebee colonies exposed to a Neonicotinoid Pesticide provided lower visitation rates to apple trees and collected pollen less often. Most importantly, these Pesticide-exposed colonies produced apples containing fewer seeds, demonstrating a reduced delivery of pollination services. Our results also indicate that reduced pollination service delivery is not due to Pesticide-induced changes in individual bee behaviour, but most likely due to effects at the colony level. These findings show that Pesticide exposure can impair the ability of bees to provide pollination services, with important implications for both the sustained delivery of stable crop yields and the functioning of natural ecosystems.

  • Bumblebee learning and memory is impaired by chronic exposure to a Neonicotinoid Pesticide.
    Scientific Reports, 2015
    Co-Authors: Dara A Stanley, Karen E. Smith, Nigel E Raine
    Abstract:

    Bumblebees are exposed to Pesticides applied for crop protection while foraging on treated plants, with increasing evidence suggesting that this sublethal exposure has implications for pollinator declines. The challenges of navigating and learning to manipulate many different flowers underline the critical role learning plays for the foraging success and survival of bees. We assessed the impacts of both acute and chronic exposure to field-realistic levels of a widely applied Neonicotinoid insecticide, thiamethoxam, on bumblebee odour learning and memory. Although bees exposed to acute doses showed conditioned responses less frequently than controls, we found no difference in the number of individuals able to learn at field-realistic exposure levels. However, following chronic Pesticide exposure, bees exposed to field-realistic levels learnt more slowly and their short-term memory was significantly impaired following exposure to 2.4 ppb Pesticide. These results indicate that field-realistic Pesticide exposure can have appreciable impacts on learning and memory, with potential implications for essential individual behaviour and colony fitness.

James E Cresswell - One of the best experts on this subject based on the ideXlab platform.

  • effects of the Neonicotinoid Pesticide thiamethoxam at field realistic levels on microcolonies of bombus terrestris worker bumble bees
    Ecotoxicology and Environmental Safety, 2014
    Co-Authors: Ian Laycock, Katie C Cotterell, Thomas A Osheawheller, James E Cresswell
    Abstract:

    Abstract Neonicotinoid Pesticides are currently implicated in the decline of wild bee populations. Bumble bees, Bombus spp., are important wild pollinators that are detrimentally affected by ingestion of Neonicotinoid residues. To date, imidacloprid has been the major focus of study into the effects of Neonicotinoids on bumble bee health, but wild populations are increasingly exposed to alternative Neonicotinoids such as thiamethoxam. To investigate whether environmentally realistic levels of thiamethoxam affect bumble bee performance over a realistic exposure period, we exposed queenless microcolonies of Bombus terrestris L. workers to a wide range of dosages up to 98 μg kg −1 in dietary syrup for 17 days. Results showed that bumble bee workers survived fewer days when presented with syrup dosed at 98 μg thiamethoxam kg −1 , while production of brood (eggs and larvae) and consumption of syrup and pollen in microcolonies were significantly reduced by thiamethoxam only at the two highest concentrations (39, 98 μg kg −1 ). In contrast, we found no detectable effect of thiamethoxam at levels typically found in the nectars of treated crops (between 1 and 11 μg kg −1 ). By comparison with published data, we demonstrate that during an exposure to field-realistic concentrations lasting approximately two weeks, brood production in worker bumble bees is more sensitive to imidacloprid than thiamethoxam. We speculate that differential sensitivity arises because imidacloprid produces a stronger repression of feeding in bumble bees than thiamethoxam, which imposes a greater nutrient limitation on production of brood.

