Reports that neonicotinoid insecticides have adverse effects on bee populations remain controversial. Some studies have been criticized as using unrealistically high insecticide dosages or conditions far removed from those in the field, and it has been suggested that bees might be able to detect the insecticides and avoid treated crops. Two papers in this issue of Nature present results that fill some of the gaps in our knowledge. In laboratory experiments Sébastien Kessler et al. use field-level doses of three commonly used neonicotinoids — clothianidin, imidacloprid and thiamethoxam — to show that both honeybees and bumblebees are able to detect their presence. However, the bees do not avoid neonicotinoid-treated food and may even prefer it. Maj Rundlöf et al. sowed oilseed rape with and without a clothianidin seed coating in matched and replicated agricultural landscapes. They found the seed coating to be associated with reduced density of wild bees, as well as reduced nesting of solitary bees and reduced colony growth of bumblebees, but they did not detect an effect on honeybees.
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