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Bumblebees feed on nectar containing toxins

Research shows that the concentration of plant toxins in nectar is too low to deter bumblebees
Photo of a bumblebee on a rhododendron

Nectar produced by flowers to attract pollinators often contains deterrent or toxic compounds produced by the plant that are normally associated with herbivore defence. The significance of these nectar toxins is not fully understood, and they may have a negative impact on pollinator behaviour and health.

Phil Stevenson (University of Greenwich/Kew) has been collaborating with Erin Tiedeken, Jane Stout (Trinity College Dublin) and Geraldine Wright (Newcastle University) to investigate whether a generalist bumblebee (Bombus terrestris) is deterred by these nectar toxins.

The team found that bumblebees continued to feed on sugar solutions containing toxins even when the toxin concentration was much higher than it occurred naturally in nectar. From these results, published in the Journal of Experimental Biology, the team conclude that it would be difficult for bumblebees to avoid flowers producing chemicals that may then harm them or the brood, and the poor acuity that bumblebees have for detecting nectar toxins allows the trait to persist in plant populations.

Pollination is a key ecosystem service provided by flower-visiting insects. It is estimated that over 87% of the world’s flowering plant species rely on pollination by insects and other animals.  Knowledge about how pollinators such as bees interact with flowers can help to understand what factors are potential hazards.  Consumption of toxins could be a stress factor contributing to pollinator declines that bees must cope with alongside pesticides, diseases and land use change. 


Tiedeken, E.J., Stout, J.C., Stevenson, P.C. & Wright, G.A. (2014). Bumblebees are not deterred by ecologically relevant concentrations of nectar toxins. The Journal of Experimental Biology 217: 1620-1625. Available online



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