  • clearance of ingested Neonicotinoid Pesticide imidacloprid in honey bees apis mellifera and bumblebees bombus terrestris
    Pest Management Science, 2014
    Co-Authors: James E Cresswell, Francoisxavier L Robert, Hannah Florance, Nicholas Smirnoff
    Abstract:

    BACKGROUND Bees in agricultural landscapes are exposed to dietary Pesticides such as imidacloprid when they feed from treated mass-flowering crops. Concern about the consequent impact on bees makes it important to understand their resilience. In the laboratory, the authors therefore fed adult worker bees on dosed syrup (125 μg L−1 of imidacloprid, or 98 μg kg−1) either continuously or as a pulsed exposure and measured their behaviour (feeding and locomotory activity) and whole-body residues. RESULTS On dosed syrup, honey bees maintained much lower bodily levels of imidacloprid than bumblebees (<0.2 ng versus 2.4 ng of imidacloprid per bee). Dietary imidacloprid did not affect the behaviour of honey bees, but it reduced feeding and locomotory activity in bumblebees. After the pulsed exposure, bumblebees cleared bodily imidacloprid after 48 h and recovered behaviourally. CONCLUSION The differential behavioural resilience of the two species can be attributed to the observed differential in bodily residues. The ability of bumblebees to recover may be environmentally relevant in wild populations that face transitory exposures from the pulsed blooming of mass-flowering crops. © 2013 Society of Chemical Industry

  • repression and recuperation of brood production in bombus terrestris bumble bees exposed to a pulse of the Neonicotinoid Pesticide imidacloprid
    PLOS ONE, 2013
    Co-Authors: Ian Laycock, James E Cresswell
    Abstract:

    Currently, there is concern about declining bee populations and some blame the residues of Neonicotinoid Pesticides in the nectar and pollen of treated crops. Bumble bees are important wild pollinators that are widely exposed to dietary Neonicotinoids by foraging in agricultural environments. In the laboratory, we tested the effect of a pulsed exposure (14 days ‘on dose’ followed by 14 days ‘off dose’) to a common Neonicotinoid, imidacloprid, on the amount of brood (number of eggs and larvae) produced by Bombus terrestris L. bumble bees in small, standardised experimental colonies (a queen and four adult workers). During the initial ‘on dose’ period we observed a dose-dependent repression of brood production in colonies, with productivity decreasing as dosage increased up to 98 µg kg−1 dietary imidacloprid. During the following ‘off dose’ period, colonies showed a dose-dependent recuperation such that total brood production during the 28-day pulsed exposure was not correlated with imidacloprid up to 98 µg kg−1. Our findings raise further concern about the threat to wild bumble bees from Neonicotinoids, but they also indicate some resilience to a pulsed exposure, such as that arising from the transient bloom of a treated mass-flowering crop.

  • Effects of imidacloprid, a Neonicotinoid Pesticide, on reproduction in worker bumble bees (Bombus terrestris)
    Ecotoxicology, 2012
    Co-Authors: Ian Laycock, Kate M. Lenthall, Andrew T. Barratt, James E Cresswell
    Abstract:

    Bumble bees are important pollinators whose populations have declined over recent years, raising widespread concern. One conspicuous threat to bumble bees is their unintended exposure to trace residues of systemic Neonicotinoid Pesticides, such as imidacloprid, which are ingested when bees forage on the nectar and pollen of treated crops. However, the demographic consequences for bumble bees of exposure to dietary Neonicotinoids have yet to be fully established. To determine whether environmentally realistic levels of imidacloprid are capable of making a demographic impact on bumble bees, we exposed queenless microcolonies of worker bumble bees, Bombus terrestris , to a range of dosages of dietary imidacloprid between zero and 125 μg L^−1 and examined the effects on ovary development and fecundity. Microcolonies showed a dose-dependent decline in fecundity, with environmentally realistic dosages in the range of 1 μg L^−1 capable of reducing brood production by one third. In contrast, ovary development was unimpaired by dietary imidacloprid except at the highest dosage. Imidacloprid reduced feeding on both syrup and pollen but, after controlling statistically for dosage, microcolonies that consumed more syrup and pollen produced more brood. We therefore speculate that the detrimental effects of imidacloprid on fecundity emerge principally from nutrient limitation imposed by the failure of individuals to feed. Our findings raise concern about the impact of Neonicotinoids on wild bumble bee populations. However, we recognize that to fully evaluate impacts on wild colonies it will be necessary to establish the effect of dietary Neonicotinoids on the fecundity of bumble bee queens.

Alaa Kamel - One of the best experts on this subject based on the ideXlab platform.

Simone Tosi - One of the best experts on this subject based on the ideXlab platform.

