Sharjah24 – Reuters: Finnish researchers have found that glyphosate-based herbicides affect the learning and memory of the important pollinator, the bumblebee, weakening its ability to forage and nest.

"Bumblebees are super important pollinators. They're bigger than honeybees. Most of us know honeybees as the most common pollinator bee, but bumblebees are the native pollinators and they're super important. Without bumblebees, we don't have berries in the forests, for example," said Associate Professor Olli Loukola from the University of Oulu.

Loukola and his colleagues found that already a small dose of the weedkiller affected the bumblebees' ability to learn and memorise connections between colours and taste and the weakened fine colour vision could severely impair bumblebees' foraging and nesting success.

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

Control bumblebees learned to distinguish colours associated with the sugar solution from colours associated with the 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.

The researchers also found that the herbicide treatment did not affect bumblebees' performance in an easier two-colour discrimination task or a 10-odour discrimination task. The results suggest that while exposure to herbicides does not make bumblebees completely colour or smell blind, it does impair their fine colour vision.

The study was published in the journal Science of the Total Environment.