Glyphosate herbicide weakens bumblebees' color vision

Finnish researchers found out how Roundup, a herbicide containing glyphosate, affects the learning and memory of bumblebees. Already a small dose affected their ability to learn and memorize connections between colors and taste. The weakened fine color vision can severely impair bumblebees' foraging and nesting success.

In the study, bumblebees were exposed to an acute dose of herbicide that pollinating bumblebees might be exposed to in a sprayed field during the day. After the exposure, the bumblebees' learning and memory were tested in a 10-color discrimination task, in which the bumblebees learned to associate five specific colors with a rewarding sugar solution and another five colors with an aversive quinine solution.

Control bumblebees learned to distinguish colors associated with sweet sugar water from colors associated with a bad tasting compound and remembered what they learned after three days. Bumblebees exposed to the herbicide learned significantly less and forgot almost everything they had learned within a few days.