Common Pesticide Causes Memory Problems in Bees, Making It Difficult for Them to Find Food

A team of researchers has found that a common pesticide affects the working spatial memory of bumblebees. This can cause memory problems and make it difficult for the bees to find food. The details are in a paper that was just published in the journal Scientific Reports.

Bees are incredibly important pollinators and vital to many agricultural operations. Bee populations have been declining for years and recent studies have pointed to pesticides as a major cause. While many of these pesticides have been labeled as “safe” for bees because they don’t outright kill them, they can have other harmful effects that lead to population crashes. Neonicotinoids (a common type of pesticide) are meant to kill pest insects without harming bees. Since the chemicals target the central nervous system, scientists believed that bees’ mental processes could be affected by exposure.

Scientists from Royal Holloway, University of London investigated the possible effects of thiamethoxam, a commonly used pesticide, on the mental processes of bees. The team exposed bumblebees (Bombus terrestris) to realistic doses of the chemical. To test their spatial working memory, the bees had to solve mazes and were compared to an untreated control group.

The bees that had been dosed with thiamethoxam, even small doses, had poorer spatial working memories when compared to the untreated groups. The bees that had been exposed to the pesticide took longer to solve mazes and made more errors, often returning to places they had already visited. In the wild, this would cause serious problems since bees might return to flowers they had already visited—wasting precious time and energy. The team also pointed out that this would cause other navigational problems; bees could get “lost” on their return home.

The findings are alarming because even if thiamethoxam doesn’t outright kill bees, it could affect their spatial memory to the point where they can’t find food or their way home. The team emphasizes that more research needs to be conducted on the effects of neonicotinoids on bees and other pollinators.


Samuelson et al. Effect of acute pesticide exposure on bee spatial working memory using an analogue of the radial-arm maze. Scientific Reports (2016).

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