Widely used pesticides have been found in new research to block a part of the brain that bees use for learning, rendering some of them unable to perform the essential task of associating scents with food. Bees exposed to two kinds of pesticide were slower to learn or completely forgot links between floral scents and nectar. These effects could make it harder for bees to forage among flowers for food, thereby threatening their survival and reducing the pollination of crops and wild plants. The findings add to existing research that neonicotinoid pesticides are contributing to the decline in bee populations. The new findings on the effect of pesticides on bee brains showed that within 20 minutes of exposure to neonicotinoids the neurons in the major learning centre of the brain stopped firing. Christopher Connolly at the University of Dundee, who led the peer-reviewed work published in the online journal Nature Communications, said it was the first to show the pesticides had a direct impact on pollinator brain physiology. A parallel peer-reviewed study on the behaviour of bees subjected to the same insecticides found the bees were slower to learn or completely forgot important associations between floral scent and food rewards. Disruption in this important function has profound implications for honeybee colony survival, because bees that cannot learn will not be able to find food," said Dr Geraldine Wright, at Newcastle University, who led the work.