The bees are not all right. Even low levels of pesticides can make it hard for them to learn and remember, seriously disrupting their foraging behavior.

In a new study, bumblebees exposed to a realistic level of a neonicotinoid insecticide called thiamethoxam. The exposed bees took longer in collecting pollen and sought pollen from a different flower compared to control bees.

The study, published March 14 in the journal Functional Ecology, is deemed the first to investigate pesticide effects on bumblebees’ ability to forage from common wildflowers with such complex shapes.

The studied bees did collect more pollen, but took longer to do so and chose to forage from different flowers. Control or unexposed bees, too, had fewer visits in order to learn how to maneuver their way to the complex flowers — they probably invested more time as well as energy in learning.

According to senior study author and environmental sciences professor Nigel Raine, these pollinators depend on learning to locate flowers, as well as figure out how they can most efficiently extract nectar and pollen.

“If exposure to low levels of pesticide affects their ability to learn, bees may struggle to collect food and impair the essential pollination services they provide to both crops and wild plants,” he warns, citing the importance of pollination in maintaining healthy ecosystems.

Previous research has implicated neonicotinoid pesticide exposure to changes in the brain, particularly in areas linked to honeybees’ memory and learning.

Bees and other insects pollinate much of the important food crops and wild plants around the world, and their decline in numbers and well-being raise concerns on food security and increasingly decreasing biodiversity.

“[P]ollinating insects are vital to support agriculture and wild plant biodiversity,” reminds lead author Dara Stanley.

Thus, if pesticides impair bumblebees’ learning ability and adaptation skills, wild bees could increasingly become vulnerable to changes in the environment.

A separate analysis showed that up to 57 different pesticides are poisoning European honeybees and worsening the declining of bee populations globally.

While it is unclear what causes colony collapse disorder and the bees’ rapidly declining populations, scientists continue to implicate pesticide use in the matter. The European Union, for instance, has banned the use of neonicotinoid pesticides.

Photo: Bert Heymans | Flickr

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