Bees and Pesticides

For the UAS Whalesong

For years, scientists have been reporting that there are decreases in pollinators on a global scale. That presents problems, such as a decrease in biodiversity and food security. Last year, a study was published that identified a group of pesticides called neonicotinoid to be a heavy player in the downfall of bees (Botías et al 2015). Other potential players in their decline are climate change, loss of habitat, and disease. Unfortunately, this group of pesticides are some of the most commonly used on crops. In a study conducted on European honeybees, researchers found that they are being exposed to up to 57 different pesticides (Kiljanek et al 2016). However, not only are the crops on the farms being covered with it, but wildflowers on those farms are also sources of exposure. 

Researchers have taken another look at how pesticides impact the ability of bumblebees and their ability to forage on wildflowers. Researchers have found that bees who are exposed to a neonicotinoid insecticide (thiamethoxam) at a level they would experience outside of the laboratory were able to collect more pollen. However, they took significantly longer to do so when compared with bees not exposed to the pesticide. Researchers also noticed that bees who were exposed selected different flowers.

The reason that flower selection is relevant has to do with how bees function. Bees have the ability to connect pollen levels and flower characteristics in order to select flowers with the most to offer (Nicholls and de Ibarra 2015). A large part of that is also based on a bees ability to learn what flowers will yield the most nectar and how to extract it efficiently (Stanley et al 2015). If pesticides are impacting the selection of  flowers, that indicates that it is impacting the bee’s ability to learn, which could result in the bees struggling to provide ecosystem services, as well as their own food collection. There have been several other studies that have obtained results indicating that, when bees are exposed to neonicotinoid pesticides, there are changes in the bee’s brain in areas associated with learning and memory.

Now, you may be thinking that this still is not a problem, because bees who were exposed are collecting more pollen. However, bees who were exposed had  difficulty manipulating flowers with complex structures. They needed significantly more visits to the complex flowers than their unexposed counterparts needed, in order to learn.

Ultimately, researchers have been publishing papers relating the decline in bees and and pesticides for years and still nothing is being done about it. It is not as simple as just banning one that is killing bees. It should go without saying that bees and other pollinators are incredibly important, both ecologically and commercially. Everyday, you come into contact with a product of pollinators.

I also believe that this is important to note as summer approaches, and people are gardening or planting flowers. Take a look at the kinds of dirt you buy, because, believe it or not, it’s often been treated with pesticides. The same can be said for some potted plants.


Botías, C., David, A., Horwood, J., Abdul-Sada, A., Nicholls, E., Hill, E., & Goulson, D. (2015). Neonicotinoid residues in wildflowers, a potential route of chronic exposure for bees. Environmental science & technology, 49(21), 12731-12740.

Kiljanek, T., Niewiadowska, A., Semeniuk, S., Gaweł, M., Borzęcka, M., & Posyniak, A. (2016). Multi-residue method for the determination of pesticides and pesticide metabolites in honeybees by liquid and gas chromatography coupled with tandem mass spectrometry-honeybee poisoning incidents. Journal of Chromatography A.

Nicholls, E., & de Ibarra, N. H. (2014). Bees associate colour cues with differences in pollen rewards. The Journal of experimental biology, 217(15), 2783-2788.

Stanley, D. A., Smith, K. E., & Raine, N. E. (2015). Bumblebee learning and memory is impaired by chronic exposure to a neonicotinoid pesticide. Scientific reports, 5.

Stanley, D. A., Smith, K. E., & Raine, N. E. (2015). Bumblebee learning and memory is impaired by chronic exposure to a neonicotinoid pesticide. Scientific reports, 5.

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