Pesticides Make Bees Dumber: Chemicals Damage Brains and Affect Foraging

Are pesticides making bees dumber? Apparently that's the case, according to new research. Recent findings suggest that the chemicals block a part of the brain that bees use for learning, rendering them unable to associate scents with food.

Bees have been disappearing from fields across the world as diseases, including the notorious Colony Collapse Disorder, have swept through entire populations. As pollinators, bees play a crucial role in the formation of crops that range from apples to raspberries to cucumbers. They can travel several miles per day as they collect pollen from flowers in order to bring back to their hives.

The newest research, though, may show that bees have something else to worry about. Published in two journals, Nature Communications and the Journal of Experimental Biology, the latest findings are detailed in two different papers. Researchers examined two common pesticides during the course of their studies. The first was neonicotinoids, which are used to control pests on oil seed rape and other crops. The second was coumaphos, which are used to kill the Varroa mite, a parasite that attacks honeybees.

In order to see the full effect of the pesticides, the researchers applied them directly to the brains of pollinators. Surprisingly, they found that the chemicals caused a loss of brain activity--essentially causing bees to be unable to make sense of their surroundings. In addition, they found that when used together, the effects of the pesticides were additive; in other words, the effect was greater when both were present.

Other experiments, though, merely exposed bees to both pesticides rather than applying them directly to their brains. The researchers noted that the bees were unable to learn and remember floral smells associated with a nectar reward.

"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 Geraldine Wright, the researcher who led the work, in an interview with The Guardian.

As bees pollinate flowers in crop fields, they're exposed to a cocktail of different chemicals that are used by farmers. This could further aid the decline of bee colonies, which are already suffering.

"Because bees do these complex learning tasks, they are very social animals and they have a complex behavioral repertoire; they don't need to be killed outright in order not to be affected," said Sally Williamson, one of the researchers, in an interview with BBC News.

Currently, European Union is debating whether to suspend the uses of some insecticides. However, they're waiting for field tests to be completed before banning them.