Bees which are exposed to too many pesticides have forgotten how to buzz and collect pollen, a new study showed.
Scientists studying "buzz pollination" - when bees use vibrations to create an electrostatic charge that lifts pollen from flowers - found those exposed to harmful chemicals became less able to collect pollen effectively.
Researchers at the University of Sterling found that neonicotinoid pesticides interfered with the vibrations.
Dr Penelope Whitehorn, head researcher on the project, said: "We found that control bees, who were not exposed to the pesticide, improved their pollen collection as they gained experience, which we interpreted as an ability to learn to buzz pollinate better.
"However, bees that came into contact with the pesticide did not collect more pollen as they gained more experience, and by the end of the experiment, collected between 47 and 56 per cent less pollen compared to control bees."
Some 80 per cent of plant species are dependent on pollination to exist.
Associate professor Dr Mario Vallejo-Marin said: "Our findings have implications for the effects of pesticides on bee populations as well as the pollination services they provide.
"The next step in this research would be to establish the mechanism by which the pesticide is affecting the bees.
"We think that pesticides may be affecting the memory and cognitive ability of bumblebees, which may be very important when conducting complex behaviours."
Last week, Environment Secretary Michael Gove backed a Europe wide ban on bee-harming pesticides.
The research was published in the journal Scientific Reports.
