Environmental stresses can cause bee colonies to fail — even if the stress levels are not high enough to kill individual insects.
Habitat decline, parasites and insecticides have all been blamed for bee colony collapses, but finding the individual causes of collapse has been problematic.
John Bryden of Royal Holloway University of London and his colleagues modelled stresses on bees and found that colonies began to decline when the number of functionally impaired bees reaches a critical threshold. The model accurately predicted the fate of 16 experimental colonies of bumblebees (Bombus terrestris), of which half were exposed to a neonicotinoid pesticide at levels that do not kill bees but do reduce their ability to learn and gather food.
Multiple stresses can put colonies on a knife edge between growth and failure, the authors say, which makes it hard to pin declines on one factor.
Ecol. Lett. http://dx.doi.org/10.1111/ele.12188 (2013)
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Why bee colonies collapse. Nature 502, 274 (2013). https://doi.org/10.1038/502274a
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DOI: https://doi.org/10.1038/502274a