  • a common Neonicotinoid Pesticide thiamethoxam alters honey bee activity motor functions and movement to light
    Scientific Reports, 2017
    Co-Authors: Simone Tosi, James C Nieh
    Abstract:

    Honey bees provide key ecosystem services. To pollinate and to sustain the colony, workers must walk, climb, and use phototaxis as they move inside and outside the nest. Phototaxis, orientation to light, is linked to sucrose responsiveness and the transition of work from inside to outside the nest, and is also a key component of division of labour. However, the sublethal effects of Pesticides on locomotion and movement to light are relatively poorly understood. Thiamethoxam (TMX) is a common Neonicotinoid Pesticide that bees can consume in nectar and pollen. We used a vertical arena illuminated from the top to test the effects of acute and chronic sublethal exposures to TMX. Acute consumption (1.34 ng/bee) impaired locomotion, caused hyperactivity (velocity: +109%; time moving: +44%) shortly after exposure (30 min), and impaired motor functions (falls: +83%; time top: −43%; time bottom: +93%; abnormal behaviours: +138%; inability to ascend: +280%) over a longer period (60 min). A 2-day chronic exposure (field-relevant daily intakes of 1.42–3.48 ng/bee/day) impaired bee ability to ascend. TMX increased movement to light after acute and chronic exposure. Thus, TMX could reduce colony health by harming worker locomotion and, potentially, alter division of labour if bees move outside or remain outdoors.

  • a common Neonicotinoid Pesticide thiamethoxam impairs honey bee flight ability
    Scientific Reports, 2017
    Co-Authors: Simone Tosi, Giovanni Burgio, James C Nieh
    Abstract:

    Pesticides can pose environmental risks, and a common Neonicotinoid Pesticide, thiamethoxam, decreases homing success in honey bees. Neonicotinoids can alter bee navigation, but we present the first evidence that Neonicotinoid exposure alone can impair the physical ability of bees to fly. We tested the effects of acute or chronic exposure to thiamethoxam on the flight ability of foragers in flight mills. Within 1 h of consuming a single sublethal dose (1.34 ng/bee), foragers showed excitation and significantly increased flight duration (+78%) and distance (+72%). Chronic exposure significantly decreased flight duration (−54%), distance (−56%), and average velocity (−7%) after either one or two days of continuous exposure that resulted in bees ingesting field-relevant thiamethoxam doses of 1.96–2.90 ng/bee/day. These results provide the first demonstration that acute or chronic exposure to a Neonicotinoid alone can significantly alter bee flight. Such exposure may impair foraging and homing, which are vital to normal colony function and ecosystem services.

  • effects of a Neonicotinoid Pesticide on thermoregulation of african honey bees apis mellifera scutellata
    Journal of Insect Physiology, 2016
    Co-Authors: Simone Tosi, Fabien Demares, Susan W Nicolson, Piotr Medrzycki, Christian Walter Werner Pirk, Hannelie Human
    Abstract:

    This work was supported by the University of Pretoria, the National Research Foundation of South Africa, the BBSRC Insect Pollinators initiative (BB/1000968/1) and the Marco Polo scholarship, awarded by University of Bologna to ST.

  • sublethal effects of a common Neonicotinoid Pesticide thiamethoxam on honey bees impact on locomotion and thermoregulation
    2015
    Co-Authors: Simone Tosi
    Abstract:

