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Bumblebee learning and memory is impaired by chronic exposure to a neonicotinoid pesticide.

Stanley DA, Smith KE, Raine NE - Sci Rep (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK.

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.

No MeSH data available.


Related in: MedlinePlus

Harnessed bees prior to PER testing (a) and in horizontal positions after feeding in the acute experiment (b).Bee harnesses were held in place with a piece of modelling clay (blue plasticine) and their head set above a piece of plastic covered cardboard (used for easy disposal the next day to prevent cross treatment contamination) on which sucrose solution was presented (photos by DAS). For additional details about the harnessing methodology see Smith & Raine37.
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f3: Harnessed bees prior to PER testing (a) and in horizontal positions after feeding in the acute experiment (b).Bee harnesses were held in place with a piece of modelling clay (blue plasticine) and their head set above a piece of plastic covered cardboard (used for easy disposal the next day to prevent cross treatment contamination) on which sucrose solution was presented (photos by DAS). For additional details about the harnessing methodology see Smith & Raine37.

Mentions: Each week colonies were randomly assigned to two groups to have their learning ability tested on separate consecutive days. Over four weeks an average of 37 foraging bees (range 17–42) from each colony were captured from the gravity feeder in the flight arena and harnessed (Fig. 337). Bees were fed with 40% sucrose solution 2 hours after harnessing, and placed in a horizontal position in a dark room overnight (Fig. 3). The following morning, bees were randomly assigned within colony to be fed 10 μl of control or 250 ppb, 10 ppb or 2.4 ppb thiamethoxam solution. The solution was pipetted onto plastic covered cardboard (Fig. 3b). The bee’s antennae were touched with untreated 40% sucrose solution to elicit proboscis extension for them to drink the droplet. Once the bees had consumed the entire droplet they were placed in an upright position and the learning task began one hour later (this time delay was chosen to ensure bees had started to metabolise the pesticide, and was estimated for bumblebees from reported rates of honeybees55).


Bumblebee learning and memory is impaired by chronic exposure to a neonicotinoid pesticide.

Stanley DA, Smith KE, Raine NE - Sci Rep (2015)

Harnessed bees prior to PER testing (a) and in horizontal positions after feeding in the acute experiment (b).Bee harnesses were held in place with a piece of modelling clay (blue plasticine) and their head set above a piece of plastic covered cardboard (used for easy disposal the next day to prevent cross treatment contamination) on which sucrose solution was presented (photos by DAS). For additional details about the harnessing methodology see Smith & Raine37.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644970&req=5

f3: Harnessed bees prior to PER testing (a) and in horizontal positions after feeding in the acute experiment (b).Bee harnesses were held in place with a piece of modelling clay (blue plasticine) and their head set above a piece of plastic covered cardboard (used for easy disposal the next day to prevent cross treatment contamination) on which sucrose solution was presented (photos by DAS). For additional details about the harnessing methodology see Smith & Raine37.
Mentions: Each week colonies were randomly assigned to two groups to have their learning ability tested on separate consecutive days. Over four weeks an average of 37 foraging bees (range 17–42) from each colony were captured from the gravity feeder in the flight arena and harnessed (Fig. 337). Bees were fed with 40% sucrose solution 2 hours after harnessing, and placed in a horizontal position in a dark room overnight (Fig. 3). The following morning, bees were randomly assigned within colony to be fed 10 μl of control or 250 ppb, 10 ppb or 2.4 ppb thiamethoxam solution. The solution was pipetted onto plastic covered cardboard (Fig. 3b). The bee’s antennae were touched with untreated 40% sucrose solution to elicit proboscis extension for them to drink the droplet. Once the bees had consumed the entire droplet they were placed in an upright position and the learning task began one hour later (this time delay was chosen to ensure bees had started to metabolise the pesticide, and was estimated for bumblebees from reported rates of honeybees55).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK.

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.

No MeSH data available.


Related in: MedlinePlus