Bees with dementia

September 2015

Photo Creative Commons
The possibility that neurotoxic effects of glyphosate herbicide (used on most GM crops) could be one of many contributing factors to bee die-off was suggested earlier this year [1].

The following month, a paper was published describing effects of glyphosate on honeybees' ability to navigate back to their hive.

Bees travel huge distances to forage for food. Using the sun as a 'compass', plus an ability to judge distance and to use environmental landmarks, they can find their way home from an unfamiliar location and even take novel short-cuts. This feat involves memory, learning-capacity, and the integration of multiple sources of internal and external information.

Researchers fed bees glyphosate at concentrations ranging from normal agricultural to worst-case exposure scenarios. The insects were then moved to a new location and tracked as they figured out their way back to the hive. This relocation procedure was repeated with some of the bees to assess their learning skills.

What was found was that glyphosate exposure made the bees dither and take longer to reach home: instead of learning and speeding up the second time around, the dithering got worse.

The authors suggested their bees were suffering from memory impairment, supporting findings by others of glyphosate's disruption to the olfactory memory which bees need for food source recognition.

This was a very small-scale, short-term experiment but suggests dire cumulative effects, especially in light of the escalating use of glyphosate on crop-plants where bees forage and its presence in water which bees might visit.

Traces of glyphosate have been detected in both organic and conventional honey, indicating that all hives are being exposed to the herbicide from multiple sources.

Clearly sub-lethal levels of glyphosate exposure have the potential to reduce foraging success and to impact negatively on the whole bee colony.


Bees are essential for the success of many crops and wildlife, and their economic value is huge. 

The possibility that glyphosate is exacerbating the harmful effects of other agri-chemicals must be urgently investigated. Put this to your MEP. 

[1] ANSWER TO BEE DIE-0FF? - June 2015

  • Maria Sol Baluena, et al., 2015, Effects of sub-lethnal doses of glyphosate on honeybee navigation, Journal of Experimental Biology, published on-line 10.07.15

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