    Neonicotinoids have been pointed to as a factor responsible for the increased honey bee colony losses in the last decades. Many studies have investigated the effects of the first marketed Neonicotinoid, imidacloprid, while fewer have focused on thiamethoxam. One recent study showed that sublethal doses of thiamethoxam lead to colony failure by decreasing forager homing flight success. We thus decided to investigate the mechanism which caused this phenomenon. Our hypothesis was that this effect was caused by impairment of forager locomotion abilities. Therefore we tested the effects of sublethal acute and chronic exposures to thiamethoxam on forager walking (Chapter 2) and flight (Chapter 3) performances. The acute treatment (1.34 ng/bee) affected walking locomotion firstly triggering hyperactivity (30 min post-treatment) and then impairing motor functioning (60 min post-treatment). 2-day continuous exposures to thiamethoxam (32.5, 45 ppb) elicited fewer effects on walking locomotion, however both exposure modes elicited an increased positive phototaxis. Similarly, in flight experiments, the single dose (1.34 ng/bee) elicited hyperactivity shortly after intoxication (increased flight duration and distance), while longer and continuous exposures (32.5, 45 ppb) impaired forager motor functions (decreased flight duration, distance, velocity). It is known that flight muscles temperature needs to be precisely regulated by bees during flight. Therefore, we further hypothesized that the impaired flight performances of Neonicotinoid intoxicated bees were caused also by thermoregulation anomalies. We tested the effects that acute thiamethoxam exposures (0.2, 1, 2 ng/bee) elicit on forager thorax temperature (Chapter 4). Foragers treated with high doses exhibited hyperthermia or hypothermia when respectively exposed to high or low environmental temperatures. In summary, we show that sublethal doses of thiamethoxam affected forager walking and flight locomotion, phototaxis and thermoregulation. We also display the intricate mode of action of thiamethoxam which triggered, at different extents, inverse sublethal effects in relation to time and dose.

  • sub lethal effects of a Neonicotinoid Pesticide on honeybee flight performances
    2014
    Co-Authors: Simone Tosi, James C Nieh
    Abstract:

    We provide the first detailed demonstration that a sub-lethal Neonicotinoid dose can alter actual honey bee flight ability. Neonicotinoids have an excitatory effect on insect neurons (Tan et al, 2007). A short-term exposure (1 hr) increased flight duration and distance by 40%. This agrees with the longer zig-zag flights of bees exposed to Neonicotinoids (Fischer et al. 2014). Long term exposure (2 days) impaired flights, reducing all measures (i.e. duration, distance, average and maximum velocity were reduced by 33, 41, 18, 17%, respectively). Thus, thiamethoxam has complex effects upon bee flight that depend upon dose and exposure time. Coupled with the navigational disruption, these effects could explain why fewer exposed bees return to the nest, gradually decreasing the colony workforce and thus its health over time. Sub-lethal effects of a Neonicotinoid Pesticide on honey bee flight performances Simone Tosi1 and James C. Nieh2 1 Alma Mater Studiorum Universita di Bologna, Department of Agricultural Sciences, 40129, viale Fanin 42, Bologna, Italy 2 University of California San Diego, Division of Biological Sciences, 92093, 9500 Gilman Dr., La Jolla, CA, USA

Dara A Stanley - One of the best experts on this subject based on the ideXlab platform.

  • bumblebee colony development following chronic exposure to field realistic levels of the Neonicotinoid Pesticide thiamethoxam under laboratory conditions
    Scientific Reports, 2017
    Co-Authors: Dara A Stanley, Nigel E Raine
    Abstract:

    Neonicotinoid Pesticides are used in agriculture to reduce damage from crop pests. However, beneficial insects such as bees can come into contact with these Pesticides when foraging in treated areas, with potential consequences for bee declines and pollination service delivery. Honeybees are typically used as a model organism to investigate insecticide impacts on bees, but relatively little is known about impacts on other taxa such as bumblebees. In this experiment, we chronically exposed whole mature bumblebee (Bombus terrestris) colonies to field-realistic levels of the Neonicotinoid thiamethoxam (2.4ppb & 10ppb) over four weeks, and compared colony growth under laboratory conditions. We found no impact of insecticide exposure on colony weight gain, or the number or mass of sexuals produced, although colonies exposed to 2.4ppb produced larger males. As previous studies have reported Pesticide effects on bumblebee colony growth, this may suggest that impacts on bumblebee colonies are more pronounced for colonies at an earlier stage in the reproductive cycle. Alternatively, it may also indicate that thiamethoxam differs in toxicity compared to previously tested Neonicotinoids in terms of reproductive effects. In either case, assessing bumblebee colony development under field conditions is likely more informative for real world scenarios than tests conducted in laboratory conditions.

