New research on pesticides affecting bees

07 October 2013

New research from Royal Holloway University suggests that pesticide levels may be affecting the bee population indirectly.

Speaking about the new research, Emma Hockridge, head of policy at the Soil Association said; “This study provides further evidence on the effects of very low pesticide doses on pollinating insects like bumblebees. The European ban on neonicotinoid pesticides is due to start in December, and although the UK will be taking part, the Government continues to ignore the strong scientific evidence pointing to the damaging impact of neonicotinoid pesticides on pollinators. There are a range of methods which farmers can use which do not require the use of neonicotinoid pesticides—in Italy government research showed banning neonicotinoid use on maize did not affect farmers’ profits.”



Bryden, J., Gill, R. J., Mitton, R. A. A., Raine, N. E., Jansen, V. A.
A. (2013). Chronic sublethal stress causes bee colony failure. Ecology Letters.


Current bee population declines and colony failures are well documented yet poorly understood and no single factor has been identified as a leading cause. The evidence is equivocal and puzzling:
for instance, many pathogens and parasites can be found in both failing and surviving colonies and field pesticide exposure is typically sublethal. Here, we investigate how these results can be due to sublethal stress impairing colony function. We mathematically modelled stress on individual bees which impairs colony function and found how positive density dependence can cause multiple dynamic
outcomes: some colonies fail while others thrive. We then exposed bumblebee colonies to sublethal levels of a neonicotinoid pesticide.
The dynamics of colony failure, which we observed, were most accurately described by our model. We argue that our model can explain the enigmatic aspects of bee colony failures, highlighting an important role for sublethal stress in colony declines.

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