  • investigating the impacts of field realistic exposure to a Neonicotinoid Pesticide on bumblebee foraging homing ability and colony growth
    Journal of Applied Ecology, 2016
    Co-Authors: Dara A Stanley, Nigel E Raine, Avery L Russell, Sarah J Morrison, Catherine Rogers
    Abstract:

    Summary The ability to forage and return home is essential to the success of bees as both foragers and pollinators. Pesticide exposure may cause behavioural changes that interfere with these processes, with consequences for colony persistence and delivery of pollination services. We investigated the impact of chronic exposure (5–43 days) to field-realistic levels of a Neonicotinoid insecticide (2·4 ppb thiamethoxam) on foraging ability, homing success and colony size using radio frequency identification (RFID) technology in free-flying bumblebee colonies. Individual foragers from Pesticide-exposed colonies carried out longer foraging bouts than untreated controls (68 vs. 55 min). Pesticide-exposed bees also brought back pollen less frequently than controls indicating reduced foraging performance. A higher proportion of bees from Pesticide-exposed colonies returned when released 1 km from their nests; this is potentially related to increased orientation experience during longer foraging bouts. We measured no impact of Pesticide exposure on homing ability for bees released from 2 km, or when data were analysed overall. Despite a trend for control colonies to produce more new workers earlier, we found no overall impacts of Pesticide exposure on whole colony size. Synthesis and applications. This study shows that field-realistic Neonicotinoid exposure can have impacts on both foraging ability and homing success of bumblebees, with implications for the success of bumblebee colonies in agricultural landscapes and their ability to deliver crucial pollination services. Pesticide risk assessments should include bee species other than honeybees and assess a range of behaviours to elucidate the impact of sublethal effects. This has relevance for reviews of Neonicotinoid risk assessment and usage policy world-wide.

  • Neonicotinoid Pesticide exposure impairs crop pollination services provided by bumblebees
    Nature, 2015
    Co-Authors: Dara A Stanley, Michael P D Garratt, Jennifer B Wickens, Victoria J Wickens, Simon G Potts, Nigel E Raine
    Abstract:

    Recent concern over global pollinator declines has led to considerable research on the effects of Pesticides on bees. Although Pesticides are typically not encountered at lethal levels in the field, there is growing evidence indicating that exposure to field-realistic levels can have sublethal effects on bees, affecting their foraging behaviour, homing ability and reproductive success. Bees are essential for the pollination of a wide variety of crops and the majority of wild flowering plants, but until now research on Pesticide effects has been limited to direct effects on bees themselves and not on the pollination services they provide. Here we show the first evidence to our knowledge that Pesticide exposure can reduce the pollination services bumblebees deliver to apples, a crop of global economic importance. Bumblebee colonies exposed to a Neonicotinoid Pesticide provided lower visitation rates to apple trees and collected pollen less often. Most importantly, these Pesticide-exposed colonies produced apples containing fewer seeds, demonstrating a reduced delivery of pollination services. Our results also indicate that reduced pollination service delivery is not due to Pesticide-induced changes in individual bee behaviour, but most likely due to effects at the colony level. These findings show that Pesticide exposure can impair the ability of bees to provide pollination services, with important implications for both the sustained delivery of stable crop yields and the functioning of natural ecosystems.

  • Bumblebee learning and memory is impaired by chronic exposure to a Neonicotinoid Pesticide.
    Scientific Reports, 2015
    Co-Authors: Dara A Stanley, Karen E. Smith, Nigel E Raine
    Abstract:

    Bumblebees are exposed to Pesticides applied for crop protection while foraging on treated plants, with increasing evidence suggesting that this sublethal exposure has implications for pollinator declines. The challenges of navigating and learning to manipulate many different flowers underline the critical role learning plays for the foraging success and survival of bees. We assessed the impacts of both acute and chronic exposure to field-realistic levels of a widely applied Neonicotinoid insecticide, thiamethoxam, on bumblebee odour learning and memory. Although bees exposed to acute doses showed conditioned responses less frequently than controls, we found no difference in the number of individuals able to learn at field-realistic exposure levels. However, following chronic Pesticide exposure, bees exposed to field-realistic levels learnt more slowly and their short-term memory was significantly impaired following exposure to 2.4 ppb Pesticide. These results indicate that field-realistic Pesticide exposure can have appreciable impacts on learning and memory, with potential implications for essential individual behaviour and colony fitness.